DEVELOPMENT OF DEFICIT IRRIGATION STRATEGIES FOR PEACH PRODUCTION

The San Joaquin Valley in California is one of the most productive agricultural regions in the world. However, crop production replies on irrigation due to the hot and dry weather and lack of rainfall in the summer. In recent years, water supply for irrigation was decreased because of the competition for water demands from residential, industrial, and environmental usages. It is necessary to find management methods to optimize the usage for the limited supply of irrigation water.

Deficit irrigation has been studied for perennial crops to help alleviate water shortage. At certain growing stages, crops which are not sensitive to water stress can receive less than full irrigations. For early-maturing peach cultivars, it has been demonstrated that established peach trees are not sensitive to moderate water stress in the postharvest growth. Field studies were conducted since 2007 to evaluate deficit irrigation management in a 1.6-ha peach orchard in USDA-ARS, Parlier, CA. A wired network of infrared temperature sensors was installed above the orchard for monitoring canopy temperature, which has been used as an indicator of crop water stress. In the first two-years of the study, canopy temperature response from different irrigation treatments was investigated. Mid-day canopy to air temperature difference was found to be most sensitive to water stress. Then we used mid-day canopy to air temperature as a primary input for irrigation scheduling for the peach trees. The relationship between fruit weight and postharvest irrigation amount indicated that up to 50% water savings could be achieved without impacting fruit size. Our findings on peach tree deficit irrigation and thermal infrared sensors for guiding irrigation scheduling can provide growers with a practical tool to save water without reduction in yield and fruit quality.