Study on interaction of salinity and cucurbit wilt disease (phytophthora drechsleri tucker) in some cucumber cultivars

Cucurbit wilt caused by Phytophthora drechsleri is one of the most important diseases in Varamin and Garmsar areas. Reduction of yield of cucurbit by this disease has been reported about 25%. Soil salinity which can cause the important damage to the plant metabolism and nutrition, is common in these regions. Cucumber is susceptible to salinity stress. Therefore salinity stress may increase the susceptibility of cucumber to Phytophthora drechsleri. Different levels of salinity (control, 0, 10, 25 and 50 mM NaCl) on three current cultivars (Tezier, Super 2000 and U. S. A.) of cucumber were investigated at the presence of P. drechsleri in greenhouse conditions. A factorial analysis for completely randomized design with 3 replications, was used for these experiments. Significant differences were observed among the different levels of salinity. Increasing stress due to salinity increased the susceptibility to the disease. Cucumber cultivars had different responses to salinity. The effects of different levels of salinity (0, 10, 25, 50 and 75 mM NaCl/l) were also investigated on growth of P. drechsleri on CMA culture at a completely randomized design with 3 replications. Variance analysis of growth area of fungus on CMA culture showed significant differences among different levels of salinity. Growth area of fungus was 6359 mm2 for control and 4725 and 4797 mm2 for 50 and 75mM NaCl, respectively.