Yield, Growth, Rooting Pattern Response to Deficit Drip Irrigation

Field trials have been conducted for five years in the San Joaquin Valley of California with Pima and Upland cotton varieties grown in a deep clay loam soil to determine responses of yield, growth and to a limited extent end-of-season root distribution patterns to drip irrigation in amounts ranging from mild to moderate deficit irrigation.  Different deficit irrigation approaches tested have included: (1) two different levels of early-season irrigation to provide different levels of initial stored soil water, and (2) different percentages of replacement of calculated evapotranspiration during specific growth stages (pre-bloom, first bloom to cutout, post cutout) at levels of 60, 80, or 100 percent of estimated crop evapotranspiration.