Long-term field response of pistachio to irrigation water salinity

A three years field study was conducted to assess the effects of moderate and high saline irrigation water on the behavior of 5-year-old female trees of pistachio. Mateur cultivar was grafted on Pistacia vera L. and Pistacia atlantica Desf. rootstocks. Different water irrigation qualities were used: (i) tap water (ECw: 1.95 dSm−1); (ii) moderately saline water (ECw: 5 dSm−1); and (iii) highly saline water (ECw: 12 dSm−1). Rootstock and scion growth were measured. Fruit yield was monitored during the three years of salt treatment and the following year after salt stress was relieved. Leaf mineral content and electrolyte leakage were determined monthly during growing seasons. Results showed that tree growth was not affected by moderate salinity after the first season of experiments but the response changed at higher salinity and when salt treatment duration increased. Salinity of irrigation water did not affect average fruit yield per tree but when saline water irrigation was stopped, yield of trees previously irrigated with highly saline water increased significantly on P. atlantica rootstock in comparison with control. Sodium and chlorides ions content in leaves accumulated proportionally to salinity level and duration. Nitrogen (N), phosphorus (P), potassium (K) and calcium (Ca) as well as K/Na and Ca/Na ratios decreased with increasing salt concentration in the irrigation water. This reduction was more significant in the second and third years of the study. Water management practice was proposed to take advantage from the stimulating effects of mild/short term salinity on growth and production of pistachio Mateur cultivar.