Effects of harvesting stages on yield and nutritional quality of African eggplant (Solanum aethiopicum L.) fruits

Abstract, Journal of Applied Biosciences, 2014

Objective: Farmers often harvest African eggplant (Solanum Aethiopicum L.) fruits at different stages of fruit maturity. The influence of these harvesting practices on fruit productivity and nutritional quality is not known. This study was conducted to determine the effect of harvesting stages on yield and nutritional quality of African eggplant varieties. Methodology and results: The experiment was laid out in a split plot arrangement in a complete randomized block design with three replications. Three African eggplant varieties (Tengeru white, AB2 and Manyire green) and three harvesting stages (1, 2 and 3) were used as main plot factor and sub plot factor, respectively. Harvesting stage 1 (immature fruits) was characterized by fruits with non-shiny peel, harvesting stage 2 (mature fruits) was characterized by fruits with shinny peel and harvesting stage 3 (overmature fruits) was characterized by fruits with yellow coloration at the bottom. Fruit yield was assessed based on number and weight of fruits per plant while fruit nutritional quality was assessed in the laboratory based on carbohydrate, fibres, calcium, potassium, magnesium, phosphorus, iron, β-carotene and ascorbic acid contents. The collected data were subjected to analysis of variance using MSTATC statistical software. Treatments mean separation was conducted based on Student-Newman Keuls at P < 5 %. Results showed that yield in number of fruits per hectare decreased while yield in metric tons per hectare increased with fruit development stages. Varieties Tengeru white and AB2 had the highest yields based on metric tons at harvesting stage 2 while Manyire green had the highest yield at harvesting stage 3. Carbohydrate and fibre contents increased while ascorbic acid, β-carotene and most minerals decreased with fruit development stages. Conclusion and application of results: This study recommends harvesting immature fruits for high vitamin and mineral contents and delayed harvesting for the highest yield. As yield and nutritional quality trends vary with varieties, further studies are required to determine the effect of harvesting stages on yield and nutritional quality of different varieties of African eggplant.

Key words: Yield, Nutritional quality, Harvesting stages, Africa eggplant