Abstract

SACRAMENTO, Luis Vitor S. do; MARTINEZ, Herminia Emilia P.; MONNERAT, Pedro Henrique  and  OLIVEIRA, Laede Maffia de. Magnesium uptake by excised roots of tomato cultivars . Sci. agric. [online]. 1999, vol.56, n.3, pp. 509-515. ISSN 0103-9016.  http://dx.doi.org/10.1590/S0103-90161999000300001.

The absorption of magnesium by excised roots of tomato plants (Lycopersicon esculentum Mill) was studied in four cultivars (Angela Hiper, Miguel Pereira, Kadá e Yokota). External Mg concentrations were between 0.06 and 0.41 mmol.L^-1. Estimated maximum uptakes (V_max) were between 4.50 and 3.42 mmol.g^-1 per 40 minutes, while estimated K_m values were between 0.43 and 0,22 mmol.L^-1 per 40 minutes. Based on K_m estimated values it can be concluded that Ângela Hiper and Miguel Pereira cultivars have higher affinity with the Mg²⁺ ion carrier than Yokota and Kada cultivars. Maximum Mg uptakes were observed for Ângela Hiper and Miguel Pereira cultivars, that have a lower number of carrier molecules in the roots.

Keywords : Lycopersicon esculentum; tomato plants; magnesium; excised roots; absorption.