Study On Index System And Genetic Characteristics Of Drought Resistance Identification In Maize

Abstract Considering the complexity of drought resistance, the morphological, physiological and anatomical characteristics of drought resistance in maize (Zea mays L.) varieties with different drought resistance were studied. The indexes systems of drought 梤esistance identification were estahl ished quantitative analyzing with methods of grey correlation degree, subordinate function values and systematic analysis of clustering. Another experiment was conducted to study the inheritance speciality of part of identification indexes of maize drought resistance. The results were as follows: 1. The growth and physiological activity of root systems were inhibited or decreased at different development stages, such as length, number, volume, dry weight, total absorbing area, active absorbing area, and oxidate ability of roots decreased evidently under water stress. The study on number and diameter of root vascular showed that the relationship between root anatomical structure and drought resistance was close. Water losing rate of uncontacted roots was defined and determined, and the relationship between it and drought resistance was closer than that of uncontacted leaves. 2. The leaf shape, leaf angle, and leaf orientation value of maize changed under water stress and the changes had not significant law. Drought resistance differed in maize cultivars partially because of differences in stomata density, size and density of vein of maize leaves; 3. Water absorbing rate of seeds, embryo-shoot length, and length and dry weight of embryo-root of maize decreased evidently, so germination was delayed and germination percentage decreased under osmotic stress. At the same time, the germination percentage of seeds was an effective index for determining drought resistance within maize germinating period. 4. Water contents in maize organs changed under water stress. The reduction of water contents was greater in leaves and vaginas than in stems and roots. 5. Cell membrane in maize leaves was injured and both of MIDA content and electrolyte leakage were increased under water stress. Percentage of thermo instability used as heat resistance had a significant correlation with the drought -12 1- resistance in different maize varieties. This trait is likely to be important in determining drought resistance. 6. The saturated osmotic potential decreased and more proline and ABA accumulated than soluble sugar, k~ and ca 2-~ This result showed that maize leaves did have the ability of osmotic adjustment. 7. The changes of bands and activities in peroxidase isozymes were more significant than others. At the same time, the differences of peroxidase and catalase isozymes in different genotypes maize were obviously than superoxide dismutase. Such results would facilitate maize breeding for improving drought resistance. 8. Establishing indexes systems of drought resistance identification of maize under water stress by the results of this study. 9. Identifying the drought resistance at germinating, seedling and other development stages, of twenty-nine maize cultivars popularly planted in Liaoning province were examined such as Dan 408. 10. Genetic analysis showed that RWC. leaves water l...