Evaluation of the Pressure Chamber for Timing Early Season Irrigations

Abstract

Use of the pressure chamber to time the initial post- planting irrigation of short season upland cotton was evaluated in a pilot study at Marana during 1992. Top yields and better overall plant performance were obtained when the initial post - planting irrigation was applied before leaf xylem potential (ψx) dropped significantly below -15 bars. Our findings were similar to those previously observed with Acala cotton in California. The authors believe more work is required before use of the pressure chamber is recommended for irrigation management in Arizona. Specifically, an effective means of separating changes in ψx resulting from day-to-day climate fluctuations from those caused by soil-water depletion must be developed. This study also clearly showed the importance of avoiding early season water stress when growing short season cotton.