Plant population and water application in maize-cowpea intercropping

Abstract

A line source sprinkler irrigation system was used to study the effect of different levels of water application in maize and cowpea in sole and intercropping systems under different plant populations. Maize and cowpea grain yields increased as the levels of water increased, with the highest  increments for maize. Intercropping had a detrimental effect on the yields of both maize and cowpea compared to sole cropping. Intercropped maize yields varied from 44% to 83% of the sole crop. The yields of intercropped cowpea decreased as the maize population increased. Maize response to plant population was determined by the available moisture. At 20,000plants/ha of sole maize reached its peak yields at 356 mm and dropped a little at the highest water level; on the contrary, yield at 40,000 and 60,000 plants/ha increased linearly as the water levels increased. The intercropped maize performance, as compared to intercropped cowpea, was better in higher water levels at all populations except under low population (10,000 plants/ha) when the proportional yield of cowpea was similar to maize yield. Land Equivalent Ratio index showed advantage for intercropping only for the combinations of cowpea with low population of maize with 200 mm of irrigated water or above.