Effect of harvesting time on root yield and nutritional composition of orange-fleshed sweet potato [Ipomoea batatas (L.) Lam] varieties in East Hararghe

Abstract

In eastern Ethiopia, sweet potato is a vital food and nutrition security crop; moreover, orange-fleshed sweet potato (OFSP) varieties are rich in beta-carotene content and have the potential to alleviate chronic Vitamin A malnutrition in the region. However, the unavailability of adaptable varieties and lack of information on production and post-harvest handling practices have limited its production and utilization in eastern Ethiopia. The research was conducted to identify the proper harvesting stage of OFSP varieties for optimum yield and nutritional compositions at Rare and Babile research stations of Haramaya University during the main rainy season of 2022. Three varieties (Alamura, Kabode, and Bakule) and four harvesting periods (120, 150, 180, and 210 days after planting (DAP) in factorial combinations were evaluated in randomized complete block design with three replications. Data were collected for growth, yield, and physicochemical composition-related parameters. Combined analysis of variance revealed the interaction effect of harvesting time and varieties had a significant (p < 0.05) effect on yield, yield-related parameters, and physicochemical components. Alamura variety produced comparable above-ground biomass (28.99 t ha−1) and the highest marketable root yield of 36.40 t ha−1 at 150 DAP, with dry matter content of 33.01 and 30.58 % at 150 and 120 DAP, respectively. Harvesting Alamura at 150 DAP also had the highest ꞵ-carotene, zinc, and iron contents of 11809 μg/100 g, 3.79, and 14.47 mg/100 g, respectively. It was concluded that growing the Alamura variety and harvesting at 150 DAP was better for obtaining higher root yield with good nutritional compositions in the study area.