An improved knowledge of effects of density of plants on yield of watermelon (Citrullus lantus) would help efforts to determine optical density and to anticipate the economic impact across different ecological zones of Nigeria. The Objective of this research was to determine the responses of two varieties of watermelon in plot design. The study was conducted in Ilesha (6008N.4001E) (7024N,3054E)and Dogondawa (100 361N,70 27 E) to represent the forest, derived Savanna and Guinea Savanna ecological zones of Nigeria, respectively.
Watermelon varieties responded differently to density of planting with respect to fruit yield. Sugar baby producing higher yields in Ilesha while Kaolack produced greater yield in Dogondawa. Forest ecology had the lowest fruit yield when compared with Savanna ecologies. Marked differences existed among the ecologies in water melon fruit response and density of planting with Ilesha having the highest responses at 11,111 plants ha-1, while highest yield was obtained at 14,815 plants ha-1 for Ibadan and Dogondawa. The average weight of fruits decreased with density of planting. This results supports the hypothesis that increasing planting densities could increase efficiency of commercial production of watermelon.