Evaluation of physiological responses of rapeseed varieties to foliar spraying of Zn and Fe micronutrients under different moisture regimes

Rapeseed (Brassica napus L.) containes 40 – 46 percent oil and rich in unsaturated fatty acids such as oleic and linoleic and has a high nutritional value. The abiotic stresses such as drought stress causes to decline the quantitative and qualitative yield of many field crops in developing countries. In order to evaluate the foliar application effects of Zn and Fe micronutrients on growth and yiels of rapeseed under deficite irrigation condition, this experiment was carried out as factorial based on complete block design with three replications in two regions of Qazvin and Karaj, Iran 2019 cropping season. Three levels of irrigation regims including whole irrigation, cutoff irrigation from flowering stage and cutoff irrigation from silique stage and four levels of micronutrients including zero (as check), foliar application of Zn, Fe and Zn + Fe as 3×4 factorial as main plot and two varieties of rapeseed as sub plot comprised experimental treatments. Results showed that seed yield, relative water content and some fatty acids such as linoleic, palmitic and stearic deccreased in response to drought stress caused by cutoff irrigation from flowering stage and micronutrients deficiency and foliar spraying of Zn + Fe enhanced them equal 136.13, 8.20, 7.72, 12.87 and 22.55 percent, respectively. Some evaluated traits such as stomatal resistance, prolin, soluble carbohydrates and oleic, linolenic and erucic fatty acids increased under cutoff irrigation condition from flowerin stage compared to whole irrigation. Result showed that integrated application of Zn and Fe as foliar spraying through increasing of stomatal resistance and increasing of stomatal conductivity and relative water content caused to enhance seed yield of rapeseed under drought stress condition.