Brief Summary of Minutes of Annual Meeting

Multistate Research Project Annual Station Accomplishments Report Topic No. 1. Managing nutrients and water in greenhouses 1. Develop and evaluate methodologies such as evapotranspiration modeling, non-contact sensing of plant responses to drought stress, and measurement of root zone water tension for plant water status assessment and compare these assessments to actual water and nutrient use for tomato, salad greens and potted ornamental plants, as a part of managing delivery of nutrients and water in greenhouses (CT, GA, NY, NE, OH, AZ, KY, NJ). Photosynthesis was characterized for Hibiscus rosa-sinensis with the goal of developing an irrigation model that maintains a high photosynthetic rate while minimizing water use. Plants were subjected to a drought period during which photosynthesis was measured at 800 µmoles s-1 m-2 of light for a range of increasingly drier volumetric water contents (VWC). Hibiscus plants were produced in the greenhouse with irrigation set points for substrate moisture levels that correlate to 100%, 100%, 98.3%, and 69% of maximum photosynthesis. Substrate moisture levels were determined and controlled using ECHO-5 dielectric probes connected to a Campbell CR1000 datalogger with AM16/32 multiplexer. Photosynthetic rate, stomatal conductance, transpiration rate, internal CO2, and leaf water potential were significantly greater for plants in the 3 wettest irrigation treatments. Plants under these treatments used 1.4, 1.2, and 1.05 times more water during the course of the experiment than those plants in the driest treatment. There was no significant difference among irrigation treatments for flower number, branch number, or plant width. Total dry weight for the second wettest treatment was greater than that for the driest treatment. This research demonstrates that plants can maintain maximal photosynthesis and growth with reduced irrigation cycles. USDA-ARS GPRG and Ohio State University (OSU) Extension developed a sensor package using the NCR-101 sensor package as a model, to be used by greenhouse growers in the NW Ohio area. A line quantum sensor and dual radiation sensor (Apogee Instruments), a CO2 sensor (Spectrum Technologies), hot wire anemometer (Extech), and infrared temperature sensor (Extech) have been purchased so far. This will enable greenhouse growers to spot check their environment with common instruments and enable better communication between researchers, extension agents, and stakeholders. The effect of a water barrier between light sources and plants in a chamber was evaluated at OSU. Water barriers are sometime used with artificial lighting to reduce heat load in chambers. It was found that the barrier cuts down long wave energy but does not affect PAR intensity. As a result, plant canopy temperature is lower compared to that without the barrier. Lower canopy temperature, in otherwise similar environment (e.g. air temperature, air relative humidity, and PAR level) in the chamber, is likely to reduce transpiration that may have further implications on the plants growth and development. The University of Georgia has started a trial at a commercial nursery to determine the benefits of soil moisture sensor-based irrigation. Previous small scale research has shown that soil moisture sensor-based irrigation works in greenhouses, but this is the first trial at a commercial scale, with several thousand plants. Water use and plant quality of plants irrigated based on substrate moisture content are compared with those irrigated according to standard nursery practices. Preliminary results indicate that soil moisture sensor-based irrigation reduces water use by 85%, while improving plant quality. In addition, leaching of water and nutrients is greatly reduced when using soil moisture sensors to control irrigation. At the end of the study, energy savings and other economic benefits (less need for plant growth retardants and fertilizer) will be quantified. Results so far suggest that soil moisture sensor have an excellent return on the initial investment. Dr Murat Kacira, joined the University of Arizona. His research will focus on non-contact sensing. 2. Evaluate the entire fertigation system, including water delivery, plant uptake, and runoff, while accounting for optimization of micronutrient, media pH, and EC levels (AZ, CT, NE, NH, NY, OH, PA). Precision Nutrient Irrigation Recipes - Recycling Effluent in Field, Nursery and Commercial Greenhouses: A Controlled Nutrient Delivery System (CNDS) ® and an Acidic Control Remediation System (ACRS)® have been recently developed. These systems are specialized tools designed for the application and precise metering of a family of fluid plant essential nutrients, fungicides, hormones, etc. Based on the mechanical principles of these systems, the product being injected into the process stream can be controlled with ultimate precision. Both systems are precise, accurate and able to replicate results as desired. This precision makes it possible to calculate, chart and deliver the exact ppm (parts per million) concentration of a nutrient element into the feed water irrigation stream. The ppm concentration can be adjusted in real time. The end result will include maximizing nutrient intake by plant roots through control of the irrigation solution pH. This will influence mass water diffusion within the growing media. Maintenance of appropriate pH will result in the solubility of the plant essential nutrients for pot-in-pot drip irrigation, drip ground irrigation, or overhead application of irrigation water. State-of-the-Art Computer-Controlled Nutrient Delivery System for Container-Grown landscape Nursery Crop Research: Development of a new nutrient delivery system, which accounts specifically for small treatment sizes required for research plots, continued at Ohio State during 2007 under the direction of Alec Mackenzie, Argus Control Systems LTD., White Rock, B.C., Canada. This site will serve as a beta test site through 2008. Landscape Nursery Crop Engineering Research Laboratory (LNCERL): The OARDC Fertigator automatically delivered water and nutrients to three different experiments consisting of 10 uniquely specified treatments totaling 428 trees. Routine measurements and services provided by our lab included: (1) pre season flow rate calibration of all 428 fertigation system emitters, (2) pre season fertigator, tensiometer and weather station calibration, (3) continuous monitoring and recording of potting medium moisture tension (PMMT), (4) daily pH and EC measurement of treatment solutions at the point of delivery, (5) potting medium volumetric water content (VWC) measurements, (6) daily records of total water and nutrients delivered to each plant and treatment, (7) as needed measurement of the pH and EC of nutrient solutions retained in container mediums using a standard pour through procedure and (8) continuous fertigation system monitoring and troubleshooting seven days per week. Effects of imidicloprid on physiology of stress tolerance of hybrid poplar: A full factorial experiment compared four species of woody plants: hybrid poplar, shrub willow, river birch, and burning bush; two levels of nutrition: 30 ppm N and 150 ppm N and two levels of imidicloprid drenching: standard concentration and zero application. In a companion experiment, three controllable factors were compared. Plant species: burning bush and hybrid poplar; nutrition: 30 ppm N and 150 ppm N and imidicloprid application method: drench, tablet and untreated (control). A dry-down period was imposed at the end both experiments to determine effects of imidicloprid on stress tolerance. The hypothesis was that trees treated with imidicloprid would lead to a greater mass of leaves, greater numbers of leaves and enhanced plant quality compared to untreated trees. Mechanisms and Outcomes of Host-Mediated Systemic Interactions between Pathogens and Insects in Austrian Pine over a Nutrient Gradient: The 2007 summer growing season was the final summer of four summers for this USDA/NRI project. Computer-controlled fertigation was employed to grow the 120 Austrian pine trees that remained during summer 2007. Three levels of fertility were delivered: (1) 30 ppm N, (2) 75 ppm N and (3) 150 ppm N with N, P2O5 and K2O added to irrigation water in 3:1:2 ratios proportionate to treatment levels. Fertigation events were delivered automatically by Q-COM GEM3 software based on accumulated evapotranspiration. Randomly selected trees and stems were challenged with European pine sawfly insect infestations and Shaeropsis sapinea (formally known as Diplodia pinea) pathogen infections. The 120 remaining trees were harvested August 22. Parboiled Rice Hulls Affect Plant Growth: A new potential growing medium component is parboiled rice hulls (PBH) which may replace perlite and/or peat. Seven growing mixes were created from peat moss, coir, PBH, bark (5/8), perlite, and vermiculite. The first media was a control with no PBH, treatments 2-4 evaluated PBH as a substitute for peat, and treatments 5-7 evaluated PBH as a substitute for perlite. All mixes had adequate aeration. Media #5 and #6 had similar container capacities and had the highest water holding capacities of the media tested. Media #4 had the lowest container capacity which was probably caused by the 30% PBH. Other media were intermediate. Calibrachoa, sunflowers, heuchera, and poinsettia were grown in the media containing different percentages of PBH. Media #1, #2 and #3 had decreasing levels of peat and coir replaced by increasing levels of PBH. There was never an instance where decreasing peat and increasing PBH increased growth. The probable explanation is that reducing peat and coir reduced the water holding capacity of the media. For media treatments #5, #6, and, #7 perlite was substituted for PBH. Substituting PBH for perlite did not affect calibrachoa growth. Perlite was the better substitute for sunflower and poinsettia; however, PBH was the better substitute for Heuchera. Again the water holding capacity may be the factor to explain the plant responses. In summary, PBH effectively substituted for perlite as a growing media amendment, but was not an effective substitute for peat moss under the conditions of this experiment. Saturated media extract testing of green roof media. Green roofs hold great promise for stormwater management, but one of the potential issues with their use in areas where runoff quality is a concern is managing the nutritent content of the media. Sufficient plant nutrients must be present to support a healthy plant community, but excess nutrients should be avoided to reduce runoff quality impacts of the green roof. To date no standards exist for evaluating nutrient content in green roofs. This study evaluated the nutrient content of over 30 established green roofs in the US. Plant community data including, surface coverage, weed and moss surface coverage, and dominant species were correlated with nutrient content data to develop a set of standard values for test results. For example total nitrogen (nitrate and ammonium) content of the media Saturated Media Extract should be between 1.5 ppm and 3 ppm. Nitrogen levels lower than this promote poor plant surface coverage and the development of moss, while levels in exces of 3 ppm do not improve sedum population surface coverage but do encourage weed growth and result in nutrient rich runoff. As a result of this study we can now test a green roof on an annual basis to determine the need for additional fertilizer. By limiting fertilizer applications to that which is required we can reduce excess nutrient runoff while making a green roof greener by optimizing plant growth. 3. Improve design of water and nutrient recirculation systems (NJ, NY, KY, OH, AZ, PA). Partial Saturation Ebb and Flow Watering (PSEFW) for short-duration watering was compared to a control floor on which water was held for 10 to 15 min, followed by 3 min to drain the floor. Three crops were grown: Geranium Allure Red Passion, two cultivars of chrysanthemum, and Poinsettia Prestige Red. When watered repeatedly by PSEFW, the root medium of these crops retained about 0.1 L/L volumetric water content less water than when watered for a longer duration. More water was taken up and used by plants under control compared to PSEFW regimes, an average of 0.55 and 0.43 L per plant per water cycle, respectively. The PSEFW treatment provided a variable, low-level water stress, and this affected the growth of geranium throughout. On 15 June, the control plants weighed 20% more than those grown under PSEFW. Initially, the PSEFW regime applied to chrysanthemum resulted in slower growth of than the controls. However by bud break, plants from both treatments had an equal fresh weight. At final harvest, fresh weight was about 20 g less for plants under PSEFW than for the controls. Dry weight differed less than fresh weight, and Nancy had greater dry matter content under PSEFW than control watering. A row of poinsettia plants inoculated with Pythium and Phytophthora were set over the inlet and outlet holes for nutrient solutions on each floor. Non-inoculated plants developed disease symptoms one month after inoculated plants were placed on the flooded floor. As many as 20 control plants developed disease symptoms, but no plants developed symptoms under the PSEFW regime. All plants with disease symptoms had roots infected with Pythium. A free copper concentration of about 1 ppm was necessary to significantly lower the density of viable pathogens to about 30% of the density observed before treatment. Pathogen densities were consistently greater in PSEFW than in control solutions. This behavior was also noted in our first attempts to isolate pathogens in Nov 2007. A slow sand filter (SSF) is under development by PhD student Peter Livingston, Agricultural and Biosystems Engineering. The SSF with 3.3 m2 of surface area will treat nutrient solution drainage from the greenhouse hydroponic system. The primary goal is to improve the performance of the SSF by maintaining the Shmutzdecke layer with mechanical cleaning methods. After an initial design and development phase, progress has been minimal. There are no new items to report on this project. Topic No. 2. Managing the aerial environment for greenhouse plant production 1. Develop design and control recommendations for naturally ventilated greenhouses (OH, NE, NY, NJ). No accomplishments during this reporting period. 2. Enhance technology transfer and research in light integral control (CT, MI, NH, NY, AZ). Over the period June 6, 2007 to the present, a coordinated CO2 concentration and daily light integral controller has been developed and tested. The algorithm for the controller was originally developed in simulation and a patent was issued in 2007. A Phase 1 USDA SBIR was received during 2007-2008 to translate the algorithm into a functional controller and then test the controller in a greenhouse setting. The controller was programmed using National Instruments LabVIEW software, with a Fieldpoint system as the sensor and output signal interface. To test the control algorithm a greenhouse compartment in the Kenneth Post greenhouses at Cornell University was placed under control of the algorithm. A matching compartment utilizing only daily light integral control was used for comparison. Three crop cycles of lettuce (24 days each, transplant to harvest) were produced during winter and spring periods, covering a range of climatic conditions from the typical low light integral and cold winter days to the transition period of the spring where shading and significant venting becomes necessary. Each compartment was controlled achieve a target integral of 16 mols/m2-day (virtual mols in the case of the CO2 supplemented compartment). There was no statistical difference in the fresh weight production of the compartments although the light integral plus CO2 control algorithm utilized 47% fewer hours of supplemental lighting than light integral control without CO2 supplementation. Topic No. 3. Integrating sustainable and economically profitable systems and processes for the greenhouse industry 1. Develop an economic analysis of the costs and benefits of supplemental lighting for seedling plugs, other greenhouse crop types, and photoperiodic lighting (AZ, CT, KY, MI, NE, NH, NY, NJ, OH). No accomplishments during this reporting period. 2. Improve the understanding of using shade to optimize production of high-quality greenhouse tomato for spring and early summer production (AZ, CT, KY, MI, NE, NH, NY, NJ, OH). Some amount of shade may be optimal to produce high quality tomatoes in a greenhouse during summer months in the northeast USA. Simultaneous comparisons were made among greenhouse sections that were either not shaded, or covered with reflective aluminized shade cloth that attenuated 15%, 30% or 50% of direct sunlight. The shade cloth was applied at the start of warm weather in June. The houses were shaded for the rest of the summer, and fruit was picked until late August. Total yield decreased linearly with increasing shade, but there was no significant difference among shade treatments in marketable yield. Marketable fruit percentage was greatest for plants grown under 50% shade. This fraction was 9% greater than in a non-shaded greenhouse in 2003, and 7% greater in 2004 and 2005. Cracked skin was the defect most affected by shade. Among sensitive cultivars, up to 35% of the fruit produced in non-shaded greenhouses had cracked skin, whereas in greenhouses covered with 50% shade, only 24% to 26% of tomatoes had cracked skin. There was no consistent trend for shade density in the fraction of fruit with green shoulder, blossom end rot, or irregular shape. The effect of shade increased with duration of shading. There was no effect of 50% shade compared to no shade on total yield within 3 weeks, but yield decreased by 20% in the interval from 3 to 6 weeks after shading, and by 30% after more than 6 weeks of shading in 2005. Marketable yield only decreased after more than 6 weeks of shading for cultivars that were not sensitive to cracked skin or uneven ripening. Shade decreased fruit size over the entire season only in 2003. In general, shading increased the fraction of marketable tomato fruit without affecting fruit size. Shading a greenhouse may have a time-dependent effect on fruit production, and water and nutrient uptake in tomato plants (Solanum lycopersicum L.), due to acclimation to light, and a dependence on stored carbohydrate and nutrients. The amounts of water, nitrogen and potassium taken up per day were calculated for successive 3-week intervals after shade was applied. The effect of shade on uptake rates was compared to the effect on fruit production rate. There was a linear decline in water, nitrogen and potassium uptake with increasing shade density. In each 3-week interval, water uptake under 0.5 shade density was 25% and 20% less than under no shade, in 2004 and 2005, respectively. Nitrogen and potassium uptake under 0.5 shade density was about 25% less than under no shade. Shading did not affect the rate of fruit production within 3 weeks of application, but after more than 6 weeks, it was 30% less under 0.5 shade density than under no shade. The use efficiencies of radiation, water, and nutrients for fruit production increased with shade density immediately after shade was applied. These effects of shade on apparent resource use efficiencies dissipated from 3 to 6 weeks after shade was applied, as the effect of shade density on fruit production became proportionally the same as the effects on water and nutrient uptake. The water and nutrient uptake of greenhouse tomato acclimated to the change in irradiance due to shade within 3 weeks, but the full effect of shade on fruit production was not seen until 6 weeks after the application of shade. 3. Quantitatively evaluate seasonal and annual water balances for greenhouses (AZ, CT, KY, MI, NE, NH, NY, NJ, OH). Water Conservation Methods for Evaporative Cooling Systems. The goal of the project was to determine how to use the least amount of water to evaporatively cool greenhouses and then educate other users of evaporative cooling systems on how to implement those strategies through demonstrations, publications, and training. The outcomes were a reduction in water use and waste by University of Arizona greenhouse evaporative cooling systems, by local nursery operators using greenhouse evaporative cooling systems, by other non-commercial users of greenhouse evaporative cooling systems, and by non-agricultural users of evaporative cooling systems. Water Use by Greenhouse Evaporative Cooling Systems and the Effect on the Greenhouse Climate in Semi-Arid Regions. This project focused on evaporative cooling methods in combination with both mechanical and natural ventilation systems. Two evaporative cooling methods are being studied; 1) pad and fan system (completed in 2005-06) and 2) high-pressure fog system. Water-use efficiency in semi-arid regions includes water used for cooling and irrigation. These will be determined for both evaporative cooling systems, in combination with ventilation and shading, to compare the amount of water required to obtain the desired greenhouse conditions, while maintaining crop production and quality. Tomato plant water use for the extreme summer conditions was measured to be 14.8 liter per square meter per day for the pad & fan evaporative cooling system and 8.9 liter per square meter per day for the drip irrigation system. At the lowest ventilation rate (0.017 m3m-2s-1) the cooling efficiency was 85 percent whereas at the highest ventilation rate (0.079 m3m-2s-1) the cooling efficiency was 75 percent. The efficiency was defined as the ratio of the air temperature reduction from outside to inside, to the difference of the outside air temperature and the inside wet bulb air temperature. Increasing the ventilation rate increased water use by the evaporative cooling system without necessarily improving the greenhouse conditions. These results are important for the design and control of evaporative cooling systems inside the greenhouse. Other accomplishments that do not necessarily relate to the 2003-2008 NE 1017 Multistate Research Project objectives: 1. A 250 kW landfill gas fired microturbine installation is being completed at the NJ EcoComplex research greenhouse facility. The system will generate electricity and heat for the 1-acre greenhouse facility. Excess electricity will be sold back to the local utility grid. The entire system is expected to be operational in the summer of 2008. 2. Under the leadership of Peter Ling (OH), colleagues from OH, AZ and NJ developed a joint proposal titled: "Development of an Undergraduate Course: Greenhouse Engineering and Technology". The proposal was submitted to the USDA Higher Education Challenge Grants Program. 3. Japanese colleagues from the research team directed by Dr. Sadanori Sase translated the book "Energy Conservation for Commercial Greenhouses", published in 2001 by NRAES. NJ helped facilitate the securing of translation rights and provided assistance with some of the translation work. 4. Colleagues from ME, GA, and OH developed a USDA Higher Education Challenge Grant entitled, Development of Interactive DVDs to Integrate Experiential Learning Diagnostics and for Rapid Diagnosis of Greenhouse Physiological, Plant Pathological, and Entomological Problems. 5. ME joined a new Sustainable Research Coalition for floricultural greenhouse growers with Roberto Lopez and Jennifer Dennis (Purdue) and Brian Krug (University of New Hampshire). The goal of this coalition is to coordinate sustainable floriculture research and Extension activities on a national level. 6. Surveys of the research needs for organic bedding plant growers and the potential market value of organically grown bedding plants were conducted. Organic bedding plant growers find insect and disease management, fertility, and managing organic substrates to be their greatest production challenges. Organic fertility is the greatest barrier against conversion to organic production for conventional growers. According to the market analysis, the average consumer is interested in purchasing organically grown ornamentals and would pay approximately 13% more for organically grown plants compared to conventionally grown plants. 7. A paper study was completed to quantify energy types and amounts required to grow and ship selected types of fresh produce into New York State from open-field production outside the state, and contrast the sources and amounts of energy required to grow the same crops in Controlled Environment Agriculture (CEA) facilities in New York State, and with open field, seasonal production in the state. An extensive final report was filed with the New York State Energy Research and Development Authority (NYSERDA). 8. Hypericum perforatum, or St. Johns wort, is currently used medicinally to treat neurological disorders, while research continues to seek practical methods to harness the plants proven potential as an anti-cancer and anti-retroviral drug source. More than other medicinal plant preparations, bioactive components of H. perforatum are often found to vary by a factor of two compared to concentrations reported on labels for the prepared drug. Variability is attributable to environmental condition fluctuations to which the plants were exposed during growth and development. Investigations were completed on the effects of varying light intensity, light integral and light quality on biomass and secondary metabolite concentration of Hypericum perforatum. A demonstration of the effects of a short photoperiod was also completed. 9. A model of a seedling nursery greenhouse was created using Simulink, a modular graphical computer language. Although validation with actual greenhouse measurements was not possible, we were able to demonstrate qualitative agreement, and showcase some of the features of the Simulink language, and highlight its utility in creating greenhouse and crop energy models. The graphical, object-oriented nature of Simulink made creating the initial model and subsequent improvements relatively easy. It is hoped that by taking a graphical and object-oriented approach towards crop modeling, will allow for greater use of models in the horticultural industry. 10. A study for alternative biomass energy sources for greenhouse heating was begun. Initial results indicate that biomass heating is quite feasible depending on fuel prices and heating system efficiency. Continued testing may reveal some design and operational problems in some biomass systems, although automation seems to be well-adopted. Proportional control and heat combustion optimization should improve efficacy for greenhouse operations. 11. John Hay was an organizer and facilitator for the April 25, 2008 Biofuels forum that included a live and video presentation on biomass heating furnaces by Mark Setzer, Heat Source One, Beatrice, NE. The archived presentation is located at: http://connect.extension.iastate.edu/p14821468/ 12. The Ohio Hydroponic Crop Research and Extension Program (OHCP) developed a water quality assessment package to assess and improve water management and fertilization practices in hydroponic facilities, a series of comparative diagnostic tools for determining nutrient imbalances in hydroponic lettuce production, and an instrumentation package of environmental sensors to assess greenhouse environmental conditions and their impact on crop growth and yield. Key outreach efforts include consultations and site visits, a monthly greenhouse newsletter, an interactive hydroponic website (www.oardc.ohio-state.edu/hydroponics/), as well as the development of fact sheets and educational bulletins. 13. The Greenhouse Crop Production and Engineering Design Short Course was held January 20 to 23, 2008, as a continuing professional education short course from the University of Arizona. The course programs can be viewed at http://www.ag.arizona.edu/ceac/. 14. Internet Sites developed include: The University of Arizona Controlled Environment Agriculture Center home page: http://ag.arizona.edu/ceac Tomato Live! Website: http://ag.arizona.edu/ceac/tomlive/index.htm Worldwide Greenhouse Education Website: http://www.uvm.edu/wge/ 15. Efficacy of PGR on Branch Architecture of Container-Grown Trees and Shrubs - Plant growth regulators (Fascination, Maxcell, Tiburon, and Exilis Plus) were applied to Hydrangea quercifolia Alice (both tissue culture and conventional cutting-produced liners), Oxydendrum arboreum, Ilex opaca Helen Hahn and Sadyr Hill, and Euonymus alatus Compacta and Rudy Haag. Branch number, height, width, and growth index were calculated and analyzed. 16. Container production of Cornus florida has been a challenge for nursery producers, in part due to root rot. Surveys showed that the most prevelant root rot was Rhizoctonia. Commercial products containing Trichoderma harzianum, a naturally occurring fungus, as the active ingredient were evaluated as a biological control for Rhizoctonia root rot of flowering dogwoods in container production. Treatments included topdressing with RootShield® Granules which was an experimental application method; drenching with PlantShield HC, 2.8 g per 5 gallons of water; drenching with 3336"; and drenching with a water control. Results indicated that an unidentified Pythium species, while found in low population levels was likely playing a key role in Rhizoctonia infections; when Pythium was controlled Rhizoctonia was not lethal, regardless of the severity of the Rhizoctonia infection.