Tuesday, November 14, 2006 - 9:15 AM

Physiological Responses of Corn and Cotton under Limited Irrigation Management.

Jonghan Ko1, Giovanni Piccinni1, Brian Trees1, Shinsuke Agehara1, Ty Witten2, and Mikhailo Kolomiets3. (1) Texas A&M Univ. Res. & Ext. Ctr., 1619 Garner Field Rd., Uvalde, TX 78801-6205, (2) Monsanto, 7200 Westfield Woods, St. Charles, MO 63304, United States of America, (3) Texas A&M University, Department of Plant Pathology and Microbiology, 2132 TAMU, College Station, TX 77843, United States of America

Plant physiological responses including photosynthesis are dependent upon various environmental conditions such as solar radiation, amount of CO2, temperature, soil moisture, and other micrometeorological and environmental factors. This study was conducted to investigate physiological responses of corn (Zea mays) and cotton (Gossypium hirsutum) under various micrometeorological conditions and grown under full and limited irrigation. We measured photosynthesis, transpiration, and water potential on individual leaves in each plant. When photosynthetically active radiation (PAR) increased, photosynthesis linearly increased until 2,000 PAR (μmol m-2 s-1) while water use efficiency (WUE) increased until 1,500 PAR and decreased after that. At various CO2 levels, photosynthesis and WUE linearly increased until 400 (μmol mol-1) and reached a plateau or increased non-linearly after that. Photosynthesis and water potential were lower under deficit irrigation. The relationship among these physiological parameters and yield is discussed in relation to the different irrigation regimes.

Keywords: Corn, cotton, deficit irrigation, photosynthesis, water use efficiency.