Effects of foliar zinc application on yield and oil quality of rapeseed genotypes under drought stress

Abstract

In order to address the effect of zinc sulfate on stability and improvement of quality of rapeseed genotypes at different severities of drought stress, an experiment was carried out for two crop years in Karaj (Iran). Zinc sulfate included two levels of non-application and application of 50 g L−1 zinc sulfate, and irrigation was applied in three levels including normal irrigation and irrigation interruption from the podding and flowering stages as factorial in main plots and five rapeseed genotypes in subplots with three replications. Under the conditions of zinc sulfate application and normal irrigation, the L155 genotype had a seed yield of 6310 kg ha−1, the highest oleic acid percentage (67.3%), and the least glucosinolate content (0.8 μmol g−1). Furthermore, under conditions of zinc sulfate application and irrigation interruption from the podding stage, HL2012 and L155 genotypes, respectively produced seed yield of 5032 and 4826 kg ha−1, the highest oleic acid percentage (65.8 and 65.7%), and the lowest seed glucosinolate (11.3 and 11.8 μmol g−1). Moreover, under the conditions of irrigation interruption from the flowering stage, HL2012 and L155 genotypes had the seed yield of 3679 and 3606 kg ha−1, the highest oleic acid percentage (64.3 and 64.2%, respectively) and the lowest glucosinolate (14.5 and 14.8 μmol g−1, respectively. In general, the positive effect of zinc sulfate application on traits such as seed oil yield increased with increasing drought stress, and the L155 genotype is recommended for all irrigation conditions, while the HL2012 genotype may be suggested for late-season drought stress for cultivation in cold temperate semi-arid areas.