Abstract
The response of white and red cultivar (cv) cocoyam (Xanthosoma sagittifolium (L.) Schott) minituber seeds to different rates of poultry manure (PM) and NPK (20:10:10) fertilizer was studied under field conditions in the 2017 cropping season on an experimental farm at Ngog Bibega, Mbankomo Sub-division, (outskirsts of Yaounde) Centre region, Cameroon. Treatment combinations comprising of three rates each of poultry manure (0, 20 and 30t ha -1 ) and NPK fertilizer (0, 120 and 150 kg ha -1 ) were factorized and fitted into a randomized complete block design with three replicates. Physico-chemical analysis of all treatment plots revealed clay loam textures and poultry manure treatment plots significantly (P<0.05) increased soil pH, organic content, total carbon and cation exchange capacity while NPK treatments significantly (p<0.05) increased available phosphorus compared to the control treatments. Poultry manure(30t ha -1 ) treatments significantly (P<0.05) enhanced plant height, leaf number and leaf area in both cultivars after 6 months of growth as compared to all other treatments. Under the same treatments of poultry manure (30t ha -1 ) the white cultivar plants recorded the most significant mean yield parameters after 9 months of growth. The average tuber number per plant (8), tuber weight (250g), tuber length (14cm) and tuber girth (18.5cm) compared to the red cultivar average yield parameters: tuber number per plant (5.7), tuber weight (124.7g), tuber length (8cm) and tuber girth (14.5cm). Biochemically the application of various treatments of poultry manure and NPK fertilizers significantly (P<0.05) influenced the changes observed in the secondary metabolites studied. Two months after planting, NPK (150kg ha -1 ) treatments showed the most significant phenolic content (1.22±0.13mg eq catechin.g -1 FW) and flavonoid content (1.08±0.16mg g -1 FW) in white cv cocoyam plants. After 6 months of growth, the poultry manure (30t ha -1 ) treatments recorded the most significant protein content (5.04±0.38mg eq BSA.g -1 FW) and peroxidase activity (4.89±1.36 UE min -1 ) in white cv cocoyam plants while red cv cocoyam plants had the most significant glucanase activity (9.33±1.17 mg eq glucose g -1 FW). NPK (150kg ha -1 ) treatments in white cv cocoyam plants recorded the most significant polyphenol oxidase activity (4.99±0.10 in D330 nm -1 min -1 UE -1 g -1 FW) 6 months after planting. Keywords: Xanthosoma sagittifolium L. Schott; Minitubers; cation exchange capacity; Poultry manure; NPK fertilizers; yield parameters and secondary metabolites. DOI : 10.7176/JBAH/9-20-05 Publication date :October 31 st 2019
Highlights
IntroductionCocoyam tubers and leaves are essentially rich in sugars, proteins, vitamins and mineral salts (Sefa & Sackey, 2004)
The growth and yield performance for the white cultivar cocoyam plants were significantly higher than those for the red cultivar cocoyam plants. These results are concordant with those obtained by Nzietchueng, 1985 who evaluated the production problems faced by different cocoyam (Xanthosoma) cultivars and showed that the white cultivar was more productive than the red cultivar
As observed from the results, it was evidenced that poultry manure (30 t ha-1) treatments significantly produced the highest means of traits assessed, while the control treatments of no poultry manure or no NPK fertilizer applied significantly produced the lowest means of the same traits over a 9 month growth and yield period in both cultivars.150 kg ha-1 NPK fertilizer treatments expressed the most significant means of traits among all the NPK fertilizer treatments in both cultivars
Summary
Cocoyam tubers and leaves are essentially rich in sugars, proteins, vitamins and mineral salts (Sefa & Sackey, 2004). It covers the food needs of more than 200 million persons in the tropical and subtropical regions and more than 400 million persons worldwide (Onokpise et al, 1999). It occupies the sixth position worldwide with an annual production of 0.45 million metric tonnes (FAO stat, 2006) and the second in Cameroon after cassava (Mannihot esculenta) in terms of tuber production. Annual production of cocoyam has since increased from 1,240,037 tons in 2005 to 2,000,000 tons (NPRT stat, 2013) with projections of 3000,000 tons by 2020
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