Brief Summary of Minutes of Annual Meeting

1. Evaluate biomass derived fuels for greenhouse heating (NE, NJ, NY).

NE tested different biomass fuels for greenhouse heating, including: whole shelled corn, dry distillers grains pelletized, wood pellets and blends between each biomass. Bomb calorimetry tests were performed on each biomass fuel and their respective ash residue obtained from an actual field burner test. Furnace and heat exchanger efficiency and cost effectiveness for each fuel type was determined. Emissions data was measured for each fuel including: carbon monoxide, carbon dioxide, nitrous oxides, sulfuric oxides, and particulate matter. A commercial biomass furnace was used for a greenhouse at Firth, Nebraska and compared to a propane furnace. The biomass furnace generally had a lower efficiency than the 81 percent, advertised for the propane furnace. Biomass furnace efficiencies typically ranged between 50 and 80 percent. During the four year study period (2008-2011),cost savings using biomass fuels ranged between 30 and 60 percent totaling over $15,000, when compared to propane. Biomass fuels were found competitive, cost effective, and sustainable when compared to propane. However, at typical natural gas rates, natural gas will be more cost effective. In rural greenhouses this is not an issue due to the inability to utilize natural gas. A grower should watch market prices and buy in bulk when costs are cheapest, specifically during non heating seasons if possible.

NE collected air emission samples for four biomass fuels. These results were statistically analyzed and determined to be significant. These tests provide more understanding into biomass emissions, although they are furnace specific. The statistical analysis confirmed the hypothesis that emissions increased with increased combustion temperature, and that corn and corn blends will emit more NOx and SOx than wood pellets.

2. Develop decision support systems for alternative fuel heating systems (NJ, NE, NY, PA, CT).

NJ: a PhD student (Ariel Martin) continues to develop a decision support system for the operation of a landfill gas fired microturbine system that delivers electricity and heat to a one-acre research and demonstration greenhouse located near the NJ EcoComplex.

NE, working with a commercial greenhouse cooperator at Firth, David Mabie (graduate student) developed the prototype LabVIEW® (National Instruments, Austin, TX) fuzzy logic greenhouse air temperature control system. LabVIEW was also used for a greenhouse heat loss calculator virtual instrument (VI). The heat loss calculator was based on the American Society of Agricultural and Biological Engineering (ASABE) Engineering Practice (EP406.3). The program estimates the total heat loss for each wall and the floor of the greenhouse with a final computation the total heat loss. A major advantage of using LabVIEW is the integration of simulation with hardware instrumentation and control. During the 2009 and 2010 production seasons, the grower kept a detailed record of both biomass and propane usage. Biomass usage in the feed hopper tank was measured volumetrically to determine the use of fuel. The burner control and the ventilation fan operation events were logged with a LabVIEW program, described in previous progress reports. The temperature rise over the cold side heat exchanger of the biomass furnace was also continuously logged along with the greenhouse environmental data. In 2010, the growers cooling system was reduced to one ventilation fan, because of an electrical problem. The greenhouse was therefore kept more of a closed condition. The greenhouse temperature was cycled between around 20°C at night and 24-25 °C during the day. The 2010 burn efficiency calculations were similar to the 2009 results. During the 2010 period, the biomass burner was able to meet steadily the 160 to 180 thousand Btuh heat loss rate of the greenhouse to maintain the desired air temperatures. There was about 26% cost savings for the heating season and a 48% savings, comparing biomass to propane during a 6-8 week growing period. One problem during low heat demand was overheating of the greenhouse, when the biomass system was left running. Another difficulty was to manually re-fire the biomass system every evening (labor and start up fuel). An automatic ignition would be preferred. A secondary heat recovery exchanger for the biomass burner flue is still being considered by the grower for improved efficiency. Overall, the grower was quite pleased with the operation.

ME has been collaborating with Georgia to develop a model that predicts plant water use in greenhouses based on environmental conditions. To develop the model, a capacitance sensor automated irrigation system is used to maintain plants at constant and high volumetric water contents (q = 0.40 L"L-1). Concurrently, light, temperature, and vapor pressure deficit are monitored. Regression analysis is used to develop the model. Previous research (Kim et al., 2011) indicated that light was the most important variable driving plant water use in greenhouses, particularly in Georgia. However, in a study conducted in the fall in Maine, light did not significantly impact water use of the shade tolerant plants Heuchera Palace Purple and Mint Frost. Vapor pressure deficit was the strongest factor impacting plant water uptake. It seems that more research should be conducted to strengthen our model.

Topic 2: Water and nutrient solution management

3. Develop protocols for irrigation that maximize water use efficiency while maintaining crop growth and quality (CT, ME, NE, PA, NY, OH, AZ). NE used capillary Mat (CapMat, Phytotronics, Inc, Earth City, MO USA) to water and fertigate a winter strawberry, cultivar, production study in a UNL East campus Quonset greenhouse. Plants were grown on two separate 6 ft by 60 ft benches with CapMats from January through April. Six-inch pots were interfaced with the CapMat fabric, along with 4 mil white polyethylene as a reflective mulch and vapor barrier. CapMats were wetted using twin wall tubing installed under the capillary fabric. A special jig device was developed to allow pots to access the fabric through the polyethylene mulch. Individual flag pots of strawberries were monitored with capacitance moisture sensors (Decagon Devices, Inc. Pullman, WA), calibrated to the potting mix formula, and installed at three zone locations (north, middle, and south) over the sixty foot length of each bench. An automatic clock typically fertigated the CapMats on selected time event schedules. However, the daily watering event had to be adjusted according to crop and environmental conditions to minimize night time humidity levels and to reduce plant disease and pest pressure. An electronic meter was used to measure greenhouse water use during the growing period. The pots were adequately watered at the three zones (50-60% volumetric content). An electronic gas meter was used to monitor natural gas use. Furnace and ventilation events controlled by a Groton II system (ACME Engineering and Manufacturing, inc., Muskogee, OK) were also monitored using electronic split core, current sensors and LabVIEW programming. The strawberry cultivar study was conducted during both 2010 and 2011, and is expected to continue in 2012. Stomatal canopy resistance was simulated, as a LabVIEW control variable for the strawberries grown in an East Campus Greenhouse and CapMat fertigation system. An adaptive, real-time dynamic energy model (VI) based on the First and Second Laws of Thermodynamics and psychrometrics accounted for canopy entropy production, net radiation, sensible and latent heat exchanges for the strawberries. Measured canopy TLeaf and air temperatures Tair, relative humidity fair, and radiation data were transmitted wirelessly from three bench zone locations to a host computer, using sensors and National Instruments LabVIEW® software. Stomatal resistance (rLeaf - s/m) was simulated as a LabVIEW Proportional Integral Differential (PID) controller (subVI) in order to balance net energy for the canopy. Latent results compared favorably from draw-down pot moisture contents, measured with the capacitance sensors.

OH used an Argus Nutrient Delivery System to deliver water and nutrients to 488 trees during the 2010 summer growing season. The system was custom designed and constructed to accurately and precisely deliver nutrient solutions during short irrigation events (5 to 10 min) in small volumes (10 to 50 L) to container-grown plants typically required for treatments in research plots. Five nutrient treatments were specified and delivered to 200 Austrian pine (Pinus nigra) trees after which the trees will be subjected to canker and insect induction summer 2011. In a second project, 180 trees were grown using three nutrient treatments to determine the effects of imidacloprid application and fertilization regimes in the nursery on subsequent establishment, growth, stress tolerance, and rates of carbon sequestration of common shade trees Homestead elm (Ulmus × Homestead) and Heritage river birch (Betula nigra) after transplanting to an urban street right-of-way in the Wooster, Ohio. Finally, 108 trees were grown for a third project that was designed to determine the effect of fertility and sugar (sucrose) application on the concentration of carbon, nitrogen, condensed tannins and phenolics (secondary metabolites) in hybrid poplar trees (Populus nigra clone 5271) and the photosynthetic rates and overall growth of the trees. For the first time, the nutrient delivery system successfully controlled pH for all treatments to a specified set point of 6.0 (+/- 5%) using a dilute sulfuric acid solution.

4. Develop irrigation protocols and filtration or sterilization methods for nutrient solution recirculation that minimize the effects of pathogens or toxic metabolites (CT, NY, OH).

NY: Pythium aphanadermatum zoospores reproduce more slowly as hydroponic solution temperature decreases. This is especially important with spinach production, for spinach is particularly sensitive to the disease. Experiments showed there was no significant difference between the final harvest fresh weights of the spinach plants grown with a root zone temperature of 15 C and those of plants grown with a root zone temperature of 20 C. Moreover, there was no significant difference between the leaf areas of plants grown under the two, suggesting that lowering the root temperature to 15 C may provide/allow for greater disease control or a longer spinach crop cycle without losing productivity or changing the appearance of the product. Chilling nutrient solution in a floating hydroponic system required relatively little energy due to the presence of insulating rafts between the solution and the greenhouse environment, used to hold the plants.

NY: Worldwide, greenhouse operations face increasing pressure to reduce irrigation demands and/or use poorer quality (high salinity) irrigation water. Led by graduate student, Gonzalo Villarino, we have addressed short term needs by developing salt management guidelines (i.e. threshold levels) for several common floriculture species. Results of this effort were published as a two article series in Greenhouse Grower Magazine and are in press in the journal HortTechnology. We are also using molecular techniques to learn more about processes that plants use to mitigate salt toxicity. The naturally occurring sugar, trehalose, has been found to enhance salt and drought tolerance of several crops when precursors to its formation (TPS and TPP) are over-expressed. However it is not well understood if this is due to trehalose acting as an osmoprotectant or rather due to signaling and metabolic responses. We are using a combination gene silencing/overexpression approach using Petunia as a model species to elucidate the role of the trehalose pathway in abiotic stress tolerance.

CT: Using recycled nutrient solution to water plants is the preferred legislative solution to prevent groundwater pollution from intensive agricultural production. Several potential problems may arise from recycled nutrient solutions to produce vegetable crops. Accumulation or deficiency of elements in nutrient solutions could have deleterious effects on plant growth, product quality, and the dietary value of vegetables. We examined the composition of a nutrient solution as it was periodically recycled to a greenhouse tomato crop (Solanum lycopersicon L.), in comparison to solutions that were used to water plants only once. Crops were grown in spring and summer in a greenhouse using rock-wool as the root medium. The transition from vegetative to fruit growth, and from cool to warm weather, resulted in a decreased demand for nitrate, and other nutrients, and an increase in electric conductivity of water drained from the root zone. These changes were greater for recycle than discharge systems, and the recycle treatment took longer to return to an optimal composition. There were no consistent effects on yield, and little difference in composition of fruit or vegetative tissue, despite the large but temporary variation in composition of the nutrient solution due to recycling. Outcomes: Information was conveyed to commercial growers via by conversations at growers meeting in Connecticut, at the experimental farm, and at their commercial operations. The general public was informed of the results through demonstrations and displays at the public open house at our experimental farm. Recirculation reduces the amount of fertilizer used to grow crops and it avoids the discharge of nutrient solution to aquifers or to treatments facilities. Recirculation can be used by the more than 50 greenhouse vegetable growers in Connecticut, only if this process does not lead to poor yield, spread of disease, or an imbalance in nutrients. So far, this refinement has been adopted by growers who produce lettuce in hydroponics, but not by growers who produce tomato crops.

OH: a Controlled Nutrient Delivery System (CNDS) designed by Bauerle continued to successfully inject essential plant nutrients at specified recipes for optimization of plant growth at a large commercial nursery. Chlorine dioxide was used in a water cleansing system to control plant pathogens in recycled effluent water. The recycled effluent was ponded with fresh water from Lake Erie. These ponds provided source water for the nurserys irrigation system. The pH of this ponded water was monitored and recorded every 5 min during the 2010 summer growing season. Even though these measurements ranged from a pH=7.5 to pH=9.5, the CNDS was capable of delivering water and nutrients to a targeted pH=6.5 thus assuring continuous availability of major and minor elements to the plants throughout the growing season.

Topic 3: Sensors and control systems

5. Improve volumetric water content sensor efficacy (ME, NY, OH). During summer 2010 OH continued a cooperative project with Willoway Nurseries, Inc. that was initiated summer 2008. Decagon 5TE Volumetric Water Content Sensors were randomly installed in four 400 tree plots (five sensors per plot) at Willoway Nurseries in Avon Lake, Ohio, summer 2010, to test their ability to monitor moisture level, EC and potting medium temperatures. Four Em50 Decagon Data Loggers were installed to record the data. A lap-top computer was used to download the data from the Em50 data loggers in the field. A continuously recording pH sensor was also installed (Spring 2010) and used to record diurnal variations of pH in a pond used to store recycled nutrient solutions at Willoway. Analysis of the data is pending.

6. Improve sensor control of the greenhouse aerial environment (light, carbon dioxide, temperature, and moisture) (NJ, OH, NY, NE, AZ).

Sensors and a datalogger were used in a greenhouse section of the EcoComplex greenhouse that is used for orchid production. Temperature, PAR, relative humidity, wind speed, and wind direction are recorded in an attempt to better characterize the indoor environment. This project is ongoing. NY has fabricated and installed a beta version of a Daily Light Integral (DLI) controller in a commercial greenhouse in Ontario, Canada. The controller implements the DLI control algorithm patented by Cornell. Operation of the DLI controller will be monitored and quantified for one year. Other sites are being investigated currently to provide a range of climate and solar conditions for beta tests.

NE developed and successfully tested a LabVIEW instrumentation and adaptive canopy energy balance model for collecting crop and environmental data to assess energy utilization, moisture condensation potential, and production performance within the greenhouse. Zone loggers communicated with a master computer using wireless technology. A system was operated with a biomass heated greenhouse at Firth, NE. Weather, greenhouse environment, and crop canopy were monitored every ten minutes. A fuzzy logic controller was also integrated for improved biomass furnace control. Adaptive energy model responses including pot-canopy water use could be viewed over the internet. Both the Firth cooperator greenhouse environment and surroundings and Campus strawberry houses were monitored at 10-minute intervals, 24-hours per day by a set of data loggers. Each house was divided into three measurement zones for air temperature and humidity, total and photosynthetically active radiation (PAR), plant temperature, floor temperature, potting soil temperature, and inside roof glazing temperature. Data was used to calculate the current sensible and latent heat exchange rates of the crop with their surroundings and moisture condensation potential on the leaves, floor, and inside glazing throughout each day from early January to late April. Outside air temperature, total solar radiation, and wind speed were also measured, but backed up with hourly data from Lincoln supplied by the High Plains Automated Weather Data Network. Ventilation fan, unit heater, and biomass burner operations are monitored with non-intrusive, split core current sensors, placed on the appropriate electric supply and control wires. A continuous record and calculation of greenhouse nighttime heat loss and daytime heat gain was obtained. OH conducted data analysis to evaluate a model as a part of establishing a user friendly interface that will allow a decision support tool to be used for general exploration. The tool can be used to analyze cooling requirements or the heat harvesting potential of user specified greenhouses by providing information such as greenhouse structural design, local weather information, and desired temperature set points.

Topic 4: Environmental effects on plant composition

7. Develop greenhouse design and management protocols to maintain high nutrition values of vegetable crops grown under various environments (AZ, CT, NJ).

CT: Composition of hydroponic lettuce: Effect of time of day, plant size, and season. Background: The diurnal variation of nitrate and sugars in leafy green vegetables may vary with plant size or the ability of plants to buffer the uptake, synthesis, and use of metabolites. Bibb lettuce was grown in hydroponics in a greenhouse and sampled at 3-hour intervals throughout one day in August 2007 and another day in November 2008 to determine fresh weight, dry matter, and concentration of nitrate and sugars. Plantings differing in size and age were sampled on each date. Results: The dry/fresh weight ratio increased during the daylight period. This increase was greater for small compared to large plants. On a fresh weight basis, tissue nitrate of small plants was only half that for larger plants. The variation in concentration with time was much less for nitrate than for soluble sugars. Soluble sugars were similar for all plant sizes early in the day, but they increased far more for small compared to large plants in the long days of summer. Conclusions: The diurnal variations of nitrate and sugars were not complementary. Delaying harvest to later in the day would increase dry matter and sugar concentration, but it would have little effect on nitrate. Outcomes: Several growers have started producing salad greens in greenhouses and high tunnels, and lettuce in hydroponics. In part this is due to information developed by this project and previous projects on this subject.

NE conducted a greenhouse, winter-time strawberry cultivar and production management study in 2011. Strawberry nutraceutical data (spring 2010) indicated a consistent range in total phenols (1.06 -1.84 mg /g). Nine of the cultivars showed significant differences when compared to the very lowest level. Similar results occurred with total flavonoids (0.28-0.62 mg/g). The antioxidant capacity study showed significant difference in varieties with Strawberry Festival and Darselect (73-75 uM/g) having more antioxidant capacity than Honeoye, Albion and AC Wendy (32-49 uM/g). Additional biochemical results for 2010 and 2011 winter grown, strawberries are currently not available for this report. The best producing strawberry cultivars - Fall/Winter 2010-2011 production peaked during the weeks of December 4 and 11, and included Albion, Chandler, Darselect, Clancy and Seascape which produced the largest amount of total berry mass and numbers. Water and natural gas usage for 2011 was 43 gal and 1920 ft3, respectively. Data from the Spring 2010 study showed that the sugar concentration and sweetness index were highest in the cultivars Albion and AC Wendy. Unfortunately these are also the cultivars with the lowest anti-oxidant capacity. Other high sugar cultivars included Strawberry Festival, Honeoye, Seascape and Dar-Select. We are waiting for the Spring 2011 results before final selection of the cultivars for 2011-2012. Preliminary start-up costs estimates. Using a selected greenhouse company as a source it appears that a 25-ft x 75-ft double poly greenhouse, with low-cost benching would cost between: $20,000-$35,000. Other companies have been contacted to provide alternative prices. Time-motion studies are underway to determine labor costs for winter-time strawberry production in Nebraska. The project has also been tracking consumer strawberry prices at traditional food markets to determine times for peak retail pricing.

8. Develop greenhouse design and management protocols to maximize production of beneficial compounds such as phytochemicals and biopharmaceuticals (NY, AZ, CT, MI, NJ).

MI: Oomycete pathogens cause significant losses in greenhouse and field ornamental and vegetable operations, and have developed resistance to control products. Oomycetes can persist for long periods of time in soil and/or plant material, and be present in irrigation water sources. Nine replicated efficacy trials with 95 treatments tested 33 products in the greenhouse and field for oomycete control. The greenhouse plant activator product, A9180A, prevented downy mildew on coleus when applied alone (0.25, 0.5 or 0.75 oz/100 gal) or tankmixed (0.5 oz + azoxystrobin 4 oz/100 gal) as a spray 10 and 3 days before inoculation (DBI). It was equally effective as a drench applied alone (0.25 oz or 0.9 oz) or tankmixed (0.25 oz + azoxystrobin 0.9 oz) 17DBI. Fluopicolide performed well in 7 trials. In the greenhouse, fluopicolide prevented basil downy mildew (1 foliar spray, 2 fl oz), geranium death due to Pythium ultimum (2 drenches, 4 fl oz), and significantly limited root rot disease of osteospermum due to Phytophthora drechsleri (2 drenches, 14 fl oz). Foliar sprays at 5-10-day intervals of fluopicolide (0.19, 0.25 pt), fluopicolide (0.25 pt) tankmixed with chlorothalonil (2 pt), and fluopicolide (0.25 pt) tankmixed with chlorothalonil (2 pt) and alternated with other products were especially effective at managing cucumber downy mildew in the field; fluopicolide (0.25 pt) was equally effective whether applied as a foliar spray or through drip irrigation. Reduced-risk products azoxystrobin, mandipropamid and mefenoxam showed promise in greenhouse trials. Azoxystrobin prevented basil downy mildew (1 foliar spray, 4 oz), and calibrachoa death due to P. drechsleri applied alone (2 drenches, 0.9 oz) or in a tankmix (2 drenches, 0.5 oz) with another product. Mandipropamid prevented calibrachoa death due to P. drechsleri (2 drenches, 8 fl oz) and basil downy mildew (1 foliar spray, 4, 6, 12 fl oz). Mefenoxam 1 fl oz reduced osteospermum root rot (2 drenches), calibrachoa death due to P. drechsleri (2 drenches), basil downy mildew (1 foliar spray), and coleus downy mildew (1 drench). Volumetric spore samplers were placed at 8 Michigan sites in 2010. Oomycete (cucurbit downy mildew) sporangia were detected in the atmosphere at all sites via the spore samplers by 3-13 May. All sites except Allegan and Frankenmuth had daily sporangial counts <340. Numbers >1,000 were observed at Frankenmuth between 20 Jul and 12 Sep, and peaked at 220,893 on 1 Aug. Numbers >1,000 were observed at Allegan between 10 Aug and 10 Sep, and peaked at 39,915 on 15 Aug. Daily sporangia numbers and confirmation of downy mildew was continually uploaded to the For Growers page at Dr. Hausbeck's website.

Topic 5: Natural ventilation design and control

9. Improve control strategies as an alternative to existing vent control systems (AZ, NJ).

10. Continue our efforts to use CFD techniques to evaluate greenhouse natural ventilation systems (AZ, NY, OH, IL).

AZ continued working on developing 3D CFD models to analyze the effect of high pressure fogging on greenhouse climate uniformity. The study is directed towards analyzing the effects of nozzle placements (i.e. in vertical and horizontal in the greenhouse domain), nozzle placement angles for climate uniformity. AZ actively involved in organization of CFD sessions in GreenSys2011 and also activities of CFD working group under ISHS. AZ is also taking leading roles in the organization of the 1st Symposium on CFD Applications in Agriculture, which will be held as a concurrent symposium under the 2012 CIGR EuroAgEng conference in Valencia, Spain.

11. Continue efforts to improve the efficiency and effectiveness of greenhouse fog cooling systems (AZ, IL, NJ, OH, NY).

AZ developed and implemented a climate control strategy for a naturally ventilated greenhouse equipped with a variable high pressure fogging system. The strategy that was developed included variable rate of fog introduced into the greenhouse, a dynamic control of the air ventilation openings, and it considered the contribution of cooling and humidification from the crop by evapotranspiration. The fogging system was operated to keep a VPD set point and the vents were operated based on an enthalpy set point to achieve a desired greenhouse inside conditions (i.e air temperature and relative humidity) for crop production. The developed strategy maintained the VPD close to the selected set point for all the experimental periods evaluated. Both in simulations and experiments, the enthalpy set point was reached only when the outside air specific enthalpy was lower than the set point and when the fogging rates used were sufficient to humidify all the incoming air needed to reach the enthalpy set point. When both VPD and enthalpy set points were reached, the greenhouse air temperature remained around desired levels. Comparisons of the developed strategy in the study to another strategy based on VPD set point, fixed ventilation opening rates and using a fixed high pressure fogging rates showed that 30.3% and 23.27% higher water and energy savings were possible with the strategy developed. Variable fogging rates strategy maintained temperature (RMSEt=2.87 oC) and relative humidity (RMSERH=7.12%) closer to pre-established set points, compared to the constant fogging rates strategy (RMSEt=4.22 oC and RMSERH=20.07%, respectively).

Other accomplishments not specifically related to the 2008-2013 NE 1035 Multistate Research Project objectives:

A document titled Guidelines for Monitoring and Reporting Environmental Parameters for Experiments in Greenhouses is under development by the International Committee for Controlled Environment Guidelines, chaired by A.J. Both.

One of the most difficult problems for those wishing to create and operate a successful CEA facility is to find head growers able to manage large hydroponic facilities. NY has received funding to initiate a Controlled Environment Agriculture (CEA) and Modified-Environment Agriculture (MEA) technology transfer center for New York State. A series of workshops has begun, ranging from overview presentations for the general public, to workshops focused on potential and current CEA and MEA owners and managers. Additionally, summer internships have been created to begin the process of training employees and managers of CEA facilities in colder climates, such as New York State.

NY has worked with Cycloptics Technologies, LLC (http://cycloptics.com/), to install and test more efficient plant lighting luminaire designs. A walk-in plant growth chamber has been retrofitted with the new luminaires, which provide twice the PPF intensity compared to the T12 VHO fluorescent lighting originally installed. In addition to improved energy efficacy, light uniformity is improved, particularly near the chamber walls. Further luminaire designs have been completed for research greenhouses to light plants uniformly while preventing light spill-over into the aisles, and commercial greenhouses to provide lighting intensity uniformity and improved efficacy. As soon as available from the manufacturer, these luminaires will be installed and their performances monitored and quantified.

NY: Silicon (Si) is not regarded as an essential plant nutrient, but has received increasing attention from the plant nutrition community due to enhanced response of plants in terms of salt and drought tolerance under conditions of adequate Si supply. Floriculture producers want to know if its economically beneficial to add Si. To this end, we have conducted experiments to determine which floriculture species accumulate Si and if there are benefits for abiotic stress tolerance. About half of the species that we have studied show enhanced salt tolerance with Si supplementation. Interestingly this does not seem to depend on the degree to which the species accumulates Si. Silicon also improved the post-harvest performance and drought tolerance of potted Poinsettia plants.

NY: Greenhouse production uses intensive amounts of water and fertilizer. Conventional overhead watering allows excess water, fertilizers, and pesticides to leach to surface and ground waters. In closed irrigation systems, excess water is captured and reused. While these closed systems limit water pollution, most New York State greenhouse producers have not adopted these systems, in part, due to expensive costs of installation. In fall 2010 use of different rates of controlled release fertilizers (CRF) were compared to conventional liquid fertilizers (LF). Nutrient leaching and plant performance was measured. We found that CRF adoption at the label medium to high rate led to plant growth equal to conventional LF. CRFs applied at the medium to high rate led to a reduction in nitrogen and phosphorus runoff by five- to ten-fold compared with LF.

OH: Activities continued at a high level in our Hydroponic Lettuce Research Laboratory during the year 2010. The purpose for research in the Hydroponic Lettuce Research Laboratory is to develop and demonstrate economically sustainable, year-round, high quality, hydroponic horticultural crop production systems that operate well in energy efficient greenhouses. The first experiment for the year was conducted for The Cleveland Foundation starting with germination of seeds January 22. The objectives were to compare two light emitting diode (LED) lighting systems to high pressure sodium (HPS) lighting during winter weather while growing three lettuce cultivars and one herb cultivar in a hydroponic growing system. Yield, product quality, and water and nutrient use efficiency for each combination of cultivar, lighting and nutrient solution temperature were to be measured. The mature plants were harvested February 19. A total of seventeen conclusions/key observations were included in the final report (April 30) to the Foundation. A proprietary agreement precludes the results from being published for two more years. Huntsman International, LLC funded an experiment (Summer 2010) where the objectives were (1) to evaluate the growth of two hydroponically grown lettuce cultivars while using four polyurethane formulations as growing cubes and compare results to lettuce grown using coconut core cubes in addition to rock wool cubes and (2) to measure the impact of three levels of nutrient solution flow rate (1, 2 and 3 Lpm) on fresh weight produced and crop quality. To make these objectives possible, Huntsman funded the purchase of 18 acrylic flow meters (0.4 to 4 Lpm). Based on main effects, the results showed two of the polyurethane cubes yielded the same as rock wool while yields for coconut core were significantly greater. The main effects of flow rate showed fresh weights of lettuce grown at 3 Lpm were over 24% greater than for flow rates of 1 or 2 Lpm. Red Bib out yielded Green Bib for all six types of cubes. After a tornado destroyed our lab and greenhouse on Sept 16, no additional experiments were run in 2010.

PA: A growth chamber was equipped with state of the art LED lighting fixtures and instrumented to monitor energy consumption and chamber environmental conditions. The lighting fixtures used were Philips iW Reach Powercore Architectural Lighting. These fixtures were used because in preliminary research Horticultural LED lighting fixtures were found to have inadequate light output to match the output of standard fluorescent and incandescent lamps used in comparison chambers. Energy consumption by the LED equipped plant growth chamber for lighting was reduced by about 85% and overall electrical consumption by the chamber was reduced by 40% compared to the control chamber. Plant growth was not affected. The fixtures used were much higher cost (~$4,000 each) and light output than currently available horticultural lighting systems and while this project demonstrates the potential for LED lighting, current costs and low light output from horticultural fixtures continue to limit cost effectiveness for commercial greenhouse or growth chamber applications. The fixtures used in this study and electrical use monitoring equipment will be installed in a greenhouse and compared with horticultural HID lighting to measure energy savings and plant growth in a greenhouse.