Relação entre adubação nitrogenada e com silicato de cálcio na severidade do Talo-Oco e da Murcha-de-Fusário do tomateiro

Abstract

Tomato crop is submitted to numerous phytosanitary issues including diseases caused by common soil-borne pathogens such as fusarium wilt, caused by Fusarium oxysporum f. sp. lycopersici, and Soft rot, caused by Pectobacterium carotovorum subsp. carotovorum. To control these diseases is a challenge and it is aggravated by these pathogens survival mechanisms that extends the infectious period. This study aimed to: a) investigate the relationship between nutritional imbalance (excessive fertilization) and severity of diseases caused by soil-borne pathogens in Nova Friburgo-RJ Region; b) evaluate the effect of nitrogen fertilizers, source and dose, on plant development and disease severity; c) investigate the relationship between silicon and tomato response to fusarium wilt and Soft-rot. For this purpose, soil and plant samples were collected in the Barracão dos Mendes Microbasin, these samples were submitted to disease diagnosis and chemical analysis. In a greenhouse, at UFRRJ, two trials were carried out with Débora Plus cultivar, one testing the effect of N doses (0, 400 and 800 Kg ha-1) using urea as a source and the other testing silicon and its effects on plant development and Soft-rot. Two more tests were made with two cultivars (Carina and Serato), different N sources (urea and Super N) and doses (400 and 800 Kg ha-1), plus a control and, a trial testing the application of Silicon effects, evaluating its effects on plant development and fusarium wilt. It was observed the presence of Soft rot in 25% of the samples and 33% of the plants with symptoms of wilting or medular rot. There was a correlation between the occurrence of the disease and the N levels in the plants, which was confirmed in the greenhouse trial. Silicon did not affect the Soft-rot severity. The effect of Nitrogen and silicon on fusarium wilt was variable, however, plants showed better vegetative growth when fertilized with a higher dose and Si application.