Elucidating the role of glucose-mediated redox homeostasis, carbohydrate metabolism, and secondary metabolite production in enhancing photosynthetic activity, ionomics, and yield in two okra (Abelmoschus esculentus) varieties

The objective of the research was to evaluate the most effective Glucose (Glc) dose for improving growth, physiological traits, and biochemical responses of two okra varieties, Sakata-713 and Neelam. At 25 days after planting, foliar treatment of different doses of Glc (0, 15, 30, 45, and 60 mM) was applied. At 30 and 45 days after sowing (DAS), sampling was conducted to analyse several physio-biochemical parameters, and 60 DAS yield traits were recorded. The data show that exogenous Glc treatment improved cell division, photosynthetic performance, gas exchange parameters, and mineral nutrient status. Furthermore, Glc treatment also improved activities of enzyme involved in carboxylation–decarboxylation balance (carbonic anhydrase) (CA), nitrogen assimilation (nitrate reductase) (NR), the Calvin cycle (Rubisco), glycolytic metabolism (hexo-kinase) (HXK), and the tricarboxylic acid cycle (succinate dehydrogenase (SDH) and fumarase (FUM)). This increase led to increase in production of osmolyte (proline), secondary metabolites (total phenols, flavonoids, and anthocyanins), and improved carbohydrate metabolism. The exogenous application of Glc maintained redox balance by reducing content of reactive oxygen species and lipid peroxidation with the help of antioxidant enzymatic scavenging system. The promotion effect of Glc followed the order: 30 mM > 45 mM > 15 mM > 60 mM > 0 mM. Moreover, Sakata-713, displayed more promising outcome than Neelam.