NUTRIENT COMPOSITION, ANTIOXIDANT COMPONENTS AND ASCORBIC ACID CONTENT RESPONSE OF PEPPER FRUIT (Capsicum annuum L.) CULTIVARS GROWN UNDER SALT STRESS

Abstract

Purpose: Salinity stress occurs due to the accumulation of high levels of salts in soil, which ultimately leads to the impairment of plant growth and crop loss. Stress tolerance-inducing compounds have a remarkable ability to improve growth and minimize the effects of salinity stress without negatively affecting the environment by controlling the physiological and molecular activities in plants. Methodology: The pots were arranged in a complete randomized design with one plant per pot and four replicates per treatment and carried out in 2017 and 2018 to study the influence of four levels of NaCl (0, 50, 100 and 200 mM) on the antioxidant, ascorbic acid, organic and inorganic compounds of three pepper fruits cultivars (‘Granada’, ‘Goliath’ and ‘Nobili’) at mature stage. Findings: The results obtained showed that salinity decreased the mineral content (Ca, K, Zn, Mg, Mn, Iron, S and P), relative water content, and agromorphological parameters of pepper fruit. This decrease was accompanied by a significant increase of Na, soluble proteins, proline content, soluble sugar (fructose, glucose) and antioxidants, including total phenolics and flavonoids, and reduced ascorbic acid and β-carotene content. It could be an indicator of salinity tolerance which explains the maintenance of a good water status among the studied plants. However, a varietal difference response to salt stress was observed between the studied varieties. Indeed, the varieties Granada and Nobili are characterized by their vigour in absence as in the presence of salt. Under the studied salinity level there was an enhancement of health-promoting compounds (phenolic compounds, flavonoids, β-carotene and ascorbic acid) synthesis in pepper fruits, with signifcant changes in other quality parameters. Unique contribution to theory, practice and policy: It is concluded that varieties ‘Granada’ and ‘Nobili’ is more tolerant to salinity compared to the variety ‘Goliath’. Hence, they have a significant role to play in agriculture, food, and economy.