Effect of Rootstock-Scion Combinations on Drought Tolerance and Yield of Grafted Watermelon (Citrullus lanatus) in Kano State

Drought stress is a primary limitation on watermelon (Citrullus lanatus) production in the semi-arid agro-ecology of Kano State, and grafting onto drought-tolerant rootstocks has emerged as a promising strategy for improving crop resilience and water use efficiency. While grafting research on cucurbits has advanced internationally, evidence for optimal rootstock-scion combinations under Nigerian production conditions is limited. This study evaluates the effect of three rootstock genotypes, bottle gourd (Lagenaria siceraria), wild watermelon (Citrullus colocynthis), and pumpkin (Cucurbita maxima), on the drought tolerance, water use efficiency, and fruit yield of grafted watermelon under induced soil moisture deficit conditions in Kano State. A factorial experiment combining rootstock type and irrigation levels (100%, 75%, and 50% field capacity) was laid out in a split-plot design with three replications. Physiological drought response parameters including leaf water potential, stomatal conductance, and canopy temperature, as well as fruit yield and quality, were measured. Results indicate that watermelon grafted onto Citrullus colocynthis rootstock demonstrated superior drought tolerance and maintained the highest fruit yield under 50% field capacity. The study recommends this rootstock-scion combination for commercial watermelon production under water-limited conditions in North West Nigeria. Keywords: grafting, watermelon, drought tolerance, rootstock, Kano State