Cotton water stress under trickle irrigation

Cotton was trickle irrigated two to three times weekly in 1984 and 1985 using buried perforated tubing under each row. Water application rates were about 0.6, 1.0, and 1.3 times estimated consumptive use (CU). The cotton was monitored for water stress using the crop water stress index (CWSI), soil water content, and yield. Significant differences in seasonal average crop water stress values, average soil water contents, and yields were obtained for the three water treatments. The wettest treatment with average CWSI values near 0.1 gave the highest yield and had the highest soil water contents before irrigation. The yield increased nearly linearly with decreasing CWSI while the water use efficiency (yield per unit of water) was highest for the 1.0 CU treatment.