Genotype Differences And Physiological Mechanisms Of Drought Response And Drought-Tolerance Of Potato

Potato(Solarium tuberosum L.) is the 4th important food crop following wheat, maize and rice in the worldwide. Because the cultivated area and the total yield of potato in China are more than those in European Union since the middle of 1990s, China has become the biggest potato producing country. For the past few years, the State and Local Government have paid much attention to the production and industrialization of potato, which was one of the cultivated crops of increasing yield and development. Drought Stress is a global problem, which can cause the reduction of yield over the sum of yield loss through other factors. Thus, studying the response of potato to drought stress, revealing the genetic, physiological mechanisms of drought tolerance are critical for potato breeding and potato production under drought conditions.Based on the preliminary experiment,6 genotypes with distinctly different drought tolerance were selected for this experiment, the photosynthetic, physiological, growth, development characters and yield traits at the different stages under different water conditions were studied with potted experiment. The results and conclusions as follows:(1) By investigating the tuber weight per plant, the tuber number per plant and the mean tuber weight in the every period, it can be found that drought stress didn't limited the tuber number per plant after the tuber initiation period. Longtime drought stress reduced the yield per plant through decreasing the tuber size and delaying the tuber bulking. The potato genotypes were sensitive to drought differently. Under water deficiency condition, for reducing the yield loss, drought-tolerance genotypes should be those maintain the number of tuber initiated during the seeding period, steadily kept increasing the tuber size after tuber formed, especially during the starch accumulation and mature period.(2) According to analysis of morphological indexes and the associated parameters among organs of plant, it could be found that under drought condition, the growth and development of potato plant was inhibited, and this resulted in the changes of matter partition among the organs after a long time of drought. Roots of potato could preserve steadily the ability of growth under drought condition, but the activity of roots was significantly affected by drought stress. The stems and leaves decreased growth vigor similarly under drought condition. But the drought-tolerance genotypes under the drought condition should be:the activity of roots was stronger; the development of stems and leaves was weakly, but the ability of transport of photosynthetic product in plant was maintained high level even heightening during starch accumulation and mature period.(3) By analysis the photosynthetic physiological traits of leaves, it could be found that drought reduced the photosynthesis ability of leaves in different ways, such as stomata closure reversibly decelerating the photosynthesis rate in the earlier period and the leaves and the photosynthesis system would be damaged irreversibly after a long time of drought, thereby decreasing the photosynthesis rate, but there were stronger ability of repair at the level of plant or the leaf growth and development was inhibited and the functional leaf area was decreased. But the roots of drought-tolerance genotypes could grow better and absorb more water; the leaves of these genotypes could be stronger growth, stronger osmotic adjustment, greater area and higher water use efficiency.(4) In total, potato have relative independent genetic basis on the yield traits, physiological characters, growth and development of plant in every period to drought response; the systematically study of the genetics of drought-tolerance and mechanism of physiology and molecular should be conducted with the technology of functional genomics. Based on the results of experiments, suggestions are proposed on the genetic improvement of drought tolerance by cross breeding, selecting drought-tolerance cultivars or types in the arid area or drought seasons, high-efficient water-saving irrigation, diagnosis of field dry condition.