Use of Physiological Parameters for Screening Drought Tolerant Barley Genotypes

With the aim of understanding and identifying the traits which can be used as the suitable criteria for quick screening of the water deficit tolerant barley genotypes, an experiment based on randomized complete blocks design with three replications was conducted during two years to evaluate the biochemical responses of 20 barley genotypes to full irrigation and terminal water stress in the field condition. Results showed large genetic differences among barley genotypes in response to water deficit, which could be utilized in breeding programs. Proline, sucrose, glucose, fructose, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), auxin, gibberellin and abscisic acid (ABA) content were significantly affected by different irrigation conditions and genotypes. Water deficit significantly increased proline, carbohydrates accumulation and activities of CAT, SOD, GPX and ABA concentration in the barley genotypes. However, indole acetic acid (IAA) and gibberellic acid (GA3) contents decreased under the terminal water stress. Cluster analysis showed that genotypes 11, 18 and 19 had higher values of proline, fructose, glucose, IAA, GA3, GPX, CAT and SOD. These genotypes could be considered as drought tolerant genotypes which can tolerate unfavorable environmental conditions as compared to other genotypes through overproduction of some osmolytes, effective phyto-hormone signaling and better antioxidant enzymes activity for scavenging reactive oxygen species and consequently enhanced potential for production of higher grain yield. Thus, it seems that biochemical and phyto-hormonal responses could be introduced as desirable and suitable indicators for screening genotypes with better potential under water deficit stress condition.