A. H. Mohammadi, Z. Banihashemi,
Volume 12, Issue 45 (10-2008)
Abstract
Pistachio (Pistacia vera L.) is an important economic crop, which is mostly planted in saline conditions in Iran. Verticillium wilt disease of pistachio caused by Verticillium dahliae is known as a serious disease for pistachio trees. The causal agent was recovered from shoot and soil samples collected from main pistachio growing areas in Kerman province. The present experiment was carried out to study the effect of salinity on disease using three common P. vera rootstocks including Sarakhs, Badami-e-Zarand and Qazvini and four levels of salinity (0, 1400, 2800 and 4200 mg NaCl per kg soil) in hydroponic culture (1/2 strength Hoagland,s solution). Salt stress was applied before inoculation on ten week old seedlings. The experiment was carried out as factorial in RCD with four replications. Two weeks after salt stress induction, four seedlings were transplanted into pots containing 5 kg sandy-clay virgin soil artificially infested with 40 microsclerotia per gram of soil with equal salinity. In NaCl treatments, Sarakhs showed lower shoot and root dry weight and higher concentration of Na, K and Cl than the other rootstocks. Based on the results, Sarakhs, Qazvini and Badami were found to be susceptible, tolerant and intermediate to NaCl, respectively. In the presence of V. dahliae, salt stress significantly reduced shoot and root dry weight and increased stem and root colonization by the pathogen and Na, K and Cl concentration compared to non-stressed inoculated plants. Sarakhs had higher percentage of colonization of stem and root by V. dahliae and concentration of Na, K and Cl than other cultivars. As a general conclusion, salt stress before inoculation by V. dahliae can increase the severity of Verticillium wilt of pistachio, especially in salt-sensitive rootstocks.
