D.F. Wanjura, D.R. Upchurch, J.R. Mahan
A dependable irrigation scheduling procedure is needed to achieve the potential benefit of correct water management with drip and sprinkler irrigation systems. A threshold temperature method for controlling drip irrigation scheduling of cotton was evaluated using 2 °C increments between 26 °C and 32 °C. Threshold temperatures ≥ 28 °C restricted water application and caused higher levels of water stress. Maximum yields were produced by 28 °C and 30 °C threshold canopy temperatures. By selecting different threshold temperatures drip irrigation can be controlled to apply different amounts of water. Canopy temperatures of well-watered cotton, tomato, and bell pepper were similar in a 1990 comparison.

The threshold temperature method was adapted to schedule irrigation of a sprinkler system in 1991 by using a minimum 3-day irrigation cycle which was modified by temperature-time thresholds. Average irrigation cycle length increased linearly as threshold time increased. Threshold canopy temperature controlled irrigation scheduling was tested on cotton but the concept is applicable to other crops.

Wanjura, D.F., Upchurch, D.R. and Mahan, J.R. (1993). CANOPY TEMPERATURE CONTROLLED IRRIGATION. Acta Hortic. 335, 477-490
DOI: 10.17660/ActaHortic.1993.335.59

Acta Horticulturae