The most effective yield-components associated with increasing yield of wheat (Triticum aestivum L.) under terminal drought stress conditions

Due to the rising drought-severity all around the world, one of the most important goals of arid agricultural systems is to increase wheat yield as a strategic crops in these areas. Improving the yield components is believed to be an efficient and vonventional strategy for increasing wheat yield. This study was carried out on 61 advanced lines and five Iranian commercial cultivars in order to identify the most effective components of grain yield (GY) under late-season drought stress conditions. The experiment was carried out based on an augment design during 2013-14 and 2014-15 growing seasons. Fertile spikes number m-2 (FSN), spike weight m-2 (SPW), grain number per spike (GNS) and plant harvest index, as the most effective variables, explained 94.06% of GY variance. FSNand SPWrevealed the maximum direct and positive effect on GY enhancement. The first and second factors, as “yield and yield-components” and “vegetative growth” factors, respectively, explained 76.4% of the data on the total variance. The highest alignment with GY belonged to SPW and FSN . The genotypes were grouped in four different clusters. Bi-plot and cluster results revealed a remarkable genetic diversity among the genotypes; therefore, these results might be helpful to identify donor parents in wheat breeding crosses for yield increscent. Finally, FSN and SPW, the main indicators for increasing grain weight m-2, were proposed as the most important grain yield-components under terminal drought stress conditions.