Evaluating the Effect of Fertilizers on Physiological Growth, Chemical, Bioactive Components and Secondary Metabolites in Vigna Unguiculata (L.)

Objective: Vigna unguiculatata (L.) (Cowpea) is an African indigenous protein-dense crop that most sub-Saharan Africans rely on for food and nutrition security. Material and Methods: The current study assessed the effect of different levels of poultry manure fertilizer (10, 30, 60 and 90 kg F/ha) and nitrogen fertilizer (30, 45, 60 and 90 kg N/ha) on the growth, yield, mineral composition, bioactive compounds and secondary metabolites in the legume crop Vigna unguiculata (L.). At the end of 15 weeks, 90 kg F/ha and 45 kg N/ha enhanced the growth, yield, mineral composition, production of ascorbic acid, total phenolic and FRAP assay, this informed our decision for the selection of this treatments (45kgN/ha, 90kgF/ha and 0kg/ha control) for further analyses of secondary metabolites. Results: Poultry manure and nitrogen fertilizer improved the mineral compositions of cowpea leaves, and different accumulation trends were noted depending on different application levels, with poultry manure responding well. Conclusion: Thus, the application of organic poultry manure at 90 kg F/ha for cowpea cultivation should potentially be recommended in the Mpumalanga Province.