Optimizing Pistachio Irrigation Management Using th e Relationship between Echo-physiological Characteristics and Water Stress

Abstract

In this research, some of the echo-physiological ch aracteristics of pistachio trees were studied to understand crop response to drought stre ss and determine the best irrigation interval. This experiment was carried out in an orc hard with a sandy loam textured soil and a commercial cultivar of pistachio named Ouhadi grafted on Pistacia vera L. rootstock for three years. The irrigation system se lected was surface flooding with intervals of 30, 50, 80, and 110 days. These interv als were chosen so as to resemble common irrigation intervals of pistachio orchards i n the region. This enabled a comparison between the best and worst conditions of trees in respect to drought stress. Total irrigation water received was a constant dept h of water to all treatments. Quantitative and qualitative yield such as weight o f fresh and dry nuts, percent of blank and split nuts, and number of nuts per ounce, veget ative and echo-physiological characteristics were considered and measured. In te rms of yield quantity and quality, the results showed vegetative and echo-physiological at tributes to be significantly different between the treatments of 30, 80 and 110 days irrig ation intervals. This means that with an increase in irrigation intervals and considering soil water holding capacity, soils were not able to provide enough moisture for the plant t o carry out its normal metabolic activities. However, in the prolonged irrigation in tervals, there were not much differences between treatments i.e. the pistachio tree could ad apt itself to the naturally occurring environmental stress conditions. Keywords: Drought stress, Relative water content, Water use efficiency.