Abstract:

This research evaluated the physiological response to drought stress of 15 different oat varieties at the seedling stage and used multivariate analyses of data for multiple traits to develop drought resistance indexes. Oat seedlings at the two-leaf growth stage in sand culture were stressed with nutrient solution containing 15% PEG. Antioxidant enzyme activity， malondialdehyde concentration， osmolyte levels， chlorophyll content， water use efficiency and relative conductivity of oat seedlings were measured at 0， 7 and 14 days of stress. Correlation analysis and principal component analysis were used to develop drought resistance indexes of the oat varieties， and cluster analysis and the membership function method were used to evaluate their drought resistance. It was found that： with increasing duration of drought stress， the antioxidant enzyme activity of the oat seedlings initially increased and then decreased； malondialdehyde content， osmolyte content and relative conductivity increased with increasing stress duration， while water use efficiency and chlorophyll content decreased significantly （P<0.05）. There was a good correlation between the 10 drought resistance indexes， with the correlation coefficient as high as 0.97. Principal component analysis showed that under drought stress， measures indicating the status of the plasma membrane system， photosynthetic factors and osmotic adjustment of the oat seedlings could be used as multivariate indexes to evaluate drought resistance， and the 15 tested oat varieties could be clearly separated into two distinct groups of differing drought resistance through scores for the first principal component. Cluster analysis further divided the tested varieties into four subgroups with different drought resistance. In particular， six varieties （Mengyan No.1， Qingyin No.1， Dingyan No.2， DA92-2F4， Qingyan No.1， Bayan No.5） displayed strong drought resistance. The cluster results also showed that the drought resistance of oat accessions from Northwest China （Gansu and Qinghai） was stronger than those from Northeast China （Jilin） and North China （Hebei）. Based on the multivariate score （D） for drought resistance from subordinate function analysis， the oat materials with the strongest drought resistance were Qingyan No.1 （0.829）， Qingyin No.1 （0.744） and DA92-2F4 （0.728）， while Longyan No.3 （0.208）， Bayan No.6 （0.240） and Zhangyan No.4 （0.241） had relatively weak drought resistance. The results of each evaluation method were consistent， but the multivariate evaluation system based on multi method correlation analysis was the most accurate and reliable. The results provide data on oat drought resistance to support selection and breeding decisions， and a methodology for generating a drought resistance index.

Key words: drought resistance, oats, principal component analysis, cluster analysis, membership function method, multivariate evaluation