Drought effect on root dry weight in three potato cultivars

Drought effect on root dry weight of three potato cultivars (Marfona, Agria, and Draga) were evaluated in a strip block design with three replicates. Stress treatments (four levels) were arranged in horizontal and cultivars in vertical plots. After cultivation practices and fertilizer applying, seed tubers were sown in 5*75 cm in nine 5-meter rows and irrigated immediately. Irrigation treatments were equal for all treatment until stress began. After 50% flowering until the end of flowering, stress treatments were applied. Root dry weights were measured every other week. ANOVA showed that any stress might decrease root dry weights as compared with the control. In stress levels, differences in root dry weights recovered in the end of growth season. In spite of yield decrease, there were no differences in root dry weights at stress levels. Some of reasons of Agria's higher yield than Draga in mild and severe drought may be its high root dry weights, so it had longer active roots and adsorbed more water and minerals from soil than Draga. It seems that there was no new root formation in the end of season period and matured roots remobilized dry matter to tubers, but in case of drought, new roots with less dry matter produced.