不同菜心品种萌发期和苗期耐热性分析及其鉴定指标筛选

Comprehensive Evaluation and Indexes Screening of Heat Tolerance at Germination and Seedling Stages in Different Cultivars of Chinese Flowering Cabbage

为明确不同菜心品种间的耐热性强弱,构建菜心品种耐热评价体系。以20个菜心品种为试验材料,通过设置正常和人工模拟37℃高温2个处理,对不同菜心品种萌发期和幼苗期的21个形态和生理生化指标进行测定,以各单项指标的耐热系数(γ)作为衡量耐热性依据,采用相关性分析、主成分分析、隶属函数分析、聚类分析、灰色关联度分析及逐步回归分析等方法相结合,对不同菜心品种进行耐热性鉴定及耐热指标筛选。结果表明,与正常处理相比,高温胁迫后各菜心品种的发芽率、发芽指数、活力指数、地上部鲜质量、地下部鲜质量、地上部干质量、地下部干质量、叶绿素质量分数和根系活力均下降,热害指数、O-2质量分数、H2O2质量分数、丙二醛(MDA)质量摩尔浓度、可溶性糖质量分数、Pro质量分数和CAT活性均升高,发芽势、根冠比、相对电导率、SOD活性和POD活性既有下降又有升高。相关性分析显示各评价指标间存在信息重叠与交叉现象,主成分分析将21个单项指标转化为3个相互独立的综合指标,隶属函数法计算获得了各品种综合耐热能力D值并排序,聚类分析将20个菜心品种划分为耐热型(6个)、中等耐热型(10个)和不耐热型(4个)3种类型;采用逐步回归方法建立了菜心耐热性评价方程,同时结合灰色关联度分析,筛选出热害指数、过氧化物酶活性、MDA质量摩尔浓度、可溶性糖质量分数、发芽势和过氧化氢质量分数等6个指标,可作为菜心耐热性综合鉴定指标。本研究结果为菜心耐热性评价、耐热品种选育、耐热机理及调控机制研究提供了理论基础。

In order to explore the heat resistance ability and establish the evaluation system of heat resistance among different Chinese flowering cabbage cultivars.20 varieties were used as experimental materials in this study,by two treatments of normal(control)and artificial simulation of 37℃high temperature,the 21 morphological,physiological and biochemical indicators of different genotypes at germination and seedling stage,were measured.Taking the heat resistance coefficient(γ)of each individual indicator as the basis for measuring heat resistance,the methods of correlation analysis,principal component analysis,membership function analysis,cluster analysis,grey correlation degree analysis and stepwise regression analysis were used to identify the heat resistance and indexes screening of different Chinese flowering cabbage varieties.The results showed that,compared with the control,the germination rate,germination index,vigor index,fresh aboveground mass,fresh underground mass,dry aboveground mass,dry underground mass,chlorophyll mass fraction and root vigor of each variety decreased,heat damage index,O-2 mass fraction,H2O2 mass fraction,MDA molality,soluble sugar mass fraction,Pro mass fraction and CAT activity increased,germination potential,root-shoot ratio,relative conductivity,SOD activity and POD activity declined and increased under high temperature stress.Correlation analysis showed that there was information overlap and crossover among evaluation indexes,though the principal component analysis,21 individual indicators were converted into 3 independent comprehensive components,based on the membership function method comprehensively obtained the comprehensive heat resistance D value of each variety,20 Chinese flowering cabbage cultivars were classified into 3 types by cluster analysis.The heat resistance evaluation equation was established by stepwise regression method,combining with grey relational degree analysis,6 indicators closely related to thermostability,including heat injury index,POD activity,MDA molality,soluble sugar mass fraction,germination potential and hydrogen peroxide mass fraction,which could be used as comprehensive identification indices for heat tolerance of Chinese flowering cabbage.This study provided a theoretical basis for evaluation of heat resistance,the research of breeding and mechanism of varieties with heat resistance.