Evaluation of Water Deficit Tolerance of 10 Potato Cultivars (Solanum tuberosum L.)Based on some Physiological Traits and Tuber Yield in Ardabil Region

This research was conducted to study the physiological traits affecting the yield of 10 different potato cultivars under water deficit conditions in a two-years study (2013 and 2014) in Ardabil Agricultural and Natural Resources Research Station. The study was performed in a split plot experiment based on randomized complete block design with three replications. The main-plots were three levels of irrigations (irrigation with 100%, 80% and 60% required water) and sub-plots consisted of 10 commercial potato cultivars (Khavaran, Savalan, Luca, Satina, Sante, Marfona, Caeser, Agria, Aula and Draga) released in the last 30 years. During the growing season, some physiological traits including relative water content, electrolyte leakage and chlorophyll content of the leaves were measured at their five different growth stages. Combined analysis of variance of traits showed that there were significant differences cultivars between years, and cultivars × water deficit stress interaction in all growth stages in terms of relative water content, electrolyte leakage, chlorophyll content and tuber yield. In terms of electrolyte leakage and chlorophyll content of the leaves, there were significant differences between years, different water stress levels, cultivars and cultivars × water stress level. In addition, in terms of tuber yield there were significant differences between years, water stress levels, cultivars and year × water stress level, cultivar × water stress level, cultivar × year. There were significant differences in chlorophyll content of the leaves under different irrigation conditios in the first, second, third and fifth growth stages of the potato. According to the results, under normal irrigation condition, cultivars Khavaran and Satina had higher relative water content, lower electrolyte leakage, higher chlorophyll content of the leaves and higher tuber yield. Under mild water stress condition, cultivars Caeser, Draga and Khavaran and under severe stress condition, cultivars Agria and Draga maintained higher relative water content and higher tuber yield; whereas cultivars Savalan, Luca, Satina and Marfona showed lower electrolyte leakage and higher tuber yield; and cultivar Savalan showed the highest chlorophyll content of the leaves and higher tuber yield under severe stress condition and thus were selected as tolerant cultivars to water deficit conditions.