Application of Physiological Traits Related to Plant Water Status for Predicting Yield Stability in Wheat under Drought Stress Condition

The objective of the present study was to model the relationship between yield stability index (YSI) and some physiological traits related to plant water status. Fifteen bread wheat (Triticum aestivum L.) genotypes with wide range of sensitivity to drought were used in a randomized complete block design with three replications under two different environments (irrigated and rainfed) in 2012-2013 at the experimental farm of College of Agriculture, Razi University, Kermanshah, Iran. The results showed that YSI had positive and significant relationship with relative water protection (RWP, r = 0.858**), relative water content (RWC, r = 0.594*), canopy temperature depression (CTD, r = 0.669**), stomata resistance (SR, r = 0.643**) and evapotranspiration efficiency (ETE, r = 0.818**), and negative significant correlation with relative water loss (RWL, r = – 0.822**) and excised leaf water loss (ELWL, r = – 0.543*) under drought stress condition. Also ETE (0.46*) and RWP (0.806) had the highest direct and indirect effects on YSI, respectively. Multiple linear regression analysis indicated that the predicting model for YSI explained 97.9% of the total variation within the measured traits. The residual plots analysis indicated no problem in the model with selected variables. On the other hand, t-test showed that some of the variables are not important to be present in this model. The results of path and stepwise multiple linear regression analysis indicated that ETE (R2 = 73.5%), RWP (R2= 11.9%), CTD (R2 = 6.9%) and RWC (R2 = 3%) were the best physiological traits related to water status for modeling of YSI.