Evaluation of rapeseed genotypes (Brassica napus L.) under drought stress conditions

Colza is one of the important agricultural crops that primarily for its edible oil. The meal remains after oil extraction is valuable as a source of protein for the livestock feed industry. In Iran, production of the rapeseed is mainly limited by drought and soil salinity. Therefore, evaluation and selection of genotypes with increased drought tolerance is important for successful agriculture in water limited area. For this aim, 16 genotypes of B. napus was investigated under two different water regimes, irrigated and non-irrigated. The experiments were laid out in a randomized complete blocks design (RCBD) with three replications. Drought resistance indices, including mean productivity (MP), geometric mean productivity (GMP), tolerance index (TOL), stress tolerance index (STI) and stress susceptibility index (SSI) were calculated based on two conditions. Analysis of variance revealed significant differences for all indices. Correlation analysis indicated strong association between Yp, Ys, STI, MP and GMP. Cluster analysis based on STI, MP, GMP and seed yield under both stressed and non-stressed conditions divided the genotypes into four groups. According to results of drought resistance indices, Dante cultivar had the highest STI (1.22) index, therefore we suggested that, this genotype is tolerant variety under mild drought stress.