Agronomic Performances and Nutritional Assessment of Three Sweet Potato Varieties (Ipomoea batatas (L) Lam.) Introduced in an Agro-ecological Zone of Groundnut Basin in Senegal

Abstract

Aims: To evaluate the agronomic and nutritional performances of three varieties of sweet potato (Kandee, Caromex and Gandiol1) cultivated for the first time in the agro-ecological zone of the groundnut basin in Senegal.
 Study Design: The experiment was arranged in Randomized Completely Block Design.
 Place and Duration of Study: The study was conducted during two growing seasons from April to August 2017 and from October 2018 to February 2019 in Sagna village (Kaffrine, Senegal).
 Methodology: The planting of the cuttings was done with a density of 0.3 x 1 m or 3333.3 cuttings ha-1. Drip irrigation was used and mineral fertilization with 15-15-15 was applied. In each elementary plot, 5 plants were checked monthly for growth and phytosanitary monitoring. The harvest took place at 145 days after planting. The yields and agro-morphological characteristics of the roots were determined as well as their nutritional value and the incidence of bio-aggressor attacks.
 Results: The success percentage of cuttings was 90.1, 90.5 and 88% for Kandee, Caromex and Gandiol1, respectively. The length development of sweet potato stems was variable between the 3 varieties. The Gandiol1 variety with stems longer than 1.6 m was very spread out contrary to Caromex whose average stem length did not exceed 0.5 m. The marketable tuber yields obtained were comparable between the varieties and were 21.5, 22.5 and 13.4 t ha-1 respectively for Kandee, Caromex and Gandiol1. The morphology of the tubers was different in shape (diameter and length) but also in flesh color. Kandee had orange flesh, rich in carotenoids (101.1 mg/kg; P<0.001), Caromex a cream color with carotenes of 43.2 mg kg-1 and Gandiol1 a white flesh. Caromex had the best proportion of dry matter (40.6%; P<0.001) compared to the other varieties. This amount of dry matter was correlated with the marketable root yield (r=0.54; P=0.04) and the carbohydrates amount (r = 0.52; P=0.05). Bio-aggressor incidence on tubers was lower for the Kandee variety (10.3%; P=0.01).
 Conclusion: Sweet potato varieties performed well in the agro-ecological conditions of the groundnut basin and showed comparable agronomic performance. The three varieties can be discriminated on the level of their nutritional quality, particularly on their β-carotene content.