If you’re going to use a loose substrate in a hydroponic production system, you may have to change how you handle starter plants and the treatment of recycled water.
Many growers of ornamental plants including annuals and perennials traditionally use a peat-based substrate such as 70 percent peat, 30 percent perlite. The growers, who produce these crops in containers, will often use the same substrates if they expand their crop offerings to include hydroponically-grown edible crops, including lettuces and leafy greens.
Bell peppers grown in greenhouse hydroponic systems follow similar environmental requirements as tomatoes and eggplants. It is a common production practice to leave all the leaves on the pepper plants. This creates very tall walls of foliage that slightly affect the plants’ nutritional requirements.
Growers have affordable options for ensuring plants receive sufficient oxygen in hydroponic production systems to maximize growth and to reduce the chances of disease.
Experienced growers are in demand, and you can accelerate your indoor and greenhouse growing know-how at the University of Arizona Controlled Environmental Agriculture Center [UofA-CEAC] in Tucson, Arizona from June 5th – 12th, 2017 at our Hydroponic Crop Intensive Workshops.
Researchers at Michigan State and Iowa State Universities are looking for feedback from hydroponic food growers to help them determine where research is needed to benefit the industry.
As I posted earlier this month, I have been fielding a lot of questions from industry peers asking why Hort Americas continues to support, sponsor and have a booth at the 2nd International Congress on Controlled Environment Agriculture (ICCEA). This event is scheduled for May 17-19, 2017, in Panama City, Panama. I thought the best way to respond was to write a two-part blog. In my first post I focused on my business reasons for participating in ICCEA. In this second post I will focus on my philosophical reasons for my involvement with ICCEA.
Recently I have been fielding a lot of questions from industry peers asking why Hort Americas continues to support, sponsor and even have a booth at the 2nd International Congress on Controlled Environment Agriculture (ICCEA). This event is scheduled for May 17-19, 2017, in Panama City, Panama. I thought the best way to respond was to write a two-part blog posting. In my first post I will focus on my “business” reasons and in the second post I will focus on my philosophical reasons.
Business opportunities in developing markets
As we all know, “the only constant is change.” This is no different in the world of commercial agriculture and production horticulture regardless of geographical locations. Panama and other Latin American countries have a very strong and proud history in agriculture and horticulture, which due to changing weather patterns are being forced to adapt. As one would expect, these changes will not come easy and will cause many farms, of all sizes, to suffer in the process. If these same farms want to continue operating and more importantly want to continue to be profitable, they will need to find a new way. My belief is that controlled environment agriculture (CEA) can and will be one of the tools that help these farms redefine themselves.
CEA is a technology-based approach to food production. The aim of CEA is to provide protection and maintain optimal growing conditions throughout crop development. Production takes place within an enclosed growing structure such as a greenhouse or building.
Panamanian government officials feel the same way. They have shown and continue to show a commitment to helping the country’s farmers.
The government’s support started in 2015 and 2016 when it committed and put to work approximately $100 million USD towards investments in innovative production techniques and strategies. In January 2017 the government announced a first-round monetary infusion of $243 million USD for fiscal year 2017 to be directed toward increasing food production using controlled environment/precision agriculture. These funds will be used to transition from current traditional agriculture and its challenges, including water, inputs, available arable land, to technology-based food production which includes CEA.
Panama funds CEA projects
Hort Americas has seen Panama’s government funding put to work. In the last 18 months the following projects have either been initiated or implemented.
* 10 Greenhouses of various sizes built with all the necessary equipment/technology.
* 2 Indoor farm food production facilities (one currently in development stage).
* 1 New university research-and-development facility.
* 1 Tissue culture laboratory.
* 1 CEA seedling production facility.
* 4 Private research-and-development facilities to test indoor food production (agricultural companies).
The following projects are currently in the planning stage.
* 1 Large-scale, world class research-and-development facility (a combined private/government/university initiative).
* 5 Greenhouses (more possible with new incentives recently announced).
* 1 Indoor food production facility.
Panama is one of several Latin American countries receiving this type of financial funding to upgrade the agriculture sector. Peru, Chile and other countries are following suit. In addition, there is a robust effort by CAF Development Bank of Latin American, and other multilateral organizations to increase their agriculture portfolio throughout Latin America, applying technology to produce food.
Hort Americas’ customers are active in the production of food and flowering crops using the technology that best fits their region. From our perspective, and depending on the crops, CEA can be designed and built to suit a variety of crops, production methods and management styles. This can be done as a greenhouse, vertical farm/plant factory or tissue culture facility.
ICCEA does two things to support CEA. First, it focuses on the education needed to support crop production regardless of the technology or geographic region. Second, it brings together people with varied backgrounds, including international investors, growers/farmers, innovators and entrepreneurs.
Due to ICCEA’s unique program and approach it not only attracts attendees from Latin America, it also attracts creative and innovative minds from around the world. In 2015, Hort Americas was amazed to meet and develop working relationships with many new businesses from the United States and Canada.
Unprecedented opportunities for everyone.
ICCEA creates opportunities for people and companies to build business partnerships. And that is what we look for–opportunity. When people have access to information and science that supports what they are interested in, good things happen. When people have the opportunity to listen to leaders from their industry, good things happen. When people have the opportunity to share great food and drink, good things happen. When people have the opportunity and time to professionally network, good things happen.
In 2015, Hort Americas had the pleasure of meeting and starting new business relationships with many new people and companies from the USA, Canada and the Caribbean (arguably more developed markets.) These attendees represented a wide array of thought, businesses, hydroponic crops and experience. It was awesome. Based on conversations we are currently having, we see even more opportunities to meet new and existing customers in 2017.
So, once again Hort Americas will be attending ICCEA in Panama City, Panama, on May 17-19, 2017. We will be there learning from leading researchers, networking and creating opportunities with government representatives, existing agricultural/horticultural businesses, entrepreneurs and manufacturers of CEA products.
Greenhouse Scout is an integrated pest management app that makes it easier to collect, store and analyze scouting data along with identifying insect pests and which beneficials can be used to control them.
Most greenhouse growers know the benefits of scouting their crops for pest insects and mites. Scouting can help to identify and minimize pest outbreaks, reduce plant damage and crop losses and save on pesticide and biological control costs.
Sudlac is coming to North America in 2017. The company’s goal is to become the leading manufacturer of shading materials for the global greenhouse horticulture market. This is apparent from the complete restyling of the company brand all the way to the development of its fast-growing team. Behind the scenes, every team member is working hard to build a solid, full-coverage distribution network.
Whether greenhouse, vertical farm or warehouse growers are propagating or producing ornamental, vegetable or cannabis crops, P.L. Light Systems offers the LED fixtures to meet their lighting needs.
P.L. Light Systems develops and manufactures supplemental lighting systems for the horticultural industry. The nearly 40-year-old company manufactures traditional light sources, including high pressure sodium (HPS) and metal halide, as well as its own light emitting diode (LED) fixtures.
“There are a lot of lighting products hitting the market right now, especially when it comes to LEDs,” said Eric Moody, P.L. Light Systems western USA Lighting Solutions Specialist. “The future of the horticultural lighting market is moving toward LEDs as the technology continues to advance. Every week it seems like there is another company entering the horticultural lighting market. Growers need to carefully look at the lighting companies they are considering working with. How long has a company been around and is it focused on horticulture or is it just buying circuit boards and selling them as LED horticulture lights?”
Even though P.L. Light Systems has been marketing horticulture grow lights for nearly 40 years, it was not one of the first companies to offer LED lights. “One of the reasons that we weren’t one of the first companies is because of the intensities and efficiencies of LEDs,” Moody said. “In 2014-2015 the market started to see LED diodes that could deliver 2.1 micromoles per joule (μmol∙J–1). When this occurred everyone that was selling LEDs to the horticulture industry got excited.
“Double-ended HPS lamps that are used in horticulture put out 2,100 micromoles per 1,000 watts, which is 2.1 μmol∙J–1. So what happened is LEDs finally equaled HPS. LEDs didn’t surpass HPS. When this happened P.L. started looking into the LED market and to surpass what was available.”
P.L. Light Systems’ HortiLED TOP and HortiLED INTER fixtures are finalists in the Horticultural Lighting Category for LEDs Magazine’s 2017 Sapphire Awards. The awards will be presented March 1, 2017, in Anaheim, Calif.
P.L. Light Systems HortiLED TOP
P.L. Light Systems HortiLED TOP light is a fully enclosed fixture with an integrated driver that delivers 2.7 μmol∙J–1. The TOP fixture measures 38 inches long by 4.7 inches wide by 3.7 inches tall and weighs 18 pounds. The fixture is available in two distribution angles, 80º and 150º, and light spectrum of red/blue, red/white, full spectrum and customized.
“P.L. started in the greenhouse market so we are catering to that segment of the market even though there are a lot of indoor growers using our fixtures,” Moody said. “We want to be sure everything we manufacture is able to be used in a greenhouse.
“The TOP fixture drivers are driving the diodes to 2.7 μmol∙J–1. But the diodes we are using are capable of going above 3 μmol∙J–1. We are driving our diodes to a lower percentage because we don’t want to overheat them and we want them to last for 28,000 hours. We are better able to control the heat by not overdriving the diodes. Our goal is to have totally passive cooling so the fixture can be hung right up under a truss and it is fully enclosed.” Moody said having a totally enclosed fixture offers an advantage over other toplight LEDs on the market.
“Other manufacturers are either installing fans in their fixtures or they are mounting the drivers separately,” he said. “The LEDs with fans built into the fixtures can suck in dust and insects. These fixtures can short out because they get a build-up of debris inside the fixture. The fans push air across an electrical circuit board. There are also water-cooled fixtures. There is a water line running from one fixture to the next.
“Other manufacturers’ fixtures are large units in order to get the light output. These fixtures might work for some indoor growers, but they’re not going to work in a greenhouse. These larger fixtures reduce the amount of sunlight reaching the plants by casting shadows over them.”
Moody said with LEDs the light is very directional so it doesn’t cover as big of a footprint as HPS.
“We offer two TOP light LEDs that have different distribution patterns,” he said. “It’s not a reflector, it’s the diode itself. We have an 80º diode which is very common. This fixture puts out an 80º wide distribution pattern. We also have a 150º diode that puts out a much wider distribution pattern. This enables us to cater light plans to the growers’ crops. It offers a lot of room to move up and down depending on how far the fixtures need to be from a crop.”
P.L. Light Systems HortiLED INTER
The HortiLED INTER fixture is made for tall vine vegetables, ornamentals and some cannabis production. “The fixtures are mounted down the center of the crop,” Moody said. “It is supplementing the light that is being received from above the crop. For a 14-foot tall greenhouse tomato crop a grower may have HPS or LED toplights above and then the interlights below. Sometimes growers will use two rows of interlight fixtures in order to get more light deeper into their crops.
“The INTER fixture has the same high output diode as our TOP fixture, but because of the cover on the INTER fixture, the output reaches 2.5-2.6 micromoles per joule depending on the light spectrum.”
The INTER LED is a fully enclosed fixture equipped with a polycarbonate cover that keeps it totally waterproof. Moody said this ensures that the fixtures are not affected by high humidity environments, mist systems and spray applications.
The INTER fixture measures 48 inches long by 2.2 inches wide by 4.8 inches tall and weighs about 4 pounds. The fixture operates with an external driver and is available with a red/blue spectrum.
“With an interlighting fixture hanging in the crop, the light distribution pattern should go out to the sides hitting all of the leaves that are around the fixture,” Moody said. “Our INTER fixtures put out what looks like a butterfly wing pattern. The light pattern goes out sideways, but at the same time it also goes down. We use reflector technology to direct the light.
“The INTER fixture has one bank of LEDs. Some other interlight fixtures are larger and heavier units because they have two LED circuit boards back-to-back putting light out on each side of the fixtures.”
Eight of the 4-foot INTER fixtures can be run together using one driver. Moody stated interlight fixtures need to be lightweight because growers hang them on crop wire or whatever is being used inside the crop.
The INTER fixture is not yet available for the U.S. market. “We are still finalizing our UL listing in the U.S. for the INTER fixture,” Moody said. “This fixture is available in the red/medium blue spectrum. The INTER fixture is expected to be available for the U.S. market by the end of the first quarter.”
P.L. Light Systems HortiLED MULTI
The P.L. Systems HortiLED MULTI fixtures are being used primarily for propagation, young plant production and vertical farming.
“Just like with the TOP fixtures, our MULTIs are available in 80º and 150º distribution outputs,” Moody said. “We also have two different lengths, basically a 4-foot (122 cm) and 5-foot (152 cm) fixture. These fixtures have an integrated driver and are available in low and high output versions. There are some applications where a low output is needed, better uniformity, closer to the crop like with tissue culture and early plant propagation applications. The high output fixture is for later in propagation or for propagation of bigger plants. For the MULTIs we can do numerous light spectrum combinations.”
Moody said the MULTI fixtures are ideal for vertical farming applications. “We can do vertical growing with lettuces, mixed greens, microgreens, all of those under these lights as well. Our MULTI lights have a higher output than most other LEDs used for this application.
“For propagation most growers use multiple layers. Typically they are built with two to four layers on racks. The MULTIs were designed to be installed on the underside of a rack pointing down toward the crop below it, from 9 inches to as far away as 2 feet from the crop.”
Grodan stone wool products offer the benefits of high irrigation efficiency, plant steerability and uniform crop development.
Grodan stone wool substrates are made from basalt rock that is processed at a very high temperature (over 2,900ºF). This hygienic, inert substrate offers vegetable and ornamental plant growers the opportunity to control growth from propagation to harvest.
“Grodan stone wool products are inert,” said Rens Muusers, Grodan Technical Sales Manager for the USA. “This means the grower has full control over what is happening in the substrate. Being inert, Grodan stone wool doesn’t bind nutrients and chemicals like other substrate types may do. Any fertilizers, pesticides or other chemicals, including growth regulators, that are applied to the stone wool are available to plants.
Linked to stone wool’s inert nature, Muusers stated growers have more opportunities to steer their crops.
“Other substrates that aren’t inert may bind elements, pesticides or other chemicals that are applied to enhance plant growth or health,” he said. “This may result in having to apply more of a chemical in order to have the same efficacy. The amount of chemical that will need to be applied to stone wool will be lower and it will be more effective than in non-inert substrates. This also helps growers to minimize their input costs.
“Using methods to control water content and EC (electrical conductivity) levels within the substrate allows growers to influence plant growth.”
Muusers stated by controlling the water content and EC in the stone wool, growers can influence the plant balance between vegetative and generative development.
“The steerability offered by Grodan products can result in earlier production, improved plant, fruit and flower quality and improved plant health,” he said. “All of these benefits result in better resilience to insect pests and disease pathogens.
“Also, stone wool can have a buffering impact on the pH in the nutrient solution, slightly increasing pH in the substrate. This increase is minimal compared to the impact of plant and microbial activity in the root zone on pH.”
Muusers indicated another benefit of using stone wool is crop uniformity.
“Because Grodan stone wool products are manufactured in state-of-the-art facilities with strict standards and quality controls, it is a very uniform substrate,” he said. “Depending on the Grodan product being used, this allows growers to produce very uniform crops. The uniformity of seedlings produced in stone wool plugs results in faster germination and quick crop establishment.
Grodan AO plugs and Grodan AX plugs
Grodan AO and AX stone wool plugs are ideal for starting many crops. The plugs are available in sheets that fit into 1020 trays. AO plugs are connected to each other at the top of the plugs. AX plugs are attached to each other at the bottom of the plugs. Muusers said there are also some options in regards to the seeding hole size as well as with the dimensions of the plugs.
“The properties of the AO plugs are exactly the same as the properties of the AX,” he said. “The only difference is where the plugs are attached to each other.
Grodan AX 25/40 cube with lettuce roots and stem post-harvest.
“AO plugs are ideal for NFT systems with smooth gutter surfaces and also for deep flow systems. Some NFT systems use gutters with grooves on the surface for which growers may prefer the wider base and greater bottom surface area of the AX plugs which may be more stable in these systems.”
Muusers said both plugs are used mainly for leafy greens and culinary herb production. There are also growers who are using them for aquatic plants.
Grodan Cress Plate
The Cress Plate is a fairly new product used primarily for the production of microgreens. It is the thinnest product of Grodan. It is only 1 cm thick, less than ½ inch.
Cress Plates come in two sizes. One size fits into 1020 trays. A larger size is used by some growers who need customized sizes. Growers are able to cut the Cress Plate sheet to the exact size they need.
“The Cress Plate has the same beneficial characteristics as other Grodan products,” Muusers said. “It’s inert, clean and hygienic. It’s a uniform product. It holds water evenly. The Cress Plate also provides quick, easy germination and even development of a microgreen crop.”
Muusers indicated growers use Cress Plates in a couple of ways.
“Some growers sell the microgreens with the Cress Plate, essentially selling a living product,” he said. “This allows the end consumer to use the freshest product longer, something that is valued by customers like restaurants. “Growers who produce baby greens and baby lettuce tend to harvest off of the Cress Plates. By harvesting higher up the plants, the plants continue to grow and produce for several harvests. This multiple harvest method is preferred to the uncommon practice of reusing substrates.”
Muusers stated reusing the Cress Plates is risky, just like reusing any substrate.
“There is the possibility of sterilizing the used substrate with steam or some other technique,” he said. “When a sterilizing technique like steam is used, it can have a negative impact on the properties of the substrate. I wouldn’t recommend harvesting and then resowing on top of a previously used Cress Plate because of the risk with potential disease issues and the potential negative impact on germination and growth.”
Grodan Delta Blocks
Grodan blocks come in different sizes and are ideal for both ornamental and vegetable crops.
“Depending on the crop, once a seedling is germinated in a plug it can be transferred into a block and then transplanted into a finish substrate to be grown on,” Muusers said. “Tomatoes and peppers are usually propagated in plugs and then transplanted into blocks. The final grower purchases the young plants in blocks and transplants them into the final substrate such as Grodan slabs. For cucumbers, which are a relatively quick crop, those are sometimes sown directly into blocks, instead of plugs.”
There are different size blocks for different size crops. A standard block size is 10 cm-by-10 cm-by-6.5 cm, which is referred to as a 4-inch block.
Muusers indicated that some growers put multiple plants into one block depending on the crop.
“For tomatoes, growers are looking for a certain head density per square meter,” he said. “The head density per square meter is sometimes achieved by growing multiple plants or by pinching the plants. Tomatoes are the primary crop that growers plant more than one seedling in a block.”
Muusers stated this method of planting multiple plants is also done with cucumbers and peppers. Another reason a grower sows multiple plants into blocks is to try to save on the cost of the blocks.“Some growers use 6-inch blocks instead of 4-inch blocks and put two plants in them,” he said. “In my opinion, it is always better to put one plant in one block. There is less competition resulting in better seedling uniformity as well as a more uniform crop.”
The blocks, like the plugs, are inert and are steerable. Muusers stated the blocks are also important in regards to irrigation efficiency—how the water content and more particularly, the EC, are refreshed within the substrate.
“Grodan focuses on good root growth and uniform root growth throughout the blocks,” he said. “Also, the blocks need to be able to withstand the rigors of handling during propagation. Their structure must remain stable throughout the growing process to be able to support the plants especially when the blocks are moved around. The blocks won’t break or fall apart.”
Grodan Gro-Slabs
Muusers indicated that Grodan slabs come in different product types developed to meet the challenges and needs of different crops.
“We have different slab types for different applications,” he said. “The slabs differ in fiber orientation and fiber thickness to deliver the kind of functionality a grower is looking for. The Grodan plugs and blocks have the same fiber orientation. They are designed for quick root establishment.”
There are Grodan slabs designed for vegetable crops. These crops are usually short term, less than one year. There are slabs designed for longer horticultural ornamental crops that are grown for longer than a year. The slabs for long term crops, including cut roses and gerbera, have a stronger fiber structure to withstand the longer production period.
“Grodan slabs are very uniform,” Muusers said. “Since the substrate is inert, they offer a high degree of crop steerability. This offers a lot of options for irrigation strategies combined with the substrate to influence plant development in a vegetative or generative way.”
David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com.
Before growers invest in supplemental lighting they need to determine the impact of natural light levels on their crops.
One of the things that University of Florida horticulture professor Celina Gómez tries to reinforce with growers when talking about supplemental lighting is the importance of the daily light integral. Daily light integral is the sum of photosynthetic light (photosynthetically active radiation) received by plants in a day. Gómez did a presentation on “Yield Responses to Supplemental Lighting” at the Northeast Greenhouse Conference in November.
“Solar DLI will determine the light intensities that growers need and for how long they will need to run supplemental lights or even if they need supplemental light,” Gómez said. “Growers should be aware of the DLI whether they are growing greenhouse vegetable or ornamental crops. It is one of the most critical factors.
“Fruiting vegetable crops have a fairly high DLI requirement, usually between 20-25 moles of light per square meter per day (mol·m-2·d-1). For most ornamental crops, the DLI won’t likely be more than 12 moles since growers are not trying to develop fruit.”
Celina Gómez, environmental horticulture professor at University of Florida, said knowing the solar DLI will determine a grower’s need for supplemental lighting. Photos courtesy of Celina Gómez, Univ. of Fla.
Gómez said growers may find it difficult to determine the optimal DLI for various crops.
“This information isn’t the easiest to find and there can be differences between similar species,” she said. “Finding the optimal DLI can be especially difficult to find for uncommon horticultural crops. During my presentation I had one greenhouse grower ask me about the optimal DLI for potato seed production.”
While knowing a plant’s DLI is important, Gómez said it is just as important for growers to know how much light is being delivered by the sun.
“Knowing what a crop is getting from the sun will determine how much a grower is going to need supplemental light or if he even needs supplemental light,” she said. “A grower may benefit from supplemental light for only a few months or for most of the entire year depending on the crop and its DLI.”
More accurate light measurement
Gómez said one area where growers are making progress is how they are measuring light intensity.
“After so many years of talking about the best way to measure light that is useful to plants, growers are realizing how to more accurately measure light,” she said. “They realize the importance of monitoring the light intensity that their plants receive from sunlight.
“I expect that more growers have invested in quantum sensors to measure light intensity and if they are still using light meters they realize they have to be able to figure out how to convert those readings that makes sense in regards to plant growth. The growers are getting it and making the conversions from footcandles to other metrics like moles.”
Still learning about LEDs
Even though growers better understand the importance of DLI, Gómez said growers can still be overwhelmed by the choice of supplemental lights available, including high pressure sodium (HPS) and light emitting diodes (LEDs).
“Most growers don’t know exactly what specific wavelengths or spectrum or what light recipe are best for their crops,” she said. “In the case of LEDs, most growers are choosing white LEDs or a combination of colors like red and blue. When I started my PhD in 2011, most available LED arrays came in combinations of red and blue. More LED light manufacturers are adding wavelengths to their range, but most commercial LED units come with fixed wavelengths.
“Most growers don’t know which specific wavelengths work best for their crops. They are relying on what they are told by the LED manufacturers. If the growers know what they want to do with a crop, then the university researchers working with the LED manufacturers could be able to advise growers on what LED lights they should be using. It’s also going to be cheaper for the light companies to manufacture fixtures with a standard recipe than to try to come up with a specific recipe for every grower.”
Gómez said LEDs have been more widely adapted by controlled environment agriculture growers operating vertical farms and warehouse facilities.
LEDs have been widely adapted by controlled environment agriculture growers operating vertical farms and warehouse facilities. Photo courtesy of Farmbox Greens
“While an increasing number of greenhouse growers are interested in LEDs, more of these growers are still using high pressure sodium lamps,” she said. “I generally don’t recommend that greenhouse growers switch from HPS to LEDs just yet. There is more information that needs to be determined for LEDs. HPS is the more established technology and greenhouse growers know what they are getting with these lamps in regards to light intensity, light quality and lifespan. When it comes to greenhouse applications, LEDs can still be considered a high risk technology for growers. Most greenhouse growers are still waiting to make the transition from HPS to LEDs.”
Additional LED research
Gómez said many of the research papers published about LEDs have focused on the effect of light quality or spectrum on several different crops.
“A lot of the plant responses are also affected and dependent on the intensity of light or light quantity– high light vs. low light,” she said. “Under different light intensities plants are going to have different responses. There is also the potential for differences in cultivar responses. Most growers are not going to use a specific red, blue, far-red, white, whatever ratio of light quality for one particular cultivar when they have hundreds of different cultivars in their production facilities.”
Another area Gómez said still has to be determined is the lifetime of the LEDs used in production greenhouses.
“This has to do with the greenhouse production environment where there can be high temperatures, high humidity and chemical application residues,” she said. “The life expectancy of a LED installed in a greenhouse in Alaska is not likely to be the same as the life expectancy in a greenhouse in Indiana due to the different environmental conditions within the greenhouses.”
Another area that Gómez said could use more research is the area of LED interlighting or intracanopy lighting.
“This is something that we were interested in when I was a student at Purdue University,” she said. “This use of LEDs even has potential applications in areas that have high light levels.
“There can be a lot of shading within the plant canopies of high wire crops like tomatoes, cucumbers and peppers, even if the light levels overhead are high. Research still needs to be done with intracanopy lighting and with the light quality of intracanopy lighting. The light quality for this intracanopy lighting may need to be different than the light quality for overhead lighting.”
Gómez said the use of intracanopy lighting could potentially provide light to those leaves that are shaded by the upper canopy or by neighboring plants.
Intracanopy or interlighting LEDs could potentially be used to increase fruit number, fruit size and fruit quality of high wire crops like tomato.
“Those leaves may be receiving low levels of light and not photosynthesizing so they are not contributing to the photosynthetic production of the plant,” she said. “There is the potential of using intracanopy lighting to increase the photosynthetic activity. We don’t know yet if that is true or if that is even going to make a difference in terms of production.
“We don’t know if the plants have already reached their maximum genetic potential. We may find out that there is increased photosynthetic activity with intracanopy lighting. The increase in overall production could include number of fruit and size of fruit. Another benefit is that a specific light wavelength could increase fruit quality. That could potentially be done with intracanopy lighting by placing the fixture close to the fruit clusters. In the case of tomatoes the levels of beneficial compounds like lycopene might be able to be increased.”
For more: Celina Gómez, University of Florida, Department of Environmental Horticulture, Gainesville, FL 32611-0670; (352) 273-4568; cgomezv@ufl.edu; http://hort.ifas.ufl.edu/people/celina-gomez.
David Kuack is a freelance technical writer in Fort Worth, Texas; dkuack@gmail.com.
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.”
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.
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.”
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.”
Next Generation 2.0 (NG2.0) is the latest substrate technology from GRODAN. This technology enables propagators and growers to produce more while using less water, nutrients and space. It creates optimal growing conditions for a whole season, and allows roots to make better use of the entire substrate. NG2.0 is available in plugs, blocks and slabs to help growers and propagators produce sustainable, healthy fresh produce for a growing population.
The growing world population means the demand for sustainably produced and healthy fresh produce is continuing to increase. The greatest challenge facing growers is creating the ideal conditions for growth: not just for a few weeks, but all year round. Precision Growing plays a vital role in this respect. It gives growers the opportunity to produce more using less water and nutrients.
The next step in Precision Growing
GRODAN introduced Next Generation Technology in 2007. Its introduction already signaled a giant leap forwards in crop management, plant steering and root development. NG2.0 is an exciting continuation of this technology that has been extensively trialed in practical situations over the past years. The response to NG2.0 is extremely positive. NG2.0 is the next step in Precision Growing (see video below).
NG2.0 adds new benefits to those already offered by Next Generation Technology. Water distribution is even more uniform and even better utilization of the entire substrate volume by the crop is ensured.
Continual new growth of roots in both the block and the slab results in a healthier and more vigorous crop throughout the whole growing season. These benefits translate to higher yields, improved fruit quality and reduce the sensitivity of the crop to diseases. NG2.0 creates the perfect substrate for growers and propagators of plants.
Phased transition to NG2.0 in North America
Beginning in 2016, GRODAN will implement NG2.0 starting in the Netherlands in a phased in approach.
Future launches of NG2.0 will occur in other markets in Europe and North America. For more information on your specific area, please contact GRODAN (see below).
About the GRODAN Group
The GRODAN Group supplies innovative, sustainable stone wool substrate solutions for the professional horticultural sector based on Precision Growing principles. These solutions are used in the cultivation of vegetables and flowers, such as tomatoes, cucumbers, sweet peppers, eggplants, roses and gerberas.
The Group offers stone wool substrates together with tailor-made advice and tools to support Precision Growing, facilitating the sustainable production of healthy, safe, and tasty fresh produce for consumers.
Sustainability plays a prominent role at GRODAN, from the production of stone wool substrates to end-of-life solutions.
Founded in 1969, the GRODAN Group is active in more than sixty countries worldwide. The Group’s head office is in Roermond, the Netherlands.
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