2010 Annual Report
1a.Objectives (from AD-416)
The objective of this unified research effort is to improve the efficiency of plant production through a multi-disciplinary team approach that focuses on scheduling, the environment, energy, nutrient, water, and chemical growth regulator resources.
1b.Approach (from AD-416)
Develop protocols to flower plants at a specified plant size for the retail environment, and extending the marketing season by producing early- or late-flowering plants for different locations in the U.S. A single product or tank mix growth retardant applications for new crops that reduce elongation most without delaying flowering and whether innovative practices such as rewetting of foliage increases efficiency of growth regulators. Identify the crops and stages of development in which lighting is most effective. In addition, photoperiodic lighting is increasingly being used to induce earlier flowering during the winter and spring. Determine how photoperiodic lighting can be maximized by investigating how light quantity, quality, and duration (including cyclic lighting) impact flowering of a range of popular garden plants. Potential energy savings will be quantified by optimizing light and temperature to produce crops in the most efficient and cost-effective manner for different locations in the U.S. Develop tools and techniques that allow growers to more precisely control and manipulate flowering of greenhouse crops. Techniques will be developed for producing 'programmed' liners that have the branching, height potential, and flower bud development necessary so that the liner can be simply transplanted and quickly finished. "Bud meters" will be developed for important floriculture crops so that growers can manage greenhouse environments in order to properly time flowering on finished crops or to possibly reduce greenhouse temperatures to save fuel costs while still hitting the targeted market dates. Determine optimal fertilziation rates and tissue nutrient levels to maximize growth of flowering plants and characterize the symptoms of nutritional disorders. Measure nutrient uptake through leaves, stems, and roots at different stages of rooting under greenhouse and controlled hydroponic conditions to match fertilizer supply with demand. Quantify the interaction of applied water and fertilizer rates on leaching of different forms of nutrients from propagation media. Identify the fertigation strategies that reduce nutrient leaching while maintaining crop health.
Managing the Greenhouse Environment for Energy Conservation.
We completed experiments that quantified how temperature and photosynthetic daily light integral (DLI) influences crop timing and quality of over 30 herbaceous ornamental crops. Plants were grown in greenhouse environments at temperatures ranging from 57 to 79 °F (14 to 26 °C) under two DLIs. Data were collected on time to flower and flowering characteristics, such as flower number. Data was then analyzed to estimate the base temperature (the cool temperature at which plants begin to grow) and when possible, the optimum temperature (the temperature at which plant development is maximal).
An experiment was also performed to determine the effect of diurnal temperature fluctuations on growth and flowering of three bedding plant crops. Plants were grown in the research greenhouses with a 16-hour day / 8-hour night at 68/57, 64/64, 61/72 °F (all with averages of 64 °F), 75/64, 72/72, and 68/79 °F (all with averages of 72 °F). Time to flower of the three crops (dahlia, French marigold, and zinnia) was similar among treatments with the same average daily temperature. Virtual Grower was then used to estimate energy consumption for greenhouse heating on a per-crop basis at three geographic locations at the six different temperature setpoints. Heating costs depended on the finish crop time, species, and geographic location, but generally they were lowest when crops were grown at a warmer day than night temperature (e.g., 68/57 and 75/64 °F). For example, compared with a day/night temperature of 68/57 °F, dahlia produced in Charlotte, NC with a finish date of 15 April is estimated to consume 15% more energy at a constant 64 °F and 36% more energy if grown at a day/night of 61/72 °F.
We are providing this information to the USDA-ARS Greenhouse Production Research Group, which is adding the crop development data into the Virtual Grower computer program. In the coming year, we are planning to experiment with additional popular bedding plant crops to develop temperature responses under a range of greenhouse growing conditions.
Improving Energy-Efficiency of Petunia Production.
We compared the flowering time of more than 20 petunia cultivars to identify early flowering cultivars. This will allow growers to improve energy-efficiency of production by selecting rapid flowering cultivars. Additionally, we have screened crop timing responses of several wild relative species to the cultivated petunia. From this work, we have identified species with faster development rates than currently available cultivars that could be used to breed faster flowering cultivars, particularly at cool production temperatures.
Progress was monitored through frequent email communication, regular face-to-face meetings during the year (6+), and occasional phone calls.