Crescimento e produção do tomateiro em sistemas de cultivo a campo, hidropônico e fertirrigado, sob diferentes doses de nitrogênio e potássio

Abstract

This work intended to evaluate the patterns of accumulation of biomass and nutrients, and the fruit yield and quality, of tomato genotypes in the field, hydroponics, and fertirrigated cultivation systems, under different levels of nitrogen and potassium. Experiments were carried out in 2005, 2006 and 2007, each year comprising different cultivation systems. In 2005 the Saladinha hybrid was used. In the field, three N levels (100, 150 and 200 kg N ha-1) and three K levels (150, 200 e 250 kg K ha-1) were applied in a 3x3 factorial design. In hydroponics, four nutrient solutions were tested, with ionic strength of 50% and 75% and N:K ratios of 1:1.5 and 1:2. In fertirrigation, the N:K ratios of 200:300, 200:400, 300:450 and 300:600 (in kg ha-1) were tested. In the field, the fruit diameter was lower at the levels 100 kg N ha-1 and 250 kg K ha-1. In hydroponics, the N:K ratio 1:1.5 increased the accumulation of biomass and nutrients in shoots. In fertirrigation, shoot N accumulation was higher at higher K levels, but commercial fruit yield was lower at the N:K ratio 300:600. Fruit yield and number were higher in protected cultivation. In 2006 two-week spaced samplings were done to obtain the rates of growth and nutrient accumulation of the Saladinha hybrid. The following N:K ratios were tested: 150:150, 150:225 and 150:300 in the field, 1:1.5 and 1:2 (at 50% of the ionic strength) in hydroponics, and 200:300 and 200:400 in fertirrigation. In the field, higher K levels stimulated the growth and nutrient accumulation at vegetative stages, but accumulation of biomass and nutrient were similar among treatments at the end of the growth. The level of 300 kg K ha-1 increased the diameter of commercial fruits. In hydroponics, maximal rates of accumulation of biomass and nutrients occurred at 45 DAT at N:K ratio 1:1.5, and at 60 DAT at N:K ratio 1:2.0, with higher values at latter ratio. In fertirrigation, the level of 400 kg K ha-1 increased the rates of growth and nutrient accumulation, and the yield and number of commercial fruits. A higher fruit yield and number was observed in hydroponics, whereas a larger diameter of commercial fruits was observed in the field. In 2006 and 2007, the proportion of commercial fruits was reduced by Neoleucinodes elegantalis in the field, the rot apical and the open locule in protected cultivation. In 2007, a 4x2 factorial was used, combining four genotypes and two N:K ratios (1:1.5 and 1:2 in hydroponics, and 1:2 and 1:3 in fertirrigation). In hydroponics, the N:K ratio 1:2 increased the mass and diameter of commercial fruits. In fertirrigation, the higher K level increased the fruit number of cherry cultivars. Fruit yield and total soluble solids were higher in hydroponics. Levels higher than 300 kg K ha-1 were not adequate to fruit yield and quality in the field. The N:K ratio of 1:2 is efficient to improve fruit quality in hydroponics. The level of 400 kg K ha-1 is adequate to fertirrigation cultivation.