David Kuack, HortAmericas.com

Substrate trials look to assist hydroponic growers avoid propagation-related issues

Substrate trials in Hort Americas’ research greenhouse are looking at conventional and organic propagation substrates along with different irrigation strategies for producing healthy starter plugs for hydroponic production systems.

Hort Americas has retrofitted a 12,000-square-foot greenhouse in Dallas, Texas, for the purpose of studying edible crop production in a variety of hydroponic production systems. The greenhouse is also being used to demonstrate products offered in the company’s online catalog.

Tyler Baras, who is the company’s special projects manager, is overseeing the trialing of conventional and organic substrates in different production systems.

Tyler Baras, special projects manager at Hort Americas, is overseeing the trialing of leafy greens and herbs propagated in conventional and organic substrates. The seedlings are transplanted into a deep water culture, NFT or vertical tower production system.
*Photos courtesy of Tyler Baras, Hort Americas*

“The trials I am focusing on are organic substrates vs. conventional substrates,” Baras said. “I’m primarily using stonewool or rockwool as the conventional propagation substrate. I am also starting to trial some loose substrates, including peat and perlite.

“The seedlings are never moved into another substrate. The seed is sown into plugs and then the rooted seedlings are moved into a deep water culture, NFT (nutrient film technique), or vertical tower production system. The plugs are really only useful for the first two weeks in propagation. Then it is really about getting the roots to grow outside the plugs so the roots grow directly in the water.”

For the organic production systems, Baras is working primarily with expandable coco plugs. He has also started working with some organic loose substrates including coco peat and perlite.

For the substrate studies Baras is working with two standard hydroponic crops, basil and lettuce, primarily butterhead lettuce.

“When I’m testing the lettuce I use either raw or pelleted seed,” he said. “With basil it’s all raw seed. Basil tends to germinate relatively easily, whether the seed is planted into a dibbled hole or sown on top of the substrate.”

Focused on irrigation strategies

A primary objective of the substrate trials is to determine the best irrigation strategies for both organic and conventional substrates.

“This is probably more important with some of the organic substrates than the conventional substrates because the organic substrates tend to hold more water,” Baras said. “One of the big challenges that organic hydroponic growers run into is overwatering their plugs because coco holds more water than conventional substrate plugs that growers are used to. Coco plugs hold more water than stonewool, phenolic foam and polymer-based peat plugs. These other plugs dry out faster than coco plugs.”

closed-bottom-organic-plug-hydroponic-substrates-growing-system — For the substrate trials, rooted seedling plugs are finished in a deep water culture, NFT (nutrient film technique) or vertical tower production system.

Baras said growers who are moving from conventional to organic production tend to use the same irrigation techniques they employed with their conventional propagation program.
“The growers will continue to irrigate the plugs a couple times per day,” he said. “With a lot of the organic plugs, when the seed is sown, they only need to be irrigated once every three days. If the plugs are overirrigated the roots don’t have an incentive to search out the water when they are planted into the production system. The search for water is what drives the seedling roots down to the bottom and out of the plugs.

“The goal of planting into plugs is to have the seedling roots grow outside of the plugs into the water of the deep water culture or NFT system. If the plugs are overwatered as young seedlings, the roots don’t make it down to the bottom of the plugs so it takes longer to start the seedlings and sometimes they just end up rotting because the plugs remain too wet.”

Type of irrigation system

In addition to looking at the irrigation frequency of plugs during propagation, Baras is studying the impact of different methods of irrigation during propagation, including overhead and subirrigation.

“When deciding whether to use overhead or subirrigation, it depends on whether raw or pelleted seed is being sown,” he said. “If pelleted seed is going to be used, a lot of times it’s advantageous to use overhead irrigation because it helps to dissolve the coating surrounding the seed. This helps to ensure the seed has better contact with the substrate. Sometimes it’s almost a little easier to get good germination with subirrigation if raw seed is used because of the direct contact with the substrate.

hydroponic-production-system-hydroponic-herbs-grodan — Growers need to avoid overwatering young seedling plugs or their roots may not make it down to the bottom of the plugs, which could delay transplanting into the production system.

“Smaller indoor growers often use subirrigation for germination. A lot of the large growers, especially those coming from the ornamental plant side such as bedding plants, usually have overhead irrigation systems installed. These growers have propagation areas set up with overhead irrigation, which can be used to start their hydroponic vegetable crops.”

Baras said most indoor warehouse growers are not going to be using watering wands or overhead irrigation in their operations.

“Most of the warehouse growers will be using subirrigation, such as flood tables,” he said. “For them it is going to be important that they select the right kind of seed to get good germination. They may have to try other techniques like using a deeper dibble or covering the seed with some kind of loose organic substrate such as perlite or vermiculite. Growers using overhead irrigation can usually sow pelleted seed without having to dibble the substrate.

“Many growers tend to have issues when they are using pelleted bibb lettuce seed with subirrigation. We are looking at ways of increasing the germination rate using dibbling with the pelleted seed or increasing the dibble size or covering the seed.”

Baras said growers who are using automation, including mechanized seeders and dibblers, prefer to use pelleted seed.

“With pelleted seed it’s easier to be more precise so that there is only one seed planted per plug cell,” he said. “I have seen automation used with raw basil seed. I have also seen organic production done where automation was used just to dibble the plug trays. Dibbling seems to be one of the biggest factors when it comes to getting good even germination.

Need for good seed-substrate contact

Baras said occasionally with tightly packed coco plugs, if the seed is not pushed down into the plug the emerging radicle may have issues penetrating the substrate.

“This helps push the radicle down so it contacts the substrate and establishes more easily,” he said. “When subirrigation is used it can be advantageous to cover the seed with vermiculite or just brush the top of the coco plug after the seed is planted to get some coverage of the seed.

“What usually affects the way that coco plugs work is the size of the coco particles. There is really fine coco. There is coco fiber, which can be mixed into the plug to help with aeration and increase drainage. We are looking at various plugs with some increased fiber content trying to aerate the plugs in order to speed up the drainage.”

hydroponic-cilantro-grodan-rockwool-deep-water-culture-grodan-ao-hydroponic-production-system-herbs — Stonewool or rockwool is the primary conventional propagation substrate in the trials. Other loose substrates, including peat and perlite, are also starting to be trialed.

Baras is also looking at using loose substrates in different ratios in plugs and then transplanting them into deep water culture, NFT, and vertical tower systems.

“One of the issues with hydroponic systems and loose substrates is these substrates can enter the production system and clog up the irrigation lines,” he said. “The trick is trying to avoid having any loose substrate enter the system. We are looking at using loose substrates and allowing the seedlings to establish longer in the plug cell during propagation before transplanting them into the production system. This enables the seedlings to develop a larger root system, which can prevent loose substrate from falling into the system.”

For more: Hort Americas, (469) 532-2383; https://hortamericas.com.

David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com.

Products being used in greenhouse trials

Fertilizer trials look at leafy greens, herb growth in hydroponic production systems

Early results from fertilizer trials in Hort Americas’ research greenhouse show knowing the levels of nutrients in fertilizer solutions can go a long way in avoiding problems with deficiencies and toxicities.

Tyler Baras, who is the company’s special projects manager, is overseeing the trialing of leafy greens and herbs in five different production systems.

“We’ve got a deep water culture or raft system using Hort Americas’ fertilizer blend with calcium nitrate and magnesium sulfate,” Baras said. “We are using that same nutrient mix in a nutrient film technique (NFT) system and a capillary mat system.

“I’m using Terra Genesis organic fertilizer in a vertical grow tower. I’m also using the same organic fertilizer for all of the seedling propagation in a flood-and-drain vertical rack.”

Tyler Baras, special projects manager at Hort Americas, is overseeing the trialing of leafy greens and herbs in different production systems, including deep water culture and nutrient film technique. Photos courtesy of Tyler Baras, Hort Americas — Tyler Baras, special projects manager at Hort Americas, is overseeing the trialing of leafy greens and herbs in different production systems, including deep water culture and nutrient film technique.
*Photos courtesy of Tyler Baras, Hort Americas*

Baras said the fertilizer recipe he is using in the deep water culture and NFT systems is based on general recommendations from Cornell University and the University of Arizona for leafy greens crop production.

Differences in nutrient levels

The deep water culture system has been running for three months. The water reservoir for the system is 8,000 gallons.

“Even if water evaporates, since it is such a large body of water, the electrical conductivity (EC) doesn’t really move much,” Baras said. “The EC has been very stable during the three months it has been operating. The reading has barely moved.”

The first trial with the NFT system, which has a reservoir of about 140 gallons, lasted for three months.

“Every week I added an additional 40 gallons of water on average to the NFT reservoir,” Baras said. “The water is evaporating and the salts are accumulating a lot faster in the NFT reservoir than in the deep water culture system. Because the NFT system has a smaller water reservoir, the quicker evaporation rate and the water replacement in the reservoir, has caused the EC to shift a lot more.”

One of the goals of the fertilizer trials is to see what salts are accumulating in the NFT system and to see how long the system can run before it has to be flushed.

Baras said even with the changes in nutrient levels all of the plants have been performing well.

“I haven’t seen any nutrient deficiencies or toxicities even as the fertilizer recipe has shifted over time. We have been trialing a wide range of crops, including butterhead and romaine lettuces, kale, spring mixes and basil. I’m trialing a lot of crops to figure out when these crops start to be impacted by possibly too much salt accumulation. I haven’t seen anything yet that is alarming.

“One of the things that I have seen over the years working with fertilizers is how wide the acceptable range is for plants to grow well. Between the NFT and deep water culture, the NFT is using half the nitrogen and the plants are performing very similarly. There are recommendations for EC, but none of these fertilizer levels are set. I have some systems that have 20 parts per million phosphorus and some that have 50 ppm and the plants look the same. Most general recommendations say 40-50 ppm. I’ll have some solutions that have 3 ppm iron and others that have 6 ppm iron. It is interesting to see how wide the range is for a lot of these nutrients and the crops are performing the same.”

During the three months that the deep water culture system has been running the electrical conductivity (EC) has been very stable with plants showing no signs of nutrient deficiencies or toxicities.

Baras said he has seen a slowing of plant growth in the NFT system.

“I’m not seeing any deficiencies or toxicities, but the crops have slowed down about a week over the deep water culture,” he said. “Depending on the crop, it’s taking a week longer to reach either the plants’ salable weight or height.

“The slowing in growth could be related to the nutrients. This could be useful information for growers. If they are checking the EC, which may have been 2.3 when a crop was started, if there is a slowing of growth, growers may want to have a water test done. The test could show that the amount of nutrients might be changing.”

Identifying what makes up the EC

During the three months that Baras had been running the NFT system he never flushed the system.

“All that I’ve done with the NFT system is add water and additional fertilizer to maintain a targeted EC,” he said. “One of the goals of the trials is to see what ions are accumulating in the system and to see how long I can run the system before it has to be flushed. When I started the target EC was 2.2-2.3. I still achieved the target EC at three months, but the composition of what was actually in the water changed.

“Originally the NFT fertilizer solution contained about 185 parts per million nitrogen. At the end of the trial the EC was the same but there was only 108 ppm nitrogen in the solution. The calcium concentration was originally 250 ppm and ended at 338 ppm. Sulphur was originally at 80 ppm and rose to 250 ppm. Nutrients have accumulated as the water evaporated. Solely going by the EC meter reading doesn’t tell the full story of what is in that water. The EC of the fertilizer solution that I started with is the same as the EC for the fertilizer solution three months later. The difference is the ions that are making up that ending EC.”

Herb production with organic fertilizer

Baras is growing a variety of cut herbs in vertical grow towers. The plants are fertilized with Terra Genesis, a molasses-based organic fertilizer. He said Hort Americas has been hearing from tower growers who are interested in trying to grow organically.

“What we are seeing is the organic fertilizer solution can change a lot over time,” he said. “The fertilizer tank solution matures as time goes on. With the organic fertilizer, the nutrients tend to balance out as the solution is run longer.

“Our city water contains calcium and some magnesium. These elements are actually the nutrients that the organic fertilizer is slightly low in. So as I run the system longer, through the addition of city water, I actually start to see an accumulation of both calcium and magnesium, which actually helps balance out the total fertilizer recipe. The balance of the nutrients has improved over time.

A variety of cut herbs are being grown in vertical grow towers and fertilized with Terra Genesis, a molasses-based organic fertilizer.

The pH was fairly unstable as it seemed to be going through several biological waves. It was moving rapidly between high and low. As I run the tank solution longer the total alkalinity has increased, which has stabilized it. The biological activity has also started to stabilize. The pH has stabilized in the upper 5 range. For the plants grown organically I have seen deficiencies pop up. The deficiencies were reduced as the fertilizer tank solution ran longer. The deficiencies appear to have balanced out.”

Baras said one noticeable difference between the NFT, deep water and vertical grow towers is how much slower the plants grow in the towers.

“I don’t know what to contribute the slower growth to yet,” he said. “It could be trying to determine the best fertilizer rate for the fertilizer. It could be the crop selection, because most of the crops in the towers are different from what I’m growing in the NFT and deep water culture.

“I’m going to start a deep water culture and NFT trial using organic fertilizer. I’ll have three different organic production systems running simultaneously so I will be able to compare the plant growth in each system. I’ll also be able to compare the growth of the same crops grown with organic or conventional fertilizers.”

Controlling biofilm, disease pathogens

Baras said one of the issues that can arise with using organic fertilizer is the development of biofilm in the irrigation lines that can cause emitters to clog.

“I am incorporating a product called TerraBella, which contains beneficial microbes,” he said. “These microbes help mobilize certain nutrients, like phosphorus, which can promote the formation of biofilms. This biofilm buildup is usually more of a problem with high water temperatures.

“About every six weeks I add a booster application of the beneficial microbes depending on the production system. The deep water culture system has a larger reservoir so I am not replacing evaporated water as often. For the other productions systems, like the NFT and grow towers, where I am replacing the water, I am incorporating the beneficials more often. For these systems, the fresh city water that is added dilutes the fertilizer solution. Also, there is chlorine in the city water that possibly could negatively impact some of the beneficial microbes.

For more: Hort Americas, (469) 532-2383; https://hortamericas.com.

David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com.

Products being used in greenhouse trials

Hort Americas retrofits greenhouse for trialing hydroponic growing systems, products

Hort Americas’ special projects manager Tyler Baras is using a 12,000-square-foot hydroponic greenhouse to teach company staff and customers what it takes to economically grow leafy greens and herbs.

Tyler Baras is a well-traveled grower. He has worked in Florida and Colorado growing hydroponic greenhouse vegetables, including organic crops. He is now taking the knowledge and experience he has gained from those growing operations and putting it to use in a 12,000-square-foot demonstration and research greenhouse in Dallas, Texas.

Baras, who is the special projects manager at Hort Americas, is overseeing the trialing of leafy greens and herbs in five different production systems along with the testing of potential products for the company’s online catalog.

“Chris Higgins, the general manager at Hort Americas, brought me to the greenhouse and asked if I would be interested in running a demonstration and research facility,” Baras said. “He was also interested in collecting data and writing a book about leafy greens production.

“After I agreed to accept the position, I drew up blueprints of the greenhouse, preparing a design of the production systems, writing a budget and proposals on how it was going to look, and how much it was going to cost to operate, including projected sales from the produce that was grown.”

Tyler Baras, special projects manager at Hort Americas, is overseeing the trialing of leafy greens and herbs in five different production systems. Photos courtesy of Tyler Baras, Hort Americas — Tyler Baras, special projects manager at Hort Americas, is overseeing the trialing of leafy greens and herbs in five different hydroponic production systems.
*Photos courtesy of Tyler Baras, Hort Americas*

The retrofitted greenhouse is located behind a grocery store and prominent Dallas garden center. The grocery store and garden center will allow Baras to test his projected budgets and produce sales.

“The greenhouse was originally built for growing bedding and flowering plants,” Baras said. “It was built with passive ventilation and was not designed for leafy greens production. We had to make some major modifications. Renovations included leveling the floor, adding a vestibule air lock, upgrading the electrical system, installing evaporative cooling pads, insect screening and landscape fabric, and upgrading the motors for the shade system along with installing new shade cloth. We have been growing in the greenhouse since September.”

Hort Americas, which is a horticulture and agriculture wholesale supply company, provided the materials for the retrofit along with the hydroponic production systems that Baras will be using. The production systems include a capillary mat system, a deep water culture floating raft system, a nutrient film technique (NFT) system, a hydroponic tower system and grow racks. Hort Americas has also provided a variety of equipment and products, including substrates, fertilizers, LED lights and other products it offers to its wholesale customers.

Collecting, disseminating production data

Dallas was chosen for the research location because it is one of the hardest places to grow hydroponic leafy greens. Baras will be trialing primarily leafy greens, including a variety of lettuces (bibb and Romaine), kale, bok choy, basil and other herbs.

“We believe that if leafy greens can be grown here then they can be grown nearly anywhere by everyone,” he said. “Year-round production here is difficult. We know that we will be able to grow during the fall, winter and spring. The tricky part is going to come during the summer when there are high temperatures and high humidity. The project will take a minimum of a year to collect the data.”

Baras said he will be collecting a lot of data including: cost per plant size, how much does it cost over the production cycle to operate each system and the labor costs involved with operating each system.

The 12,000-square-foot demonstration and research greenhouse contains five different production systems including a deep water culture floating raft system.

“The goal is to collect data that can be used by everyone,” he said. “We are going to collect data that includes the total light delivered. If growers in more northern latitudes are dealing with lower light, they can look at the light levels we maintained in the greenhouse and reach those same levels using supplemental light so that they can mimic the exact same conditions.

“The data collected will be available to whoever has an interest in reading about it. This will enable growers to be knowledgeable about making decisions about these production systems and operating them. They will also have access to some real world baseline data from trials so they will know if they are achieving the proper metrics. For example, we will share the data of how long it took to grow a certain size head of lettuce or a certain weight of basil using specific inputs. Growers will be able to look at real world environmental conditions under which a crop was grown.”

Preliminary results

Baras said based on initial production results what makes most financial sense at this time is growing basil and lettuce.

“Our initial metrics from the data that we have collected have been good,” he said. “We are producing 8- to10-ounce heads of bibb lettuce in 38 days and we are harvesting commercial size sleeved basil in 26 days from seed.

“Most commercial standards for lettuce in the U.S. are between 6 and 10 ounces. For basil there is a wide range in regards to the standard size for weight. Generally it is done by size or by what fills up a 10-inch tall sleeve. We have been able to fill a 10-inch sleeve and make it look really good.”

Preliminary production results include harvesting commercial size sleeved basil in 26 days from seed.

Having experienced a warmer than normal October, Baras said the water temperature in most of the production systems has been 85ºF or warmer.

“Generally the water temperature for most hydroponic crops is between 65ºF-70ºF,” he said. “The water temperature here is definitely warm, but we are still having really great growth. So far it is looking like we can grow a crop during the summer. But we haven’t gone through a full summer yet and that is going to be the real test.
Baras said they want to try to avoid chilling the water and will only use this production technique as the last resort.”

“We are trying to find ways around having to chill the water, including increasing the level of dissolved oxygen in the water using a variety of methods. This includes using Venturi aerators, and if needed, injecting liquid oxygen. These methods are less costly than running chillers. Chillers can be expensive and they use a lot of energy.
“We really want to find a model that is going to be acceptable to small scale growers. We are trying to keep the inputs to a minimum and still achieve our production goals.”

Teaching and trialing

Baras said the greenhouse has already been used for onsite training.

“That is one of our main goals with the site,” he said. “We want to be able to bring in people and provide them with hands-on training, both our customers and the Hort Americas staff. For example, we want to be able to show them how to blend fertilizer, what the process looks like for moving seedlings through a hydroponic system, how to measure light levels in a greenhouse and best pest control methods.

“We want to be able to assist customers who are starting to build a greenhouse and are looking to install hydroponic equipment. The greenhouse will enable them to see what is involved before they make any purchases.”

Dallas Grown — The greenhouse will be used to provide training to Hort Americas’ customers and staff, as well as the trialing of new products.

The greenhouse will also be used for trialing new products.

“Companies often approach Hort Americas about carrying their products, the greenhouse will enable us to put them through real world trials before they’re put in our online catalog,” Baras said. “Some of the products we plan to trial include dosing systems, monitoring systems for greenhouse environmental control and meters for measuring pH and EC. We are open to looking at other equipment and other automation technology.”

For more: Hort Americas, (469) 532-2383; https://hortamericas.com.

David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com.

Products being used in greenhouse trials

LEDs offer option for photoperiodic control

Research at Michigan State University shows growers have a choice when it comes to lights for photoperiodic control.

As light bulb manufacturers phase out the production of incandescent bulbs, growers are looking for replacements to control flowering of ornamental plants. Researchers at Michigan State University have compared the efficiency and efficacy of LEDs for flowering applications with traditional light sources including incandescent, fluorescent and high-pressure sodium lamps.

“After we determined that LEDs were as effective at controlling flowering as other traditional light sources, we began to look more closely at how different wavebands emitted by LEDs actually regulate different aspects of flowering and photomorphogenesis,” said Michigan State Ph.D. graduate research assistant Qingwu (William) Meng. “In our experiments we used experimental LEDs manufactured by a company in Japan called CCS and commercial LEDs from Philips Lighting. For this particular study we used four different LEDs that are commercially available to growers to control flowering.”

photo-1-qingwu-william-meng-gh-photo-courtesy-qingwu-william-meng-mich-st-univ — Qingwu (William) Meng is studying how different wavebands emitted by LEDs actually regulate different aspects of flowering and photomorphogenesis.
***Photos courtesy of William Meng, Mich. St. Univ.***

Meng used an Apogee spectroradiometer to collect data from the four different LEDs.

“We measured the spectral output from 350 nanometers to 850 nanometers,” Meng said. “We were able to measure the total light intensity from each of the four lamps to quantify the exact spectral distribution.”

Lamp placement impacts light intensity

Meng said he did not compare the light output data he collected with data reported by the light manufacturers.

“It is relatively difficult to find light intensity data from some of the light manufacturers,” he said. “What some companies report in regards to light output is the total photon flux from the light source captured by an integrating sphere device that we don’t have here at Michigan State. Others show a graph of the emission spectrum, but the spectral data are not available.

“For greenhouse flowering applications the lamps can be installed at different heights. Depending on the distance between the bottom of the light source and the plant canopy, there can be different levels of light intensity. Even though a light may be advertised to have a very high light output, if the lamps are hung high above the plant surface then growers are going to get a lower light intensity at the plant level. It is very situational and depends on how far apart the lights are spaced out in the greenhouse and how high the lights are installed above the plant canopy.”

Ensuring proper light spacing

Meng said growers typically space out LED lights for flowering regulation about 10 feet apart horizontally.

“Light uniformity and light intensity are the two most important characteristics,” Meng said. “To ensure that there is an accurate layout of the lights, it is ideal to conduct a trial to see exactly what is happening below the lights. Growers can go into a greenhouse at night and measure the light intensity under the lights to see if the light intensity is sufficient and the light distribution is uniform. Light uniformity is very crucial. A grower doesn’t want to cause non-uniform flowering of the same crop.

“Growers can take one light and then measure the light output at different points under the light. By measuring the light distribution, growers can determine where the highest output and lowest output occur under the lamp. If growers don’t have the expertise to develop a light map, they can consult lighting experts.”

Some lighting companies have developed software to design light maps.

Differences in wavelength effects

Meng said for effective photoperiodic control only 1-2 micromoles per square meter per second (µmoles/m²/s) at plant height is needed either to promote flowering of long-day plants or inhibit flowering of short-day plants.

If red or far red are the predominant wavebands provided by LED lamps, 1-2 micromoles per square meter per second should be effective for speeding up the flowering of long-day crops.

“For specific wavebands, red light is the most prominent in terms of regulating the flowering pathways of plants,” he said. “The four LEDs lamps we tested that are all marketed for flowering applications, all have some level of red or red/far-red light. If red or far red are the predominant wavebands, then 1-2 µmoles/m²/s should be effective for most flowering crops.

“In contrast, if only blue light, which is from 400-500 nanometers, is used to regulate flowering, there won’t be any effect if a low intensity of 1-2 µmoles/m²/s is provided. Blue light at 1-2 µmoles/m²/s doesn’t create long days for a variety of photoperiodic crops. However, when the intensity of blue light is elevated to 15 or 30 µmoles/m²/s, blue light is able to regulate flowering as effectively as red or as a red/far red combination. Overall, the efficacy of a lamp depends on its light spectrum.”

Differences in plant species sensitivity

Meng said for different ornamental species or cultivars there are different sensitivity levels in terms of the light spectrum that should be used to control photoperiod. He trialed about 20 different photoperiodic ornamental crops popular with commercial growers.

“For long-day plants, including petunia and pansy, there should be red light or a combination of red and far-red light to speed up flowering,” he said. “Some crops, like snapdragons, are really sensitive to far-red light. In this case, growers should use lamps that emit both red and far-red light to accelerate flowering, otherwise flowering won’t be promoted at all.”

He said for petunias, plants flower earlier under red light, but with both red and far-red light, flowering can be promoted even more.

“In order to achieve the benefits of photoperiodic lighting to promote flowering of long-day plants, growers should look at the crops they’re producing, and then decide what kind of spectrum the LEDs should have to provide the maximum capability of flowering promotion,” Meng said.

For more: Qingwu (William) Meng, Department of Horticulture, Michigan State University, East Lansing, MI 48824; http://www.hrt.msu.edu/people/qingwu_william_meng
Meng is working with professor Erik Runkle; runkleer@msu.edu;
http://www.hrt.msu.edu/people/dr_erik_runkle

Funding for this research was provided by USDA National Institute of Food and Agriculture’s Specialty Crop Research Initiative, Michigan State University’s Project GREEEN, and horticulture companies supporting Michigan State University floriculture research. Nate DuRussel, Michigan State University greenhouse research technician, provided greenhouse technical assistance, and C. Raker & Sons and Syngenta Flowers donated plant material.

David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com.

New horticultural lighting blog

LightHort is a science blog created by Qingwu (William) Meng to communicate the latest scientific findings on light in horticulture to the public. Meng is working with graduate students from various institutions, including Michigan State University and Purdue University, specializing in photobiology and horticultural lighting to employ various forms of multimedia to effectively deliver scientific ideas worth sharing. A variety of topics are covered ranging from sole-source lighting for plant factories to photoperiodic and supplemental lighting for greenhouse operations. Follow LightHort on its website, Facebook and Twitter.

Monitoring is crucial for growing lettuce and leafy greens year round

Since lettuce and leafy greens have short production cycles, greenhouse growers need to stay focused if they want to be successful growing these crops year round.

The increasing demand for locally-grown vegetables is causing more field vegetable growers, ornamental plant growers and new growers to look at trying to satisfy this market. Cornell University horticulture professor Neil Mattson said he works with all three types of growers.

“I see both vegetable field growers and ornamental greenhouse growers trying to produce lettuce and leafy greens year round,” he said. “Both are quite common. Field vegetable growers are looking for a crop that can generate year-round cash flow. Ornamental growers are looking to fill their greenhouses in the off-season. A lot of ornamental growers no longer produce poinsettias in the fall or spring bulb crops and spring plant propagation that they would normally do in the winter. Growers could have as much as a six-month window when their facilities are not being used.”

Mattson said ornamental growers tend to better understand what it takes to grow a year-round crop.

“Ornamental growers tend to be aware of differences in crops and the problems that can arise,” he said. “They also understand the concept that there is much less light in the winter so they may have to consider using supplemental light. Ornamental growers are usually aware of the high cost of heating a greenhouse year round, especially during the winter.

“In general, field vegetable growers who have greenhouses, may only be using those structures in the spring to produce their transplants. That means they may be used to heating a couple months each year.”

Controlling environmental parameters

During this year’s Cultivate’16 conference and trade show in Columbus, Ohio, Mattson did a presentation on the year-round production of leafy greens using controlled environment agriculture (CEA). The main environmental conditions growers need to monitor and control include light, temperature and relative humidity.

Light

Mattson said in the northern half of the United States light availability during the winter months is the most difficult environmental issue to deal with when growing plants year round.

“The target light level for lettuce production is 17 moles of light per square meter per day (daily light integral, mol/m²/d) for optimal growth,” he said. “In most parts of the country achieving that target usually isn’t an issue during the summer. In the winter, in the northern part of the country, light levels can be 5 mol/m²/d on average and even 1-3 mol/m²/d is common. That is three to five times less light than what is needed for optimum lettuce growth during the winter.”

Photo 1, Lettuce overview 1, Neil Mattson, Cornell Univ. — The target light level for lettuce production is 17 moles of light per square meter per day (daily light integral) for optimal growth.
*Photos courtesy of Neil Mattson, Cornell Univ.*

Mattson said supplemental light, using LEDs or high pressure sodium lamps (See the Lamps Needed Calculator, can be provided to deliver higher light levels to increase lettuce biomass. But going above 17 mol/m²/d can cause growers to have issues with tip burn.

“In the case of head lettuce, a grower can go from seed to harvested head (5-6 ounces) in 35 days if there is 17 mol/m²/d. If there is only 8.5 mol/m²/d, it takes the plants twice as long to produce that same biomass.

“For baby leaf greens, if they are seeded and transplanted and grown on for two weeks before harvesting and only receive 8.5 moles of light, the plants will only produce half the yield. If a grower normally harvests 10 ounces per square foot and there is only half the light, the plants will produce only 5 ounces per square foot.”

Mattson said a rule of thumb for New York is a grower can light a 1-acre greenhouse and produce the same yields as not lighting a 3-acre greenhouse to produce the same yields during the winter months.

Temperature

Lettuce and many other leafy greens are cold tolerant. Mattson said a lot of growers want to grow them cold.

“The Cornell CEA research group proposes that these crops be grown at fairly warm temperatures so that they have the faster 35-day crop cycle,” he said. “This is based on having 17 mol/m²/d and a daily average temperature of 70ºF-75ºF during the day and 65ºF at night.

“During the winter the issue with temperature is paying to heat the greenhouse. It’s easy to control the temperature, growers just have to be willing to crank up the thermostat.”

Mattson said temperature can be really hard to control in southern climates in the U.S.

“Under hot conditions, temperatures in the 80s and 90s, head lettuce is going to bolt prematurely,” he said. “It can be difficult to drop the day temperature low enough to avoid early bolting.”

Beyond trying to reduce the air temperature, research done by the Cornell CEA group has shown that lowering the root zone temperature to 74ºF or less using chilled water can help prevent premature bolting.

“Chilling the root zone temperature allows growers to grow using warmer air temperatures by having the cooler water temperature,” Mattson said. “This is an effective way to chill the plants even when the air temperatures reach the 80s and 90s.”

Mattson said the biggest issue with warmer air temperatures occurs with lettuce and spinach. Warmer temperature and long day conditions can both cause spinach to experience premature bolting. Mattson said warmer temperatures can also promote Pythium root rot on spinach. Spinach is much more susceptible to this water mold than lettuce or other leafy greens.

“Chilling the root zone temperature can help to prevent the disease organism from developing as quickly as at warmer temperatures,” Mattson said. “If the root zone temperature can be kept cool, it won’t completely avoid the Pythium issue, but it will help control it.”

Pythium baby leaf spinach, Neil Mattson, Cornell Univ. — Cooling the root zone temperature won’t completely avoid Pythium disease, but it will help control it.

Pythium spinach closeup, Neil Mattson, Cornell Univ. — Close-up view showing Pythium root rot on spinach.

The Cornell CEA group found that the optimum root zone temperature for spinach was 64ºF-65ºF. At this temperature Pythium was deterred, but there was no crop delay. If the root zone temperature is lowered to 62ºF, plant growth is slowed.

Relative humidity

Mattson said the relative humidity for lettuce and leafy greens should be between 50-70 percent. He said the lower humidity helps to limit pathogen issues.

“High humidity favors powdery mildew and Botrytis,” he said. “High humidity also favors the physiological disorder tip burn. Tip burn is caused by a calcium deficiency. The higher the relative humidity the less transpiration occurs in the plant resulting in the plant not taking up an adequate amount of calcium.”

Lettuce tipburn, Neil Mattson, Cornell Univ. — High humidity favors the physiological disorder tip burn, which is caused by a calcium deficiency.

Mattson said a relative humidity lower than 50 percent can cause an outer leaf edge burn, which is a physiological disorder.

“This is a different disorder than tip burn caused by calcium deficiency,” Mattson said. “The outer leaves develop lesions where the veins end on the edge of the leaves. The lesions occur where the sap exudes out of the veins and then is reabsorbed by the plant and there is a kind of salt buildup.”

Fertilization, water quality

Although fertilization and water quality are not environmental parameters, growers can have issues with both if they don’t monitor them. Lettuce and leafy greens are not particularly heavy feeders compared to other greenhouse vegetables like tomatoes and other vine crops. Mattson said lettuce and leafy greens are relatively forgiving crops when it comes to fertilization.

“Growers need to monitor the nutrient solution every day in regards to pH and electrical conductivity (EC),” he said. “The reason for testing the nutrient solution at least daily is because in hydroponics the nutrient solution pH can change by one or two units in a day.”

Mattson said for container crops like petunia and geranium, pH does not usually change by more than one unit in a week. He said container growers may check the pH every week, and some may only do it every two weeks. But for hydroponics a grower needs to stay on top of changes in pH.

In addition to daily pH and EC monitoring, Mattson said a detailed elemental analysis of the nutrient solution is important.

“Periodically, about every four weeks, growers should send a sample of their nutrient solution to a testing lab to determine if the plants are absorbing nutrients in the proportions the growers expect,” he said. “Certain elements in the solution may decline over time and a grower may have to add more of these elements and less of others.”

Mattson said some systems, like CropKing’s Fertroller, have automated sensors which measure pH and EC in line so it’s a real time measurement. The controller makes the necessary adjustments.

“Typically if a grower is putting high alkalinity water into the system, the pH tends to creep up over time, so the controller automatically adds acid to reach a target pH,” he said. “Likewise, the machine does that with EC too. If the EC is going down because the plants are taking up nutrients, the controller adds fertilizer stock solution to reach a target EC.”

Mattson said iron deficiency due to high pH is the most common nutrient disorder he sees on lettuce and leafy greens. Occasionally magnesium deficiency occurs because the water source contains enough calcium, but not enough magnesium.

Iron deficiency due to high pH is usually the most common nutrient disorder on lettuce and leafy greens.

“Many fertilizers don’t include calcium and magnesium, so growers can run into issues with magnesium deficiency,” he said. “Basil tends to have a high need for magnesium. We usually recommend basil be provided twice as much magnesium as lettuce.”

Photo 6, Basil magnesium deficiency, Neil Mattson, Cornell Univ. — Basil tends to have a high need for magnesium and usually should receive twice as much magnesium as lettuce.

Mattson said growers should test their water more frequently to determine if there have been any changes in the alkalinity of the water, including calcium, magnesium and sodium concentrations.

“In the Northeast this summer, we are experiencing a drought,” he said. “I’ve heard from growers who say the EC of their water is going up, which implies that some salt levels are going up. But we don’t know specifically which salts and that would be useful to know what specifically is changing.

“It really depends on their water quality. In particular, EC, alkalinity and whether there are any nutrients in high concentrations, like sodium, can be an issue. It really comes down to how long they are trying to capture and reuse the water. In our Cornell system we have traditionally grown in floating ponds. We use that same water cycle after cycle for several years. We can continually use the same water because we start with deionized water. However, even if the water has fairly low salt levels, using the same water will result in the accumulation of sodium to harmful levels over time.”

For more:
Neil Mattson, Cornell University
School of Integrative Plant Science, Horticulture Section
49D Plant Science
Ithaca, NY 14853
(607) 255-0621
nsm47@cornell.edu
https://hort.cals.cornell.edu/people/neil-mattson
http://www.cornellcea.com
http://www.greenhouse.cornell.edu

Cornell Controlled Environment Agriculture “Hydroponic Lettuce Handbook”

David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com.

Taking LEDs to the next level

McGill University bioresource engineer Mark Lefsrud said it’s time to take plant research and production to a higher level with LEDs.

Much of the research that has been done with LEDs for the last 50 years has been conducted with low light levels.
“The biggest research area right now is with LEDs at high intensities of light,” said Mark Lefsrud, associate professor in the Bioresource Engineering Department at McGill University in Quebec, Canada. “We have to get into high intensity lighting studies to truly understand what is happening in plants. NASA has done some preliminary work with high intensity LEDs, but we have taken the research further.”

Mark Lefsrud, McGill University — Mark Lefsrud at McGill University is starting to do high intensity lighting studies to understand what is happening in plants under light levels of 5,000 micromoles and higher.
**Photos courtesy of Mark Lefsrud, McGill Univ.**

Lefsrud said most of the earlier LED studies that he and other researchers have been doing have looked at light levels of 150 micromoles of light (micromoles per square meter per second or μmol·m-2·s-1) and lower, and how the plants responded to those light levels.

“No one grows plants at 150 micromoles,” he said. “Plants are usually grown at 300 micromoles and higher. We have gone well above 1,500 micromoles and in some of our LED tests, we have gone as high as 5,000 micromoles. The plants start responding to what I consider to be more normal field type conditions.”

Incorrect assumptions

Lefsrud said the reactions of plants to higher light levels are not what the assumptions have been up to this point for all the earlier research.

“One assumption is that shade plants can’t handle light levels as high as sun plants, which is actually backwards,” he said. “We have found that it is the complete opposite. We are finding that shade plants are able to handle higher light intensities better than sun plants.

“Lettuce is considered a shade plant and tomato is considered a sun plant. When we shine 5,000 micromoles of light on these two plants, the tomato plant suffers and we can kill it quite easily. We don’t see the death of lettuce at higher light levels. Lettuce carries on like nothing has happened to it.”

Lefsrud said that one assumption is sun plants tend to be more succulent with thicker leaves so they can handle higher light levels.

“Another assumption is that shade plants, even though they’re called shade plants, aren’t true shade plants,” he said. “They’re sun spot plants. They can handle the bright light beams that come through the plant canopy and then the light beam disappears and they prepare for the next beam. The sun spot plants have more adaption for fluctuations in light levels as opposed to sun plants which have to receive more continuous high light.”

Higher light level LEDs

Lefsrud said it’s possible that growers haven’t tried producing at higher light levels because they were unaware that the plants can tolerate these levels.

“Another reason is that we have never been able to achieve higher light levels of 5,000 micromoles from these lamps,” he said. “And would it be cost effective to even try to produce these light levels? Now that we know that we can achieve higher light levels, let’s see what we can do with them. As research scientists we have to get up to higher light intensities. Currently we are trying to do things up around 10,000 micromoles of light.

“We’ve had to make the high light lamps ourselves or had them custom made to reach these light levels. That is one of the challenges—being able to manufacture lights that can reach these high light levels.”

Lefsrud said nearly half the energy that is going into an LED comes out as light, the other half is heat that has to be dealt with.

“The lights that give off these higher levels generate a lot more heat,” he said. “We have to use a water cooled jacket to cool the LEDs that produce 5,000 micromoles.

“Most LED bulbs can’t handle that kind of heat and burn out. When we started pushing these bulbs, the manufacturer told us the bulbs can’t handle the heat. We were told the bulbs would only last a few seconds at these high intensities. We cooled the bulbs down to -20ºC (-4ºF) with a water jacket and were able to run the bulbs for two weeks.”

Lefsrud said the technology is coming quickly and he expects that within the next year LEDs will be able to deliver these higher light levels.

“It’s not only the plant reactions at those light levels, but it also changes how the lights can be installed,” he said. “Growers won’t have to shine light only from above any more. The lights will also be able to shine from below or on the side. The lights could be mounted on booms and be moved. There are also more possibilities with interlighting.

“We have assumed that the lamps have to be shined from above like the sun. We have done many research tests that have shone the lights from below the plants and they do just as well as when the light is shined from above.”

Maximizing plant growth

Another part of Lefsrud’s LED research deals with maximizing growth with the minimum amount of light possible.

“What are the wavelengths (colors) of light that produce the most amount of plant growth with the least amount of light possible?” he said. “We chose to study lettuce, tomato and petunia looking at the PAR light spectrum that was available. We have been looking at other wavelengths where we see plants growing at twice the normal rate. We are finding that the plants grow faster as we get away from far red light and more into the red.

“We think that we can produce lettuce plants at twice the speed. For a lettuce crop that grows heads weighing 20 grams in the first two weeks, we can speed up the crop development to produce 40 gram heads in the same amount of time. We can theoretically double the growth rate. Lettuce seems to be a more aggressive crop than tomatoes. We are not sure about the growth rate for tomato and petunia as we haven’t completed the research.”

Mark Lefsrud, McGill University tomato — Mark Lefsrud found the best growth rate for tomato is around an 8:1 to 10:1 red to blue ratio, around 640 nanometers for the red and 440 nanometers for the blue.

Lefsrud said the research is narrowing in on a few wavelengths that most researchers haven’t been paying much attention to.

“From a growth standpoint, we don’t think far red is useful at all,” he said. “It’s red and a couple of other wavelengths.

“We found the best growth rate for tomato is around an 8:1 to 10:1 red to blue ratio. Roughly around 640 nanometers for the red and 440 for the blue. The more blue that was used, the more flowers and fruit were produced. High levels of red (19:1) was one of the ratios we trialed, where we saw more vegetative (leaf) growth occurred, but there wasn’t as much flowering and fruit.”

Lefsrud said his research has not gone as far as determining what levels of red and blue light should be given while the plants are vegetative or when they are start to flower.

“We are fairly sure that higher levels of red light increase the vegetative growth and then after that a grower would want to go to a higher level of blue light for tomato,” he said. “For tomato, 40 days after germination, the plants should be given more blue light. There are a number of research papers that have indicated that higher levels of blue light cause increased flowering. We believe that the blue light is critical.”

For more: Mark Lefsrud, McGill University, Bioresource Engineering Department, Ste.-Anne-de-Bellevue, QC, Canada; (514) 398-7967; mark.lefsrud@mcgill.ca; http://www.mcgill.ca/biomass-production-lab

David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com.

Are you using social media to promote your brand, your industry?

Kevin Folta, chairman of the Horticultural Sciences Department at the University of Florida, said more researchers, farmers and students need to be using social media to promote themselves, their research and their industries.

Kevin Folta, professor and chairman of the Horticultural Sciences Department at the University of Florida, has been writing online blogs since the late 1990s.

“Initially it was a way for me to communicate funny ideas and comedy,” Folta said. “I did a lot of blogs that covered critical thinking and skepticism, especially for like UFOs, quack medical claims and the anti-vaccine movement. It was kind of over-the-top criticism.”

Folta said he found having his own website was a great way to get his name out to the scientific community as well as to the public. He quickly learned that social media was also a good way to disseminate science communication. He began to use social media to promote his own research.

“I also used to program websites in HTML,” he said. “When I was in grad school I had a business on the side creating websites for companies in my town. I would walk into a business and explain to them how they should have a website that will come up on a computer and people can learn about their company, including their business hours and how to contact them. They would say they’re not interested because that it would never catch on.”

Focused on social and science issues

Folta began writing social and science commentary blogs in 2003. He now writes about six blogs per week depending on the prevailing news and what topics are appearing in social media.

“My blog, called Illumination, takes current topics and provides a scientific overlay,” he said. “I try to use my blog to provide a trusted source of good information for someone looking for clarification on scientific topics.

“I write mostly about the reality of genetic engineering concepts. Clarifying the reality. I also write about nutrition, climate, vaccines and other areas that have some public controversy and scientific consistency. The blog articles are inspired by current topics or current situations arising as I communicate science. Something I’ve learned, something I want to share. Most of them are commentary and distillation of something about science. Lately I have been writing a lot on transparency and conflict of interest.”

Kevin Folta, professor and chairman of the Horticultural Sciences Department at the University of Florida, uses different social media platforms to discuss his research, talk about science and to support the ag industry.
*Photo courtesy of Kevin Folta, Univ. of Fla.*

Folta said all of the topics he writes about are serious.

“People do misinterpret my sarcasm and snark,” he said. “The blogs are meant to make people laugh or to make a topic approachable or enjoyable. How do you reach more people with cool stories? You make them laugh. You help them enjoy clever visual language to disseminate rather dry topics.”

Supporting American farmers

One of the recent topics of Folta’s blog has been the Environmental Working Group’s Dirty Dozen list of fruits and vegetables contaminated with pesticides.

“The Environmental Working Group publishes this list of fruits and vegetables it says shouldn’t be eaten because they’re covered with pesticides,” he said. “I want to provide some clarity to that claim. I know the kind of pesticides that are used and the group is wrong and is hurting farmers.

“Social media gives me the megaphone I need to do my job to protect the farming interests in my state. This is a big part of what I focus on. With a presence of bad information on the web, I want to be the person who stands up for agriculture whether or not anyone else will.”

Folta said one of the most important things occurring on social media is the discussion of science, including food and farming.

“Scientists and farmers, people who know the most about these topics, aren’t participating,” he said. “This is why there is such a sorry state of research funding that all of the food scientists complain about. My colleagues and my students don’t realize we hold the power to fix this just by getting involved.”

Generating more research funding

Folta said being able to promote the research of scientists and students is one of the advantages of using social media.

“Generating awareness of your research program and showcasing the research of students and postdocs helps to develop a brand,” he said. “When my grant proposals come across the desk of reviewers, they know it is going to be sound science and that it is going to be shared with the public. Social media can be a conduit to make research relevant and penetrating to the taxpayer, the people who are financing the research. It is a great way to show a return on government investment.”

Folta said he gives talks to grad students and postdocs on the importance of social media.

“I tell them they have to have a blog,” he said. “They have to personalize themselves as scientists. They can’t be an inaccessible person with a lab coat, who publishes a few research papers a year and doesn’t talk to the public. You have to be an approachable, interactive, trusted source of information. The only way you gain that trust is by letting the public understand who you are as a person.

“The students understand that they have to do this. The problem with students and postdocs is that they don’t have content. They think they don’t have anything to write about. They don’t understand that they have to share with people in cyberspace what happened today. They’re not comfortable with that or they’re just not good at writing about it.”

Folta trains faculty and students on how to promote themselves and their research programs using social media.

“It’s been slow to catch on,” he said. “One of the biggest surprises has been some of the recalcitrant faculty that you thought would never do it. Some of them turn out to be all-stars. They quickly realize the power of the medium. Once they get in and get comfortable, they see how it influences the visibility of their excellent work.

“This is the beauty of Twitter. You don’t even have to write anything. By going into Twitter and reading, endorsing and retweeting what you find is useful information, you still develop a brand. People will know that they can look at your feed and consider you to be a reliable and trusted conduit to good quality information and clever writing.”

Expanding social media presence

Folta also has gotten into producing weekly podcasts. He has been doing the podcasts since June 2015.

“I get as many of the podcasts interviews as I can from the compelling people who I meet and who I read about online,” he said. “I put those interviews together and do the production, including the artwork. It’s a lot, but I really enjoy it. Most of the podcasts are between 30-60 minutes long. They take about three hours a week to put together. In June, I got the 200,000th podcast download. That is a pretty good investment.

“My podcasts have the most unfortunate name of “Talking Biotech Podcast”. It’s really not about that. It’s really about genetics in action. We talk about topics in medicine. We’ve talked about the way plants were domesticated. We talk about technology and the ways that it is being used to help people. We have even talked about cheese making.”

kevin-folta-podcast — This month Kevin Folta received his 200,000th podcast download. Started in June 2015, the podcasts focus on genetics in action.

Folta said he uses the podcasts to talk about how biotechnology is a tool that can be used to do good things.

“I want to make people more comfortable with technology,” he said. “I can talk to an expert to help people understand it.”

Folta said the different forms of social media he uses have complimentary roles.

“Twitter is a transitory rapid message that has wide penetration,” he said. “For the blog, someone has to know about it, stumble upon it or be drawn to it through Twitter or Facebook. Facebook is kind of in the middle. It is a repository for good topics of interest from people in science. You’re able to develop good presence and penetration by optimizing all of tools to their maximum.”

Folta said an increasing number of university programs and departments with communication groups are realizing that social media is the modern day press release.

“Social media is where you disseminate your information and keep your name in the front of the public’s mind,” he said. “More universities have dedicated people who work to communicate faculty research to the public. The problem is that some of these people don’t necessarily understand the science and it reads more like jumbles of facts rather than a an interesting story that connects the public and the scientists. We need to be more in that space. We are doing better all the time.”

Folta said there are good researchers worldwide who understand the power of social media and use it effectively.

“In my university unit the leaders of the department were told they need to be on Twitter,” he said. “I love Twitter because I write a blog and then disseminate it to 12,000 Twitter followers and then it goes out to thousands more people. I use Twitter to amplify or advertise my blog and podcasts. I also use Twitter to amplify other ideas that I really like and other writing that I really like.

“The problem is that from students to faculty, they don’t think they have the content. They know the tool, they just don’t know what to do with it. They don’t think it’s important enough to show them planting something in the greenhouse on social media. But that’s the idea. For their friends it doesn’t matter. But for someone who wants to learn more about it, it has to be there. If you aren’t there someone else will be, and that other voice might not get the science right.”

Folta said more researchers and students also need to be writing blogs.

“We could even start asking students to generate essays and assignments as social media entries,” he said. “Instead of an essay for an exam being written on paper, it should be written as a blog entry. This way the student also is creating web content for curious people to find.

“This is how we can use social media to disseminate good information. This is something that we are going to see more and more of going forward.”

For more: Kevin Folta, University of Florida, Horticultural Sciences Department, Gainesville, FL 32611; (352) 273-4812; kfolta@ufl.edu; http://www.hos.ufl.edu/faculty/kmfolta.

David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com.

Direct-to-consumer food sales could help growers succeed

A study of data collected in the 2007 and 2012 Census of Agriculture shows that direct-to-consumer sales could help growers remain in business longer.

In January 2015 a group of economists at the USDA-Economic Research Service released the publication “Trends in U.S. Local and Regional Food Systems: A Report to Congress”. The purpose of the report was to provide Congress with information regarding the “scope of and trends in local and regional food systems.”

As the demand for local food continues to increase along with consumer interest in locally-grown, USDA has made it one of its priorities looking at related topics including improving the rural economy, expanding food access and increasing nutrition, assisting agricultural producers and strengthening local markets.

Defining direct-to- consumer sales Nigel Key, a USDA-ERS economist and co-author of the Congressional report, studied some of the data that was collected to determine if direct-to- consumer sales had an impact on the survivability of farmers.

“I examined farms that sold directly to consumers, which is a subset of local food producers,” Key said. “I looked at whether farms that had direct-to- consumer sales were more likely to survive longer in business and grow more or less compared to farms that don’t do direct-to-consumer sales. That was the focus of my research.”

Key said direct-to- consumer sales would include roadside stands, farmers markets, pick-your-own farms, on-farm stores and community supported agriculture.

“These sales wouldn’t include intermediaries that would aggregate the food and then sell it to schools or to supermarkets,” he said. “It also wouldn’t include selling to restaurants that then prepare the food and sell it to consumers. That would be local food, but that wouldn’t be selling directly to consumers.”

Tracking business survival

Key used the 2007 and 2012 Census of Agriculture data, which essentially includes all farms.

“We looked at all farms and broke them out by their sales categories: $1-$10,000; $10,000-$50,000, $50,000-$250,000 and over $250,000,” he said. “The Census of Agriculture is conducted every five years. The last one was in 2012 and the one before that was 2007.

“Looking at the 2007 census at producers who were selling directly to consumers, we determined how many of those producers showed up in the 2012 census and were still in business. We compared this data to the farmers who weren’t selling directly to consumers in 2007 and how many of those producers showed up in the 2012 census. We tracked business survival rate.”

Key said that 55.3 percent of all farms showed up again in the 2012 census compared to 60.9 percent of those producers with direct-to- consumer sales. The higher survival rate for direct-to-consumer sale producers was true for all of the different size sales categories. There was a significant increase in the probability of survival occurring for farmers with direct-to- consumer sales.

“The small farmers only had a 45.3 percent rate of survival compared to 72.8 percent for large farmers, but in every category survival was higher for direct-to- consumer sales,” he said. “For large growers with direct-to-consumer sales survival was higher, 78.1 percent. For the small direct-to- consumer sales farmers, survivability was 54.9 percent. In every sales category, there was a higher survival rate for direct-to- consumer sales farmers. We also looked at beginning farmers. These are farmers who have been in business less than 10 years. We basically saw the same effects.”

Reasons for increased survivability

Key said one of the reasons that there is a higher survival rate among farmers doing direct-to-consumer sales, is the amount of time these farmers are spending marketing their product.

“The direct-to- consumer farmers may be getting a higher price, but they are also spending more time marketing their product,” he said. “So in a sense they are a farmer and a marketer. As a result, for the same level of sales they don’t need as much farm equipment and they don’t need as much land. From the data we saw farmers who sell directly to consumers have $20 worth of machinery per dollar of sales compared to $31 worth of machinery per dollar of sales for those farmers who market through conventional channels.

“We saw similar results for the amount of land being farmed. Direct-to- consumer farmers had $240 in land per dollar sold compared to $309 in land per dollar sold for farmers selling through conventional channels. If a farmer doesn’t have to have as much land and machinery then he doesn’t have to borrow as much money.”

Key said farmers who were doing direct-to- consumer sales also had less debt.

“With less debt, the direct-to- consumer farmers likely have lower interest payments relative to their assets so they have a lower debt-to- asset ratio,” he said. “A lower debt-to- asset ratio makes a farmer less susceptible to production and market shocks.”

Slower growth rates

When Key looked at the growth of farms that remained in business in both 2007 and 2012, the farmers with direct-to- consumer sales had slower growth than the farmers with no direct-to-consumer sales.

“It’s kind of puzzling, why would these direct-to- consumer farmers have higher survival rates and lower growth rates?” he said. “One possibility is the direct-to- consumer sales tend to be more labor intensive. So given the same amount of sales, the direct-to- consumer farmers were hiring substantially less labor. So it makes it difficult to expand if expanding means having to hire someone. That can be a costly upgrade as compared to purchasing more land where a farmer can farm more of the land himself. Even though a farmer may not be able to grow the business, he may be able to survive.

“These direct-to- consumer farmers may also enjoy their work more. They like interacting with their customers. We don’t have any data to support that, but those are just my thoughts.”

For more: Nigel Key, USDA-Economic Research Service, Resource and Rural Economics Division, Farm Economy Branch; (202) 694-5567; nkey@ers.usda.gov.

David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com.

Meeting the demand for locally grown ethnic produce

Rutgers University researchers are studying the viability of growing ethnic specialty crops in greenhouses and hoop houses for local and regional sales.

While consumer demand for organic products continues to increase so does the demand for locally grown produce. USDA reports that industry data estimates that U.S. local food sales totaled at least $12 billion in 2014, up from $5 billion in 2008. To support this growing local market USDA has provided more than $1 billion in investments to over 40,000 local and regional food businesses and infrastructure projects since 2009.

Focusing on Asian and Hispanic crops

Researchers at Rutgers University in New Brunswick, N.J., have studied the potential market for ethnic specialty crops along the U.S. East Coast. Based on the results of their findings the researchers are now looking at those crops which have the potential to be adapted to greenhouse and hoop house production.

“At Rutgers we have a specialty crop research group,” said Albert Ayeni, who is ethnic crop research specialist. “We have been funded for about $2 million by the USDA. Our research group, led by Dr. Ramu Govindasamy, has documented the rapidly increasing population of Asians (Chinese and Asian Indians) and Hispanics (Mexicans and Puerto Ricans) on the U.S. East Coast. As of 2010 the population of these ethnic groups stood at about 6 million people.

“We are looking at two broad ethnic groups, Asian and Hispanics. We are studying what kind of crops these two ethnic groups are asking for that can be grown in New Jersey and other states along the East Coast. We have done a comprehensive study of what are the demands for these ethnic crops. We also studied the average prices for which these crops are sold.”

Some of the crops that the Rutgers researchers have studied include: exotic peppers (Capsicum spp.), roselle (Hibiscus sabdariffa) and tiger nuts (Cyperus esculentus cv. sativus), amaranth (Amaranthus spp.), African eggplant (Solanum aethiopicum) and okra (Abelmoschus esculentus).

Ayeni said okra is a popular crop in the southern U.S., but is not grown much in the Northeast.

“Based on our studies, these crops on the East Coast are sold in different ways– by the pound, ounce or in a bunch,” Ayeni said. “A bunch can vary from a $1.50 to $2 or more depending on the crop and market. We are looking at what the price limits are depending on which part of the East Coast the crops are sold. We are studying the markets in Florida, Massachusetts and New Jersey.

“We have conducted studies and collected information that could help growers determine which are the best ethnic crops economically. This could help growers know what to grow to target specific ethnic niches. Location has a lot to do with what price can be charged for a crop. What we found is that some products can be sold for twice as much in bigger markets like New York City.”

Ethnic specialty crop trials Ayeni said extensive greenhouse and hoop house trials have been done with exotic peppers, roselle and tiger nuts (chufa).

“This is the second year that we have worked with roselle,” he said. “We have worked with tiger nuts for about four years and exotic peppers since 2009.

Exotic peppers have been studied by Rutgers University researchers since 2009. The fruit is in high demand by Africans, Asians and Hispanics. Photos courtesy of Albert Ayeni, Rutgers Univ.

The peppers contain high levels of capsaicin which has numerous significant health values along with high amounts of vitamin A. The fruit is in high demand by Africans, Asians and Hispanics.

Roselle contains high levels of antioxidants and facilitates iron bioavailability. Its leaves are in high demand by Asian Indians and Hispanics. Its fruit is in high demand by Africans and Hispanics.

Tiger nuts are considered a super snack food. These gluten-free tubers are high in fiber and vitamins with a moderate level of iron. Tubers are highly sought after by Africans and the U.S. market is growing rapidly.

“With a greenhouse most of these crops can be grown any time of the year,” Ayeni said. “If roselle is grown outdoors, it can’t be planted in this part of country until the middle of May to early June because it is a tropical plant. Plants can be harvested for foliage from July until October. For the cultivars we are currently evaluating, outdoor production for flowers and fruit is not feasible for African Green, African Red and Indian Red types. For these roselle types, the onset of frost in late October and early November stops further plant growth or kills the plants, preventing flower/fruit maturity.

“This is a limitation for field production. However, the “kenaf” type roselle, identified as Indian Green in our studies, can be grown from June to October in New Jersey. With this roselle type, the leaves and fiber are of greater economic significance than the fruit.”

Roselle (Hibiscus sabdariffa) is grown for both its leaves and fruit. The leaves are in high demand by Asian Indians and Hispanics. Its fruit is in high demand by Africans and Hispanics. — Roselle (*Hibiscus sabdariffa*) is grown for both its leaves and fruit. The leaves are in high demand by Asian Indians and Hispanics. Its fruit is in high demand by Africans and Hispanics.

Ayeni said roselle grows well in the greenhouse year round. In a hoop house the yields were not as high as the greenhouse. Supplemental lighting was used in the greenhouse trials during winter to grow roselle.

“The plants respond well to supplemental light,” he said. “For the supplemental lighting we used high pressure sodium lights and provided 16 hours of photoperiod in a 24-hour cycle. In the greenhouse, supplemental lighting can be used to produce a significant quantity of foliage any time of the year.

Research results

Jalapeno/serrano-type peppers grow and fruit well under greenhouse and hoop house conditions.

Sweet minibells and African poblano do better in a greenhouse than in a hoop house. The habanero/African bird’s-eye- type performs poorly in both the greenhouse and the hoop house.

Roselle grows and fruits better in the greenhouse than in the hoop house. In other trials, roselle exhibited greater growth in the hoop house. Ayeni said more research needs to be conducted to understand how time of planting affects performance in a hoop house.

Tiger nuts thrived much better in the hoop house than in the greenhouse. Considerable adjustments are needed to controlled environment parameters in the greenhouse, probably temperature and light, to be able to mimic the hoop house conditions that produced high tuber yields.

Tiger nuts (Cyperus esculentus cv. sativus) grew better under hoop house conditions than in a greenhouse. The plant’s gluten-free tubers are high in fiber and vitamins and are considered a super snack food. — Tiger nuts (*Cyperus esculentus* cv. *sativus*) grew better under hoop house conditions than in a greenhouse. The plant’s gluten-free tubers are high in fiber and vitamins and are considered a super snack food.

Ayeni said they also want to compare plant production in pots versus growing the plants directly in the soil under cover (i.e. tunnel production).

“The market for locally grown ethnic foods continues to expand,” Ayeni said. “We want to encourage growers to consider ethnic specialty crops so they may target production to meet the rapidly growing demand in the United States. These crops lend themselves to year-round production for sale, including at farmers markets.

“In general, immigrants from all over the world cherish the plant varieties that are prevalent in the food systems of their home countries. I would be delighted to see Rutgers University lead the way in promoting local production to make these crops available as fresh as possible to a growing consumer population.”

For more: Albert Ayeni, Rutgers University, Department of Plant Biology and Pathology, New

Brunswick, NJ 08901; (848) 932-6289; ayeni@aesop.rutgers.edu;

http://plantbiopath.rutgers.edu/faculty/ayeni/ayeni.html.

David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com.

Can hydroponics be organic?

Regardless of whether you think hydroponic production can be organic, the bottom line is all methods of food production should be considered when trying to feed a growing world population.

There is currently much discussion and debate occurring about whether hydroponic production can be labeled as organic. In September 2015 the USDA’s National Organic Program appointed a 16-member task force to look at hydroponic and aquaponic production practices and how they align with USDA organic regulations.

Gene Giacomelli, director of the Controlled Environment Agriculture Center (CEAC) at the University of Arizona, said that regardless of whether plants are being grown using a traditional organic approach or one of the various combinations of hydroponics practices (soilless culture), fundamentally all of these production methods are simply attempting to grow plants for their economic, nutritional and social values. The goal is to use the best available techniques to produce crops of highest quality with the minimum of resources.

“Regardless of the production method, plants must be provided with the environment they need to grow,” Giacomelli said. “The basics of growing plants besides light, carbon dioxide, water and the potential of their crop genetics, there are plant nutrients that have to be distributed to the plant roots.

“Consider that the nutrients have to be dissolved in the water near the roots. Then the water with the nutrients is absorbed through the root membrane. Plants are basically harvesting the nutrients from the water adjacent to their root system. Where nutrients come from or how they get there are not important in the plants’ decision to use a nutrient. If a nutrient is present and the plants need it, they’ll use it.”

Soil, soilless or no soil

Giacomelli said using traditional farming practices including organic production, field-grown plants grow for a while in the soil until the nutrients are depleted. Then the soil’s nutrients can be recharged by incorporating animal and plant manures.

“One of the ways to grow plants is in soil and to apply components that will break down naturally from plant manures and animal manures,” he said. “Nutrients from these manures can be dissolved in the water and absorbed by the plant roots.”

Giacomelli said plants can also be grown in many different ways and as long as the water and nutrients are delivered to the roots the plants will grow.

“However, there are benefits for the growers to use hydroponics, such as avoiding issues with soil-borne diseases, soil-hosted insects, poor soil drainage and aeration, which are detrimental to plant growth,” he said. “Many growers have made the switch to soilless substrates for their root zone, which can be made of organic components, but may not contain any soil from the Earth. These organic root zone materials can be placed within containers that may be extended as one for an entire row of plants, or for small units as for individual plants. USDA regulations allow for organic growers to produce their plants in containers. That is legal.”

Hydroponic growers can avoid issues with soil-borne diseases, soil-hosted insects, poor soil drainage and aeration. Photo courtesy of American Hydroponics — Hydroponic growers can avoid issues with soil-borne diseases, soil-hosted insects, poor soil drainage and aeration.
*Photo courtesy of American Hydroponics*

Giacomelli said there are natural microorganisms in soil that surround the root system and presumably encourage the effectiveness of the nutrients found in the root zone of the plant.

“Can this also occur in a hydroponic system or a pure water culture system since there is little or no substrate at all?” he said. “What if the grower is making a compost tea or purchasing a formulation that is a natural degradation of plant or animal manures and takes the supernatant liquid and then injects it through the irrigation system and pumps the microbes through the water? Aquaponics uses fish waste to fertilize the plants. Is this considered organic?”

Giacomelli said one of the things being studied is the production of quality greens in aquaponic systems using low nitrate levels.

“These nitrate levels are lower than what would be used in a typical hydroponic system,” he said. “We are trying to figure out what is allowing this to occur. Is it the water movement around the roots? Or are there some microbiological agents helping the plants be more efficient in extracting those limited nitrate molecules in the water? We must work with a microbiologist to help us answer these questions.”

Comparing production methods

Giacomelli said one of the fundamental questions when discussing growing organically is whether the food produced is better than food grown using other production methods.

“‘Better’ could mean nutritionally or it could mean for food safety,” he said. “Usually if it’s organic then there are no pesticides. What I do know is exactly what is on the tomatoes coming out of our university greenhouses. I don’t know necessarily what is on an organic tomato coming out of a field. There is less insect and disease pressure in a greenhouse than in an open field, and thus a lesser need for control procedures.

“Growers trying to produce food in resource-limited locations, such as where water is scarce or phosphorus is hard to find, are going to have other factors to consider when choosing how to grow their plants. In these situations growers are going to want to capture and recycle the water and nutrient solution.”

Gene Giacomelli, director of the University of Arizona’s Controlled Environment Agriculture Center, said since there is less insect and disease pressure in a greenhouse than in an open field, there is a less need for control procedures.

Giacomelli said there are environmental ramifications which should come into discussion about organics.

“What does organic production and its demands do to the environment?” he said. “A system that recycles water and nutrients has an energy expense, but this balances out in the gain of water and nutrients.

“We began looking at things like how many grams of edible biomass did we produce per kilowatt hour of electricity. Or, can we produce more edible biomass per input of electric power using containerized growing in controlled environments? Or what about edible biomass produced per input of plant nutrients? Comparing field organic production to a recirculating hydroponic system, the field organics systems cannot compare from a balanced budget viewpoint. Resource use efficiency is greater in a containerized system.”

The impact of light

Giacomelli said light has never been a consideration when talking about whether a crop is organic. But he expects in the future it will be.

Only recently have we been able to talk about artificial light and its relation to growing plants organically,” he said. “When plants receive a full spectrum of light from the sun, the plants pick and choose what’s naturally available and uses it.

“When plants are exposed to very narrow light spectra from LEDs, particularly red and blue light, plants will grow. There are indications that there are other wavelengths that have been and will be discovered and proven to change the growth rate of plants. This could impact the production, as well change the potential quality of the plants. Plants grown under these wavelengths could be higher in lycopene or sugars or some other nutritional compounds. Based on the recipe of light given to plants, they could be grown more efficiently while enhancing their nutritional value. We await the results from the research that is rapidly proceeding.”

Looking at the big picture

While defining what is organic and what isn’t may be more important to some growers than others, Giacomelli said the agricultural industry shouldn’t lose sight of the big goal.

“I want the field organic industry to grow and I want the organic hydroponic industry to also grow,” he said. “By their development and expansion, we will help feed people. We are going to need both. There are places where both of them should be done and places where neither of them should be done. They are not mutually exclusive. We need to look at the practical aspects. Give me the bottom line based on all these factors and I will be able to tell you whether to grow in controlled environments. On the other hand, if you have the right climate and can grow outdoors organically that works too.

“We will never be able to feed all of the people in the world by a strict traditional organic definition of food production alone. There will be other agricultural practices that may not be organic or be somewhere in between. However, container production of food within controlled environments can help to meet a demand for organic food production.”

For more: Gene Giacomelli, University of Arizona, College of Agriculture and Life Sciences, Agricultural and Biosystems Engineering, Tucson, Ariz. 85721; (520) 626-9566; giacomel@ag.arizona.edu; http://ceac.arizona.edu

David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com.

GAP-audited growers should have an easier time complying with food safety rules

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Greenhouse and controlled environment agriculture growers who are participating in USDA’s GAP program are expected to have an easier time meeting Food Safety Modernization Act rules.

The burden of proving a grower is exempt from the Food and Drug Administration’s Food Safety Modernization Act’s rule falls squarely on the shoulders of the growers. Phil Tocco, food safety educator at Michigan State University Extension, said there are growers who will be exempt from meeting the Act’s rules.

Continue reading GAP-audited growers should have an easier time complying with food safety rules

Colorado State University’s new horticulture center will focus on research with LEDs

An agreement between Colorado State University and Philips Lighting to equip its new 27,000-square-foot horticulture center with LEDs will put the focus on using the lights for improving ornamental and vegetable plant production.

When officials at Colorado State University went looking for property to build a new football stadium they didn’t have to look far. They decided that the land on which the 65-year-old W.D. Holley Plant Environment Research Center resided was the perfect location for the new stadium.

“The old horticulture facility, which had been built in 1949, was considered a hot property by school officials,” said Steve Newman, who is greenhouse crops extension specialist and professor of floriculture. “To replace the old site, the university provided the department with a new $7.5 million 27,000-square-foot research and teaching facility. There is also a 3-acre outdoor area for plant trials.

“The horticulture center was built in eight months. The university facilities team that I worked with to design and build the center was awesome.”

Greenhouse specs

The horticulture center’s new greenhouse is a Nexus Vail model frame which is covered with Thermaglas polycarbonate. It is equipped with Ludvig Svensson retractable heat curtains and Wadsworth Control vents, Modine Effinity 93 natural gas unit heaters and American Coolair fan boxes. The control technology is all Wadsworth Control Systems.

Colorado State University’s 65-year-old W.D. Holley Plant Environment Research Center has been replaced with a new $7.5 million 27,000- square-foot research and teaching facility. — Colorado State University’s 65-year-old W.D. Holley Plant Environment Research Center has been replaced with a new $7.5 million 27,000-square-foot research and teaching facility.

The 21,000-square-foot greenhouse is divided into six bays. All of the bays are connected by a ventilation corridor that has a 20-foot high gutter line. One bay will contain a Crop King NFT trough system consisting of six modules. The other half of the bay will be equipped with a traditional raft culture set up that has six 5-foot by 10-foot rafts.

“I’m a hard core supporter of Colorado companies,” Newman said. “We are also trying to make the greenhouse as energy efficient as we can.”

Perfect timing

In December 2014, Ron DeKok, North America director of business development, Philips Horticulture LED Solutions, visited Newman to discuss supporting LED research at Colorado State.

“Ron visited me on the same day I was given permission to talk about the budget for the center,” Newman said. “The timing was perfect. He asked me what kind of LED research CSU wanted to do and I asked him how committed Philips was to supporting LED research at the university. He said let’s equip the facility with Philips lighting and we’ll do research projects together.

“The greenhouse is being equipped with the latest Philips horticulture LED fixtures, including top lighting, interlighting and flowering lamps. One house will have suspended interlighting modules for high wire vegetables. We are looking at being able to do all kinds of ornamental and vegetable plant research using different combinations of the fixtures.”

Crops to be studied

Newman said it hasn’t been determined yet how much of the greenhouse space will be dedicated to ornamental and vegetables crops.

Steve Newman, who is Colorado State’s greenhouse crops extension specialist and professor of floriculture, said the new horticulture center will be used for research, teaching and training.

“I expect the research is going to be about 60 percent ornamentals and 40 percent vegetables, but that could change,” he said. “Initially the greenhouse vegetable production will be used primarily for teaching and demonstration. We will get into the vegetable research later.

“Our primary focus initially is going to be on ornamental plug production and reducing plant bench time after transplanting. This includes whether we can grow better quality plugs using LEDs with less plant growth regulators. We will be looking at root development under LED lights, trying to increase rooting and production efficiency. This includes trying to improve rooting of stage 4 tissue culture propagules coming out of overseas production.”

Newman said fellow researcher and horticulture professor Bill Bauerle is planning to use the greenhouse’s corridor to study hops production using LEDs.

“Northern Colorado is becoming a central location for craft breweries,” Newman said. “There is a lot of interest in locally grown hops for the craft breweries.

“The 20-foot high ventilation corridor is ideal for growing hops. We are redesigning and reconfiguring to install the LED interlighting in order to get good vegetative growth. The hops plants will receive natural light from above and the LED interlighting between the rows. The local craft brewers are very interested in the hops research that we are planning to do.”

Collaborative research

Newman said that Philips has some of its own research agenda items that it would like to study in the horticulture center.

“The research that the company wants to do is not that different than the research that we want to do,” he said. “What Philips is planning to look at fits in with everything else that we are doing in many ways. The company will be making some specific requests. The company will be funding those project directly just like any other research program.

“The Philips research team I’m working with is very grower-oriented. The company is interested in finding out how many LED lights does it take to produce a bedding plant crop more

efficiently. How LEDs can be used to produce better quality plants. Meanwhile we will be doing our own research taking advantage of the lights. The hops research was not an agenda item for the company four months ago. Bauerle went to company officials and said let’s do this hops research and they agreed that it was worth doing.”

Philips Lighting has some of its own research agenda items that it would like to study in Colorado State’s horticulture center, but the research is not much different than what university scientists want to do. — Philips Lighting has some of its own research items that it would like to study in Colorado State’s horticulture center, but the research is not much different than what university scientists want to do.

Newman said that Philips is interested in looking at vegetable production for the warehouse farming market, which it refers to as its city farming program.

“Unfortunately we don’t have the type of facility set up to do the warehouse style growing on site,” Newman said. “I would like to see us go into that type of production eventually. Initially with our vegetable crops we will look at biomass production. We will be putting in NFT lettuce trials.

“We also want to study nutraceutical compounds, including vitamins, and if LEDs can increase the production of nutraceuticals in vegetables. I am working with my colleagues in the horticulture and food science departments looking at the mouth feel in regards to high quality lettuce production. We will also probably look at tomatoes to increase production efficiency, plant yield, and lycopene development in the fruit. We will probably start looking to do that research in the fall.”

Future plans

Newman said he is in negotiations with the university’s dining services department to produce vegetables for its dining centers.

“I am in negotiations with dining services, which is looking to start vegan salad bars in the dining halls,” he said. “Dining services wants to put in salad bars with as much produce as possible grown in Colorado. They would like to have a certain percentage of that produce be CSU student grown. We are going to redo our student farm to try to accomplish that during the growing season. We will also be trying to grow as much of the leafy greens in this new facility to provide to the dining services’ salad bars.

“I am also working very closely with a university environmental hygiene staff person. We have to be sure that we are in compliance so that whatever produce we sell to the dining halls is as safe as it needs to be. We have to set up a good agricultural practices (GAP) plan and to review the guidelines of the Food Safety Modernization Act that just went into effect. The students who are growing the produce have to be trained in the exact practices they need to follow to deliver quality, safe food. The students have to be taught the proper ways of growing and handling food from the greenhouse to the table. All of the practices that we have to incorporate are the same as if we were going to sell the produce to a retail grocery store.”

For more: Steve Newman, Colorado State University, Department of Horticulture and Landscape Architecture; (970) 491-7118; Steven.Newman@ColoState.edu.

David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com.

Photos courtesy of Steve Newman, Colo. St. Univ.

Maintaining the optimum temperature, oxygen and beneficial microbe levels are integral in hydroponic systems

While providing the proper soluble salts and pH levels are important in hydroponic systems, don’t overlook the significance of maintaining the optimum temperature, oxygen concentration and microbe level in the nutrient solution.

Maintaining the proper soluble salts (electrical conductivity) level and pH are critical in hydroponic systems like nutrient film technique and floating rafts. While monitoring these properties are important, growers should not overlook the importance that temperature, oxygen level and microbial activity play in the growth of plants in these production systems.

“It’s not as much about maintaining root health as it is about managing the conditions in the rhizosphere, which is the region around the plant roots,” said Rosa Raudales, assistant professor of horticulture and greenhouse extension specialist at the University of Connecticut. “The area around the roots undergoes a lot of biological and chemical activity. Microorganisms in the rhizosphere feed on the exudate of the roots. Managing the rhizosphere and the conditions in the nutrient solution are critical to maintaining plant health.”

Hydroponic root system health, Rosa Raudales, Univ. of Conn. — Factors that can impact root health in hydroponic systems include soluble salts, pH, temperature, oxygen level and beneficial microbial activity.
*Photo courtesy of Rosa Raudales, Univ. of Conn.*

Maintain optimum root temperatures

While providing the proper air temperature in a greenhouse or controlled environment agriculture system is important, maintaining the optimum root temperature can have a bigger impact on the health and production time of a crop.

“If higher temperatures are maintained in the root zone then the plants are going to lose a lot of energy,” Raudales said. “Temperatures above the optimum in the root zone affect the cell membrane integrity of the roots. A disruption of the cell membranes affects the function of the roots resulting in less nutrient uptake, which affects crop cycles and yields.

“If plants are grown at root temperatures lower than the optimum, the plants grow slower because their metabolism is slower. In the worst case scenario, if freezing temperatures occur then ice crystals could form in the cells resulting in cell leakage and cell disruption.”

Cornell University researchers have conducted studies (http://www.cornellcea.com/attachments/Cornell%20CEA%20Lettuce%20Handbook%20.pdf) to identify the specific temperatures that are ideal for hydroponically-grown vegetables.

“Cornell researchers found the temperature of the nutrient solution had a greater effect than the air temperature,” Raudales said. “Lettuce plants exposed to air temperatures ranging between17ºC (62.6ºF) and 31ºC (87.8ºF) had consistent yields as long as the nutrient solution had a consistent temperature of 24ºC (75.2ºF). This research was done in the 1990s, but it still has application today.

“Cornell researchers did a similar study with spinach and they found the optimum root temperature was 22ºC (72ºF). They tested air temperatures ranging from 16ºC to 33ºC (60.8ºF-91.4ºF) and they found as long as the root temperature was 22ºC, the air temperature could be in that range and plants still produced optimum yields. For tomatoes the optimum root temperature is 25ºC (77ºF).”

Raudales said growers who are producing hydroponic leafy greens like lettuce and spinach have the option of installing a water heater to maintain the optimum root temperatures.

“It is easier and less expensive to heat the nutrient solution than to keep the whole greenhouse warm,” she said. “Heating the greenhouse does not make economic sense, when the research indicates that the temperature of the nutrient solution is a more important factor. If a grower is producing lettuce and spinach, which can tolerate lower air temperatures, it makes sense to run the greenhouses cooler and to install a water heater to adjust the nutrient solution temperature.”

Maintain adequate oxygen levels

Raudales said the dissolved oxygen level in a hydroponic solution needs to be maintained so respiration can occur in the roots.

“When oxygen levels are low in the root zone, the roots do not take up the nutrients required for growth,” she said. “Low oxygen levels cause increased ethylene production in the roots. If there are higher ethylene levels in the roots then the roots start to mature and die. The more oxygen present, the better the nutrient uptake and the better the root system.”

Raudales said there is also an inverse relationship between the oxygen level and solution temperature.

“If the root zone temperature is high, then the oxygen level is going to go down,” she said. “This is another reason why the root zone temperature is so important. The optimum oxygen level should be greater or equal to 6 parts per million of dissolved oxygen in the root zone. Plants should be able to handle 6-10 ppm without any problems.”

Raudales said growers who are using nutrient film technique systems typically don’t need to do any type of aeration. The movement caused by the flow of the water is usually enough to keep the oxygen level high enough in the solution.

Raudales said growers who are using floating rafts usually incorporate some type of oxygen-generating system.

“There are different ways of oxygenating the water,” she said. “One is aerating the water where air is being pumped into the water. Air is not pure oxygen, but it contains enough oxygen for what is needed in the hydroponic solution.”

Raudales said another reason for maintaining a high oxygen level in the hydroponic solution is the effect it can have on pathogenic fungal zoospores.

“If there is more oxygen, then zoospores don’t survive as well,” she said. “Zoospores don’t want completely anaerobic conditions, but they do better in conditions where there is less oxygen.

Pathogens of concern include Phytophthora, Pythium, Thielaviopsis basicola and Xanthomonas.

“Growers should try to keep the oxygen level high. If there are warmer temperatures, then there are lower oxygen levels. When there are lower oxygen levels the plants are not as healthy and more zoospores tend to survive. This is one of the reasons why there tends to be more disease issues during the summer than during the winter.”

Raudales said growers who are using floating rafts should be measuring the oxygen level regularly. Meters for measuring dissolved oxygen look like pH meters and are simple to operate.

Maintain beneficial microbes

Raudales said beneficial microbes are present naturally in water. Commercial products with beneficial microbes can also be incorporated into the hydroponic solution.

“Growers who are using the floating rafts tend to treat the nutrient solution like gold,” she said.

“They don’t want to replace it because they have a solution which is very high in beneficial microbes. Growers can inoculate the nutrient solution with a commercial biocontrol product or they can allow the good microbes to build up with time.

“As long as growers maintain the other parameters at optimum levels, including root temperature, pH, nutrients and oxygen levels, there typically isn’t a problem with diseases. This is very comparable to what happens with plants grown in substrates. The microbes build up naturally in the water just like in a substrate. These microbes feed on the exudates of the roots.

They need carbon sources that they wouldn’t get just from the nutrient solution. The system has to be clean, but it doesn’t have to be clean to the point of having to start with a fresh solution every time a new crop is planted.”

For more: Rosa Raudales, University of Connecticut, Department of Plant Science and Landscape Architecture; (860) 486-6043; rosa.raudales@uconn.edu; http://www.greenhouse.uconn.edu.

David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com.

Food Safety Modernization Act could impact growers exempt from the new federal rules

Although greenhouse and controlled environment agriculture growers may be exempt from implementing Food Safety Modernization Act rules, produce buyers may make compliance mandatory.

U.S. Centers for Disease Control and Prevention estimates 48 million people are sickened each year by foodborne pathogens. Of those people about 128,000 are hospitalized and 3,000 die each year.

On Nov. 13, 2015, U.S. Food and Drug Administration finalized three rules of the Food Safety Modernization Act. The purpose of FSMA, according to a FDA press release is to prevent foodborne illness “that, for the first time, establish enforceable safety standards for produce farms and makes importers accountable for verifying that imported food meets U.S. safety standards.” FDA said FSMA’s “final rules will help produce farmers and food importers take steps to prevent problems before they occur.”

“The recent multistate outbreak of Salmonella in imported cucumbers that has killed four Americans, hospitalized 157 and sickened hundreds more, is exactly the kind of outbreak these rules can help prevent,” said Michael Taylor, FDA deputy commissioner for foods and veterinary medicine. “The FDA is working with partners across the government and industry to prevent foodborne outbreaks. The rules will help better protect consumers from foodborne illness and strengthen their confidence that modern preventive practices are in place, no matter where in the world the food is produced.”

The three final rules released by FDA in November are the Produce Safety rule, the Foreign Supplier Verification Programs rule and the Accredited Third-Party Certification rule. FDA has finalized five of the seven major rules that implement the core of FSMA. In September 2015, FDA released the Preventive Controls for Human Food rule, which mandates preventive practices in food processing and storage facilities.

Produce Safety rule

The Produce Safety rule is the one rule that should have the biggest impact on outdoor farmers, greenhouse growers and controlled environment agriculture (CEA) growers. FDA used public comments and input collected during farm visits, meetings and listening sessions to develop a rule it says aims at reducing contamination risk while providing flexibility for farmers and growers.

This rule “establishes science-based standards for growing, harvesting, packing and holding produce that are designed to work effectively for food safety across the wide diversity of produce farms.” The rule’s standards include “requirements for water quality, employee health and hygiene, wild and domesticated animals, biological soil amendments of animal origin such as compost and manure, equipment, tools and buildings.” The rule’s standards have been designed to “help minimize the risk of serious illness or death from consumption of contaminated produce.”

The Food Safety Modernization Act’s Produce Safety rule includes standards for water quality, employee health and hygiene, equipment, tools and buildings.

One crop that the rule specifically addresses is the production of sprouts, which have been frequently associated with illness outbreaks. FDA reports that between 1996 and 2014, there were 43 outbreaks, 2,405 illnesses, 171 hospitalizations and three deaths associated with sprouts. Among the outbreaks was the first documented case of Listeria monocytogenes associated with sprouts in the United States. This crop is particularly vulnerable to microbial contamination because of the warm, moist conditions in which they are produced.

Exemptions to the Produce Safety rule

The earliest compliance date for the Produce Safety rule for some farms is two year after the effective date of the final rule. There are exemptions to the rule for some producers. These include farms that have an average annual value of produce sold during the previous three-year period of $25,000 or less. Also to be eligible for a qualified exemption, the farm must meet two requirements:

1. The farm must have food sales averaging less than $500,000 per year during the previous three years.

2. The farm’s sales to qualified end-users must exceed sales to all others combined during the previous three years. A qualified end-user is either (a) the consumer of the food or (b) a restaurant or retail food establishment that is located in the same state or the same Indian reservation as the farm or not more than 275 miles away.

Buyers driving food safety regulations

Dr. Elizabeth Bihn, director of the Produce Safety Alliance at Cornell University, said prior to FSMA, buyer demand has been the primary driver for implementation of food safety practices. “Consumers are buyers, but they are not protecting a name brand like Kroger or Wegmans or Wal-Mart,” Bihn said. “These companies are protecting their brands. They are going to have much higher stipulations for food safety then the consumers at farmers markets. There is some consumer demand for increased accountability for food safety, but it’s not as big a driver as the retail buyers’ demand. This includes most large food retailers.”

Bihn said greenhouse vegetable growers and CEA growers may receive added pressure from buyers to follow FSMA whether or not they are exempt from it.

“If a buyer tells a grower, “I’m not buying your produce unless you have a third party audit,” and the grower wants that company’s account, then the grower is going to do the audit,” Bihn said. “Legally a grower may be exempt from the regulation, but a buyer may say it doesn’t matter, the grower will still have to meet the regulation. There are still going to be markets that don’t require growers to meet the regulation if their operations are exempt from it. If you are a greenhouse grower who sells to a market that’s not requiring compliance with FSMA and you are exempt from the regulation, you may not have to do anything related to the regulation. Also, I can see third party audits, like the Harmonized GAPs audit, being updated to align with the rules to make sure that growers who have audits done meet the federal regulations as well.”

Increased interest in food safety

Even before the final rules were released, Bihn said she is receiving increased inquiries from greenhouse growers about food safety. “Greenhouse growers are trying to decide if they are subject to FSMA rules and how the required practices might fit with what they do with their greenhouses,” she said. “They are trying to figure out if they need to be concerned with meeting food safety regulations. They are going to be in the same situation as field farmers and asking the same questions. Are buyers asking the growers to meet the regulations? Greenhouse growers not subject to the regulations could easily get pushed into following the regulations if their buyers tell them in order to do business with them, the growers must follow the regulations.”

Bihn said her job is to help guide produce growers, whether they are field farmers, urban farmers, greenhouse growers or CEA growers, toward implementing food safety practices.

“Initially there may be frustration, hostility and denial,” she said. “All of those things will occur when growers first hear what they have to do. When they finally sit down and start to learn something about food safety and start to ask how can I fix this, then they start to make progress really fast.

“I love farmers who question everything. They don’t understand why doing something is a risk. They tell me I’ve never killed anyone so what’s the problem. That’s the engagement that I need to get them to think about it. They need to get to where they understand all farms can have produce safety risks and admit that they need to learn something about food safety so that they can make adjustments within their operations and put practices in place to reduce the risks.”

Industry job opportunities

Bihn said she has been encouraging Cornell students majoring in horticulture to get a minor in food science. She has also been encouraging students majoring in food science who are interested in produce safety to get a minor in horticultural production.

“There are food science students who have no idea how farms operate,” she said. “Unfortunately this sometimes results in food science professionals offering ideas for problem solving that may not be doable.”

Bihn said that food safety has traditionally been housed with the food science departments and crop production has been housed with the horticulture department.

“It’s time for there to be some cross pollination between these two departments,” she said. “It has been slow to happen. We now have a Masters of Professional Studies degree at Cornell that merges horticulture and food science. There are jobs out there, but they are difficult to fill because there are people who know production or there are people who know food pathogens, but there are very few people who know both.”

Bihn said she has received requests from her horticulture colleagues at Cornell to give guest lectures on food safety and to collaborate on publications about incorporating food safety guidelines into field publications.

“The fruit and vegetable industry as a whole is certainly saying food safety is something that we need to be incorporating,” she said.

For more: Dr. Elizabeth Bihn, Cornell University, Department of Food Science; (315) 787-2625; eab38@cornell.edu.

Produce Safety Alliance, http://www.producesafetyalliance.cornell.edu.

National Good Agricultural Practices Program, http://www.gaps.cornell.edu.

David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com.

Producers of greenhouse food crops can’t be sloppy growers

Growers can reduce the chance of disease infestation on greenhouse vegetable crops by incorporating a strict sanitation program and minimizing plant exposure to moisture.

Sanitation and moisture management are key factors in controlling diseases on greenhouse food crops, said Michigan State University plant pathologist Mary Hausbeck.

“Preventing greenhouse diseases starts with sanitation,” she said. “I can walk into a greenhouse head house and predict how many disease problems I’m going to find just by what I see in the head house area. Is it clean? Is it neat and orderly? Sanitation is a mindset. It either carries through from the head house to the growing areas or it doesn’t.”

Hausbeck said growers should try to do a thorough job of removing any plant debris that may be left in the greenhouse, including “pet” plants that may be left in hallways or in the corners of the greenhouse.

“When a grower is making a changeover to another crop there shouldn’t be any other plants left in the greenhouse,” she said. “That is the safest approach.”

Hausbeck said growers should also make sure there is a weed-free perimeter that goes all the way around the outside of the greenhouse.

“There should not be any weeds growing around the greenhouse,” she said. “Growers need to have a critical eye to make sure there is nothing around the greenhouses that can harbor pests or diseases. Ideally all of that needs to be removed.”

Moisture management

Hausbeck said growers should make every effort to limit plant exposure to moisture.

“This includes moisture in the air—relative humidity, moisture on the foliage—leaf wetness, and moisture in the growing medium,” she said. “Moisture is a big driver for disease prevention and control. Growers should limit the amount of moisture by decreasing the relative humidity, watering during the time of day when the foliage can dry rapidly or not getting the foliage wet at all and not overwatering the plant root system. These are things that are important when growing ornamentals and are helpful when growing vegetables. It’s moisture more than temperature. When the humidity is 85 percent and higher, growers should do what they can to reduce the moisture in the growing environment and be vigilant for moisture-loving diseases such as Botrytis to develop.”

Hausbeck said unlike ornamental crops, root rots on greenhouse vegetables are usually not major diseases that wipe out a crop. She said some ornamental crops can suffer considerable losses from the root pathogens Pythium and Phytophthora.

“Diseases that have tended to be major problems on vegetables in the greenhouse include the foliar pathogens downy mildew on cucumbers and cladosporium leaf mold on tomatoes,” she said. “Leaf mold can overwinter in plant debris and soil.

Diseases that tend to be major problems on greenhouse vegetables include cladosporium leaf mold on tomatoes.
*Photos courtesy of Mary Hausbeck, Mich. St. Univ.*

“Vegetable pathogens tend to be crop specific. At the recent 29^th Annual Tomato Disease Workshop I attended, most of the conversations centered around bacterial diseases on tomatoes. Those disease pathogens tend to be introduced via the seed. One disease that tomato producers talked about a lot is bacterial canker. This pathogen (Clavibacter michiganensis subsp. michiganensis) can move through hydroponic systems and from plant to plant through root grafting.”

Insect-vectored viruses

When it comes to viruses, ornamentals and vegetables are susceptible to some of the same viruses, including impatiens necrotic spot virus (INSV), tobacco mosaic virus (TMV), cucumber mosaic virus (CMV) and tomato spotted wilt virus (TSWV).

“These viruses have caused sporadic problems for ornamental growers and they can move onto vegetable crops with some devastating results,” Hausbeck said. “If thrips are a problem and there is a reservoir of INSV or TSWV in infected plants somewhere in the greenhouse, ornamental growers transitioning to vegetables need to know the symptoms on susceptible ornamental crops. They need to be especially vigilant since ornamentals can be infected without obvious symptoms.

“In the greenhouse, vegetables are susceptible to some of the same viruses that have caused problems with ornamental crops, including TMV. This means applying the same precautions such as employees not smoking and washing their hands after cigarette breaks. Ornamental growers need to be aware that they don’t get to walk away from these viruses just because they have switched to vegetables.”

Downy Mildew — Downy mildew is a foliar pathogen that can be a major problem on cucumbers.

Hausbeck said some of the viruses (INSV and TSWV) that attack ornamentals can be moved quite readily to food crops like lettuce via thrips.

“Pathologists don’t like to see the mixing of vegetables with greenhouse ornamentals,” she said. “That’s because INSV and TSWV can be brought into a greenhouse via infected cuttings or prefinished ornamentals. The virus can then be moved to vegetable crops by thrips. Growers need to monitor for thrips. If there are ornamentals growing in one part of the greenhouse, there is a risk that a virus may be moved from ornamentals to the vegetables.

“A virus such as TMV can also be introduced to greenhouse vegetables through infected ornamentals. The virus is easily spread among plants through physical contact such as grower handling.”

Chemical control limitations

Hausbeck said as ornamental growers move into food crop production they may not recognize that there are more limitations on fungicides that can be used on vegetables.

“Over years of production, ornamental growers are used to managing Pythium and Botrytis,” she said. “Those are some of the diseases that can also occur on greenhouse vegetable and herb crops. Growers may think that they can grab the same chemicals they are using on ornamentals like geraniums and poinsettias and use them on food crops. Depending on the product, this may not be legal.”

Hausbeck said on some ornamental fungicide labels the list of plants is very broad.

“Since these chemical labels may be broad in their application to ornamental plants, growers may mistakenly believe that the same product can be used on vegetables,” she said.

Bacterial Canker — *Clavibacter michinganesis* subsp. michiganensis, which causes bacterial canker on tomatoes, can move through hydroponic systems and from plant to plant through root grafting.

Hausbeck said it is important for ornamental growers who are expanding into vegetables to recognize that they are growing food.

“Food is tightly regulated,” she said. “Growers cannot use a product that isn’t expressly allowed by label to be used on specific vegetable crops. If a crop is on the label, then the grower has to determine if the label allows the use of the product within as greenhouse setting. If there is no mention of a greenhouse on the label, then the product can be used as long as its use in the greenhouse is not restricted. This should be verified through state agencies or through the product registrant.

“Vegetable growers need to read and reread the label before applying any chemical. Growers can’t assume that they can use some of their trusted products to combat a disease like powdery mildew when it occurs on a food crop. And even though ornamental growers can use Truban for the control of Pythium, the fungicide is not labeled for greenhouse vegetable crops.”

Hausbeck said even though some of the pathogens will be similar on ornamentals and vegetables, greenhouse growers need to become educated about the products needed to manage diseases on food crops.

“Growers need to know the key disease threats for the specific crops that they want to produce,” she said. “Manage the greenhouse environment to keep it as clean and dry as possible. When a fungicide is needed, know which products are legal to use on vegetable crops within the greenhouse and know which tools work best.”

For more: Mary Hausbeck, Michigan State University, Department of Plant, Soil and Microbial Sciences; (517) 355-4534; hausbec1@msu.edu; http://www.psm.msu.edu/people/mary_k_hausbeck_professor_and_extension_specialist.

David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com.

Consider using biological controls if adding edibles to your greenhouse crop mix

Greenhouse ornamental plant growers adding edible crops to their product mix should consider incorporating biological controls into their integrated pest management program.

An increasing number of ornamental plant growers are looking to take advantage of the growing demand for locally produced edible crops. Whether it’s for sales in their own garden centers, roadside stands, farmers markets, grocery stores and restaurants, the demand for locally-grown produce continues to increase.

Continue reading Consider using biological controls if adding edibles to your greenhouse crop mix

LEDs have the potential to change how crops are grown

The use of LED grow lights to provide specific light wavelengths could allow growers to increase nutritional values of edible crops, enhance the intensity of foliage and flower color and improve the postharvest longevity of ornamental and edible crops.

Improvement in the light intensity delivered by light emitting diodes (LEDs) is helping to expand their use for the production of both edible and ornamental crops. Research with LEDs has been going on for about 30 years. Only within the last 10 years have increases in the light
intensities of LEDs allowed researchers to study the direct effects of narrow wave bands of light on plant physiology.

“LEDs are now available to deliver all blue, all red, all green, all yellow light or mixtures,” said University of Tennessee plant sciences professor Dean Kopsell. “White LEDs are almost a broad spectrum light source. White LEDs are actually mostly blue light with a little bit of red, yellow and green light with a white phosphor over them.”

Kopsell and his colleagues at the University of Tennessee are studying the impact individual types of light can have on the nutritional qualities of edible crops. Their work is focusing on crops that can be produced relatively quickly in 25-35 days, including microgreens and baby greens. They have also begun looking at some herbal crops including basil, tarragon and chives.

Researchers at the University of Tennessee are finding that exposing plants like brassicas to blue light is having a significant effect on their nutritional values. Photos courtesy of Dean Kopsell, Univ. of Tenn.

“Some of the unique things we are finding are when we change the light quality environment, going away from broad band light sources like fluorescent, incandescent and HIDs, and exposing plants to narrow band wavelengths of red and blue light, many things are changing in the plants. These narrow bands of light are having an effect on several plant quality parameters from a metabolic standpoint.”

Potential of specific light wavelengths

University of Tennessee researchers have found that exposing plants to narrow wavelengths of the light spectrum has resulted in the increased production of antioxidants and anti-carcinogenic compounds within the plants.

“What is even more interesting is some of the primary metabolites like the mineral nutrients are also increasing,” Kopsell said. “We are shifting the light ratios and putting more blue light into the mix. Blue light is close to the ultraviolet (UV) range and has higher energy values than red light. Because of the higher energy level associated with blue light, the more blue light we are exposing the plants to, it seems the more significant the results are on nutritional values.

“We haven’t got hard data yet, but everything that we can see, smell and taste, these blue lights not only affect nutrient uptake, and anti-oxidant metabolism, but they also affect aromatic compounds and flavor compounds. They make them more intense.”

Although researchers have only recently begun to study the impact of narrow light wavelengths on plant physiology, Kopsell said this will be the major use of LEDs in future applications.

“Not only is a grower going to be able to select the type of light and intensity from the LED manufacturer, but eventually the grower will know when is the critical time to apply a specific amount of light to a crop. One of the things that we have seen with these short term crops is using the light as a finishing-off treatment. The crops are grown under regular light conditions like any grower would have the ability to do and then just before harvest the plants would receive a specific type of light for a certain period of time. This light treatment would stimulate the plant physiology uptake and metabolism right before the plants go to the retail market.”

Kopsell said research exposing leafy brassicas to blue light prior to harvest has intensified pigments and green leaf color.

“We increased the green pigments in the leaves so that they looked more vibrant,” he said. “Other research has shown that UV light increases the anthocyanin compounds in leaf lettuce. Providing a little UV light, which is blocked out in most greenhouse environments, at the right time, a grower can get a crop to color up quickly before the plants are shipped out. What we have done with leafy greens to intensify the color of the leaves can also be done with petal tissue. By changing the light quality a grower could get more vibrant flower colors.”

Need for fine tune management

Kopsell said whether plants are grown outdoors, in a greenhouse or in a closed controlled environment with artificial light, the plants are using specific wavelengths from the available light source.

“Horticulture, floriculture and agronomic researchers know how much light is needed in order to produce crops with broad spectrum light,” he said. “The million dollar question that hasn’t been answered is how much light is needed from LEDs to achieve that same level of production? It is going to be less than the daily light integral (DLI) from a broad spectrum light source. But, right now we can’t tell you how much less it’s going to be.

“Applying specific light wavelengths when the plants need them, whether it’s for juvenile growth, flowering or fruiting, we don’t have a good grasp on the amount of light that the plants actually need. If a grower is only going to supply his plants with red and blue light, how much less light can a grower use in that production system?”

One of the reasons that plants will not require as much light from LEDs is because of the reduction in light stresses.

University of Tennessee studies have shown LED grow lights provide a less stressful light environment for plants.

“Providing specific types of red and blue light, the amount of stress on plants is reduced because the plants don’t have to tolerate the light not being used for metabolism and physiology,” he said. “We have data that shows LEDs provide a less stressful light environment for plants. So we have to determine how much less light is needed. It is going to require an extra level of management to know what kind of light, how much light and when to apply it. Growers are going to be able to use LEDs to fine tune the light environment. It’s going to depend on the crop, how it’s being grown, where it’s being grown and how the crop will be used. Is it an ornamental, edible or medicinal crop? It’s not going to be as easy as sticking a seed or cutting into a substrate and letting Mother Nature take control. It’s really going to take some fine tune management. But the future looks bright so far.”

For more: Dean Kopsell, University of Tennessee, Plant Sciences Department, Institute of Agriculture, Knoxville, TN 37996-4561; (865) 974-1145; dkopsell@utk.edu.

David Kuack is a freelance technical writer in Fort
Worth, Texas; dkuack@gmail.com.Visit our corporate website at https://hortamericas.com

High tunnels offer benefits for berry crop growers

Research at Michigan State University has shown that high tunnels can extend the season, increase yields and reduce the disease losses of berry crops.

Continue reading High tunnels offer benefits for berry crop growers

LEDs, fluorescent lights help Two Bros Hydro expand its business

Bob McVey and Ed Olanowski, owners of Two Bros Hydro, are using LED and fluorescent lights, vertical farming and a new greenhouse to expand their vegetable and fruit production.

Continue reading LEDs, fluorescent lights help Two Bros Hydro expand its business

RainFresh Harvests uses solar and wind power to sustainably grow its business

Barry Adler, owner of RainFresh Harvests, started a greenhouse vegetable business with the goal of being as sustainable and environmentally-friendly as possible.

Barry Adler, owner of RainFresh Harvests in Plain City, Ohio, was exposed to the use of solar power as a renewable energy source for greenhouses when he was a graduate student at Virginia Tech. He continued to be involved with the use of greenhouses during the 22 years he worked at the Scotts Co., including conducting fertilizer research. Because of his familiarity with greenhouse production it made sense for Adler to look at it as a business option when he left Scotts in 2002.

Continue reading RainFresh Harvests uses solar and wind power to sustainably grow its business

Substrate trials in Hort Americas’ research greenhouse are looking at conventional and organic propagation substrates along with different irrigation strategies for producing healthy starter plugs for hydroponic production systems.

Focused on irrigation strategies

Type of irrigation system

Need for good seed-substrate contact

Products being used in greenhouse trials

Grodan AO Plugs, Rockwool Cubes

Washed 4.5kg Coco Coir Peat Block

Early results from fertilizer trials in Hort Americas’ research greenhouse show knowing the levels of nutrients in fertilizer solutions can go a long way in avoiding problems with deficiencies and toxicities.

Differences in nutrient levels

Identifying what makes up the EC

Herb production with organic fertilizer

Controlling biofilm, disease pathogens

Products being used in greenhouse trials

Hort Americas Hydroponic Fertilizer (9-7-37)

Terra Bella Organic Fertilizer – 1 Liter jug

Grodan AO Plugs, Rockwool Cubes

Pre-Empt, OMRI-listed Organic Hydroponic Nutrients 2.5 gal jug

EpsoTop Magnesium Sulfate K+S, 25kg Bag

Yara Tera Calcium Nitrate

Hort Americas’ special projects manager Tyler Baras is using a 12,000-square-foot hydroponic greenhouse to teach company staff and customers what it takes to economically grow leafy greens and herbs.

Collecting, disseminating production data

Preliminary results

Teaching and trialing

Products being used in greenhouse trials

Hort Americas Hydroponic Fertilizer (9-7-37)

Terra Bella Organic Fertilizer – 1 Liter jug

Grodan AO Plugs, Rockwool Cubes

Pre-Empt, OMRI-listed Organic Hydroponic Nutrients 2.5 gal jug

EpsoTop Magnesium Sulfate K+S, 25kg Bag

Yara Tera Calcium Nitrate

Research at Michigan State University shows growers have a choice when it comes to lights for photoperiodic control.

Lamp placement impacts light intensity

Ensuring proper light spacing

Differences in wavelength effects

Differences in plant species sensitivity

New horticultural lighting blog

Since lettuce and leafy greens have short production cycles, greenhouse growers need to stay focused if they want to be successful growing these crops year round.

Controlling environmental parameters

Light

Temperature

Relative humidity

Fertilization, water quality

McGill University bioresource engineer Mark Lefsrud said it’s time to take plant research and production to a higher level with LEDs.

Kevin Folta, chairman of the Horticultural Sciences Department at the University of Florida, said more researchers, farmers and students need to be using social media to promote themselves, their research and their industries.

Focused on social and science issues

Supporting American farmers

Generating more research funding

Expanding social media presence

A study of data collected in the 2007 and 2012 Census of Agriculture shows that direct-to-consumer sales could help growers remain in business longer.

Tracking business survival

Reasons for increased survivability

Slower growth rates

Rutgers University researchers are studying the viability of growing ethnic specialty crops in greenhouses and hoop houses for local and regional sales.

Focusing on Asian and Hispanic crops

Research results

Regardless of whether you think hydroponic production can be organic, the bottom line is all methods of food production should be considered when trying to feed a growing world population.

Soil, soilless or no soil

Comparing production methods

The impact of light

Looking at the big picture

Greenhouse and controlled environment agriculture growers who are participating in USDA’s GAP program are expected to have an easier time meeting Food Safety Modernization Act rules.

An agreement between Colorado State University and Philips Lighting to equip its new 27,000-square-foot horticulture center with LEDs will put the focus on using the lights for improving ornamental and vegetable plant production.

Greenhouse specs

Perfect timing

Crops to be studied

Collaborative research

Future plans

While providing the proper soluble salts and pH levels are important in hydroponic systems, don’t overlook the significance of maintaining the optimum temperature, oxygen concentration and microbe level in the nutrient solution.

Maintain optimum root temperatures

Maintain adequate oxygen levels

Maintain beneficial microbes

Although greenhouse and controlled environment agriculture growers may be exempt from implementing Food Safety Modernization Act rules, produce buyers may make compliance mandatory.

Produce Safety rule

Exemptions to the Produce Safety rule

Buyers driving food safety regulations

Increased interest in food safety

Industry job opportunities

Growers can reduce the chance of disease infestation on greenhouse vegetable crops by incorporating a strict sanitation program and minimizing plant exposure to moisture.

Greenhouse ornamental plant growers adding edible crops to their product mix should consider incorporating biological controls into their integrated pest management program.

The use of LED grow lights to provide specific light wavelengths could allow growers to increase nutritional values of edible crops, enhance the intensity of foliage and flower color and improve the postharvest longevity of ornamental and edible crops.