Study of some abiotic elicitors effects on morphological and phytochemical traits of Karelā

Karelā (Momordica Charantia L.) is a tropical vegetable with high nutritional and medicinal value. This plant belongs to the cucurbitaceae family and has a valuable anti-diabetic effect. The use of elicitors in order to produce environmentally friendly biological products in conjunction with modern agriculture can increase the qualitative and quantitative growth of medicinal plants and reducing the effects of environmental stresses on these plants. This research was carried out to investigate the effects of abiotic elicitors, Ethrel, Carrageenan and Brassinosteroid, on traits of Karelā, Hybrid Baby Doll variety.

This research was performed as factorial experiment based on a completely randomized design with three replications. This experiment included a simple study of the abiotic elicitors of brassinosteroid (0.1, 0.5, and 1 mM), carrageenan (200, 400, and 600 mg / L), Ethrel (100, 300, and 600 μM), and control (no elicitation) on Karelā, Hybrid Baby Doll variety. There were 30 experimental units in a solid MS medium containing 3 percentage sucrose. After a period of growth, at a stage of 4 to 6 leaves, seedlings were transferred to the greenhouse. The effect of these elicitors was evaluated on the morphological (leaf length, leaf width, leaf area, fruit length, fruit diameter, fresh and dry weight of fruit, and plant yield) and phytochemical traits (total phenol, total flavonoid, antioxidant activity, photosynthetic pigments, carotenoids, and antidiabetic secondary metabolites Momordicin and Charantin) of Karelā.

The analysis of variance results showed that, there was a statistically significant difference (p˂0.05) between experimental treatments on morphological and phytochemical traits of Karelā. In this study, the highest leaf area (72.52 cm), total chlorophyll (28.9 mg / g FW), and total flavonoids (4.99 mg Q/ g DW) was measured from elicited plants with etherel. Maximum fruit length (35.4 mm), carotenoids (1.8 mg / g FW), total phenol (35.17 mg G / g DW), antioxidant activity (79/31 percent), and momordicin (22.64 μg / g DW) was obtained from elicited plants with carrageenan. The highest fresh weight of fruits (23.95 g), yield of fruits per plant (1305 g) and charantin content (58.38 μg / g DW) was obtained of elicited plants with brassinosteroid.

The results of our experiment showed that elicitation with etherel led to an increase in morphological and phytochemical traits including leaf area, fruit length, chlorophyll b, total chlorophyll, and total flavonoids. While the highest fruit yield, and Charantin accumulation was obtained from brassinosteroids stimulation treatment. Carrageenan was more effective on total phenol, antioxidant activity, and Momordicin than other treatments. Elicitation with carrageenan increased the amount of secondary metabolite of Momordicin by 182% compared to the control treatment and elicitation treatment with brassinosteroid increased the amount of secondary metabolite Charantin by 60% compared to the control, which confirms the effective role of these elicitors on increasing antidiabetic substances in this plant. According to the findings of this study, use of elicitor compounds such as etherel, carrageenan and brassinosteroid, is an important strategy to produce Karelā with high morphological and phytochemical yield.