Genetic dissection of grain yield traits in a large collection of spring wheat ( Triticum aestivum L.) germplasm

Understanding genetic architecture of a crop germplasm is necessary for designing a successful breeding program. Herein, we evaluated a large collection of 500 spring wheat accessions for 2 crop seasons to dissect the genetics of 11 yield components and their direct and indirect contributions to grain yield (GY). The genetic estimates of broad sense heritability ( h 2 ), genetic advance (GA), phenotypic correlation ( r p ) , genotypic correlation ( r g ), and path coefficient analysis were performed. Significant genetic variation was observed for all yield traits suggesting that GY can be improved by exploiting the studied yield traits. Phenotypic coefficient of variation ( V p ) was greater than genotypic coefficient of variation ( V g ) for all studied traits. Higher broad sense h 2 and GA were observed for grains per plant (GpP), spikes per plant (SpP), spikelets per spike (Spt/S) and grain yield (GY). The GY exhibited significant and positive correlation with all studied traits except with spikelet density (SptD). The GpP and TGW exhibited positive direct effect on increasing grain yield. Taking together, SpP, GpS, TGW and SDW are the major contributors to improving genetic yield potential of bread wheat with spring growth habit. The negative correlation between GY and SptD was dissected in path coefficient analysis as negative indirect effect of SptD on GY through reduced GpS and TGW. Our study provides new insights on the association of GpP, TGW and SDW in bread wheat. The GpP, TGW and SDW are influenced by SpP, Gpt/S, G/Spt, SptD, AL and PH with indirect effects on GY. To improve yield potential in wheat, the traits with direct effects (GpP, TGW and SDW) and indirect effects (e.g., SptD) can be used as selection criteria.