Evaluation of Drought Tolerance Indices of Promising Canola Lines (Brassica napus L.) at Changes in Planting Date

In order to evaluate drought tolerance indices in promising canola lines affected by planting date, a split plot experiment with randomized complete block design with three replications at research field of Seed and Plant Improvement Research Institute of Karaj, Iran was conducted in 2015-16 and 2016-17. In this study, sowing dates were October 20 (normal) and November 10 (delayed planting) in the main plots, and promising canola lines including L1112, L1091, L1093, L1206 and Okapi were included in the sub-plots. To evaluate different physiological indices of drought tolerance, two separate environments were considered including normal irrigation (control) and irrigation interruption from the pod formation stage to the next (late season drought stress). The results of combined analysis showed that late season drought stress and delayed planting date reduced the yield in all studied lines. Geometric Mean Productivity, Stress Tolerance Index, and Mean Productivity have been selected as superior indices in order to recognizing tolerance line in this study. According to the results of this experiment, line L1206 was introduced as the top line in this study, which is likely to be cultivated in rotation with autumn wheat and, on the other hand, withstand water deficit stress at the end of the growing season.