Evaluation of Grain Yield of Bread Wheat (Triticum aestivum L.) Promising Lines and Detection of Yield Related Agro-Morphological Traits under Terminal Moisture Stress

In order to evaluate the productivity of 20 bread wheat promising lines using multivariate statistical methods, an experiment was conducted based on a randomize complete block design under terminal moisture stress, in 2011-2012. Factor analysis showed that the three first factors explained 66% of total variance. Plant height, peduncle length, 1000 kernel weight, harvest index, biological yield, peduncle weight and shoot weight were detected as the most effective traits on the grain yield. In addition, the bread wheat lines number 17, 14 and 15 out-performed the other lines under the terminal moisture stress condition. Cluster analysis using Ward method grouped the lines in four clusters, i. e. the first cluster consisting the best lines with the highest grain yields. Discrimination function analysis confirmed the clustering results. The results of stepwise regression analysis indicated that the days to 50 percent physiological maturity, plant height, total leaf area, harvest index and biological yield were the most effective traits on grain yield under the conditions of present experiment (i.e. they explained 86 percent of the yield variance). Results of path analysis showed that the harvest index and biomass yield left the maximum direct positive effects on the grain yield. The latter traits can, therefore, be hired for indirect selection of drought tolerant bread wheat lines under terminal moisture stress condition. The line 17 with a greater earliness and the maximum relative grain yield was recognized as the most suitable line under the conditions of the present experiment.