Study on genetic variation and relationship between plant characteristics and grain yield in long spike bread wheat (Triticum aestivum L.) genotypes-using multivariate analysis

To study genetic variation and to determine the relations between different plant characteristics with grain yield, seventy long spike bread wheat genotypes together and two commercial cultivars (Chamran and Bahar) were evaluated using Alpha Lattice design with two replications, in Karaj Field Station, Seed and Plant Improvement Institute (SPII),, Karaj, Iran. Thirty traits including grain yield and its components, plant and grain morphological and quality related traits were measured and recorded for all genotypes. Factor analysis determined three factors that accounted 96% of total variations among genotypes. These factors were yield components, quality related traits and grain yield and its components. Stepwise regression analysis showed that biological yield, grain weight.spike-1 and number. of spike m-2 were of higher importance among other grain yield components. Path analysis coefficients showed that the highest direct effects for grain yield were biological yield, grain weightsSpike-1 and number. of spikes m-2. Cluster analysis with Ward's method based on all measured traits and quality related traits resulted in three and four groups, respectively.