Trickle irrigation is the most efficient method of irrigating peach orchards in Texas. With a trickle irrigation system, a producer may make full use of a limited or low-volume water supply to apply precise amounts of water to the root zones of individual trees. Improved irrigation scheduling methods offer the potential for further savings in water and energy to pressurize the water since peach trees require less than a fully-watered state for production. This report describes research to determine the crop coefficients for peach trees that would result in an optimum irrigation schedule. One major effort evaluated the physiological response of the peach tree to varying irrigation regimes. This thrust indicated that a crop coefficient as low as 0.53 produced similar physiological responses (leaf water potential, leaf resistance, and transpiration rate) as a crop coefficient of 0.7. The critical period for initiation of stress was during the period before harvest. A large twin weighing lysimeter facility was designed and installed. Preliminary results for mature peach trees showed water use rates at the maximum evapotranspiration rate approached a crop coefficient of 1.0. The research indicates that the peach tree is a luxury consumer of water; improved irrigation scheduling is achievable
