Enhancing the medicinal properties and phytochemical content of bitter melon (Momordica charantia L.) through elicitation with brassinosteroid, ethrel, and carrageenan

Bitter melon (Momordica charantia L.) is well-known for its high protein, steroid, alkaloid, mineral, lipid, triterpene, and phenolic compound content, as well as its medicinal properties, particularly its anti-diabetic effects. To investigate the impact of elicitors on the morphology and phytochemical characteristics of bitter melon (Jounpouri cultivar) over two consecutive years (2018 and 2019), we conducted a field experiment. The study aimed to determine the effects of Ethrel, brassinosteroids (BRs), and k-carrageenan on yield and the production of anti-diabetic agents in M. charantia farm crops. The elicitors included ten levels, ranging from a control group to Ethrel (100, 300, and 600 mg l^{- 1}), brassinosteroids (BRs) (0.1, 0.5, and 1 mg l^{- 1}), and k-carrageenan (200, 400, and 600 mg l^{- 1}). These characteristics included leaf area, leaf length, leaf width, fruit parameters, carbohydrate content, total phenols and flavonoid accumulation, antioxidant activity, total acid, ascorbic acid, momordicine, and charantin. Across both years, we observed the highest flavonoid accumulation and antioxidant activity in the Ethrel treatment group. Specifically, applying 0.5 mg l^{- 1} BRs and 300 mg l^{- 1} Ethrel led to an 18.8% and 14.8% increase in momordicine content, respectively. All elicitor treatments, particularly at 0.1 mg l^{- 1} BRs, significantly increased leaf area, leaf length, and leaf width compared to the control group in both cropping years. Additionally, the application of all elicitors resulted in increased fruit weight, dimensions, and yield over the two consecutive years. Notably, in 2018, 600 mg l^{- 1} Ethrel contributed to enhanced fruit weight and yield, while in 2019, 0.5 mg l^{- 1} BRs exhibited the same effect. Metabolic and physiological changes in bitter squash induced by employed elicitors over two different years (2018-2019) are strongly dependent on a variety of environmental factors such as temperature and rainfall. In conclusion, using BRs as an elicitor has the potential to optimize the health benefits of bitter melon by increasing the content of two bioactive molecules, momordicine and charantin.