Early Sowing Date as A Cultivation Strategy to Alleviate Drought Effects ‎On Yield Components of Different Canola Genotypes

Water shortage or drought stress is an environmental factor that strongly affects crops ‎productivity in various regions of the world. Sowing date as a factor affecting the growth ‎and yield of oilseed crops can alleviate drought stress occurring in reproductive stage. To ‎assess this, agronomic and physiological response of five canola genotypes (L1030, L1204, ‎L1110, L1114 and Okapi) to drought stress were evaluated at two early and late sowing ‎dates (7th and 27th October, respectively) as a two-year field experiment. Results showed ‎that drought stress significantly reduced the seed yield and yield components of all ‎genotypes at both sowing dates, which was a consequence of damage to photosynthetic ‎pigments, reduction of relative water content. However, early sowing was able to alleviate ‎drought stress effect; as seed yield of different genotypes at early sowing were 38-47% ‎higher than late sowing. Moreover, the measured oil content was not influenced by drought ‎stress and sowing date, so the highest oil content at both sowing dates were recorded in ‎L1204 genotypes. Finally, the results showed that sowing of suitable genotype in the proper ‎date could be an appropriate approach to canola sowing in semi-arid areas.‎