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 2010-2011. grain yield per plot was significantly and positively associated with biomass, 1,000-grain weight, harvest index, chlorophyll content, and grains per spike at genotypic level. the line 65 exhibited lowest mean of audpc value (632) indicating its potential as resistant parent. cluster analysis grouped all the 324 spring wheat lines into 19 clusters using ward’s method. extreme divergence was observed among clusters. by using d2-statistics, the highest inter cluster distance (584.72) was found between clusters viii and xix. cluster viii recorded highest mean values for chlorophyll content, peduncle length, bio-mass, grains per spike, 1000-grain weight and grain yield. the major contributing trait towards genetic divergence was found to be audpc (60.36%). first 5 principal components (pc1, pc2, pc3, pc4 and pc5) accounted for proportionate values of 20.66, 17.96, 15.07, 8.28, and 7.38%, respectively, contributing 69.35% of the total variability. the second pcs had high positive pc value for plant height, biomass, and 1,000-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.