长江中下游地区糯玉米花期耐热性鉴定及评价指标筛选

Identification of heat tolerance of waxy maizes at flowering stage and screening of evaluation indexes in the middle and lower reaches of Yangtze River region

全球气候变暖趋势日趋明显,高温热害已成为限制糯玉米丰产稳产的主要非生物胁迫之一。鉴定糯玉米的耐热性,筛选耐高温评价指标,可为耐热糯玉米品种的选育提供理论支撑。本研究以长江中下游地区主推品种为试验材料,设置2种增温方式(覆膜增温处理和延迟播种处理)以及自然对照处理(CK),测定了13个与耐热相关的指标,采用主成分分析、隶属函数法、聚类分析和逐步回归分析相结合的方法,对糯玉米花期耐热性进行综合评价。结果显示,与对照相比,除叶绿素a和光系统II最大光化学效率外,各指标在高温处理下的降低幅度均达到显著或极显著水平。利用主成分分析将13个单项指标转换为3个相互独立的综合指标,其贡献率分别为64.46%、15.06%和7.76%,代表了糯玉米耐热性87.28%的原始数据信息量;通过隶属函数计算综合耐热评价值(D值),将10个参试糯玉米品种划分为3类,分别为3个耐热型、4个中等耐热型和3个热敏感型。筛选出的耐热型品种为苏玉糯2号、中糯2号和苏玉糯901,生产中应用这些品种可能在一定程度上减轻高温热害对糯玉米生长发育造成的不利影响。最后,利用逐步回归分析建立了糯玉米耐热性评价方程预测供试材料的耐热性,预测值(PV)与D值基本一致,确定了产量、F_v/F_m、叶面积指数和花粉活力作为糯玉米花期耐热性评价指标。本研究筛选出的耐热品种和鉴定指标可为今后耐热糯玉米品种的选育提供理论依据。

Heat stress has acknowledged as one of the major threats to waxy maize production as a result of global warming gradually seriously.Heat resistance identification and indices screening could provide the theoretical basis in breeding heat-resistant cultivars.In the present study,13 heat-related parameters of 10 waxy maize cultivars from the middle and lower reaches of Yangtze River area were measured under normal temperature treatment(CK)and two heat stress treatments(artificial warming treatment and delayed sowing treatment).Principal component analysis,membership function method,cluster analysis,and stepwise regression analysis were used to comprehensively evaluate the heat resistance of waxy maize at flowering stage.The results showed that most indices under heat stress decreased significantly compared with CK,except for chlorophyll a and PS II primary light energy conversion efficiency.Three independent comprehensive components were obtained from 13 single traits using a principal component analysis,and their contribution rates respectively were 64.46%,15.06%,and 7.76%,which represented 87.28%information of the original data.Ten testing cultivars were divided into three heat-tolerance types that were heat tolerance category,medium heat tolerance category,and high temperature sensitive category based on comprehensive heat tolerance values(D)calculating by membership function methods.SYN2,ZN2,and SYN901 were identified as the heat-resistant cultivars,and planting these cultivars could partly alleviate the negative effects of heat stress on waxy maize production.Finally,stepwise regression method was used to establish a predictive equation to evaluate heat tolerance,which indicating that predictive values(PV)calculated by the predictive equation were basically consistent with D value.The results showed that yield,Fv/Fm,leaf area index,and pollen viability could be used to identify heat-resistant cultivars of waxy maize.The heat tolerant cultivars and identification index selected in the study could serve as a basis for subsequent breeding heat tolerant cultivars of waxy maize.