Evaluation response of different genotypes of spring canola to water deficit

ABSTRACT: In order to evaluation spring canola (Brassica napus) genotypes at three moisture levels, this research was conducted in Zahak Agriculture Research Station of Zabol, in 2007 cropping season. This site located in South Eastern of Iran with precipitation less than 50 mm in year. These genotypes were evaluated in three separate experiments. First experiment was non-stress, (irrigation in roset, budding, flowering, poding and grain filling stages), second experiment was early season of drought stress that from sowing timing until budding stage, approximately 80 day after sowing water interruption (pre-anthesis drought stress) and three experiment was water interruption from flowering stage until end maturity (post–anthesis drought stress). A randomized complete block design was used with three replications. Results analysis of variance grain yield showed significantly difference between genotypes. Mean grain yield of canola genotypes were 4074 kg/ha, 3227 kg/ha, and 2979 kg/ha, under non-stressed, early season drought stress and end season drought stressed conditions, respectively. Among the genotypes, Hyola 401 and Hyola 420 Hybrids were outstanding in non-stress and early season stress conditions, respectively. But Under end season drought stress, highest seed yield belong to Hyola60, Hyola 308, Hyola 401 hybrids and RGS003 cultivar. Five drought tolerance indices were calculated based on relative grain yield under drought and normal conditions. In non-stress and stress conditions, have above genotypes highest amount of stress tolerance index (STI), geometric mean productivity (GMP), and mean productivity (MP). Calculated correlation coefficients revealed positive and significantly correlation between STI, GMP and MP indices and grain yield under stress and non-stress conditions Therefore these indices can be used as a selection criterion for selecting high-yield genotypes under stress and non-stress conditions. Also based on results these study, genotypes Hyola401, RGS003 and Hyola 420, their production was stable when the environment changed than other genotypes, so can be used as a suitable genetic source for improvement drought tolerance in breeding programs.