Yield performance of cowpea varieties (Vigna unguiculata (L.) Walp) under varying plant populations and phosphorus fertilizer rates in Nigerian savanna zone

Abstract

Two field trials were conducted during the 2023 rainy season in Dutsin-Ma and Funtua to assess the yield performance of cowpea varieties (Vigna unguiculata (L.) Walp) as influenced by plant population and phosphorus fertilizer rates in the savanna zone of Nigeria. The treatments consisted of a factorial combination of three varieties (SAMPEA 20T, SAMPEA 19 and ZAFA), three plant populations (22,267, 26,667 and 33,333 plants ha^-1) and three phosphorus rates (30, 60 and 90 P2O5 kg ha^-1). A Randomized Complete Block Design (RCBD) was used with three replications. The varietal effect significantly (P<0.05) increased cowpea yield and yield components. SAMPEA 19 demonstrated superior grain yield ha^-1 performance (1766kg) compared to ZAFA (1671kg) and SAMPEA (1514kg) in Dutsin-Ma, while ZAFA yielded superior (1915kg) to SAMPEA 19(1856kg) and SAMPEA 20T(1782kg) in Funtua. The plant population of 33,333 cowpea plants ha^-1 produced significantly higher grain yield ha^-1 (1747kg) than that of plant population 26,667(1603kg) and 22,267(1600kg) in Dutsin-Ma, while plant population of 26,667 gave significantly higher grain yield ha^-1 (2016kg) than 33,333(1782kg) and 22,267 (1755kg) in Funtua. Applying phosphorus fertilizer significantly (P<0.05) increased cowpea yield and yield components. Applying 30 P2O5 kg ha^-1 produced significantly higher grain yield (1880 kg ha^-1) than 1547 and 1524 kg ha^-1 for 60 and 90kg P2O5 ha^-1 in Dutsin-Ma, respectively, and higher grain yield (2051 kg ha^-1) than 1802 and 1700 kg ha^-1 for 60 and 90kg P₂O₅ ha^-1 in Funtua, respectively. Applying 30 kg P₂O₅ ha^-1 is the most suitable rate for cowpea production in both locations.