Fontes de nitrogênio e potássio aplicados via fertirrigação na cultura do tomate | Sources of Nitrogen and Potassium applied by fertigation in tomato

anglais. This work was carried out at EPAGRI - Experimental Station of Caçador, SC, to evaluate the production of tomatoes as a function of sources of nitrogen (N) and potassium (K) applied by fertigation. The experimental design was randomized blocks, with four replications and 8 and 10 treatments in the growing seasons 2007/08 and 2008/09, respectively. Leaves were analyzed for the nutrients N, P, K, Ca, Mg, Fe, Zn, Cu, Mn and B. The total and the marketable production was obtained by classifying the fruits into extra AA, extra A and unmarketable. In both crops, the mean total production was close to 100 t.ha-1, independent of the source of N and K used. This allows to choose the source according to their preparation and application by fertigation, and according to the cost per unit of nutrient applied. Visual symptoms of deficiency or toxicity were not observed when the leaf content of a nutrient was below or above the normal range of concentration.

portugais. Resumo: O trabalho foi realizado na Epagri/Estação Experimental de Caçador com o objetivo de avaliar o efeito de fontes de nitrogênio (N) e potássio (K) aplicados via fertirrigação sobre a produção de tomate de crescimento indeterminado. O delineamento experimental foi blocos ao acaso, com quatro repetições, sendo oito e dez tratamentos nas safras 2007/08 e 2008/09 respectivamente. Determinaram-se os teores foliares de N, P, K, Ca, Mg, Fe, Zn, Cu, Mn e B na folha diagnóstica. Na colheita, avaliou-se a produtividade total e comercial classificando os frutos em extra AA, extra A e descarte. As fontes de nutrientes utilizadas nas duas safras não influenciaram a produtividade do tomate, que foi próxima de 100t.ha-1. Isso permiteescolher a fonte segundo sua praticidade de preparo e aplicação via fertirrigação e de acordo com o custo por unidade de nutriente aplicado. Para todos os teores foliares de nutrientes que estavam abaixo ou acima da faixa recomendada para a cultura não se observaram sintomas de deficiência ou toxidez nas plantas.Abstract: This work was carried out at EPAGRI - Experimental Station of Caçador, SC, to evaluate the production of tomatoes as a function of sources of nitrogen (N) and potassium (K) applied by fertigation. The experimental design was randomized blocks, with four replications and 8 and 10 treatments in the growing seasons 2007/08 and 2008/09, respectively. Leaves were analyzed for  the nutrients N, P, K, Ca, Mg, Fe, Zn, Cu, Mn and B. The total and the marketable production was obtained by classifying the fruits into  extra AA, extra A and unmarketable. In both crops, the mean total production was close to  100 t ha-1, independent of the source of N and K used. This allows to choose the source according to their preparation and application by fertigation, and according to the cost per unit of nutrient applied. Visual symptoms of deficiency or toxicity were not observed when the leaf content of a nutrient was  below or above the normal range of concentration.