Antioxidant Content and Quality of Fruits as Affected by Nigari, an Effluent of Salt Industries, and Fruit Ages of Sweet Pepper (Capsicum annuum L.)

Nigari, an effluent of salt industries, is less expensive fertilizer. Without testing its effect on bioactive substances, it may not be suitable for fertilizer. Greenhouse trials were conducted over two years to evaluate antioxidant content, fruit quality, yield, and mineral contents in fruits and leaves of sweet pepper ‘Papri new-E-red’ by application of three nigari concentrations at 0, 2 and 4 mL L-1 and additional N P K to equal the standard. Capsaicin, ?-carotene, ascorbic acid, fruit quality attributes, and fruit mineral compositions were evaluated at five different ages of fruits at 25 Days after fruit set (DFS), 35 DFS, 45 DFS, 55 DFS, and 65 DFS. Results revealed that capsaicin, ?-carotene, ascorbic acid, fruit quality, and mineral contents in fruits and leaves of sweet pepper increased with increasing rate of nigari compared to the control. Furthermore, capsaicin, and ?-carotene increased linearly with the advancement of fruit ages, but not ascorbic acid. Exceptionally, ascorbic acid increased until the turning of fruit maturity at 45 DFS and after that decreased drastically. Total soluble solid (oBrix) and titratable acidity (TA) were higher at 45 DFS, although an increasing trend was found for most of the mineral contents with maturing fruits. We concluded that a higher amount of antioxidant and improved fruit quality with higher yield and moderate mineral contents in fruits could be achieved by application of 2 mL L-1 nigari to sweet pepper in soilless culture. We can also suggest harvesting sweet pepper fruits between 45 to 55 DFS.