Effect of Maize densities on the productivity of intercropped cowpea varieties in Limpopo Province

Abstract

Intercropping maize and cowpea are among the best cultivation practice to increase the crop yield per unit area. However, the great challenge faced by researchers is finding an appropriate combination of planting density and intercropping pattern to preserve cowpea production when maize population density is high under intercropping conditions. A field experiment was conducted to evaluate the effect of maize planting densities on the growth and yield of intercropped cowpea varieties. Study was conducted at the Aquaculture Research Unit, University of Limpopo during 2022/2023 growing season. Maize variety (PAN7469) was intercropped with two cowpea varieties (Brown mix and Dr Saunders) in a 2×2×2 factorial arrangement in a Randomized Complete Block Design (RCBD) with four replications. The experiment consisted of eight treatments from three factors: two cowpea varieties (Brown mix and Dr Saunders), two maize densities (24 700 and 37 000 plants/ha), and two cropping systems which were sole and intercropping. For cowpea, days to 50% flowering, physiological maturity, plant height, number of branches per plant, canopy width, leaf chlorophyll content, above ground dry matter, pod length, number of pods per plant, seeds per pod, hundred seed weight and grain yield were determined. The data for all measured parameters were subjected to the analysis of variance using Statistix 10.0 version. The analysis of variance revealed that the interaction of maize density and cowpea varieties significantly influenced all growth parameters and yield components of cowpea except above ground dry matter and number of seeds per pod. Cowpea grain yield had the mean range of 0.8 to 0.32 t/ha, and the sole crops produced the highest grain yield than intercropped cowpea. Planting Brown mix variety at 37 000 plants/ha maize gave significantly higher grain yield than planting Dr Saunders at both maize densities. Maize-cowpea intercropping had a Land Equivalent Ratio (LER) greater than one, which clearly showed high productivity and better utilization of growth factors in intercropping than sole cropping. Therefore, the results suggest that the maximum of 37 000 plants/ha maize is suitable for maize/cowpea intercropping and should be adopted by farmers due to biological efficient and economic benefits.