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[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℃、12h)及恢复处理(25℃、24h)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。
[Objective] The research aimed to study the cold tolerance of cotton seedlings with different genotypes, screen the identification index of low temperature tolerance and establish a reliable mathematic evaluation model for cold tolerance of cotton, which lays the foundation for the selection and popularization of new cold tolerant cotton varieties and evaluation of cold tolerance of large-scale varieties. [Method] Fifteen cotton cultivars (lines) were used as materials to study the photosynthetic gas exchange parameters, chlorophyll fluorescence kinetics parameters, photosynthetic parameters, chlorophyll fluorescence parameters and photosynthetic rate of seedling leaves under cold stress (5 ℃ and 12h) Chlorophyll content, soluble sugar content, malondialdehyde content, free proline content and relative electrical conductivity were measured. Based on the indexes of cold tolerance of individual indexes, Analysis and step-by-step regression methods to evaluate its cold tolerance. [Result] 12 individual physiological indexes were transformed into 7 independent comprehensive indexes by principal component analysis. According to the membership function and cluster analysis, 15 cotton varieties (lines) were divided into 3 categories according to their cold tolerance; Stepwise regression to establish the mathematic model of cotton seedling cold tolerance evaluation, D = 0.275-0.244Fo1 + 0.206Fv / Fm1 + 0.326gs2-0.056SS + 0.225MDA + 0.038REC (R2 = 0.995), the estimated accuracy is greater than 94.25%, and screened 6 A cold tolerance identification indicators, namely Fo1, Fv / Fm1, gs2, SS, MDA and REC. [Conclusion] The seedlings of cotton cultivars with high cold tolerance were harmed less under low temperature stress and maintained high photosynthetic electron transfer ability. Leaf stomatal conductance of leaves was higher after temperature recovery, which was convenient for photosynthetic gas exchange. Which could help the recovery of photosynthetic ability. Under the same stress, the rapid identification and prediction of the cold tolerance of cotton cultivars could be carried out by measuring 6 indexes Fo1, Fv / Fm1, gs2, SS, MDA and REC.