Effect Of Water Stress On Physiological And Biochemical Characters Of Potato

The physiological and biochemical characteristics of different drought-resistant potato(Solanum tuberosum L.) cultivars were studied with systematic method, and the emergence of drought-induced protein in leaves were discussed. On the basis of these, the relation of physiological and biochemical indexes and drought resistance in potato were clarified with theory and method of gray system. Meanwhile, the same physiological and biochemical characteristics of same cultivars in seedling of potato under water stress were studied in compare with test-tube plantlets and field plants. The main results as follows: 1.The relative water content of potato descended under water stress, the drought-resistant cultivars can maintain higher water content and the range of declining is smaller in the leaves. 2.The proline accumulated and content of free amino acid increased under water stress. The accumulation of proline of drought-resistant cultivars is more than the drought-sensitive cultivars, and the accumulation of free amino acid of drought-resistant cultivars is lower than drought-sensitive cultivars in field. However, the changes of proline and free amino acid in test-tube plantlets were same among the cultivars, which was probably relevant with lower ability of test-tube plantlets in adverse circumstances. 3.SOD,POD,CAT activity in leaves of potato changed under water stress. At early flowering stage, the activity of SOD declined, and drought-resistant cultivars was declined lower than drought-sensitive cultivars, the activity of CAT increased and drought-resistant cultivars maintained higher levels, and the activity of POD increased or decreased, ranges of drought-resistant was more, but the activity of drought-sensitive cultivars declined in the field under water stress. The activity of SOD increased under light water stress (10%PEG) and heavy water stress(20%PEG), the activity of CAT increased under 10%PEG water stress, but under 20%PEG water stress the activity of CAT decreased, even lower than control. The POD activity increased under 10%PEG and under 20%PEG, the POD activity of drought-resistant cultivars increased, but other cultivars was lower than comparison. In conlusion, the changes of the SOD, CAT, POD activity in leaves of test-tube plantlets were not significant. 4. MDA content increased in leaves of potato under water stress. MDA content of potato in the pot increased after water stress, and the increased range of drought-resistant cultivars was smaller than drought-sensitive cultivars and maintained lower level. MDA content increased in test-tube under 10%PEG and 20%PEG water stress due to cell membrane harmed heavly. 5. Under water stress, the soluble protein content of drought-resistant cultivars increased more. Under 10%PEG water stress the soluble protein content in test-tube increased, but under 20%PEG water stress the change of soluble protein content varied. Water stress can cause changes of synthesis of protein, and the changes of protein components of different drought-resistant cultivars was same. 6.With gray correlative degree analysis, the results showed that relative water content and MDA content of leaves in the pot can be regarded as the important index of drought resistance identification, soluble protein content, SOD activity, POD activity, activity CAT can be as good reference indexes to identify drought resistance.