Assessing genetic diversity for some Pakistani bread wheat (Triticum aestivum L.) genotypes under drought stress based on yield traits

Drought is one of the most influential abiotic stress factors affecting bread wheat productivity worldwide. Therefore, the current experiment was conducted to evaluate the genetic variability presenting 19 bread wheat genotypes under two environments (normal and drought). Under normal conditions, grain yield per plant (GYP) exhibited the highest positive significant correlation with the number of grains per spike (NGS) (0.90***), biological yield (BY) (0.88***), 1000-grain weight (TGW) (0.83***), harvest index (HI) (0.77***), number of spikelets per spike (NSP) (0.52***), arithmetic mean diameter (AMD) (0.52***), grain mean diameter (GMD) (0.50***), equivalent mean diameter (EMD) (0.50***), grain length (GL) (0.46***), grain width (GW) (0.46***), grain thickness (GT) (0.34**), and spike length (SL) (0.27*). However, GYP showed a negative yet insignificant correlation with spike compactness (SC) (− 0.18) and peduncle length (PL) (− 0.08). Under drought stress, GYP exhibited a significantly positive association with BY (0.94***), HI (0.92***), NGS (0.86***), TGW (0.63***), aspect ratio (AR) (0.49***), grain sphericity (SPH) (0.40**), GW (0.39**), NSP (0.38***), and SL (0.28*). Principal component analysis (PCA) revealed that the first 4 PCs explained 88.9