Effects of Drought Stress on Physiological Index and Photosynthetic Traits at Seedling Stage of Winter Potato

Purpose Four potato varieties (Hui-2, Hezuo88, Lishu6 and Xuanshu2) were cultivated in pots in winter, and the effects on physiological indexes and photosynthetic parameters were studied under drought stress to provide a theoretical base for drought resistant cultivation and quality drought-tolerant winter potato varieties selection.Method Four main potato cultivars (Hui-2, Hezuo88, Lishu6 and Xuanshu2) used in Yunnan, were selected for drought stress. When the soil moisture content was 20% to 40% of the maximum amount of water in the field, the proline content, soluble sugar content, soluble protein content, SOD activity, POD activity, CAT activity, MDA content, soil water content, chlorophyll a, chlorophyll b, chlorophyll a/b, total chlorophyll, transpiration rate, net photosynthetic rate, stomatal conductance and intercellular CO₂ concentration were detected.Results The proline content, soluble sugar content, soluble protein content, SOD activity, POD activity, CAT activity and MDA content increased significantly under drought stress, however, the soil water content, chlorophyll a, chlorophyll b, chlorophyll a/b, total chlorophyll, transpiration rate, net photosynthetic rate, stomatal conductance, intercellular CO₂ concentration decreased. Chlorophyll a was more sensitive than chlorophyll b. Drought resistance ranks of four potato cultivars were as follows:Hui-2 > Xuanshu 2 > Hezuo88 > Lishu 6.Conclusion Under severe drought stress, the changes of physiological properties, fluorescence parameters are closely related with drought resistance.