Evaluation of Drought Tolerance in Bromus tomentellus Genotypes

Bromus tomentellus is one of the important and valuable grass species for forage production. In order to study the seed and dry forage yield and drought tolerance, eleven genotypes of B. tomentellus were evaluated in two separate experiments under irrigated and rainfed conditions using randomized complete block design with three replications in Agricultural Research Station of Broujerd, Iran, during 2005-2006. Using principal component analysis of drought resistance indices as mean productivity (MP), tolerance index (TOL), stress susceptibility index (SSI), stress tolerance index (STI) and geometric mean productivity (GMP) and seed yield and forage yield in irrigated (Yn) and rainfed (Ys) conditions, genotypes were distributed in two-dimensional diagram based on of the first two principal components. Genotype 3752M with average seed yield of 265 kgha-1 and genotypes 587M, 587P7, 587P12 and 587P3 with average forage yield of 1680.3 to 1897 kgha-1 exhibited suitable drought tolerance.