Photosynthesis and production of West Indian cherry irrigated with saline waters under nitrogen/potassium fertilization

Resumo

Fertilization management is a technique that has been studied for the mitigation of salt stress in plants. In this perspective, this work aimed to evaluate the effects of combinations of potassium and nitrogen fertilization on the photosynthetic pigments, photosynthetic efficiency, and production of the West Indian cherry irrigated with waters of different salinities, between 420 and 550 days after transplanting. The experiment was conducted in an open field at the Center of Sciences and Agrifood Technology of the Federal University of Campina Grande, using 60 L lysimeters, in a randomized block design with a 5 x 4 factorial scheme, corresponding to five salinity levels of the irrigation water – ECw (0.3; 1.3; 2.3; 3.3, and 4.3 dS m-1) and four combinations of nitrogen and potassium fertilization (C1 = 70% N + 50% K2O; C2 = 100% N + 75% K2O; C3 = 130% N + 100% K2O, and C4 = 160% N + 125% K2O) of the dose recommended for the West Indian cherry, with three replications and one plant per plot. The cv. Flor Branca was studied through its grafting on a rootstock of the cv. Junco. The irrigation with ECw above 0.3 dS m-1 reduced the contents of chlorophyll a and b in the leaves, the photochemical efficiency, CO2 assimilation rate, instantaneous carboxylation efficiency, instantaneous water-use efficiency, and the number of fruits per plant. The combined fertilization with 70% of N + 50% of K2O increased the photosynthetic pigments, photosynthesis, and the number of fruits per plant, as well as mitigated the deleterious effects of water salinity on the production per plant up to the ECw of 2.3 dS m-1, which revealed to be the most adequate combination for West Indian cherry fertilization.