Impacts of Moderate Deficit Irrigation on Pima Versus Upland Cotton Varieties

Two studies were conducted in a clay loam soil at the University of CA West Side REC that included Pima and Upland cotton varieties grown under both subsurface drip and furrow irrigation.  Goals of the study were to assess differences in responses of Pima and Upland varieties to deficit irrigation.  The types of deficit irrigation practiced in these studies were very different based on the irrigation method used, furrow versus subsurface drip irrigation.  Deficit irrigation as practiced in a low-frequency irrigation system (furrow irrigation) consisted of eliminating specific irrigations such that the more severe deficit treatments had longer time periods without stress relief and rewatering.  Deficit irrigation as practiced in the higher-frequency subsurface drip system studies consisted of reduced application amounts in deficit irrigation treatments, but with the same frequency/timing of irrigations for all irrigation treatments.  Impacts of these deficit irrigation treatments to be reported will focus on growth and yield responses, but will also describe some specific impacts on measures of plant stress levels, boll retention patterns and fiber quality.