Brief Summary of Minutes of Annual Meeting

Annual Meeting

University of Nebraska, Lincoln

Lincoln, NE

June 29-30, 2017

Multistate Research Project

Annual Station Accomplishments Report

PROJECT NUMBER:             NE-1335        

TITLE:                                    Resource Management in Commercial Greenhouse Production

PROJECT DURATION:         October 1, 2013 – September 30, 2018

REPORTING PERIOD:         June 24, 2016 – June 30, 2017

REPORT DATE:                    August 25, 2017

OBJECTIVES (included as a reminder):

1. To develop up-to-date water and nutrient as well as energy management guidelines for greenhouse crop production and provide stakeholders with educational opportunities that teach proper implementation at their own facilities.
2. To develop these guidelines using research and development involving sensors and control strategies devised by current team members, and through and future collaborations among team members who may become part of this research project.

METHODS (please include your accomplishments where appropriate):

Topic 1: Water and Nutrient Management

1. Develop and test irrigation and fertilization practices to improve water and fertilizer use efficiency in greenhouse production
2. Conduct research to further refine irrigation/fertilization systems

UNH: Project results indicated that peat-based substrates amended with wood fiber and coconut coir may require growers to adjust their fertilizer and irrigation program. Recommendations on fertilizer nitrogen form, substrate lime type and rate, and irrigation frequency for different blends of peat, coir, and wood fiber blends were developed.

CTNH: Temperature changes the composition of plants through its effects on metabolism and nutrient uptake. Hydroponic lettuce growing in naturally sunlit greenhouses was subjected to two temperature treatments. Minimum temperatures were 20° or 10°C, and ventilation temperatures were 26 and 16^oC, for warm and cool treatments, respectively. Tissue composition data for three plantings were subjected to analysis of variance with fixed effects of warm or cool temperature, high or low daily light integral, and am or pm harvest time. Plant size was included as a covariate. Warm compared to cool temperature increased relative growth rate by 85% for small plants of 2 to 5 g fw, compared to 30% for medium plants of 20 to 60 g fw. Warm temperature increased specific leaf area for plants grown under a low light integral of 4.5 mol^.m^-2.d^-1, compared to a high light integral of 15 to 17 mol^.m^-2.d^-1. Dry matter content was 20% greater for plants grown under cool compared to warm conditions. Total reduced nitrogen was 7% less under cool temperature. The concentration of nitrate was 40% lower, while the concentration of sugars was about 50% higher, under cool compared to warm temperature. Cool temperature increased the tissue concentrations of malic acid and potassium, but had no effect on phosphorus.

Maine has been researching a propagation system that applied water to the base of the stem in an enclosed container (aeroponics), rather than overhead as in traditional mist. Aeroponics was compared to over-head mist for vegetative propagation of a variety of plants including Lantana camara and Hydrangea paniculata. For the plants tested, the benefit of this system appears to be that roots form sooner in aeroponics compared to over-head mist. Plants propagated in aeroponics generally have longer roots, and roots have a greater dry mass compared to over-head mist. There is the potential to save water when propagating plants in aeroponics as well. Solenostemon scutellarioides (Coleus) propagated using overhead mist used the same amount of water for three typical mist cycles (30 seconds) as plants would use in aeroponics for an entire propagation cycle (several weeks).

Virginia Tech surveyed nursery and greenhouse operators to evaluate their use of BMPs and barriers to implementing new BMPs to assist us in developing publications and resources to assist producers in improving production efficiency and reduce environmental impact.

NE: A total of five cultivar studies of Basil (Ocimum spp.) were conducted in late fall 2014 through spring 2015, fall 2015, spring 2016, fall 2016 and spring, 2017 where plants were grown using a capillary mat (CapMat) irrigation/fertigation bench system (a sandwich of white reflective /black plastic polyethylene top, capillary mat, black 6 mm polyethylene), in a double polyethylene-glazed Quonset style greenhouse (ENT-3), located on the east campus of the University of Nebraska-Lincoln.  Decagon GS3® electronic sensors were installed in the root balls of selected 8 pots (2 cultivars) to sense and monitor volumetric water content, electrical conductivity, and media temperature. The primary hypothesis for these studies was to predict final herbage (dry weight) of basil, based on electronic sensor inputs and other factors.  A growth parameter (height of the sensor plants) as an outcome was initially tested.  Height data was collected for each of the sensor plants in 2017, involving the cultivars: Mrs. Burns Lemon and Italian Large Leaf.  There were three plants per pot in this study. Basically these plant height responses do not necessarily follow a classical sigmoidal growth model. However, approximate reasoning modeling (Fuzzy Logic discussed under objective 2) should follow the growth process closely.  There has been considerable statistical analysis interest from researchers relative to large amounts of data from electronic sensors and subsequent plant growth responses.  During the final year of this project, Dr. Walt Stroup (UNL) and one of his statistics graduate students have agreed to work with our sensing data, as a RCBD repeated measures experiment.

NY: Microgreens (young leafy greens harvested at the emergence of a true leaf are a relatively new profitable niche crop for greenhouse operations. However, very little information is available in the scientific literature regarding cultural practices. The influence of liquid fertilizer (applied at 0, 50, 100, 150, and 200 ppm N from a complete liquid fertilizer) was evaluated on three brassica microgreens (arugula, mustard and mizuna). All species exhibited increased fresh weight as fertilization increased from 0 to 200 ppm N, with fresh weight about double at 200 ppm N than the unfertilized control. Seeds were sown in a peat/perlite based soilless media. Substrate depth within a flat was also studied and significantly enhanced yields were found when a flat was filled nearly to the top (as opposed to shallow filling to save on substrate).

CT (Storrs): The University of Connecticut finalized a series of experiments to understand how biofilm accumulates in irrigation pipes and how biofilm interacts with pathogens and nutrients in the nutrient solution. Results indicate that pipe materials affect the rate and final accumulation of biofilm and that diseases incidence is lower when biofilm is present in the pipes.

CT (Storrs): The University of Connecticut finalized a trial to estimate the phytotoxicity threshold of Impatiens walleriana to residual concentrations of 2-32 mgl/L of free chlorine in the irrigation water. Plants irrigated with 2 mg/L were no different than plants irrigated with no chlorine residues. Plants irrigated with 4 mg/L of free chlorine exhibited reduced plant weight, but no visual lesions on the foliage or flowers. Plants irrigated with 8-32 mg/L presented clear phytotoxicity symptoms. Results indicate that irrigation water with chlorine threshold for Impatiens walleriana is 2 mg·L−1 of free chlorine.

1. Test irrigation systems in parallel utilizing the same set of greenhouse crops and cultural conditions to develop metrics for their use

1. Develop outreach materials for commercial greenhouse operations for effectively implementing these systems to save water and fertilizer resources

Maine presented information on water requirements of various herbaceous perennials at New England Grows, which is a large regional trade show. This information was a summary of research in Maine over the past ten years regarding how much water a variety of perennial plants need for growth and development. These recommendations were developed by growing perennials in a moisture sensor automated irrigation system at various soil moisture levels (varying from 5% to 40% soil moisture).

Virginia Tech conducted a workshop on hydroponic production of greenhouse vegetables that included lectures and hands-on demonstrations for about 40 people. Comments after the workshop included appreciation for the training and decision support tools. As a result of the workshop, one attendee has joined our team as an online graduate student starting this fall. All presentations have been posted on the Fresh Produce Food Safety YouTube channel

NY: A series of three extension articles regarding visual symptoms of nutrient deficiencies in hydroponic lettuce, basil, and arugula was developed. The project was completed by a female undergraduate student who grew plants in hydroponic nutrient solutions lacking particular elements of interest. Photos and written symptoms of nutrient deficiencies were documented. The article series has been published both at e-Gro.org and Inside Grower magazine.

CT (Storrs): Delivered a total of 17 formal presentations (equivalent to approximately 340 contact hours) to growers on topics directly or indirectly related to water quality and nutrient management.

CT (Storrs): Published a total of 17 articles on popular press magazines with readerships of ~20K (Greenhouse Grower Magazine and GPN magazine), and ~4K (e-Gro).

CT (Storrs): Co-sponsored five workshops in CT and co-chaired education program in the northeast which provided a total of 60 contact hours to approximately 1232 individuals.

CT (Storrs): Provided a total of 71 individual recommendations on water, nutrient and environmental management to greenhouses growers in the US .

Topic 2: Alternative Energy Sources and Energy Conservation

2. Develop guidelines and approaches to improve greenhouse heating system efficiency

3. Develop guidelines and approaches for the use of alternative energy sources

Virginia Cooperative Extension provided access to and funding for energy audits and renewable feasibility studies for 66 agricultural operations in Southside and Southwest Virginia. Between 2014 and 2016, 71 farms were accepted into the energy program, 5 farms withdrew, 64 of the 66 remaining farms completed an energy audit with 2 farms delaying their audits, 31 farms have used approximately $214,000 in grant funding along with over $610,000 in individual funds to implement energy retrofits, and 35 farms have funds remaining in their energy accounts for additional improvements. The 64 completed farm energy audits identified potential annual energy savings of 873,968 kWh in electricity and 429,847 gallons of propane with efficiency improvements resulting in a projected 3,151 MTCO2e greenhouse gas emissions reductions and an annual energy-cost savings of $850,734. Approximately 46% of the energy conservation measures had a payback period of less than 5 years. The Agriculture Energy Efficiency Initiative has delivered 20 educational programs on energy efficiency practices and technologies. Partnerships are in place with USDA Rural Development, Virginia Department of Mines, Minerals and Energy, Old Dominion Electric Cooperative, and other organizations to support this project. Updated by Dr. Martha Walker on 13 Jan 2017

NY: During a multi-year research project, several commercially available HPS and LED fixtures were obtained and tested for PAR efficacy and light distribution (collaborator A.J. Both at Rutgers) and plant growth responses of baby leaf greens. In initial trials, plant performance of baby leaf greens was quite similar between LED and HPS (under a background of sunlight in a greenhouse). Based on PAR efficacy (µmol/J), the most efficacious LED fixture was 40% more efficacious than the top performing HPS fixture. However, due to the high initial cost, a simple payback for LED was estimated to be about 12 years (in a scenario regarding lighting greenhouse lettuce in upstate New York. Following the initial phase of the project 1 LED (Philips GreenPower LED Toplighting DR/B – Low. B) and 1 HPS model (Gavita Pro 6/750e DE FLEX) were chosen for additional greenhouse trials lighting a larger crop area based on PAR efficacy and plant performance. A lighting array above a ca. 340 square foot growing area in the greenhouse was designed for each of the two models. Using AGi32 lighting design software we were able to achieve 95% light uniformity across the array. The two arrays will be used for a year-long study on energy efficiency and plant morphology of hydroponic baby leaf greens.

Topic 3: Sensors and Control Strategies

4. Evaluate and develop novel sensors and environmental control strategies

NJ: As a result of our lamp testing, we proposed a product label that contains key product information useful to greenhouse growers interested in using supplemental lighting for crop production. 

NE: The use of approximate reasoning such as fuzzy set theory could be a useful mathematical tool for plant and horticultural production studies. Plant harvest weights and electronic sensor data that were recorded were used for training and internally validating fuzzy logic inference and classification models, MATLAB® (Mathworks, Nattick, MA) ANFIS and the Fuzzy Logic Toolbox.  Studies showed that GENFIS2 ‘subtractive clustering’ of data, prior to ANFIS training, resulted in good correlations for predicted growth (R2 > 0.85), with small numbers of effective rules and membership functions.  Cross-validation and internal validation studies also showed good correlations (R2 > 0.85).   Using a neural-network and fuzzy logic, a simple fuzzy inference model was found to fit the 2017 growth height hypothesis for GS3 sensors and two cultivars as inputs, quite well.  Additional approximate reasoning modeling through testing and validation will include the actual individual plant heights (3 per pot).  A detailed discussion of this modeling approach and it’s used for these cultivar horticultural studies will be presented in an upcoming American Society of Agricultural and Biological Engineering paper in July 2017, and further updated and refined for a refereed journal article.

5. Outreach activities (presentation, publications, demonstrations) to stakeholders

NJ: The proposed lighting label has been presented to scientific and grower audiences across the US and at a scientific conference in Australia. Several lighting manufacturers have responded positively and indicated they would be adding the proposed label to their products. We plan to continue our outreach efforts for expanded implementation of the label.

NY: In New York State the greenhouse vegetable industry continues to grow at a rapid pace. According to the latest data available (USDA Census of Agriculture) whole value of greenhouse vegetables increased by 10.6% annual between 2007 and 2012. A meeting was organized for diverse members (producers, suppliers, produce buyers, and financiers) of the controlled

environment agriculture (CEA) industry. The board has semiannual meetings and has formed four working committees: Association/Policy, Education, Finance, Research & Development.

NY: Eight presentations were given reaching more than 835 commercial greenhouse/controlled environment agriculture industry members. Two webinars (one on nutrition for hydroponic crops and one on greenhouse lighting) reaching a national audience of 215 were given. Four trade journal articles, and three website extension bulletins reaching a national commercial greenhouse audience were published. A summer floriculture field day was co-organized reaching 100 attendees. n Integrated Pest Management hands-on workshop was coorganized with 45 participants. The workshop included session on alternatives to liquid fertilizer to reduce nutrient leaching and decrease fertilization costs. Regarding an academic audience, five relevant peer reviewed journal articles were published and five presentations were given at academic meetings. week-long training program for six USDA Cochran Fellows from Jordan was held (in collaboration with UC Davis colleagues) on hydroponic production methods to improve water use efficiency in vegetable

production.

Other accomplishments that do not necessarily relate to the NE-1335 Multistate Research Project objectives:

UNH: A variety of outreach presentations on crop fertility, managing the greenhouse environment, integrated pest management have been delivered in New Hampshire and out of state. Private funding has been secured to conduct research and educate growers on using new wood fiber substrates. University of New Hampshire research and extension are collaborating with the USDA and commercial greenhouses in New Hampshire to model light, carbon dioxide, and temperature interactions in the greenhouse. University of New Hampshire research and extension personnel are looking into improving postharvest quality of flowering and edible crops produced in greenhouses.

CTNH: We previously developed a steady-state model of vegetative growth based on the hypothesis that growth is the minimum of the supply of non-structural carbohydrate, NSC, from photosynthesis, and the demand of NSC to synthesize new tissue. Here we incorporate sink inhibition of photosynthesis in a dynamic model of growth hour by hour, and assume that starch synthesis and breakdown provides sufficient NSC for growth and respiration during both day and night. It is not clear whether photosynthesis inhibition changes within the photoperiod or only from one day to the next. When this dynamic model was applied to tomato plants which had been pre-adapted under high or low light, respiration in darkness was first predicted to be constant, and then decreased with time, when NSC fell below the value needed for maximum growth. When predicting growth for tomato seedlings in a growth chamber at various temperatures between 9 and 36^oC, the correlation between predicted and actual minimum values of NSC was greater for the dynamic model (R² = 0.83) than the steady-state model (R²=0.65). A large fraction of photosynthesis must be inhibited to predict NSC accurately under demand-limited conditions, in contrast with little inhibition under supply-limited conditions.  This combination could be achieved only by relating inhibition to the minimum NSC content over a diurnal cycle, rather than NSC hour by hour during the day.

NJ: A variety of outreach presentations on high tunnel construction, greenhouse lighting, energy consumption, and electrical safety have been delivered at local and out-of-state venues. A $50K travel grant was secured from the USDA to help support travel expenses of NCERA-101 members who attended the 5^th International Controlled Environment Meeting (AusPheno) in September 2016 in Australia. Rutgers University is contributing to a consortium headed by Cornell University and Rensselaer Polytechnic Institute, that is funded by NYSERDA and aims to study greenhouse lighting and systems engineering.

NE: Additional impact – Training future female horticultural and biological systems engineers (STEM) as well as male undergraduate future scientists

Two UCARE undergraduate female biological systems engineering students (Funded in part by gifts from the Pepsi Quasi Endowment and Union Bank & Trust, that support UNL undergraduate research) performed studies in basil leaf response studies to thermal stress and basil leaf cultivar identification, using machine vison methods and LeafGUI (Price, et al, 2012).  NE1335 funding also supported a third undergraduate student. Four additional undergraduate horticulture students (2 female) were employed through NE 1335 and Horticulture Specialty Block grant funding.  Impact: two students graduated and are employed in a job of their choice based on experience gained by participating in this project. Two (1 female) are continuing through this next year.