Effect of foliar application of micronutrients and salicylic acid on seed and oil yield of canola (Brassica napus L. cv. Neptune) under drought stress conditions

To investigate the effect of foliar application of micronutrients and salicylic acid on seed and oil yield of canola under drought stress conditions,  a field experiment was carried out as spilt factorial plots arrangemnts in randomized complet block design in 2016-17 and 2017-18 cropping seasons in Lorestan University, Khorramabad, Iran. Experimental treatments included; irrigation at two levels: (A1) irrigation at 80% of field capacity (non- stress) and (A2) irrigation at 30% of field capacity (drought stress) assigned to main plots and foliar application of combination of iron, zinc and manganese elements at two levels: (B1) zero, and (B2) concentration of 2‰ and salicylic acid foliar application at four levels: (C1) zero, (C2) 0.5, one (C3) and (C4) 1.5 mM were randomized in sub-plots. The results showed that water deficit stress decreased total chlorophyll content (12%), Silque number per plant (20.4 silique.plant-1) and increased peroxidase enzyme activity (22%). Application of micronutrients increased chlorophyll content (13%) and carotenoids (10%). Salicylic acid foliar application with concentration of 0.5 mM had the highest seed oil content (40.9%). The highest water productivity (1.26 kg.m-3) was obtained in irrigation at 80% of the field capacity, foliar application of two per thousand concentration of iron, zinc and manganeze, and foliar application of 1.5 mM salicylic acid (A1B2C4). In 2016-17, the highest seed yield (4427 kg.ha-1) was obtained from the application of irrigation at 80% of the field capacity, foliar application of 2‰ micronutrients and foliar application of 1.5 mM salicylic acid (A1B2C4). In 2017-18, the highest seed yield (4955 kg.ha-1) was obtained irrigation at 80% of the field capacity, foliar application of 2‰ micronutrients and foliar application of one mM salicylic acid (A1B2C3). The results showed that under drought stress conditions, simultaneous application of micronutrients and salicylic acid increased seed yield and significantly increased oil yield (1449 kg.ha-1) as compared with control treatment (803 kg.ha-1). Based on the results of this experiment, foliar application of iron, zinc, and manganese micronutrients together with 1.5 mM salicylic acid improved seed and oild yield of canola under drought stress conditions.