| Potato growing areas are mainly distributed in arid and semi-arid areas in China. Drought is one of the most important factors for low yield per potato and the instability of the yield. Therefore, it is of theoretical and practical value to study the influence of water stress on potato physiological characteristics and to seek effective control measures on drought resistance to improve the per unit area yield of potatoes. Potting and field work were combined to study the physiological characteristics and nutritional quality under water stress. Regulations for drought resistant related physiological characteristics by straw mulch, plastic mulch and water-retaining agent were studied. Main results were as follows.1. The influence of water stress on potato growth and physiological characteristics was obvious. The longest lengths of potato plants and of root were observed under low water stress. They were increased by 1.73% and 1.15%, respectively. Root volume and fresh weight were slightly decreased and leaf Plastic mulch permeability, MDA and proline contents, SOD and POD activities were slightly increased compared with normal water supply. The yield reduced only by 8.04%, which was on the second place. The positive influence of moderate water stress on potato growth was inferior to low water stress. Water logging stress significantly inhibited root growth and reduced root volume, activity and total absorption area and the maximum level of active absorption area. Severe water stress induced the increase of Plastic mulch permeability in leaves, MDA and proline contents, and the activity of SOD and POD in early stage of potato.2. Low water stress could significantly reduce the contents of chlorogenic acid in two potato cultivars. The antioxidant substance activity, total polyphenols content, and chlorogenic acid content were lower by 21.69%, 12.41% and 23.13% respectively compared with normal water supply in Russian blue potato tuber. And those indexes reduced by 2.96%, 5.68% and 17.51% respectively in Shepody. Activity of antioxidant substance and total polyphenol content decreased less than chlorogenic acid content. The activity of antioxidant substance, total polyphenol and chlorogenic acid content on Russian blue purple potato varieties under low water stress were lower than the role of Shepody. These indexes above reduced more sharply. 3. Total nitrogen content and (15)~N isotopic content under low water stress in tubers in two potato cultivars were the closest to normal water supply. (15)~N isotope content in potato under Waterlogging stress was in the third place. The total nitrogen content and (15)~N isotope contents of Shepody under low water stress treatment were lower than normal water treatment by 1.13% and 5.11% respectively, while the contents of these characteristics above in Russian blue reduced more than Shepody. When the soil moisture content did not reach the best of field capacity (75%) for potato growth, by improving soil moisture content could accelerate nitrogen cycle and accumulation, and also caused the increase of the content of (15)~N isotopes.4. Straw mulch and it combined with water-retaining agent increased moisture content in 0～80cm soil layer significantly. Both of the two measures could increase plant fresh weight and length of plant. They could also lower phase-Plastic mulch permeability, decrease MDA and proline content and increase the activity of SOD, POD in late growth stage. The stress effect on plants from dry land was reduced by these control measures. The effect of plastic mulch between lines combined with water-retaining agent on potatoes was secondary to the measures above. Straw mulch and it combined with water-retaining agent and plastic mulch between lines combined with water-retaining agent increased the yield of potato by 49.69%～107.85%.5. When water-retaining regent was applied in holes, of 15cm depth, with the amount of 60kg/hm2, it could significantly increase length of plant, fresh weight, dry weight, stem diameter and root length, and reduce Plastic mulch permeability, MDA, and proline contents, activities of SOD and POD in early growth stage, and increase chlorophyll content, which showed that these measures could reduce the effect on plants from dry land. Compared with control group, yield of the three measures above increased by 8.19%, 8.41% and 8.23%, respectively. The water-retaining regent applied by sink pattern, of 10cm～20cm depth, with asuplication amount of 30～90kg/hm2, increased the yield of potatoes by 4.10%～8.41%, and that increased by 4.83%～8.23% of the depth of 10cm～20cm.6. Conclusions on the relationship between morphological indexes, physiological characteristics, tuber nutritional quality and yield of potatoes by correlation analysis was made.Aboveground parts of potato, including length of plant, fresh weight and stem diameter, POD enzyme activity, fresh weight and length of root, which is the underground part and indexes in tuber, including chlorogenic acid, total phenolic content, antioxidant substrate activity, total nitrogen, (15)~N isotopes showed significant or very significant positive correlation with potato yield. A significant negative correlation between the content of MDA and proline and potato yield was also obtained. All the indexes above could be used to Evaluate drought resistance of potatoes and to speculate the yield and quality of potatoes in dry land. |
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