The Effect of Non-biological Elicitors on Physiological and Biochemical Properties of Medicinal Plant Momordica charantia L.

Carla (Momordica charantia L.) is a medicinal plant of the Cucurbitaceae family, which has antibacterial, anticancer, anti-tumor, hypoglycemic, hypertensive, and cholesterol properties. In this study, the effects of zinc oxide nanoparticles (ZnO-NPs) (20, 60, and 100 ppm), jasmonate (100, 250, and 500 μM), and chitosan (10, 50, and 100 μM) were measured on the growth and some physiological and biochemical parameters of Carla plant. The results revealed the highest shoot weight of plants at 250 μM jasmonate and 10 μM chitosan, while ZnO-NPs had no significant effect on shoot weight. ZnO-NPs (20–60 ppm) and jasmonate (100 and 200 µM) significantly increased chlorophyll a content, but chitosan showed no effect on chlorophyll a content. Secondary metabolites such as phenols, flavonoids, and carotenoids as well as carbohydrate and proline content were significantly increased by all elicitors in a dose-dependent manner. Antioxidant enzyme activity showed varied responses to different concentrations of elicitors. Jasmonate increased catalase (CAT), ascorbate peroxidase (APX), and guaiacol peroxidases (GPX) activity in a dose-dependent manner. Chitosan at all concentrations significantly increased CAT and APX enzymes activity, while at 100 μM concentration significantly increased GPX enzyme activity. ZnO-NPs did not affect GPX and AXP enzymes activity. Our findings confirmed for the first time that non-biological elicitors at specific levels have a significant growth promotion effect as well as increased production of valuable secondary metabolites in M. charantia.