Vol. 7, Issue 11, Part I (2025)

Chili pepper production in the Guinea Savannah agro-ecological zone of Ghana is predominantly rainfed, making it highly susceptible to irregular rainfall patterns and low soil fertility. To mitigate these challenges and enhance productivity, the use of supplementary irrigation (SI) and recommended fertilizer application has been well-known as a potential strategy. This study aimed to evaluate the growth and yield performance of chili pepper under SI compared to rainfed conditions cultivated under different fertilizer rates. A 4 × 2 factorial experiment was conducted at the WACWISA experimental site located within the University for Development Studies, Nyankpala Campus, set up in a Randomized Complete Block Design (RCBD) with 3 replications. Treatments included four fertilizer levels (0, 100, 150, and 200 kg/ha) and two water regimes: rainfed and supplementary irrigation. Growth and yield parameters were collected and analyzed using ANOVA. Results revealed that supplementary irrigation combined with the highest fertilizer rate (200 kg/ha) produced the tallest plants at all observed intervals (2, 4, 6, and 8 weeks after transplanting), while rainfed plots without fertilizer recorded the lowest growth. SI also promoted a higher number of leaves, with 29.8 at 2 weeks after transplanting (WAT) and 48.3 at 4 WAT, compared to rainfed plots which recorded the lowest. Similarly, applying 200 kg/ha NPK resulted in the highest leaf number (47.5) at 4 WAT compared to 26 in control plots. The highest leaf area index (LAI) and chlorophyll content (69.50 SPAD) were also observed under SI. The interaction of SI and 200 kg/ha NPK produced the greatest biomass and highest yield (3.51 tons/ha), while rainfed conditions without fertilizer had the least (1.50 tons/ha). These findings demonstrate that supplementary irrigation, when combined with 200 kg/ha NPK fertilizer, significantly improves the performance of chili pepper in Northern Ghana.