Tomato nutrition and growth as related to the humic acid-boron interaction in contrasting soils

Abstract

The objective of this study was to evaluate the effect of carbon-humic acid rates (C-HA) and their interaction with soil available B contents on the nutrition and growth of tomato. The experimental design adopted was a completely randomized blocks in a 2x5 factorial scheme, with two rates of B, a treatment without B to maintain the current level of available B in soil, and a treatment with the addition of B aiming to raise its level in soil to 2 mg kg^-1. Boron rates in soil were combined with five concentrations of C-HA (0, 5, 10, 50 and 100 mg kg^-1 of soil), with three replicates. Shoot (S) and root (R), and total (S+R) dry matter (DM) were analyzed as well as the ratio R/S, besides the availability of B in soil and plant tissue. Soil texture and OM content are factors that modulate the dry matter production and the effect of C-HA concentrations on the tomato growth. Regardless of the evaluated soil, in the treatment without B the tomato growth was lower than other treatments and the tomato DM decreased when increased the C-HA concentration. The B treatments increased DM (especially on the roots) when the C-HA concentration was increased.