Effect of Spacing and Plant Population on the Yield of Cowpea in Sokoto State

This study examines the effect of inter-row and intra-row spacing on plant population density and grain yield of cowpea in Sokoto State, North West Nigeria. Cowpea is a critical protein-rich legume crop in the semi-arid North West, providing food security and income for farming households while fixing atmospheric nitrogen that benefits subsequent crops. Optimum plant population is essential for maximising yield through efficient canopy light interception and minimising intra-specific competition. This study establishes a randomised complete block design experiment at the Usmanu Danfodiyo University Sokoto Teaching and Research Farm, testing four inter-row by intra-row spacing combinations: 75x20, 75x30, 60x20, and 60x30 centimetres. Plant population ranges from 44,000 to 83,000 plants per hectare across treatments. Growth parameters including canopy cover, plant height, number of pods per plant, and grain yield are measured at key growth stages. Findings reveal that the 75x20 centimetre spacing producing 66,000 plants per hectare achieves the highest grain yield of 1.8 tonnes per hectare, offering the best balance between individual plant productivity and canopy coverage. Wider spacing at 75x30 produces fewer pods per unit area despite more pods per plant. Narrower inter-row spacing reduces individual plant branching. The study concludes that 75x20 centimetre spacing is the optimal plant population for cowpea in Sokoto State conditions. It recommends this spacing in extension recommendations for the state's cowpea-producing communities.

Keywords: cowpea, plant spacing, plant population, grain yield, Sokoto State.