Two field experiments were conducted in Borborema, State of São Paulo, from periods of October to December of the 2001 and February to April of 2002, with the objective of evaluate the yield of watermelon (Tide hybrid) (Citrullus lanatus (Thumb.) Matsum. & Nakai) in function of sources and doses of potassium. The experimental design was a randomized complete block, with three replications, in a 3 x 4 factorial scheme, being evaluated sources: potassium chloride, nitrate and sulphate and doses: 50, 100, 200 and 300 kg K2O ha-1. The average weight of fruits, number of fruits and production per plant and yield were evaluated. The biggest number of fruits for plant was achieved with 190 and 300 K2O ha-1 of KNO3 and KCl, respectively. The weight of fruit differed among sources only in the second experiment, where KCl provided greater weight. Maximum yield were obtained with doses of 132, 193 e 205 kg K2O ha-1, respectively from K2SO4, KNO3 e KCl. In the experiment from October to December of 2001, were obtained the greatest average weight, production of fruits per plant and yield, while the biggest number of fruits per plant was achieved in the experiment of February to April of 2002.
Citrullus lanatus; plant nutrition; potassium fertilizers
