Influence of drought stress and application of ammonium sulfate on quality of rapeseed oil

Abstract

Nowadays, drought stress is one of the most highlighted consequences of global warming, resulting in various environmental and economic drawbacks in the planting systems of important oil seed crops, particularly rapeseed. In the present study, an experiment was performed to assess the influence of drought stress and the application of ammonium sulfate on the quality of rapeseed oil during 2015-2016 and 2016-2017. This study was designed using a factorial split-plot based on complete randomized blocks with three replicates. Irrigation factors consisted of two levels (normal and irrigation interruption at the pod formation stage and at the elongation stage) and ammonium sulfate was included at two levels (0 kg/ha and 150 kg/ha), as a factorial set in the main plots (in factorial status in main plots) and cultivars (in subplots). The results showed the highest amount of grain oil (45.5%) was obtained in the second year of the experiment and under normal irrigation. The amount of oil increased by 2.5% using ammonium sulfate compared with the normal condition. The highest amounts of palmitic acid (5.2%) and oleic acid (65.5%) were obtained using the BAL128 line under normal irrigation, while the least palmitic acid (4.3%) and oleic acid (63.8%) were obtained using the Nima cultivar under irrigation interruption. The BAL128 line had the highest percentage of grain oil. Under normal irrigation, the use of ammonium sulfate decreased the amount of glucosinolate to 22.9%. The overall results of this study suggested that the BAL128 line was superior to the other genotypes in terms of the yield and quality of fatty acids; therefore this line might be applicable for farming or as a parent or both to increase the yield and quality in future breeding systems.