Adubação orgânica e mineral na cultura da melancieira no semiárido paraibano terceira safra.

Abstract

In recent decades we have sought alternative production that seeks the sustainability of agrosystems, ensuring production in quantity and quality. To this end, new technological alternatives are needed to mainly meet the nutrient needs of plants, which are supplied through the use of industrialized inputs. With this comes the search for the use of renewable resources acquired in the production unit itself. The objective of this study was to evaluate the effect of the combined and isolated use of mineral and organic fertilizers on the watermelon crop. The experiment was conducted in an area located at the Federal University of Campina Grande (UFCG), Campus Pombal - PB, during the period from December 2015 to March 2016. The experimental design was in randomized blocks with four replicates arranged in a factorial scheme 3x5, where different concentrations of N, P and K nutrients (50, 100 and 150% of NPK recommendation for melancholy) were allocated to factor (A), and in factor (B) five proportions of organic and mineral fertilizer , 75/25, 50/50, 25/75 and 0/100). The NPK dose corresponding to 100% was 120 kg ha-1 for N, P and K. Gaseous changes, fruit dry mass, total yield, length, width, fruit firmness, titratable acidity, soluble solids and pH. The physiological evaluations (gas exchange) were performed at 45 days after transplanting (DAT) and the other variables analyzed at 68 DAT. The concentration of 50% of the NPK recommendation for the melancholy culture was the most efficient in increasing the physiological characteristics of photosynthesis and transpiration in the ratio of 100/0 and the concentration of 150% was the one that presented the best result in the proportion of 100 / 0 for stomatal conductance. For fruit production (kg / ha) and total dry weight of fruits (g) the concentration of 150% of NPK in the proportion of 0/100 presented the best values for both variables. Regarding the length and width of the fruit, the concentration of 150% of NPK in the proportion of 100/0 observed the best results, already for the variables of firmness, soluble solids, titratable acidity and pH the concentration of 150% of NPK in the proportion of 0/100.