2007 Annual Report 1a.Objectives (from AD-416) Plant nutrients are taken up and used differentially based on species, ontogeny, and environment. Currently, much is known about the requirements through time for specific species in different plant parts for a 'typical' greenhouse environment. Additionally, the responses of these nutrients are known to respond in specific ways to environmental stimuli and stress. The interaction of plant nutrient requirement with environment is not well understood. The objective of this research is to study nutrient uptake and partitioning of petunia, as a model crop, as influenced by temperature, humidity, and light. The results obtained from the nutrient uptake studies will help design better nutrient recommendations for floriculture growers, minimize nutrient leaching, optimize production practices for any given environment, and improve the chances of profitable bedding plant production. Better nutrient management would improve water and fertilizer use, improve plant quality and reduce nutrient discharge into the environment. 1b.Approach (from AD-416) To study environmental interactions on nutrient uptake and partitioning, a multi-chambered system is needed in a single location to ensure accurate environmental control and rigorous statistical replications. A 12 chamber phytotron facility located at Wooster, OH would meet the need of the proposed nutrient study. The facility can provide up to 600 'mole'm-2's-1 photosynthetically active radiation, and accurate air temperature and relative humidity controls. It could also be fitted for computer based data acquisition and control for temperature and humidity monitoring and gas composition control (CO2 enrichment and monitoring). For the majority of the studies, two light levels (600 'mole'm-2's-1 and 100 'mole'm-2's-1) and two temperatures (10ºC and 25ºC) will comprise a single block. The block will be replicated 3 times in the completed 12-chamber system. Within each chamber, at least 12 plants will be grown to allow for 4 sequential, destructive harvests per trial. Water status of groups of plants will be monitored using infrared thermometry, and multispectral imaging techniques. Micro lysimeters and soil moisture probes will be used to estimate water usage by the plants and amount of available water in the root zone. Harvested plants will be separated into new and old leaves, new and old stem tissue, flower buds and petals, and if possible, root tissue. The plant material will be oven dried, shipped to the Greenhouse Production Research Group in Toledo, OH, then ground to a fine powder and extracted with a microwave digester. Finally, prepared tissue, soilless media, and/or nutrient solution will be injected into the ICP-OES for elemental analysis, or combusted with a C-H-N analyze. 3.Progress Report This report documents research conducted under a Specific Cooperative Agreement between ARS and The Ohio State University. Additional details of the research can be found in the report for the parent project 3607-21000-011-00D Develop Improved Technologies for Soilless Greenhouse Plant Production to Minimize Water, Labor, Agrochemical Inputs and Environmental Impacts. Work in the past year was focused on developing the 12 growth chambers into a whole canopy photosynthesis system capable of measuring real-time CO2 flux. Small (4L) whole-plant test chambers were built and design considerations were included for scaling up to the large chambers (>1000 L). The intent is to use the system for rapid assessment of plant responses to biotic and abiotic stresses. These accomplishments address NP-305, Component I, Problem Statement A. The ADODR monitored activities regularly through personal contacts, telephone conference calls, and site visits.