Podridão apical e produtividade do tomateiro em função dos teores de cálcio e amônio

Abstract

The blossom-end rot of tomato is characterized by the appearance of a necrotic tissue in the distal part of the fruit. This disorder is not caused directly by the calcium deficiency, but it results from the ex-pression of some genes in stress conditions. Interactions between temperature, water availability, high saline or ammonium concentration, etc., control the appearance of the blossom-end rot in the fruits. The aim of this pa-per was to evaluate the influence calcium and ammonium on the productivity and blossom-end of tomatoesgrown hydroponically. The experiment was carried out in the green house of the Department of Agronomy of the Federal Rural University of Pernambuco, and consisted of factorial arrangement between six levels of cal-cium and two levels of ammonium in the nutrient solution (6 x 2), with six replications in experimental design of randomized blocks. Calcium treatments were the concentrations of 120, 140, 170, 200, 240 and 280 mg L-1, and ammonium treatments were the absence of this cation in the nutrient solution and the addition of 28.4 mg L-1, corresponding to 15% of total-N of the nutrient solution. The blossom-end rot, productivity, fruit diameter and number of fruits were evaluated. The data were submitted to the analysis of the variance and regression. The calcium addition caused a reduction in the tomato productivity, and the treatments with ammonium caused a lesser incidence of blossom-end rot.