Biostimulant-mediated cellular repair by improving antioxidant dynamics and osmoregulation against metal stress in canola

Abstract

Global crop yield and growth are severely impacted by hazardous heavy metal contamination of the soil and water. Hence, this study examined the effects of three different levels of cadmium (Cd) stress (concentrations of 0, 1.5, and 2.25 mM) and the foliar application of a biostimulant, i.e. Moringa leaf extract (MLE), on a range of physiological, biochemical, and morphological parameters of two canola (Brassica napus L.) cultivars, Punjab (V1) and Super (V2). More Cd was accumulated in both the aerial and subterranean sections of V1 than in V2. The morphological and physiological indicators showed a substantial (p < 0.05) deterioration as a result of the Cd buildup. The ascorbic acid, malondialdehyde (MDA), and hydrogen peroxide (H2 O2) levels were considerably (p < 0.05) elevated under Cd stress. V1 had considerably higher H2 O2 levels than V2, which suggests that the oxidative stress levels were higher. Additionally, the activity of some antioxidant enzymes, such as catalase and peroxidase (POD) (65% and 40%, respectively), were decreased by the higher concentration of Cd (2.25 mM). V2 demonstrated stronger antioxidant defense mechanisms than V1, as seen by a 115% increase in POD activity, a 70% increase in shoot fresh weight, and a 49% increase in amino acids following the MLE application. Despite this, V2 was still able to withstand the Cd. Under Cd stress, the foliar treatment of MLE increased the yield, growth, biochemical, and physiological characteristics of both V1 and V2. The findings indicated that applying MLE foliar spray can improve crop productivity and lessen the impacts of metals on B. napus L.