Applying plant-based irrigation scheduling to assess water use efficiency of cotton following a high-biomass rye cover crop

摘要

This study addressed the potential of combining a high biomass rye winter cover crop with predawn leaf water potential (PD) irrigation thresholds to increase agricultural water use efficiency (WUE) in cotton. To this end, a study was conducted near Tifton, Georgia under a manually-controlled, variable-rate lateral irrigation system using a Scholander pressure chamber approach to measure leaf water potential and impose varying irrigation scheduling treatments during the growing season. PD thresholds were 0.4 MPa (T1), 0.5 MPa (T2), and 0.7 MPa (T3). A winter rye cover crop or conventional tillage were utilized for T1-T3 as well. Reductions in irrigation of up to 10% were noted in this study for the driest threshold ( 0.7 MPa) with no reduction in lint yield relative to the 0.4 MPa and 0.5 MPa thresholds. Drier conditions during flowering (2014) limited plant growth and node production, hastened cutout, and decreased yield and WUE relative to 2015. We conclude that PD irrigation thresholds between 0.5 MPa and 0.7 MPa appear to be viable for use in a PD scheduling system with adequate yield and WUE for cotton production in the southeastern U.S. Rye cover positively impacted water potential at certain points throughout the growing season but not yield or WUE indicating the potential for rye cover crops to improve water use efficiency should be tested under longer-term production scenarios.