Assessment of yield and yield components of doubled-haploid lines of rapeseed under drought stress

This study aims to evaluate the yield and yield components of 99 doubled haploid lines of rapeseed. It was performed at Ramin Agriculture and Natural Resources University in Khuzestan in two moisture conditions (normal irrigation conditions and drought stress after flowering) in the form of an Augment design with three controls (Hayola 401, Hayola 420, and RGS003) in six replications during the period of 2014-2015 crop year. The results showed that there was a significant difference between the studied genotypes for the number of siliques per plant, number of seeds per silique and seed yield in both conditions. Drought stress in the flowering stage reduced seed yield and yield components. The results of this study also suggested that there is a great variety between the doubled haploid lines of the studied rapeseeds in terms of yield traits and yield components that can be used to improve and modify the rapeseed yield. According to the results of stepwise regression, the trait of the number of siliques per plant in non-stress condition and the trait of 1000-seed weight in drought stress condition can be used as a criterion for selecting and improving superior lines. The results of cluster analysis in both stress and non-stress conditions divided the studied genotypes into 4 groups. According to the stress sensitivity index (SSI) and stress tolerance index (STI), lines 53, 87, and 84 had a high value of STI and a low value of SSI. Therefore, these lines can be used in future plant breeding programs. Lines 85 and 53 also had the lowest yield reduction among high yield lines under drought stress condition and are introduced as compatible, high yield lines under drought stress condition. It is recommended to use these lines in rapeseed breeding programs due to the high diversity among the studied lines.