阴雨寡照或密植等造成的弱光胁迫严重影响玉米生长发育。鉴定玉米种质耐荫性，筛选耐荫性评价指标，建立简单、方便、有效、可重复性的耐荫评价模型对于挖掘耐荫基因、创制耐荫品种、提高玉米种植密度具有重要意义。本研究以196个玉米自交系材料为研究对象，于大喇叭口期到散粉期设置50%遮荫和自然光照两种光照强度，测定株高、穗位高、茎粗、穗位叶SPAD值和地上部干重等20个指标。基于各指标耐荫指数进行相关性分析、主成分分析、隶属函数法和聚类分析，综合评价自交系材料的耐荫性，并采用逐步回归分析建立耐荫性预测模型。结果表明，遮荫胁迫使株高、茎粗、穗位高、地上部干重、比叶重以及穗下叶叶长等17个指标显著降低，播种到散粉天数显著增加。相关性分析表明16个指标耐荫指数间存在显著相关，表明指标信息存在重叠及交叉。通过主成分和隶属函数分析，将16个指标转化为5个独立的复合指标，并得出不同自交系材料的耐荫综合评价值D值，对D值聚类分析，将196份自交系材料分为5类，其中，2份高耐荫型、77份耐荫型、77份耐荫中间型、31份弱光敏感型和9份弱光高敏感型。将D值与耐荫指数进行逐步回归分析得到最优数学模型，D=0.150*UELW+0.249*UELL+0.402* PH+0.232*LELL+0.148*LFLW+0.115*SDW-0.688（R2=0.940, F=489.383, P < 0.01），筛选出穗上叶叶宽、穗上叶叶长、株高、穗下叶叶长、旗下叶叶宽和地上部干重6个指标可作为玉米耐荫性鉴定指标。试验结果可为玉米耐荫机理研究、耐荫基因挖掘和培育高光效品种提供理论依据。

Shading stress caused by overcast rain or dense planting seriously affect the growth and development of maize (Zea mays L.). Identification of shade-tolerant maize germplasm resources and screening of its evaluation indexes to establish a simple, convenient, effective and reproducible shade-tolerance evaluation model are of great significance for exploring shade-tolerant genes, creating shade-tolerant varieties and improving maize planting density. In this study, 196 maize inbred lines were used as research materials, and two light intensities were set with ambient sunlight as control (CK) and 50% of ambient sunlight as shading treatment (S) from the growth stage of the twelfth extended leaf to the pollen shedding. We measured 20 indexes including plant height, ear height, stem thickness, SPAD value of ear leaf, and shoot dry weight, etc, at the end of the treatment. Based on the shade tolerance coefficient of each index, correlation analysis, principal component analysis, membership function and cluster analysis were performed to comprehensively evaluate the shade tolerance of these inbred lines, and a stepwise regression analysis was used to establish a predictive model of shade tolerance identification. The results showed that 17 indexes including plant height, stem thickness, ear height, shoot dry weight, specific leaf weight and length of the lower ear leaf decreased significantly after shading treatment, and days from sowing to pollination increased significantly. Correlation analysis showed that significant correlation among the shade tolerance coefficient of 16 indexes, indicating information overlap and crossover. Through principal component analysis and membership function, the 16 indexes were transformed into five independent composite indexes, and we calculated the comprehensive evaluation value (D value) of the shade tolerance of different inbred line materials. We found that the 196 inbred lines were divided into five categories through cluster analysis used D value, among which, two inbred lines were highly shade tolerance, 77 shade tolerance, 77 intermediate shade tolerance, 31 shade sensitive, and nine were highly shade sensitive. The optimal mathematical model was obtained by stepwise regression analysis of the D value and the shade tolerance coefficient of each index, D=0.150*UELW+0.249*UELL+0.402* PH+0.232*LELL+0.148*LFLW+0.115*SDW-0.688（R2=0.940, F=489. 383, P < 0.01） Six indexes, width of upper ear leaf, length of upper ear leaf, plant height, length of lower ear leaf, width of lower flag leaf and shoot dry weight, were screened, which can be used as indicators to evaluate shade tolerance of maize inbred lines. Results of this study could provide theoretical basis for research of shade-tolerant mechanism, excavation of genes of shade tolerance and breeding of maize varieties with high light efficiency.

本研究由河南省重点研发专项(241111114300)；科技创新2030-农业生物育种重大项目(2023ZD04028)；2024年河南省科技攻关项目(242102111106)资助。