Evaluation of drought tolerance in alfalfa (Medicago sativa) accessions under normal and dryland farming system

In order to evaluate drought tolerance of alfalfa (Medicago sativa), 49 accessions of the species were examined in two separate experiments using simple lattice designs under normal and dryland farming system during 2005-2007 in Tabriz, Iran. Forage dry matter yield was evaluated during two years. Results of combined analysis showed significant differences among the genotypes and among the years. Means of forage dry matter yield were 9.01 and 4.94 ton/h under irrigation and dryland farming systems, respectively. Cluster analysis correctly distributed the genotypes in the relevant groups based on yield and STI Index. Group 3 with genotypes of 14, 25, 37, 32, 11, 13 and 10 with average yield of 6.42 ton/h and STI= 0.95 was recognized as drought tolerant group. Based on stress intensity SI=0.452, Stress Tolerance Index (STI) and Stress Tolerance (TOL), genotypes 14 (Khoramabad) and 32 (Faridan) with average values of 8.74 and 7.26 ton/h respectively had the highest production in dryland farming system, that were recognized as drought tolerant accessions.