Investigation and Importance of Relationships of Grain Yield and Yield Components in Wheat Breeding (Triticum Aestivum L.)

Determining the relationships between grain yield and some yield components of wheat is most important in permanent yield production. Using path coefficient analysis in order to determine key traits affecting majorly yield, and also to study direct and indirect effects of yield and yield components, this research was performed during 2006-2009 ys using 94 doubled-haploid (DH) lines, their parents and five local Iraninan cultivars in triple lattice designs, using path analysis method to determine key traits which had the most effects on yield and also to determine direct and indirect effects of yield components. The results showed the significant positive correlations between grain yield with seed per spike, harvest index, fertile tiller number and flag leaf width, and also negative significant relationships between grain yield and total tiller number, plant height and number of nodes. Path coefficient analysis results indicated strong significant direct effects of yield related traits such as HI (0.27) and 100 seed weight (0.09) on grain yield. The results of this study, according to the homogeneity of DH lines, showed that characters: harvest index, 100 seed weight, spike length, fertile tiller number, flag leaf length and width could be appropriate indicators to be selected for improving and enhancing the grain yield in bread wheat.