Identifying drought- tolerant cultivars of canola (Brassica napus L.) under Karaj climatic condition

 Available water for irrigation of canola decreases towards the end of the season, due to reduced rainfall and the simultaneous late-season irrigation for other spring crops. Therefore, the possibility of the plant facing drought stress in the final stages of growth is very likely. So, the selection of drought-tolerant genotypes is very important in arid and semi-arid regions.

 The field experiment (2016- 2017 and 2017- 2018) was conducted as a split-plot arrangement in a randomized complete blocks design with four replications in Karaj agricultural research station. Treatments included drought stress regimes (common irrigation, withholding irrigation from the silique setting stage, and flowering stage) in main plots and canola genotypes (Talayeh, Okapi،SLM046, Ahmadi, Zarfam، Licord, Neptun, NataliGK Gabriella, and Opera) in sub-plots.

 The results showed that drought stress significantly reduced the number of pods per plant, the number of seeds per pod, 1000-seed weight, seed yield, growth period duration, oil content, oil yield, and water use efficiency (WUE). Under common irrigation, the highest seed yield was obtained from okapi، Neptun, and Natali genotypes with 5558, 5698, and 5076 kg ha-1, respectively. Under drought stress, SLM046، Zarfam، Natali and Opera had the highest seed yield with 3144, 2864, 3237, and 2951 kg ha-1 in withholding irrigation from the silique setting stage and 2377, 2472, 2441, and 2539 kg ha-1 in withholding irrigation from the flowering stage, respectively. GMP, MP and STI indices were highly correlated with seed yield under both stress and non-stress conditions. Therefore, they were introduced as suitable indices to identify superior genotypes for both environmental conditions. Accordingly, the most resistant genotypes were Okapi, SLM046, Zarfam, Neptun, Natali and Opera.

Based on the results, Okapi, SLM046, Zarfam, Neptun, Natali and Opera are recommended as suitable genotypes for cultivation in Karaj climatic conditions.