Brief Summary of Minutes of Annual Meeting

Topic 1: Energy conservation and alternative energy sources 1. Evaluate biomass derived fuels for greenhouse heating (NE, NJ, NY). NE has been working on biomass heating systems for greenhouses. A grower was asked to measure usage of fuel in hopper tank. The dimension of the hopper and depth of leveled grain was used to calculate the volume of fuel used. Actual burner ON/OFF events and other events such as the ventilation fan operation were logged with the LabVIEW program. The temperature rise over the cold side heat exchanger was continuously logged along with other environmental data and events. Average temperature rises over the cold side varied from 40 to 67 F. Air flow through the exchanger was measured around 1200 cfm, using a traverse of velocity measurements across the air inlet port. Based on calorimetric heat values (app. 6200 Btu/lbm) and bushels of corn burned (app. 0.5 bushels/ hour), the total available energy presented to the burner varied from 151, 090 to 198,418 Btuh. Burner output from average measured air temperature rises in the heat exchanger varied from 95,292 to 156,145 Btuh. Heat loss from the greenhouse was calculated using American Society of Agricultural and Biological Engineering practice (EP406.3), taking into account the inside and outside air temperatures along with incidental ventilation events. Using these methods, the apparent biomass, heating efficiency ranged from %39-68 depending on environmental conditions. A secondary heat recovery exchanger for the biomass burner flue is being considered by the grower, the biomass auger control is being reevaluated.

NE tests reflective and transmission coefficients for four different colored commercial mulch plastics (white, black, red and dark olive). The greenhouses were fully instrumented to monitor temperature, humidity, and light quantity and quality and energy. White polyethylene (4 mil) gave the best reflectance coefficients and was chosen as the covering for the capillary mats used in the next phase of this study. Forced air furnaces are used in our prototype greenhouse. A polyethylene jet tube from each furnace runs under each of two benches and all heat is supplied in this manner. Total fuel consumption versus set temperatures is being recorded. Project is ongoing.

NJ, in partnership with other faculty members and a commercial grower, has submitted a proposal to the NE Sun Grant Initiative. The proposal describes a project for the on-farm production of biomass (switchgrass) that, after processing, will be used as a fuel source for greenhouse heating.

2. Develop decision support systems for alternative fuel heating systems (NJ, NE, NY, PA, CT). NJ started on the development of a decision support system for the operation of a landfill gas fired microturbine delivering electricity and heat to a one-acre research and demonstration greenhouse located near the NJ EcoComplex. A survey was conducted with greenhouse growers in New Jersey to determine how they are coping with rising energy costs and how we can help them compete with this uncertainty.

PA researched on using unheated high tunnels for bedding plants to determine which plant taxa were sufficiently cold tolerant to be grown in early spring and to evaluate relative marketability , cost of production compared with those produced in a traditional spring heated greenhouse. A stand-alone Quonset greenhouse served as an unheated high tunnel. A computer controlled greenhouse section was set to heating setpoints of 60 NT and 60 DT, served as the comparison. The ventilation setpoints were 70F day and night. Sixteen species of plants, with 50 plants per species for a total of 2,400 plants, were obtained as propagated material. Liners were transplanted into 4 pots with one-half of the plants placed in a 60 NT greenhouse, the other half moved to the unheated high tunnel. The HT was in a protected location on campus, and had a double layer polycarbonate cover which buffered the interior temperature and prevented temperatures from falling below 32°F when ambient outdoor temperatures were in the 20s. Plants grown in the high tunnel took longer to become salable than those grown in the greenhouse, but not all plant taxa responded similarly. The 1st group of plants tolerated the colder temperatures in the high tunnel and was only slightly delayed in development compared to the plants in the heated greenhouse (i.e. Pansy crop). The 2nd group (i.e. snapdragon) were cold tolerant, but displayed a greater delay for the high tunnel plants to become salable. The 3rd group (Verbena) of plants was not very cold tolerant and was delayed substantially by production in the high tunnel compared to production in a heated greenhouse. The low and variable temperatures in the HT increased the crop time to sale for all the crops in the experiment. The delay depended on crop, and varied from 1-2 weeks to 3-4 weeks. Many plants grown in the HT were more compact than those grown at 60 F and this might seem to be an advantage for the consumer since they look more appealing. Many bedding plants grew well, albeit slowly in an unheated high tunnel, there may be potential to use HT as a part of the bedding plant production system in the Northeast and other areas with similar spring climate conditions.

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).

AZ designed developed a machine vision guided system for plant health/growth monitoring. Objective of the study were to develop a methodology using morphological, textural, temporal plant features for the automated non-contact monitoring and to evaluate capability of developed methodology for early detection of tipburn due to calcium deficiency on lettuce. A robotic camera positioning system and an image processing module structured the system. Extracted plant features included Top Projected Canopy Area (TPCA) as a morphology; Red-Green-Blue (RGB), Hue-Saturation-Luminance (HSL) values as color; entropy, energy, contrast, and homogeneity as textural features. The system was capable of extracting listed plant morphological, textural and temporal features autonomously. The developed methodology was capable of identifying the calcium deficient lettuce plants one day prior to the visual stress detection by human vision. Among the extracted plant features TPCA, energy, entropy, and homogeneity showed to be promising markers for timely detection of calcium deficiency in the lettuce crop studied. The future studies will focus on establishing a multi-sensor based plant monitoring platform for resource savings in CE plant production systems.

AZ continued working with aquaponics system for intensive fish and vegetable production. Research goals of the project include determining the biomass production (fish&plants) that can be achieved per unit of resources (water, nutrients, space), exploring the physiological interactions in the aquaponics system, developing production techniques for large scale applications. The Feed Conversion Ratio is used to measure the production efficiency of fish. Plant biomass and Chlorophyll Concentration Indices are used to determine plant growth and quality. Greenhouse aerial, aquaponics growing variables were monitored/controlled. The complete water chemistry of the system is analyzed biweekly. One year research has established synergistic relationship between the fish component, the filtration component, hydroponic plant component. Current research focused on Tilapia and lettuce.

AZ has designed and constructed an automated and remotely monitored three floating hydroponic system (FHS) for research. The sustainable management of reduced, reused water and fertilizer in this hydroponic system is being evaluated for production of fresh green salad crops. The automated FHS used LabView for realtime monitoring of EC, pH, dissolved oxygen, nutrient temperature in the root zone, and air temperature, relative humidity, light intensity, CO2 in aerial environment.

AZ has initiated a new project on soilless strawberry production under semi-arid conditions. The focus includes efficiency of water and fertilizer use. A preliminary data are being collected and a new proposal was submitted to California Strawberry Commission for the possible funding in 2011.

CT examined a system to rapidly deliver and remove water in ebb and flow watering systems for flooded floors. Less water was absorbed by the root medium and little if any water drains out of the pots. This improved plant quality and prevented spread of disease. Several parameters have been examined varying between this partial saturation ebb and flow watering on a flooded floor compared to full saturation watering. Plants took up 20-30% less water and fertilizer. Biomass until flower development, bloom, stem height, were also reduced by 10-20% under partial saturation. In one experiment with Poinsettia, inoculation of some plants with Pythium resulted in wilting of 20 of 240 non-inoculated plants grown under full saturation. No plants were affected under partial saturation. Post harvest quality of leaves and flowers in a controlled environment were similar under the two watering regimes. Several growers of ornamental potted plants in greenhouses are implementing ebb & flow watering, or increasing the area of production using ebb & flow watering (an increase of about 5 acres in CT in 2009).

ME, collaborating with the Univ. of Georgia, determined how light, temperature, and relative humidity impact water use of two commercially important greenhouse crops: Petunia and Poinsettia. Substrate water content was maintained at 0.45 L/L for both species, and plants were grown in three different container sizes. The amount of water applied to plants was monitored using a datalogger, and modeling was used to determine the impact of environmental variables on plant water use. Plants grown in larger containers utilized more water throughout the experiment and attained greater biomass. Thus far, models indicate that light appears to be the single greatest factor influencing water use in both species.

NE conducted research on using capillary mats to water and fertigate a test crop of thirteen strawberry cultivars. From Jan-Apr, plants were grown on two separate benches with capillary mats in 6-inch pots directly on the mat, over 4 mil white polyethylene as a reflectance mulch. Capacitance moisture sensors were calibrated to the potting mix used and installed in two pots at three zones along the cap-mat for a sixty foot run. All pots seemed to be adequately watered in the three zones (40-70% volumetric content). An automatic clock fertigated the mats for a 5 minute event. A single daily watering event was originally programmed for January, but had to be increased in February and March. Seven of 13 cultivars produced strawberries. In addition to total number and berry sizes, nutraceutical properties are being quantified.

NE studied capacitance moisture sensor to measure volumetric water content in pots growing strawberries in a growth chamber with high pressure sodium and metal halide lights. Photoperiod and temperatures were programmed hourly to match a January day in the greenhouse. A thermodynamic energy balance using leaf temperature allowed estimation of latent heat loss and evapotranspiration. The adaptive model was written in LabVIEW and used a PID module to estimate canopy resistance control. Pot moisture utilization was calculated for two-hour dry down periods and compared with the thermodynamic model. Moisture utilization was within 10% of the latent heat calculation. The thermodynamic model tested in the growth chamber was also used with three zones in the greenhouse and produced similar evapotranspiration numbers. However, the volumetric soil moisture lost in the pots was adjusted for the cap-mat irrigation events.

NY researched to determine if Si improves the salt tolerance of several floriculture species grown in a soilless peat-based substrate. Initial work was to screen twenty-one floriculture species growing in conventional peat-based substrates for Si accumulation and morphological impacts. All species accumulated measurable levels of Si. Eleven species showed enhanced leaf Si concentration with Si supplementation. Several species exhibited subtle but significant changes in growth parameters, such as increased flower diameter when receiving Si; but morphological effects were not consistently correlated with enhanced Si accumulation. Of twenty-eight floriculture species examined, 40 mM NaCl reduced growth of all but one species. Si enhanced growth of salt stressed plants for twelve species, with a dry weight increase ranging from 47 to 152%. Si did not affect growth of unstressed (0 mM NaCl) plants. Experiments were conducted with Impatiens hawkeri (New Guinea Impatiens) to confirm the Si effects and elucidate mechanisms for salt tolerance. Si mediated salt tolerance was likely a result of several mechanisms. Si enhanced NaCl exclusion by roots and increased cell membrane integrity in leaves of salt stressed plants that had Si. Interestingly, Si reduced expression of three antioxidant enzymes (APX, GR, and MDHAR) in root tissue under salt stress, suggesting there was a reduction in oxidative stress of Si treated plants.

NY quantified nutrient leaching and growth of Chrysanthemum in response to liquid fertilizer, CRF, or a combination of the two. Leachate nutrient concentration was significantly affected by fertility treatment and production week. When averaged across the entire sampling interval, liquid fed only plants had five times more phosphorus and nitrogen leaching compared to CRF only. Plant dry weight was significantly reduced for plants not receiving any liquid feed; and plant diameter was reduced for treatments receiving less than 6 weeks of liquid feed. When CRF is used as the primary fertilizer source nutrient leaching can be substantially reduced in garden mum production. But, CRF alone appears unable build up initial substrate fertility required by early vigorous growth of chrysanthemums. We attempted to use higher CRF rates to achieve similar size to liquid fed plants. CRF only treatments dramatically reduced leaching, but none were successful in producing comparable plant size/quality as liquid feed. Four weeks of liquid feed followed by only CRF resulted in a three-fold reduction in nutrient leaching and produced a plant comparable in size to liquid only.

OH has installed Decagon 5TE Volumetric Water Content Sensors randomly in 20 of 200 Austrian pine tree containers in our Landscape Nursery Crop Engineering Laboratory (summer 2009) to test their ability to monitor moisture level, EC and medium temperatures. Four Em50 Decagon Data Loggers were used to record the data. The sensors performed satisfactorily. During summer 2010, a calibration procedure will be developed for these sensors followed by additional testing in container-grown plants. Uncomposted ground pine bark and hard wood chips were evaluated for their physical properties during summer 2009 continuing into winter 2010 as components for container mediums since Canadian Sphagnum Peat Moss has tripled in price during the last several years. Air capacity measurements for a newly formulated mix were 28.3% for 1 gal, 29.5% for 3 gal and 34.6% for 7 gal containers compared to traditional mix measurements of 24.7% for 1 gal, 29.9% for 3 gal and 32.5% for 7 gal containers.

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).

Topic 3: Sensors and control systems 5. Improve volumetric water content sensor efficacy (ME, NY, OH).

AZ has been working on physical characterization of a new substrate for automated irrigation management using microtensiometers (MT) on characterizing foam glass, a highly porous substrate and the use of a MT to trigger irrigation, when the matric potential is lower than desired. Experiments with this substrate and stone fibers were conducted resulting in similar yields with 95% confidence interval. Research involved physical characterization of the foam glass with particle size < 1.25 cm and the development of a MT. The MT consists on a pressure transducer, stainless steel tubing, stainless steel porous cap and a solid block of the foam glass. The water movement inside the foam glass growing bag is going to be simulated using Hydrus 3D. The simulation of water flow and irrigation will be manipulated to have ideal scenario to maximize water efficiency. The simulations of irrigations will be tested in a growing bag with mature tomatoes plants in greenhouse.

NY has developed a risk analysis model to simulate the effects of Pythium phanidermatum on the production of hydroponic baby-leaf spinach under varying nutrient solution temperatures. The simulation suggests that every two degree drop in the nutrient solution temperature approximately halves the frequency of Pythium outbreak within the temperature range of 18 to 24C. Every two day reduction of the amount of time the crop spends in a deep-flow pond approximately halves the frequency of Pythium outbreaks within a crop production range of 12 to 16 days in pond. Production strategies that relied solely on natural light failed rapidly with outbreak frequencies on the order of several per year, in contrast to significantly fewer than a single outbreak per year in the conditions with supplemental lighting, where plants reach harvest weight more rapidly.

Objective 3 involving the water and nutrient delivery system. 6. Improve sensor control of the greenhouse aerial environment (light, carbon dioxide, temperature, and moisture) (NJ, OH, NY, NE, AZ).

NE has been using data loggers for monitoring greenhouse and surroundings and campus strawberry houses. Each house was monitored in three measurement zones for air temperature, humidity, total and PAR, plant, floor and potting soil temperature, inside roof glazing temperature. The latter were used to calculate 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 Jan-late Apr. Ventilation fan, unit heater, and biomass burner operations were 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 were calculated using these data and the formulae of the ANSI/American Society of Agricultural and Biological Engineering Standard EP404.3 Heating, Ventilating and Cooling Greenhouse. The loggers communicated with a central computer located in the North end of the house using wireless technology. An additional set of Campbell CR10X battery operated loggers were used for backup and data collected once a week. We also begun operation of a real time, adaptive model which collects the appropriate measurements and calculates the energy and production performance of a greenhouse. The LabView model accounts for heating and ventilation by calculating sensible and latent heat exchanges with the greenhouse and its surroundings. The First Law energy balance includes both short and long wave radiation exchanges with the crop. Entropy production or eternal heat loss verifies integrity of calculations. Model produces estimates of crop water use essential in plant growth and development.Various energy balance solvers are tested. Adaptive model monitors moisture condensation at the leaf surface, interior glazing, and the floor. Moisture condensation and water drip on plant leaves is a primary factor in disease and insect infestation. Greenhouse thermal models are driven by weather data, which is available from the High Plains Automated Weather Station Network for over 150 locations within the region. The objective is making such a system grower friendly and assisting his operation.

NJ installed sensors and a datalogger 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.

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).

AK has been conducting research to determine the potential for LED greenhouse lighting. Production greenhouses at high latitudes have a large demand for supplemental lighting. More energy efficient lighting technologies have a large impact on economics of year round greenhouse operations. Panels (300 W) with red LEDs supplemented with 10 percent blue LEDs (peak emission at 456 nm), tri-band LEDs with 40 percent red (660 nm), 40 percent orange-red (630 nm) and 20 percent blue (460 nm), and white LEDs are tested in a controlled environment production area. Lettuce and Rudbeckia hirta 'Toto' are grown below the LED panels and as a comparison under high-pressure sodium, metal halide and 5T fluorescent lamps. PAR at plant height was 150 umol/m2/s1 for all lamp types. An LI-6400 photosynthesis system with a clear top leaf chamber is used to measure net photosynthetic rate(Pn) . Measurements are made on exposed single leaves at 400 ppm CO2. Pn are in the range of 3.5 to 4.0 umol CO2 m2/s-1 independent of lamp type suggesting PAR to be more important for rate of Pn than the spectral energy distribution.

AZ completed several experiments toward applications of LEDs in greenhouse plant production. Among them, the experiments conducted during 2008-2009 were for testing supplemental lighting quality (UV, blue, green, red, and farred) for their effects on bioactive compounds of leaf lettuce. Anthocyanins concentration increased by 11% and 31% with supplemental UV-A and blue respectively, carotenoids concentration increased by 12% with supplemental blue, phenolics concentration increased by 6% with supplemental red while supplemental farred decreased anthocyanins, carotenoids and chlorophyll concentration by 40%, 11% and 14%, respectively, compared to those under in the white light control.

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

MI tested biopesticides, reduced-risk products, experimentals, and industry standards for control of oomycetes with greenhouses trials. The biopesticide, Reynoutria sachalinensis, extract of giant knotweed (Regalia SC), significantly reduced downy mildew infection of coleus leaves, while it was less effective than reduced-risk products (azoxystrobin, mandipropamid, fenamidone, mefenoxam), experimental BAS 651F (dimethomorph + ametoctradin) and standards (fluoxastrobin, dimethomorph). Biopesticides, Gliocladium virens (SoilGard 12G), Bacillus subtilis (Companion), Streptomyces lydicus (Actinovate) and Trichoderma harzianum (RootShield), were compared with standards etridiazole (Truban 30WP), dimethomorph and reduced-risk mefenoxam for control of oomycetes (Pythium spp., Phytophthora drechsleri and Phytophthora nicotianae) on calibrachoa and verbena. Etridiazole, dimethomorph and mefenoxam performed significantly better the inoculated controls in all trials. Streptomyces lydicus combined with etridiazole was especially effective in all trials and prevented death due to Pythium spp. on calibrachoa and verbena, P. drechsleri on calibrachoa, and limited death due to P. nicotianae on verbena to 16.7%. Other biopesticide treatments which prevented plant death were Gliocladium virens (Pythium on calibrachoa), Trichoderma harzianum (Pythium on calibrachoa), and Streptomyces lydicus (P. drechsleri on calibrachoa). Biopesticide treatments which were significantly better than the control included Gliocladium virens for P. nicotianae on verbena, and Bacillus subtilis for Pythium on verbena and calibrachoa and P. nicotianae on verbena. The biopesticide, Reynoutria sachalinensis, significantly reduced downy mildew infection of cucumber leaves, although not as effectively as propamocarb (Previcur Flex 6SEC) or reduced-risk cyazofamid (Ranman) or fluopicolide (Presidio 4SC) all tank-mixed with chlorothalonil (Bravo Weather Stik 6SC). Airborne sporangial concentrations were positively related to average temperature and negatively correlated with both average relative humidity and leaf wetness at all of the sites monitored in 2008 and 2009. Rainfall was not significantly correlated with sporangial concentrations at any of the sites monitored in 2009, but it was positively related to sporangial concentrations at the Monroe County site in 2008. The concentrations of airborne sporangia showed a marked diurnal periodicity with the highest concentrations between 0800 and 1300 hours and a pronounced peak at about 1000 hours.

NY has been working on environmental control to increase genetic expression of valuable chemicals in tobacco. Research has been nearly completed to quantify effects of environmental control on the production of a useful industrial enzyme, using extractions from hydroponically-grown and genetically-modified tobacco (chloroplast transform). The effect of plant spacing on biomass yield and target enzyme output indicated that maximum productivity of target enzyme, measured as mass per unit area per unit time, can be achieved in a range of final plant spacing. The best plant spacing appears to fall in the middle of the range examined, near 1ft2/plant. Plants are unable to take full advantage of additional space when flowering commences, as leaf growth is curtailed. Tobacco grows very slowly in absolute terms during the first three weeks since the seed starts out so small, and for this reason harvest of seedling sized plants for biomass is also a dubious proposition.

AZ continuously seeks for funding in this area (biopharmaceutical production in greenhouse using transgenic crops). However, during the reporting period, AZ could not secure the fund and therefore no activities under this project area, unfortunately. )

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 CFD modeling to evaluate various side/roof vent configurations, compared the results with a set of previous experiments conducted in a wind tunnel with naturally ventilated multi-span greenhouse with scaled models. The study compared three dimensional temperature distributions obtained for different ventilation cases from wind tunnel study with CFD simulations to validate the model. A satisfactory quantitative agreement was found for vertical and horizontal temperature distribution between the experimental and simulation results. Thus, two new turbulence models were used checking the effect on the agreement with experimental results to have a better knowledge of the simulations set up for future validations. AZ continues to actively involve in organization of CFD sessions in related conferences, the next ISHS CFD Working group technical sessions are scheduled for GreenSys2011, July, Greece.

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

AZ continued on developing climate control strategies for a naturally ventilated greenhouse equipped with variable high pressure fogging system. The cooling demand inside the greenhouse varies during day/seasons. Thus, it may be advantageous using variable pressure fogging (VPF) system, where specific fog rates can be supplied based on the cooling demand. But, absence of effective cooling strategies is limiting extensive use of the system. A computer simulation was developed to compare a proposed control algorithm for VPF to a typical on/off fixed pressure fogging system based on vapor pressure deficit (VPD). Results showed that VPD based fixed pressure fogging strategy consumed more water and energy compared to the VPF system. Cycling of the pump was smaller and higher stability of temperature and relative humidity were achieved by the operation of the VPF system.

Other accomplishments that do not necessarily relate to the 2008-2013 NE 1035 Multistate Research Project objectives: NJ, a new course Energy Technology and its Environmental Impact was developed and taught. This 300-level course was developed around the textbook written by F.M. Vanek and L.D. Albright titled Energy Systems Engineering: Evaluation and Implementation. Studies are ongoing for the 250 kW microturbine installation at the EcoComplex greenhouse. The system has been operational intermittently due to unforeseen maintenance and repair issues. Some electricity was generated and used on-site and the remainder exported to the local electric grid.

NY compared single and double seeding for baby-leaf spinach production in deep-flow ponds. The objective was to facilitate scaling up from bench-scale spinach production to commercial-greenhouse-scale production. In the commercial-scale-up project, 48 standard 338-cell Seedling trays (each 13.5 inches by 26.5 inches in horizontal dimensions, 1.75 inches high) were seeded weekly, germinated for three days in a growth chamber, and placed in one of two ponds and grown for 12 to 14 days. These experiments demonstrated no yield difference between single seeding all cells and double-seeding half the cells. Double-seeding, while maintaining the same plant density, is recommended when using 1 ¾ inch high cells of the type used in these experiments. This halves the amount of medium needed. However, reusing root medium from spinach production proved not to be a viable option to save resources, for the root disease, Pythium aphanidermatum, remained viable in the recycled and heat-treated medium, leading to disease outbreaks in subsequent crops.

NY Most floriculture crops are sensitive to ethylene, an odorless, colorless gas produced naturally by plant materials or by incomplete combustion of heating fuels and engine exhaust. We conducted experiments on chronic ethylene effects on 30 bedding plant species. Results from the first year indicate that flowering was variably inhibited by 10 or 50 ppb ethylene for most species, though some eventually recovered from the effect. Where flowering did occur in ethylenes presence, flower size was reduced and flower senescence was more rapid compared to control. In general, 10-50 ppb ethylene was a growth inhibitor for most species, while for others it encouraged branching and growth. These results lend support to the hypothesis that ethylene response, whether growth promotion or inhibition, can be incorporated into a single concentration dependent biphasic response model.

OH worked on a new design for insect scouting for greenhouses. Scouting is the backbone of all integrated pest management program. Timely, accurate insect pest population estimates and spatial variability information can reduce the number of pesticide applications by 30 to 60%. As the manual scouting process is laborious and time consuming, and performance of passive insect collection methods are often affected by temperature, we initiated an effort to develop a high efficiency insect collection prototype for greenhouse applications. A suction device, and a yellow sticky tape mounted on a traveling boom were evaluated for the insect collection task. Greenhouse tests were conducted to evaluate the collection efficiency of a conventional scouting method (i.e. stationary sticky card) and two prototyped mobile scouting methods under two greenhouse temperatures. The vacuum-based approach was found most reliable. It resulted in the same collection efficiency while collecting adult whiteflies from poinsettia plants for two different temperatures: 13.5 and 28.5 C.

OH continued to work on nutrient film technique (NFT) for lettuce. Results from a series of four designed experiments indicate choice of growing cube composition has a marked impact on yields (or conversely growing time) when using NFT for hydroponically-grown lettuce crops. Rock wool growing cubes are currently used most frequently by hydroponic lettuce growers and is an industry standard. Lettuce grown in a new plastic fiber growing cube yielded 29% less mass (wb) than rock wool in Autumn 2008 (Experiment No. 1) and 34% less in Spring 2009 (Experiment No. 2). However, for Experiments No. 3 and 4 (Summer, 2009), lettuce grown in coconut core cubes and a commercially available mix of peat moss, perlite and vermiculite (Oasis fertis) cubes yielded 19% and 14% more lettuce, respectively, than rock wool. Purpose for research is to develop/demonstrate economically sustainable, year-round, high quality, hydroponic crop production systems operating in energy efficient greenhouses.