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 (Vmax) were between 4.50 and 3.42 mmol.g-1 per 40 minutes, while estimated Km values were between 0.43 and 0,22 mmol.L-1 per 40 minutes. Based on Km 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.
Lycopersicon esculentum; tomato plants; magnesium; excised roots; absorption