Drought stress effects on accessions of two species Agropyron repens and Agropyron tauri using drought resistance indces and plant growth

In this study, the effects of water stress on seedling growth characteristics were studied in Agropyron tauriþ and Agropyron repens. The experiments were conducted in the greenhouse of Fars Agricultural and Natural Resources Research and Education Center in 2010. Six Agropyron repens genotypes and four Agropyron tauri genotypes were selected from the gene bank of Research Institute of Forests and Rangelands and were arranged in a factorial experiment in a completely randomized design with three replications. Factors A and B were the genotypes and drought levels, respectively. Drought stress levels were 100, 75, 50 and 25% of field capacity, and the measured characteristics were shoot length, root length, root/shoot ratio, seedling length, seedling fresh weight, seedling dry weight, dry weight/fresh weight ratio, and leaf area. There were statistically significant differences among drought treatments, genotypes, and interaction effects of accessions with land, in most of the above characteristics. Five drought resistance indices including stress susceptibility index (SSI), tolerance index (TOL), stress tolerance index (STI), mean productivity (MP), and geometric mean productivity (GMP) were calculated. By assigning the highest indices, the genotype A.tauri (99) showed the highest resistance in most of the traits tested.According to the obtained results, genotype A.tauriþ (99) as the best and genotypes A. repens (211), A. repens (217), A. repens (224), and A. repens (225) in the next rank could be recommended for rangeland improvement and reclamation in arid regions.