Evaluation of Irrigation Termination Management on Yield of Upland Cotton, 1995

A single field study was conducted in 1995 at the Maricopa Agricultural Center (1100 ft. elevation) to evaluate the effects of three dates of irrigation termination on yield a common Upland cotton variety (DPL 5415). Planting date was 3 April (469 HU /Jan 1 86/55° F thresholds). Following difficult establishment, crop vigor was generally low all season, with a relatively strong level of fruit retention. Three dates of irrigation termination an -1T3) were imposed based upon crop development into cut -out, with IT1 (21 August) set such that bolls set at the end of the first fruiting cycle would not be water stressed and could be fully matured. The third termination (IT3) date was 22 September, which was staged so that soil moisture would be sufficient for development of bolls set up through the first week of September. The second irrigation termination (IT2, 1 September) was intermediate to IT1 and IT3. Lint yield results revealed a 139 lb. lint/acre difference between IT1 and IT3, which was statistically significant (P < 0.05)