Abstract
Bell pepper, a non-climacteric fruit, is a very important economic product in most parts of the world. It is cultivated for its high carotenoid and Vitamin A and C content. There is currently a worldwide trend for the consumption of organically produced fruit and vegetables, because of the perception that it is of superior quality than conventionally produced products. The objective of this study is to compare the yield and postharvest quality of bell peppers grown with conventional and organic hydroponics. In this study, a 10% Bokashi (mixed with inert medium) compost was identified as suitable to supply nutrients in the organic hydroponic system for comparison to a conventional hydroponic system. The results indicated that plants grown with the Bokashi hydroponic system were shorter, had fewer and smaller leaves and produced 67% less fruit. Bell pepper plants grown by conventional hydroponics had a greater photosynthetic efficiency and productivity than those grown in the organic Bokashi hydroponics medium. It was noted that the Rubisco levels in the leaves of the organic Bokashi plants were higher, possibly because of mineral and salt stress. The efficiency of Photosystem II (PS II) , as measured by Quantum yield (QY), was higher in plants grown by conventional hydroponics and that the QY of PS II appeared to be the determining factor in photosynthetic productivity. It was also noted that Bokashi plants are under stress, due to the higher levels of lipid peroxidation that occurred much earlier in the development of the leaf in Bokashi grown plants than in plants grown with conventional hydroponics. Bokashi grown bell peppers also had a lower ability to scavenge ROS than bell peppers grown with conventional hydroponics, because the activity of SOD was significantly lower. The yield of bell peppers grown with Bokashi hydroponics was much lower and the fruit of an inferior quality compared to peppers grown with conventional hydroponics. The quality of bell peppers grown by conventional hydroponics was, in almost all aspects measured in this study, markedly better than that of bell peppers grown with Bokashi hydroponics throughout the postharvest storage period. The results of this study show conclusively that the peppers grown with conventional hydroponics produces better yield and postharvest quality product than Bokashi hydroponics.
Ph.D. (Botany)