| Drought is the primary limiting factor to yield increase and production development of maize in our country.The research of drought-resistant on maize germplasm,has vital significance on developping drought-resistant varieties and ensurring food production.Thirty maize inbred lines including twenty-six lines bred from Shaan A and Shaan B groups under many locations,low fertilization and low irrigation as materials and four elite inbred lines(zheng58,chang7-2,PH6 WC and PH4CV)as controls,were planted under different irrigation conditions,traits including SPAD-value of ear leaf,dry matter accumulation and straw stiffness were collected,used for establishing the optimum regression model by stepwise regression analysis and define the selection index of drought resistance in maize inbreds.Through clustering analysis the fuzzy membership and the drought resistance index based on production,cleared drought resistance of the different genotype inbred lines.Typical inbred lines selected from filed experiment were planted to study the effect of polyethylene glycol on physiological and molecular mechanism.Therefore,strengthening the selection pressure of breeding environment and carrying out the strategy of drought stress selection,which can effectively improve the water utilization efficiency of maize germplasm.The main result as follow:1.The grain yield of 30 inbred lines was significant difference under two water conditions in every point of each year.The filed as the primary index,30 inbred lines could be divided into 11 high-yield of drought-resistant type,12 low-yield of drought-susceptible type,3 low-yield with drought-resistant and 2 high-yield with drought-susceptible type.2.The results elucidated that straw stiffness;dry matter accumulation after flowering and SPAD reading from ear leaf could be used as a secondary drought resistance index in maize.Meanwhile,the degree of membership and the drought index were used to classi fy the resistance degree of the 30 inbreds by clustering method,two high resistant inbred,twelve resistant inbreds,four moderate resistant inbreds,twelve susceptible inbreds were obtained.3.The ‘KB081',‘KA105',‘KA225'and‘XCA-1'as the as the maize inbred lines have the characteristics of high yield,the SPAD-value of ear leaf,the straw stiffness,the dry matter accumulation,the drought index,have the strongest resistance to drought.4.The soluble protein content,malondialdehyde content and superoxide dismutase,peroxidase activity and proline content of leaf has significantly increased under drought sterss;Compared with drought sensitive inbred lines,the increased amplitude of leaf SOD activity,POD activity and proline content is greater in drought-resistant inbred lines after drought stress.5.After two days' rewater,a significant reduction in the leaf SOD activity,soluble protein content and MDA content is down but still significant difference between normal irrigation,and drought-resistant inbred lines has greater declined than drought sensitive inbred lines.The leaf POD activity of drought sensitive inbred lines increased significantly under rewaterring.The leaf proline content of drought-resistant inbred lines decreased after rewatering,and there is no significant difference compared to normal irrigation,however the difference in drought sensitive inbred lines was significant.6.The value of SPAD significantly reduced in drought sensitive inbred lines under drought stress,and the value did not return to control level after rewaterring,while there was no significant change in drought-resistant inbred lines under this process.The SOD gene expression quantity of drought-resistant inbred lines is higher than drought-resistant inbred lines.Comprehensive analysis shows that drought tolerant inbred lines have stronger ability of drought resilience after rewaterring. |
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