Physiological basis of drought tolerance in potato grown under long-term water deficiency

Coping with water shortages without compromising tuber yield is a majorchallenge for potato (Solanum tuberosum L.) production in northern China. In thisstudy, we used three potato cultivars with different sensitivities to drought toevaluate the effect of long-term drought stress on morphological and physiologicalcharacteristics under field conditions during three growing seasons (2009-2011).Our aim was to identify the specific drought tolerance traits of the potato cultivarsto enable their cultivation in arid and semi-arid regions. Our results show that thedrought-tolerant cultivars had higher tuber yields under conditions of drought duean increased number of tubers per hill and increased individual tuber weight.Compared with the drought-sensitive cultivar Neishu no. 7, the drought-tolerantcultivars Kexin no. 1 and Konyu no. 3 had stronger root systems and a highercapacity for water absorption at later developmental stages and a higher leafrelative water content, which conferred enhanced water retention under droughtconditions. Moreover, the levels of superoxide radical and hydrogen peroxide werelower and the activities of antioxidative enzymes, including superoxide dismutase,peroxidase and catalase, were higher in the drought-tolerant cultivars underdrought stress conditions. These combined characteristics allowed the cultivars toexhibit different levels of water deficiency. The above agro-morphological andphysiological parameters could be used as a basis for breeding potato varieties withenhanced drought tolerance.