Effects Of Drought Stress On Growth,Yiled And Quality Of Different Barley Genotypes

Water is the lifeblood of agriculture, as well as the whole national economy and the lifeblood of human life. The utilization level of water resources condition has become the evaluation of a country or a region of the important indices for sustainable development. Relatively lack of water resources in our country, at the same time there are uneven distribution of time and space and the phenomenon such as serious soil erosion and high sediment content. Therefore, with the development of industry and agriculture and the increase of water demand, the contradiction between supply and demand of water resources will become more prominent, shortage of agricultural water will be a more serious trouble. So far, the drought is still one of the biggest obstacles of developing agriculture for many countries and regions in the world. In all biological and environmental damage from adversity to agriculture drought ranks second only to plant diseases and insect pests.Compared with other natural disasters, drought is the main factors affecting grain production in China, because the grain loss caused by drought to take more than half of all natural disasters grain losses. Therefore, discover and use of crop tolerance and adaptability to drought stress, which make significant sense to make full use of land and natural resources, stability and development of agricultural production. However, grouting maturity is the biggest period of requirement of water for crop, if the growth period comes across any drought stress, which will bring serious yield loss for crop. This study aims on the analysis of the effect of drought in filling stage on of barley water metabolism, osmotic adjustment, photosynthesis characteristic, production quality and the influence of genotype differences, at the same time comparing the correlation relationship between physiological indexes and yield under the stress condition, and analysis different reacts to early and later stage of the drought for barley, to provide theoretical basis and technical support for selecting resistant barley and breeding. In addition, in natural conditions, drought often accompanied by the emergence of high temperature, although studies about the effect on separate stress are so much, the research on the effects of both stress on crops metabolic pathways is countless. In the arid and semi-arid region, drought and high temperature, which are two kinds of natural disasters, appear at the same time. Nowadays, study has found that, under the combined stress, the response of molecular and metabolic reactions is unique for crops, but not sure whether is consistent with the response of drought, high temperature when alone. Therefore, we analyzed and research barley physiological and biochemical responses under different drought stress from two directions. The main research results are as follows:1. XZ5and XZ150, drought resistance genotypes and sensitive genotype XZ147in seedling period, cultivars Triumph (Tr) as materials, artificial simulation of drought by using pot experiment, two kinds of treatment:control and drought stress, when80%plants came into heading process, drought treatment up to14days, then watered again and maintained the normal water supply until the harvest. The effect of drought stress on water metabolism and osmotic regulation substances and the differences between genotypes for filling stage was analyzed. The results showed that, under drought stress, barley osmotic potential and relative water content of flag leaf fall, there were significant difference between genotypes. As for growth traits, XZ5and XZ147had minimum decrease, while XZ150performance was poorer. Performance of cultivars Tr different from the wild genotypes in the process of drought stress, after re-watering Tr physiological indicators suggested that no any change, while wild species had a different degree of recovery. It was worth noting that the changes of soluble sugar and proline drought at the kernel-filling stage completely different from the change in the seedling stage, which might relate to material transport in grouting period of crop.2. The effect of drought stress on photosynthetic characteristics, yield and quality in barley grouting period and genotypic differences was studied. The results showed that under drought stress, barley flag leaf chlorophyll content declined, photosynthesis weakened. Under drought stress wild barley XZ147biomass above ground fell18.8%compared with the controls, XZ5, XZ150fell by23.8%,22.4%than control; cultivated varieties Tr fell by26.1%. At the same time, the grains yield fell, the empty grain rate increased. XZ147had better performance than other genotypes. For L/W, the change of different genotypes was not identical, and the trend of the change of the length and width are different. Under drought stress, the C/N of grains decreased, protein content rose, and the number of starch granules type B was significantly decreased, the shape of type A also has certain degree of change.3. The effect of drought、heat and combined stress on physiological and biochemical response in barley seedling stage and genotypic differences was studied. Results showed that the adverse impact of combined stress beyond the single stress conditions. Drought, high temperature and combined high temperature and drought stress made free water content, water potential and osmotic potential of three genotypes decreasing, while water saturation deficit and bound water content increase. Overall, the genotype with strong drought resistance had a small range of change in osmotic potential and water saturation deficit. Under drought, high temperature and combined stress, the content of K+decreased, but the content of Mg2+, Ca2+seemed no obvious change, osmotic substances (soluble sugar, soluble protein) rising rapidly. However, as the stress degree aggravating, chlorophyll content in different genotypes have varying degrees of decline, P23-39had the least reduce. Under high temperature, drought and combined stress, the content of MDA, SOD, POD, CAT, APX activity also changed accordingly. P23-39had the least rise in product of membrane lipid peroxide MDA, and the activity of antioxidant enzymes rise in the minimum.