Evaluation of different sweet potato varieties for growth, quality and yield traits under chemical fertilizer and organic amendments in sandy ferralitic soils

Abstract

Taffouo Victor Désiré*, Nono Gilles Vivien and Simo Claude Department of Botany, Faculty of Sciences, University of Douala, 24157 Douala, Cameroon. Received 18 August, 2017; Accepted 10 October, 2017 Growth, quality and yield components of sweet potato ((Ipomoea batatas (L.) Lam. Var. Tib1, IRA1112 and Red tuber coat) were investigated under three fertilizer sources (inorganic-NPK (100 kg/ha), green manure (Eichhornia crassipes) or poultry manure at 12 t/ha, singly or in combination) with three replications. Application of E. crassipes and poultry manure fertilizers in combination significantly (P < 0.05) increased the shoot length, tuber yield, chlorophyll content and harvest index in all varieties. The highest plant dry weight (480.60 g/plant), shoot length (263.23 cm), number of leaves (75.33) and tuber yield (18.66 t/ha) harvested were found in Tib1 when plants were supplied with both E. crassipes and poultry manure; while the lowest plant dry weight (62.54 g/plant), shoot length (195.45 cm) and tuber yield (2.11 t/ha) were recorded in Red tuber coat when plants were enriched only with inorganic-NPK. Leaf protein content of sweet potato varieties was positively influenced by inorganic-NPK, E. crassipes and poultry manure, singly or in combined treatments compared to leaf lipid and carbohydrate contents. A combination of high-yielding sweet potato varieties (Tib1) and adequate use of E. crassipes and poultry manure, singly or in combination could enhance sweet potato growth performance in sandy ferralitic soils. Key words: Field performance, nutritional potential, soil amendments, fertilizer, Ipomoea batatas. INTRODUCTION