A nano-bioengineered cobalt oxide biostimulant mediated regulation of physiological, biochemical, and antioxidant mechanisms in Zea mays.

Biogenic synthesized cobalt nanoparticles (NPs), dose optimization toxicity, and metabolic studies of Zea mays are very important before their application in the field. Here, we investigate the morphological, biochemical, and metabolic response of summer maize (Zea mays) against bulk cobalt chloride and Withania-assisted bioengineered cobalt NPs. It was found that cobalt chloride as bulk and concentration of 100 mg/L NPs inhibits growth via significant changes their metabolic and biochemical molecules. While biogenic assisted with Withania, cobalt NPs with concentrations of 50 and 100 mg/L have shown a significant increase in shoot length by 15% and 9% respectively. Root length was found to be decreased at 25 mg/L and 50 mg/L as compared to control. Fresh and dry weight was found to be increased at 25 mg/L and 50 mg/L. However, chlorophyll contents seemed to decline at 25 mg/L and increased at 50 mg/L. Carbohydrate content was found to be decreased at 50 mg/L and 25 mg/L by 76% and 70% respectively. Starch content was found to be increased at 25 mg/L and 50 mg/L by 28% and 33% respectively. Nitrate content was found to be decreased at 50 mg/L by 17%. However, higher tested concentrations showed a very much decrease in these compounds. Results displayed that a small quantity of cobalt oxide nanoparticles had a stimulatory impact on the seedling development while a higher quantity encouraged an inhibitory effect. 100 mg/L also showed an increase in activities when comparison was done against control. At 25 mg/L all activities were found to be maximum. This increased level suggests that the congregation of these secondary metabolites generates an oxidative response in plants when exposed to Cobalt oxide nanoparticles and cobalt chloride. However, further mechanistic research should be adopted as our experimental findings ruled out the generalized phytotoxicity of plants.