| Sunflower (Helianthus annuus L.), one of the four major oil crops in the word, is also the important oil crops in China. The main planting areas of sunflower were in arid and semiarid area of north China where had a serious impact on seed germination, seedling survival, growth and productivity because of drought. In order to provide a basis for the study on the drought resistance of sunflower, we chose 10 inbred lines and Fi as materials and used five different concentration PEG-6000 gradient (10%,15%,20%, 10%,15%) to simulate drought stress conditions. The effect of drought stress on seed vigor, drought resistance of germination stage and physiological properties under different treatment methods were studied in this test.The test results obtained mainly as follows:1. Different drought stress had different influence on seed vigor. The relative germination ratios, germination potential, radicle length, germ length, seedling fresh weight, germination index, vigor index and seedling survival rate showed descend trend with the rising of the concentrations of PEG Seed germination index and vigor index decreased significant under 10% PEG treatment with other indicators increasing and had little difference among the materials. Germination rate, germination potential, germination index, radicle length, germ length, vigor index, seedling fresh weight and seedling survival rate showed significant decreasing under 15%-20% PEG treatment, and there also had significant difference among the materials. Seed germination were severely suppressed under 30% PEG treatment. The results showed that the optimal concentration of drought stress were 15%-20% PEG and the lethal concentration was 30% PEG.2. Correlation analysis showed that the germination rate, germination potential and seedling survival rate were not significantly negatively correlated with relative conductivity and malondialdehyde (MDA) contents, had significantly positively correlation with SOD, POD and CAT activity and vigor index were significantly negatively correlated with relative conductivity and malondialdehyde (MDA) contents under normal condition. In addition, the germination potential, germination rate and vigor index were very significant or significant positive correlative with relative conductivity and malondialdehyde (MDA) contents, and germination potential, germination rate, vigor index and seedling survival rate had very significant or significant positive correlation with SOD, POD and CAT activity under PEG drought stress.3. Gray correlation analysis for 13 physiological indexes showed that the relative ermination index, relative vigor index, relative germination rate,relative germination tential, relative radicle length, relative seedling fresh weight and relative germ length had high correlation with drought resistance identification. Using fuzzy membership function method to evaluate the indexes, drought resistance of 10 samples in the seedling is as follows:K59>K59×K55>K58>117A>K58×K55>117AXR15>K55>26A >26A×R15>R15.4. The sunflower seeds soaked by 0% PEG and 20% PEG after treating with dry-wet treatment and different methods of coating treatment. The results showed that seed germination rate, germination potential, germination index, vigor index and the activity of CAT, POD, SOD were significantly improved and the relative conductivity and MDA content were significantly reduced under dry-wet treatment and coating treatment. Comparative analysis for different treatment methods indicated that the effect of iron coating method was the best, followed by plastic bag and large bottle method, the dry-wet method was the last. In addition, the variation of indicators under different treatment methods for the seeds soaked by 20% PEG had been obviously corrected, which illustrated that the treatment for seeds were helpful to adapt to the drought environment and improve the drought resistance. |
PDF Full Text Request