Abstract: This research used two commercial varieties of bermudagrass (Cynodon dactylon) as control and evaluated performance of 41 germplasm accessions of bermudagrass collected from different habitats in Xinjiang province under drought and control treatments. After 30 days of drought treatment, the chlorophyll content, green leaf proportion, relative conductivity, leaf relative water content, proline content, malondialdehyde content, speed of growth and aboveground biomass under natural drought stress were measured. Based on these data, correlation analysis and principal component analysis were performed to construct multi-trait evaluation indicators, and combined with membership function analysis, cluster analysis, grey correlation analysis and discriminant analysis methods to comprehensively evaluate multiple trait expression linked to drought resistance, develop key indexes for identification of drought resistance, and clarify the relationship between drought resistance of germplasm accessions and their habitat climate zone. It was found that the relative conductivity, proline and malondialdehyde content of the tested germplasm significantly increased under drought stress, and the relative water content, chlorophyll content, aboveground biomass, speed of growth and green leaf rate significantly decreased. There were differences in response to drought stress between all indices. The eight measured traits were reduced by principal component analysis to six independent scores, representing 87.34% of the total data variation. The result of membership function analysis based on drought resistance comprehensive evaluation value (D), comprehensive drought resistance coefficient (CDC), and weighted drought resistance coefficient (WDC) analysis and cluster analysis showed that accessions designated C₁₁₈, C₁₃₈ and C₂₄ had strong drought resistance, while accessions designated C₁₀, C₁₃₄ and C₃₂ had weaker drought resistance. The grey correlation analysis indicated that relative conductivity, leaf chlorophyll content and malondialdehyde content could be used as key indexes for drought resistance evaluation of bermudagrass germplasm, and discriminant analysis indicated that there was no significant correlation between drought resistance of Xinjiang Bermudagrass germplasm and its habitat climate zone. The comprehensive analysis showed that the drought resistance of C₁₁₈, C₁₃₈, C₂₄ and other germplasm acessions was better than that of the commercial variety Tifway. Hence this research has provided excellent germplasm for breeding new bermudagrass varieties with good drought resistance, and provided materials for further study of physiological and molecular mechanisms of bermudagrass drought resistance.

Key words: drought stress, Cynodon dactylon, drought resistance index, comprehensive evaluation