ABSTRACT

This study was conducted to evaluate the response of cowpea cultivars to different August sowing dates in a rainforest agroecology and determine the best agronomic practices for maximizing productivity.

A field experiment was conducted at the Teaching and Research Farm, University of Benin, Nigeria, during the late cropping season (August–December 2024). The soil was classified as sandy, with low organic carbon (1.378%) and total nitrogen (0.07%), indicating poor fertility and moisture retention. The pH in water was 6.05, suggesting moderate acidity, which could influence nutrient solubility. A randomized complete block design (RCBD) was used, with four sowing dates (August 7, 14, 21, and 28) as treatments. Data on growth parameters, flowering dynamics, and yield components were collected, and statistical analysis was performed using ANOVA with LSD at a 5% probability level.

Results showed that sowing date significantly affected cowpea reproductive stages (p < 0.0001). Early sowing (August 7) resulted in prolonged vegetative growth (62 days to 50% flowering), whereas late sowing (August 28) led to a shortened vegetative phase (53 days to 50% flowering). Similarly, pod maturity ranged from 69 days (August 7) to 59 days (August 21). Cowpea sown on August 7 recorded the highest grain yield (32.1 g/plant) and stover yield (34.0 g/plant), while the lowest yield was observed in the August 28 sowing date (grain: 15.0 g/plant, stover: 13.0 g/plant) (p = 0.0014). The study concluded that sowing date significantly influence cowpea

growth, flowering dynamics, and yield performance in rainforest agroecologies. Early sowing (August 7) resulted in prolonged vegetative growth and the highest grain yield, while late sowing reduced productivity due to a shortened growth phase and increased exposure to adverse environmental conditions. It was recommended that farmers should adopt early-August sowing to optimize grain and biomass yield.