Photosynthetic efficiency parameters as indicators of agronomic traits of winter wheat cultivars in different soil water conditions

In an effort to find breeding methods for improving drought stress tolerance and grain yield, twelve photosynthetic efficiency parameters have been measured on ten cultivars of winter wheat (Triticum aestivum L.), along with water use (WU), water use efficiency (WUE) and agronomic traits of grain yield (GYP), biomass weight (BWP), harvest index (HI), yield stability index (YSI) and stress tolerance index (STI) in the vegetative pot trial with control (B1) and drought stress (B2) treatments. Drought stress induced in three different stages of development has caused decrease in water use efficiency based on biomass (WUEb) (B1: 2.94 g L-1; B2: 2.71 g L-1) and grain yield (WUEg) (B1: 1.03 g L-1; B2: 0.89 g L-1), as well as GYP and BWP. Dissipation energy flux per excited cross section (DI0/CS0) observed in the drought stress treatment in the tillering stage of growth gave significant negative correlation coefficient (P≤0.05) with agronomic traits of tested wheat cultivars (GYP:-0.75; WUEg and STI: -0.74; YSI: -0.67). Performance index (PIABS) measured in the drought stress conditions in the flag leaf stage was in significant positive correlation with GYP and WUEg (r=0.64). Lower values of absorption flux per excited cross section (ABS/CS0), electron transport per excited CS (ET0/CS0) and dissipation energy flux per excited CS (DI0/CS0) and higher values of PIABS, measured on wheat genotypes (cultivars) in the drought stress conditions of pot trial, could indicate higher tolerance to drought stress conditions. Results of the studied photosynthetic efficiency parameters of wheat cultivars were also the good predictor for important agronomic traits, especially, when they were detected in the early stage of growth