Growth Analysis and Oil Quality of Canola (Brassica napus L.) Treated with Zinc Nanochelate and Zinc Sulfate Under Different Irrigation Regimes

Rapid climate change and global warming are leading to more droughts worldwide, posing a serious threat to sustainable agricultural production. This study aimed to evaluate two types of zinc (Zn) fertilization effects at various concentrations on growth and oil quality of canola under different irrigation regimes. Experiment was conducted in a split-split plot arrangement as a complete block design with four replications. The treatments consisted of drought stress with three levels (control, irrigation stop at flowering or mid-season (MDS), and irrigation stop at pod filling or late-season (LDS)) as main factor, two types of Zn fertilization (Zn sulfate and Zn nanochelate) as the first sub-factor, and Zn concentration with three levels (0, 3, and 5 ppt) as the second sub-factor over 2018 and 2019. Results revealed that although most traits were not affected by the year, drought significantly reduced yield attributes, oleic acid, and linoleic acid. In addition, the decreasing trend of leaf area index (LAI), total dry matter (TDM), crop growth rate (CGR), and relative growth rate (RGR) was more pronounced under MDS. The detrimental effects of irrigation stop at both phases on the investigated attributes were mitigated by Zn fertilization. Additionally, under stress, Zn-nanochelate outperformed Zn-sulfate, especially at higher concentrations (5 ppt). Overall, it can be concluded that foliar spraying of canola plants with Zn nanochelate under drought stress at a concentration of 5 ppt can be a beneficial strategy to counteract the detrimental impacts of drought, particularly during the most vulnerable growth phase of the crop.