Genetic Evaluation of Spring Wheat (Triticum aestivum L.) Recombinant Inbred Lines for Spot Blotch (Bipolaris Sorokiniana) Resistance and Yield Components under Natural Conditions for South Asia

The objectives of the present study were to evaluate spring wheat recombinant inbred lines (RILs) of diverse origin by estimating genetic parameters viz., variability, character association, cluster analysis, and principal component analysis (PCA) for spot blotch resistance and yield components at BHU Agricultural Research Farm during ۲۰۱۰-۲۰۱۱. Grain yield per plot was significantly and positively associated with biomass, ۱,۰۰۰-grain weight, harvest index, chlorophyll content, and grains per spike at genotypic level. The line ۶۵ exhibited lowest mean of AUDPC value (۶۳۲) indicating its potential as resistant parent. Cluster analysis grouped all the ۳۲۴ spring wheat lines into ۱۹ clusters using Ward’s method. Extreme divergence was observed among clusters. By using D۲-statistics, the highest inter cluster distance (۵۸۴.۷۲) was found between Clusters VIII and XIX. Cluster VIII recorded highest mean values for chlorophyll content, peduncle length, bio-mass, grains per spike, ۱۰۰۰-grain weight and grain yield. The major contributing trait towards genetic divergence was found to be AUDPC (۶۰.۳۶%). First ۵ principal components (PC۱, PC۲, PC۳, PC۴ and PC۵) accounted for proportionate values of ۲۰.۶۶, ۱۷.۹۶, ۱۵.۰۷, ۸.۲۸, and ۷.۳۸%, respectively, contributing ۶۹.۳۵% of the total variability. The second PCs had high positive PC value for plant height, biomass, and ۱,۰۰۰-grain weight. The breeding objectives of the present experiment was to identify genetically diverse wheat spot blotch resistant RILs for developing high yielding spot blotch resistant cultivars especially adopted to south Asia in future breeding programs.