Investigating the effect of foliar spraying of salicylic acid and methanol on yield and yield components of Brassica napus under drought stress

This research was conducted to study the effect of salicylic acid (SA) and methanol (M) spraying on yield and components yield of rapeseed, Hayola 401 cultivar, under deficit-irrigation stress conditions in Khuzestan province, Shams Abad, Dezful region in 2016 and 2017 crop years. In this research, the irrigation cycle was conducted in three levels (70, 140, and 210 mm evaporation) as the main plot, SA in three levels (0, 100, and 200 µmol), and M in 3 levels (0, 10, and 20 v %) as the secondary plots with three replications. According to the simple effect of deficit-irrigation treatment, SA and M spraying treatments showed a significant difference in 1% p-value at the most evaluated traits except the plant height and the number of pods. The two-way effect of deficit-irrigation stress and SA and M was significant only in the traits of pod length at a 1% significant level. The results showed that the maximum yield of grain was obtained under deficit-irrigation stress with 70 mm evaporation, 100 µmol SA solution spraying and 20 v% M spraying (3272 kg/ha). In addition, the minimum yield of grain was obtained under the deficit-irrigation stress condition with 210 mm evaporation, zero-spraying SA, and 10 v% M spraying (315 kg/ha). The maximum oil percentage was observed in stress with 70 mm evaporation, 200 µmol SA spraying, and 20 v% of M (50.3%). In addition, the minimum oil percentage was observed in 210 mm evaporation and zero-spraying SA and M (31.7%). Based on the results, the best deficit-irrigation treatment was 70 mm evaporation, and yield decreased by increasing the deficit-irrigation stress. Moreover, the gain yield and oil percentage increased by M and SA solutions spraying.