Nitrogen and potassium concentration in the nutrients solution for the production of tomato (Solanum lycopersicum)

Abstract

This study viewed to determine the effects of N and K concentrations in the nutrients solution on the productivity and fruit quality of tomato plants growing in a hydroponic medium. The experiment was carried out from January through April of 2011, in Jaboticabal, São Paulo, Brazil. The experiment was divided in two phasesthe first took place during the vegetative development of the plants and it consisted of the doses of N of 137.5, 192.5, 247.5, and 302.5 mg L -1 , keeping K concentration at 275 mg L -1 . In the second phase, during plant reproductive growth, the treatments consisted of the K doses of 137.5, 206.25, and 275 mg L -1 and the N dose which yielded the best results during the previous phase. At the end of the vegetative phase, leaf N content, first raceme height, internode length, and stem diameter were determined, and it was verified to have no significant effect of treatments upon the characteristics, and therefore considered the lowest N rate (135.5 mg L -1 ) as most appropriate. At the reproductive phase, increasing doses of N caused yield reductions of clusters 1 and 2. As to K concentrations, the largest yield of cluster 2 resulted from the concentration of 202.5 mg L -1 . The largest fruit yield resulted from the N and K concentrations of 177.2 and 188.7 mg L -1 respectively, this means N:K relation of 1:1.1. The soluble solids content of fruits from clusters 1 and 2 was not influenced by variations in N and K concentrations.