2012 Annual Report 1a.Objectives (from AD-416): To determine the response of corn to endogenous ethylene produced during specific growth stages during water stress. 1b.Approach (from AD-416): Procedure 1. Plot size: 6 rows by 10 m, with two row buffers between plots a. Replicated 8 times 2. Corn Variety: Dekalb 5259 triple stack 3. Irrigation Levels b. 100% ET until the V6-V7 growth stage 1). Withhold water until leaves begin to curl in the middle of the day. 2) Apply 25 g/ha of 1-MCP 3) Remain under water stress for 7-10 d after application 4) 100% ET for the rest of the season. 4. 1-MCP application rate: 25 g a.i./ha applied in 200 l/ha with appropriate surfactant as designated by cooperator. 6. Measurements a. Plant height (internode length) (early application timing only) b. Leaf elongation (hand measures of leaf length and width and/or NDVI) c. Transpiration (Porometry) d. Gas exchange (CO2 and H2O) every day after application and 3 weeks after drought is relieved. e. Rate of senescence (SPAD of leaf above ear leaf and leaf below ear leaf– regular intervals; or canopy level multispectral analysis) f. Yield of middle 2 rows of each plot g. Yield components (kernel #/ear; 1000 kernel wt. test weight, etc.). 3.Progress Report: A study on the effects of 1-MCP, a plant growth regulator that interferes with a plant’s response to ethylene, on corn grown under three different levels of irrigation continued with a new cooperative agreement between USDA-ARS and Agrofresh. In 2012, we concentrated on applying 1-MCP to water stressed corn at the V10 growth stage and then returning the plants to full irrigation for the rest of the season. The plots were set up with paired controls and yield parameters will be measured at the end of the season. Greenhouse studies begun in January 2012 on the interactions between ethylene and 1-MCP application in corn and sunflower showed that plants treated with 1-MCP were not as stunted when treated with ethylene (ethaphon) compared to plants treated with ethylene alone.