Effect of potassium and calcium upon the yield and fruit quality of Cucumis melo.

The aim of this work was to study the effect of potassium and calcium in combination with nitrogen upon the yield and fruit quality of outdoor-grown melon (Cucumis melo L.). Two experiments were simultaneously performed through the use of two cultivars: ‘Honey Dew Green Flesh’ (Inodorus group) and ‘Sivan’ (Charentais group). A completely randomized experimental design was used with nine treatments resulting in a factorial arrangement of 3 x 3 due to the use of three doses of K and three doses of Ca. Doses were administered through fertigation with the injection of the fertilizers into a drip irrigation system, expressed as follows in relation to N: N:K (1.8:1.0 – 1.0:1.0 – 0.0:1.0) and Ca:N (2.0:1.0 – 1.0:1.0 – 0.0:1.0). Fertilization with nitrogen and phosphorus was the same in all treatments, through the application of an equivalent of 160 kg ha-1of N and 45 kg ha-1 of P. Yield (Mg ha-1) was measured as well as fruit quality attributes: firmness (kg); pulp or mesocarp thickness (mm) and rind thickness (mm); and total soluble solids (%). Differences were observed between the two varieties. The application of K showed the greatest effect on the quality and yield of the harvested fruit. However, this effect was not observed with Ca.