EVALUATION OF HYBRID VIGOR IN COWPEA (VIGNA UNGUICULATA L.) UNDER DIFFERENT MOISTURE LEVELS

Cowpea (Vigna unguiculata L. Walp) is a major grain legume in sub-Saharan Africa, valued for its high protein content and ability to thrive in marginal environments. However, drought remains the most important constraint to its productivity in semi-arid regions such as northern Nigeria. This study evaluated hybrid vigor (heterosis) in selected cowpea genotypes under three moisture regimes (100%, 60%, and 30% field capacity) using a split-plot arrangement in a Randomized Complete Block Design with three replications at the Borno State University Research Farm during the 2024/2025 cropping season. Ten genotypes comprising six parental lines and four F1 hybrids were assessed for growth, yield, physiological traits and heterosis. Significant genotype × moisture level interactions were observed for most traits. Mid-parent heterosis (MPH) and better-parent heterosis (BPH) were positive and significant for grain yield, number of pods per plant, and 100-seed weight under all moisture regimes, with the highest heterosis recorded under severe stress (30% FC), indicating that hybrid vigor is maintained or even enhanced under drought. Certain hybrids consistently outperformed their better parent by more than 45% for grain yield under severe moisture stress. The study identified promising drought-tolerant hybrids suitable for the Sudan savanna ecology. The results underscore the potential of exploiting heterosis as a strategy for developing climate-resilient cowpea varieties for resource-poor farmers in drought-prone environments. Keywords: Cowpea, hybrid vigor, heterosis, moisture stress, drought tolerance, Sudan savanna