Águas salinas e combinações de adubação com NPK no cultivo de pinheira no segundo ciclo.

Abstract

In the semi-arid region of Northeastern Brazil there is the presence of water with high concentrations of salts used for irrigation, which causes alterations in the growth, physiology, and production of crops, being one of the main factors that limits the yield of plants. Thus, the practice of fertilization stands out in the management of plant production, by providing essential nutrients to crops and the possibility of minimizing the deleterious effects caused by salt stress. In this context, the objective of this research was to evaluate the physiology, production and post-harvest quality of pine fruit irrigated with different salinities, under different combinations of nitrogen, phosphorus and potassium fertilization in the second cycle of cultivation. The experiment was developed in a protected environment, with randomized block design, in a 2 x 8 factorial scheme. The treatments consisted of the combination of two levels of electrical conductivity of irrigation water - CEa (0.8 and 3.0 dS m-1 ) associated with eight fertilizer combinations with nitrogen, phosphorus and potassium (100: 100:100; 100:100:125; 100:125:100; 100:125:125; 125:100:100; 125:100:125; 125:125:100 and 125:125:125% of the recommended dose of N: P2O5:K2O), with three repetitions. Regarding the results, irrigation with water of 3.0 dS m-1 decreased the synthesis of chlorophyll a and total, carotenoids contents, total number of fruits, compromised the photochemical efficiency, fruit production, total number of seeds, average fruit weight, equatorial and polar diameter of the fruits of pine plants. The highest maximum fluorescence of pine irrigated with 3.0 dS m-1 water was obtained at 125:100:100% combination of N: P2O5:K2O of the recommended dosage. The highest ascorbic acid content under 0.8 dS m-1 with the 125:125:100% N: P2O5:K2O supply. In addition, fertilization with 125:125:100% N: P2O5:K2O caused higher soluble solids contents and ripening index regardless of the salt level. The pH of the pine fruit pulp increased under irrigation with water of 3.0 dS m-1.