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 crop 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 responses 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, i.e. reduction of relative water content. however, early sowing was able to alleviate the effect of drought stress as seed yield of different genotypes at early sowing were 38-47% higher than late sowing. moreover, the oil content was not influenced by drought stress and sowing date, so the highest oil contents at both sowing dates were recorded in l1204 genotypes. finally, results showed that sowing suitable genotype in the proper date could be an appropriate approach to canola cultivation in semi-arid areas.