Field Performance of Xanthosoma sagittifolium L. Schott Minitubers Grown Under the Influence of Poultry Manure and NPK Fertilizers: Changes in Content of Some Secondary Metabolites

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