Root zone heating suppressed the yellowing of tomato leaf by the stimulation of magnesium uptake

Abstract

Root zone heating suppressed the yellowing of tomato leaf by stimulation of magnesium uptake on the rock wool cultivation of hydroponics. The reaction to root zone heating is different between the varieties (‘Reiyo’ and ‘Momotaro Haruka’). ‘Reiyo’ did not appear any symptom of leaf yellowing, even on the medium without heating. The concentrations of the two valence cations; Ca and Mg, and micro nutrient; Cu, Zn decreased in the leaf whose leaf became yellow. Especially Mg contents of yellow leaves of ‘Momotaro Haruka’ remarkably decreased up to 55% of that of the heating treatment. Because the correlation coefficient between Mg concentration and the values of chlorophyll content is highest among the 7 different minerals, these result supposed that the decrease of chlorophyll contents caused by Mg deficiency induced on the lower root zone temperature.