Effect of different doses, application forms and sources of P in the conservation of seedless watermelon

ABSTRACT

The effect of doses, sources and application forms of P was evaluated for the conservation of seedless watermelon. With this purpose we planted the watermelon cv. Style. Treatments consisted of two doses of P (80 and 289 kg/ha P₂O₅) in two application forms (foundation and cover), using triple superphosphate on the foundation, and monoammonium phosphate (MAP) on coverage. Moreover, an additional treatment was evaluated, using the highest dose (289 kg/ha P₂O₅) splitted with MAP in the foundation and cover, totalling five treatments. In the lab, a complete randomized factorial research was installed, in a factorial 5x5, with five phosphate fertilizations and five fruit storage periods (0, 14, 21, 28 and 35 days after harvest), with four replications. A sample of eight fruits was evaluated at time zero and the other fruits were stored at a temperature of 9±2°C and 85±2% RH, remaining for 7, 14, 21 and 28 days and, additional seven days at a temperature of 23±2°C and 60±2% RH. We evaluated the fruit mass, length, diameter, pulp thickness, shape, weight loss (PM), pulp firmness (FP), soluble solids (SS), titratable acidity (AT), soluble sugars (AS), relationship SS/AT and lycopene. Fertilization (doses, application form and P sources) did not affect weight, length, diameter, pulp thickness, fruit shape, mass loss, firmness and fruit lycopene content. However, there was interaction between the factors fertilization and storage for AS and SS/AT ratio. There were increases in PM and decreases in the contents of SS, AS, AT and lycopene on fruits during storage. However, phosphorus fertilization on the lowest dose (80 kg/ha), applied via foundation, resulted in better results in seedless watermelon post-harvest conservation, maintaining higher levels of AS and SS/AT on pulp up to 35 days of storage.

Keywords:
Citrullus lanatus; fertilization; postharvest