Microscopic Examination of Biosynthesis of Anthocyanins in Leaves of Vigna radiata under Saline Stress; a New Insight

The irrigation water used for the cultivation of crops contains soluble substances like Cl, SO₄, CO_3, and others, referred to as salts, necessary for plant growth. The salinity may recover soil texture while, on the other hand, it inhibits plant growth and reduces crop yields if in excesses. The current article aims to monitor the visual accumulation of anthocyanin in the leaves of plant Vigna radiata cultivated under salinity in a half-strength Hogland solution. Anthocyanins extracted from plants are generally used as natural colours in cosmetics, dyes, and food additives. The relationships between salt stress and anthocyanin content in leaves of Vigna radiata were investigated under a photo camera microscope. The experiment was conducted after 2 days of germination in the dark and then shifted into nutrient media viz 0, 15, 20, and 25 ppm NaCl. Visual monitoring revealed the reduction in plant growth directly related to the increase in salinity. The leaves were harvested after 15 days, washed, cleaned and subjected to monitored anthocyanin synthesis under a photo camera microscope. It was observed that the red and purple regions in leaves appeared under salinity and were found to increase as NaCl concentration increased. The colour of anthocyanins reveals the presence of flavonols, dihydro flavonols, and hydroxycinnamic acids. The highest anthocyanin content (red and purple regions in leaves) was observed under high salinity conditions (25 ppm). Microscopic evaluation of leaves recommended that more searches be undertaken to enhance anthocyanin contents under salinity in anthocyanins-rich fruits and vegetables that may be extracted for antioxidant, anti-inflammatory, pharmacological and other diet purposes.