Soil Salinity and Water Stress and Their Effect on Susceptibility to Verticillium Wilt Disease, Ion Composition and Growth of Pistachio

The effects of soil salinity and water stress on Verticillium wilt, ion composition and growth of pistachio were studied in a greenhouse experiment (18–32°C). Treatments consisted of three levels of salinity (0, 1200 and 2400 mg NaCl/kg soil), three levels of water stress (3, 7 and 14 day irrigation regimes) and two Pistachio cultivars (Sarakhs and Qazvini, common rootstocks in Iran). Infested soil containing 50 microsclerotia/g of a pistachio isolate of Verticillium dahliae was used for all treatments and non‐infested soils were used as control. The experiment was arranged in a completely randomized design with three replications. Eight‐week‐old pistachio seedlings were transferred to infested and non‐infested soil and then exposed to salt stress and thereafter water stress. Shoot dry weights of both rootstocks were reduced significantly with increasing NaCl levels; however, increasing irrigation regimes reduced salt injury. Salt stress significantly increased shoot and root colonization by V. dahliae in both cultivars. Moreover, increasing of salinity level was positively correlated with increasing concentrations of Na⁺, K⁺ and Cl^? in both cultivars, but negatively correlated with increasing irrigation regimes. Based on these results, Sarakhs and Qazvini were found to be sensitive and tolerant to the effect of irrigation regimes, salinity and Verticillium wilt disease, respectively. Although there were no interactive effects of irrigation and salinity on V. dahliae infection.