Nitrogen and potassium nutrition differentially affect tomato biomass and growth

We evaluated the effect of nitrogen and potassium nutrition on phenological stages on the vegetative biomass production and growth of tomato cultivated hydroponically. Nitrogen concentrations of 10, 12, 14, and 16molcm-3 in the vegetative stage were evaluated, while potassium concentrations of 5, 7, 9, 11, and 13molcm-3 were evaluated for the reproductive stage. In the vegetative stage, the addition of N caused significant differences in the vegetation dry biomass (VDB), with the largest responses observed at concentrations of 14 and 16molcm-3. For the reproductive stage, a significant response was only observed for K. The 5-13molcm-3 increases in the K concentration raised the VDB. Growth (net assimilation rate NAR, relative growth rate RGR, and crop growth rate CGR) was characterized by a quadratic behavior in the vegetative stage. In the reproductive stage, NAR and RGR exhibited an asymptotic negative trend, while CGR exhibited a positive quadratic trend. Nitrogen and potassium positively affected the growth variables evaluated in the vegetative and reproductive stages, increasing the productive potential of hydroponically cultivated tomato