The Effect of Water Stress on Root Rot Disease of Pistachio Seedlings Caused by Cylindrocarpon destructans

The effect of water stress on plant growth parameters and root rot disease of pistachio seedlings caused Cylindrocarpon destructans was evaluated under greenhouse conditions. Treatments consisted of three levels of soil moisture [(D0= 80%, D1= 50% and D2= 30% of Field capacity (F.C.)] and two levels of fungal pathogen (F0= control and F1= C. destructans). The experimental arrangement was factorial with completely randomized design with five replications. Four months after inoculation, inoculated plants were uprooted and the shoot and root dry weight, shoot and root fresh weight, shoot height, root length and leaf numbers of each seedling were determined. According to the results, the main effect of water stress caused a significant reduction (at 1%) in all plant growth parameters. The main effect of fungal pathogen caused a significant reduction (at 1%) in shoot fresh weight, root and shoot dry weight, shoot height, root length and leaf numbers. Water stress and C. destructans interaction caused significant reduction on root dry weight and shoot height at 1% and shoot dry weight and root length at 5%. Water stress increased the negative effects of the pathogen on pistachio seedlings. In this regard, the interaction between C. destructans and D2 (30% F.C.) had the greatest impact on reducing growth parameters. Disease severity also increased by increasing water stress.