不同棉花基因型幼苗耐寒性分析及其鉴定指标筛选

【目的】研究不同基因型棉花幼苗耐寒特性，筛选耐低温鉴定指标，建立可靠的棉花耐寒性数学评价模型，为棉花耐寒新品种选育、推广及大规模品种耐寒性评价奠定基础。【方法】以15个棉花品种（系）为试验材料，对其在低温胁迫（5℃、12 h）及恢复处理（25℃、24 h）下幼苗叶片的光合气体交换参数、叶绿素荧光动力学参数、叶绿素含量、可溶性糖含量、丙二醛含量、游离脯氨酸含量和相对电导率等12个生理指标进行测定，以各单项指标的耐寒系数作为衡量耐寒性的依据，运用主成分分析、聚类分析和逐步回归等方法对其耐寒性进行综合评价。【结果】通过主成分分析将12个单项生理指标转换为7个相互独立的综合指标；通过隶属函数法和聚类分析将15个棉花品种（系）按耐寒性强弱划分为3类；通过逐步回归建立棉花幼苗耐寒性评价数学模型，D=0.275-0.244Fo1+0.206Fv/Fm1+0.326gs2-0.056SS+0.225MDA+0.038REC（R2=0.995），估计精度大于94.25%，并筛选出6个耐寒性鉴定指标，分别是Fo1、Fv/Fm1、gs2、SS、MDA和REC。【结论】耐寒性强的棉花品种(系)幼苗叶片在低温胁迫下受到伤害较轻，能保持较高的光合电子传递能力，经常温恢复后叶片气孔导度较高，便于光合气体交换，有助于光合能力的恢复；在相同逆境下，通过测定Fo1、Fv/Fm1、gs2、SS、MDA和REC等6个鉴定指标，可进行棉花品种耐寒性强弱的快速鉴定和预测。

Analysis of Chilling-Tolerance and Determination of Chilling-Tolerance Evaluation Indicators in Cotton of Different Genotypes

【Objective】The objective of this study was to investigate the chilling tolerance of cotton seedlings of different genotypes,to screen suitable evaluation indicators of chilling-tolerance,and to establish the mathematical evaluation model on cold tolerance,which would provide a theoretical basis for discovery and promotion of chilling tolerant germplasm,breeding of new chilling-tolerant varieties and evaluation on chilling tolerance of a large number of cotton varieties.【Method】The chilling comprehensive evaluation of chilling tolerant coefficient(CTC) about photosynthetic gas exchange parameters,chlorophyll fluorescence kinetics indexes,chlorophyll content,relative soluble sugar content,relative MDA content,relative proline content and relative electric conductivity in leaves of cotton seedlings of fifteen different genotypes under low temperature stress(5℃,12 h) and recovery treatment(25℃,24 h) were evaluated by principal components analysis,hierarchical cluster analysis and regression analysis.【Result】The results showed that the 12 single indexes could be classified into 7 independent comprehensive components.The cluster analysis was used to divide 15 cotton cultivars into three chilling-tolerance types.The mathematical evaluation model for cotton cold tolerance was established,D=0.275-0.244Fo1+0.206Fv/Fm1+0.326gs2-0.056SS+0.225MDA+0.038REC(R2=0.995),and the evaluation accuracy of the equation is higher than 94.25%.Six indexes closely related to the chilling tolerance,Fo1,Fv/Fm1,gs2,SS,MDA and REC,were screened,too.【Conclusion】Higher chilling tolerant varieties,which had lighter injury under low temperature stress,were able to maintain more photosynthetic electron transport capacity,and higher stomatal conductance after recovery treatment was contributed to gas exchange and recovery of photosynthetic.Determination of the six indicators under the same condition can be used for rapid identification and prediction of other cotton varieties,which is very useful for the breeding,promotion,identification and screening of chilling tolerant germplasm.