Assignment of the relations among traits and regression and path analyses of grain yield in promising lines and cultivars of temperate and cold regions bread wheat

In order to study of the relationships among the traits, specially relative traits tospike; 30 genotypes of bread wheat were evaluated in a randomized complete block design with three replications during 2009-2010 cropping seasons at the Agricultural Research Station of Islamic Azad University, Tabriz Branch. In this research, 19 traits including grain yield and its components, phonologic and morphologic traits were measured. Based on consequences of correlation analysis, grain yield contained positive and significant correlation with plant height, number of spike per plant, spike weight, spike length, spike width, number of spikelet per spike, number of prolific floret per spikelet, grains number of main spike and grain weight of main spike. With conclusion of stepwise regression analysis, the traits of spikes number per plant, grains weight of main spike and grains number of main spike were entered in the regressional model, respectively and as whole explained 71% of grain yield variation. According to the results of path analysis, the greatest positive direct and indirect effect on augmentation of grain yield were appertained to grains weight of main spike and grains number of main spike, respectively; thus these traits were distinguished as the most cardinal effective components on grain yield.