关键词: 高粱, 耐盐种质资源, 关键指标, 耐盐性评价, 线性回归方程

Abstract:

【Objective】To screen salt-tolerant sorghum germplasm resources and identify the key indicators for evaluating sorghum salt tolerance, so as to provide a scientific basis for the subsequent research on salt-tolerant germplasm and the stress-resistant cultivation of sorghum in saline soils. 【Method】Using 160 domestic sorghum varieties (lines) and 25 foreign varieties (lines), totaling 185 sorghum varieties (lines) from different countries and regions as experimental materials, the relative values of 9 trait indicators (germination potential, germination rate, seedling length, seedling dry weight, seedling fresh weight, root length, root dry weight, root fresh weight, and number of lateral roots) were analyzed under 150 mmol·L^-1NaCl solution treatment with vermiculite as the substrate. Correlation analysis, principal component analysis (PCA), cluster analysis, and subordinate function method were employed to screen salt-tolerant germplasm resources. Piecewise linear regression and multiple stepwise linear regression were used to identify key indicators determining sorghum salt tolerance at the seedling stage and conduct comprehensive evaluation.【Result】Under salt stress conditions, the 9 trait indicators of sorghum at the seedling stage showed varying degrees of variation. Among them, seedling dry weight exhibited the most significant variation, while lateral root number was least affected. Correlation analysis revealed diverse relationships among the traits: Relative germination rate showed negative correlations with relative seedling length and relative lateral root number, whereas all other traits displayed positive correlations. The highest correlation coefficient (0.54) was observed between relative seedling length and relative root length. Through principal component analysis (PCA), the 9 traits were reduced to 4 comprehensive indicators, accounting for 72.10% of the cumulative variance. The subordinate function method was applied to calculate the comprehensive D values for all 185 varieties. Cluster analysis using the hclust function in R categorized the sorghum accessions into four salt-tolerance groups: highly salt-tolerant, salt-tolerant, moderately salt-tolerant, and salt-sensitive. Taking the comprehensive D value as the dependent variable and the other 9 indicators as independent variables, piecewise linear regression models were constructed, showing positive trends between all traits and D values. A multiple stepwise linear regression equation was further established: F=0.25RGR+0.255RSL+0.377RGP+0.283RSFW, (R²=0.894, P<0.01).【Conclusion】Thus, the germination potential, germination rate, seedling length and seedling weight were the key indicators for screening sorghum salt tolerant varieties in 150 mmol·L^-1 NaCl environment. Among the high salt tolerance varieties, sweet 319, Xin 52, MY 2, sweet 11, Sudan 1-2, and sensitive salt varieties S29241, N2902, 6-5A, IS-3977, 90111 were selected.

Key words: sorghum, salt tolerance germplasm resources, key indicators, salt tolerance evaluation, equation of linear regression