Effect of Plant Growth Regulators on Physiology of Stevia rebaudiana Bertoni

Abstract

Medicinal plants have long served as a major source for developing effective therapeutic agents. Excessive intake of sucrose-rich foods is closely linked with several metabolic disorders, including obesity, hypertension, atherosclerosis, coronary complications, high cholesterol levels, and sleep disturbances. Due to these risks, artificial sweeteners are frequently incorporated into beverages, confectionery items, sauces, pickles, and other food products. Stevia rebaudiana Bertoni offers a natural and safer alternative, particularly for individuals with diabetes, as its leaves contain highly sweet steviol glycosides. Secondary metabolites are influenced by plant growth regulators (PGRs) by varying the growth of plant and its physiological aspects. In the present study, Stevia plants treated with 25, 50 and 100 ppm of Indole-3-Acetic Acid (IAA) and Gibberellic Acid (GA₃) at 10 days interval for 60, 120 and 180 days. The findings revealed that GA₃ at 50ppm markedly enhanced protein and proline levels, whereas IAA at the same concentration significantly increased total carbohydrates and free amino acids compared with the control. Higher concentrations (100 ppm) of both PGRs showed a suppressive effect on all physiological parameters. Overall, the results suggest that low doses of IAA and GA₃ promote growth and improve physiological attributes of Stevia, with GA₃ being more effective for protein and proline enhancement and IAA for carbohydrate and amino acid accumulation.