Asian Research Thesis Index

Abstract

Studies were conducted to evaluate the impact of plastic mulches viz. black, clear and bare soil in the modification of plant growing environments on three hot pepper hybrids namely Sky Red, Maha and Wonder King in poly/plastic tunnels during the year 2005-06 and 2006-07. Hot pepper hybrids and plastic mulches had significant effect on plant growth and yield attributes. By using clear plastic mulch intensive weed proliferation was problematic issue; however under black plastic mulch almost complete weed suppression was achieved which results in increased fruit yield than hot peppers grown under clear plastic mulch and bare soil (control). The pattern of antioxidant accumulation was envisaged in hot peppers harvested at different stages; immature green, mature green, color break, red ripe and dried fruit. Capsaicinoids had significant distribution in mature green stage while progressive accretion of carotenoids and ascorbic acid was observed at dried and red ripe stage of all hybrids, respectively. However, the pattern of total phenolic contents biosynthesis was found significant at immature green stage in Sky Red where as in Maha at color break stage and in case of Wonder King at red ripe stage. Aflatoxin contamination in hot pepper hybrids was investigated under various temperatures (20, 25 and 30°C) and packaging regimes (polyethylene and jute bags) during five months storage period. Aflatoxin detection under these conditions had lower levels than the existing regulatory limits ascribed by European Commission (EC No. 1881/2006) that is 10μg kg -1 for total aflatoxins. Aflatoxin contamination and microbial load was increased significantly with the increase in temperature and storage duration which was heavily infested when samples packed in jute bags and stored at 25 and 30°C respectively. Storage duration and temperature regimes had inverse relation on antioxidant quality of hot pepper ecotypes as well. Further attempts were made to decontaminate aflatoxin contaminated samples of hot pepper hybrids (from previous study) subjected to gamma radiation (2, 4 and 6 kGy) and its effect on antioxidant stability was again assessed after three month storage. Higher the irradiation dose, lower the concentration of carotenoids and ascorbic acid ascertained in hot pepper ecotypes; however, capsaicinoids and polyphenols rendered greater stability at higher irradiation dose during storage. Irradiated samples of hot peppers had 7% xireduction in aflatoxin contamination as compared to non-irradiated (control). Total fungal population had inverse relation with increasing radiation dose and complete inhibition was observed when irradiated at 6 kGy and no further fungal proliferation was seen during three months storage at ambient conditions.

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