Evaluation of Drought Tolerance of Barley (Hordeum vulgare L.) Genotypes Using Physiological Characteristics and Drought Tolerance Indices

To evaluate reactions of barley genotypes to drought stress during seed germination, seedling and adult plant stages, twenty genotypes and two cultivar were studied in controlled conditions and field experiment under normal irrigation and water stress conditions. Physiologic characteristics, drought tolerance indices and all characteristics of germination were measured. The results showed that with decrease of water potential (0 to 0.1Mpa) all characteristics of germination were significantly decreased. The highest germination stress index (GSI) were obtained by genotypes Lingnee 131/3/4679/105//Yea168.4 and CWB 117-77-5-9-5 and the lowest by genotypes 168.4 Lignee 131/ArabiAbiad and CWB117–77–9–7//Antares/ky63–1294. Positive and significant correlation was observed between germination percent and GSI. In field experiment, drought stress reduced early growth rate, relative water content and relative water loss. Based on stress tolerance index (STI), genotypes Grivita/CWB117-5-9-5 and Wieselburger/A hor1303-61//Sis were more tolerant to drought condition compared to the other genotypes. Positive and significant correlation was found between stress tolerance index (STI) and grain yield in both normal irrigation and stress conditions, early growth rate, germination percent in stress conditions and also with germination stress index at 5% probability level. Based on higher correlation between STI and grain yield in both normal and drought conditions, this index was found to be the best index for selecting drought resistant genotypes.