| Elymus breviaristatus is a second-class protected plant which belongs to the ElymusL. inPoaceae family in China. It is one of the most important perennial and sparse forage in northwest plateau of Sichuan province. In this study, simulated drought stress by PEG-6000 and natural drought method by plot culture to identify drought resistance of six E. breviaristatus germplasms collections in germination and seedling stages, then physiological and biochemical indexes were measured in germination stage and seedling stage. Membership values were calculated by subordination function method in indexes of different test materials. Then weight coefficients of the indexes were determined by principal component analysis. Membership values which can determine drought-resistant ability of test materials were got after weighted average. Cluster analysis was performed on 6 materials by the Squared Euclidean distance method when using relative values of 13 indexes from 6 materials, so that different drought resistance materials were classified. Strong drought resistance materials were screened out to provide theoretical data on collection, protection, evaluation, utilization and breeding for germplasms resources of Elymus.L.The main results are as follows:(1) Germination rate, germination potential, sprout index of drought resisting, vigor index of drought resistance, germ length, radicle length of 6 materials were inhibited under the stress with high concentration of PEG-6000. Moreover, with the increase of PEG-6000 concentration, the extent of inhibition increased. Compared with CK, the germination rate of 204290 and 205104 were dropped 95.77% and 80.95% respectively with the concentration of 15%.While the concentration of 5% PEG-6000 had a positive effect on seed germination. In the concentration of 5%, the changes of GDRI, VI, germination rate, germination potential, radicle length were 94.74%～144.84%, 78.44%～138.21%,94.17%～132.39%,90.63%～164.29%,83.92%-118.09%.(2) Under drought stress, the relative water content of leaves in test material is lower than that of CK. With the increase of drought stress time the relative water content of leaves are decreased, the minimum value came at the 21d which was 58.51%～79.38% of CK. Ch1 content decreased with drought stress time went on. REC, MDA content, Pro content, POD activity increased with the increase of drought stress time. The maximum value which was 109.77%～526.10%,97.10%～301.70%,1354.50%～2193.04%, 230.33%～440.68% of CK came at the 21d.SOD activity increased with drought stress time increases at first and then decreases. The maximum which was 142.48%～199.24% of CK came at the 14d.(3) According to principal component analysis on the relative value of each indexes in 6 materials,weight value of each indexes were got. Drought resistance strong-to-weak sequence of test material in germination stage was got by subordination function method::Hong 10-5>205176>205133>Hong 6-5>204290>205104; the weighted average of the membership functions were 0.430,0.408,0.343,0.332,0.271and0.214. Drought resistance strong-to-weak sequence of test material in germination stage was 205176>205133>Hong 10-5>204290>Hong 6-5>205104, while the weighted average of the membership functions were 0.662,0.559,0.468,0.363,0.354 and 0.277.In germination stage and seedling stage, drought resistance of 205176 is stronger and 205104 is the weakest among 6 materials.(4) Cluster analysis was performed by the Squared Euclidean distance method when using relative values of 13 indexes from 6 materials. The results showed that 6 materials were divided into 3 types when the Squared Euclidean distance was 15.The first type includes 2 materials,204290 and 205104 which has slight drought resistance. Hong 10-5 and Hong 6-5 belong to the second type which has normal drought resistance. 205176 and 204290 are the third type which has strong drought resistance. The results are consistent with the analysis of membership function.(5) With the membership function analysis and cluster analysis results,205176 and 205133 were recommended as breeding material in drought resistant which can govern sandy land. Secondly, Hong 10-5 and Hong 6-5 can be considered.204290 and 205104 are not recommended. |
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