Objectives The aim of this study was to investigate the difference in magnesium (Mg) uptake among different tomato cultivars, and to provide a scientific basis for selection of tomato cultivars with high uptake efficiency.
Methods Two hydroponic experiments were conducted using three widely planted tomato cultivars (‘Zhongza No.9’, ‘Gailiangmaofen’ and ‘Jinpengchaoguan’) in North China. A 24 h uptake kinetics experiment (Mg levels: 0, 0.6, 1.2, 1.8, 2.4, 3.0 mmol/L) at two different temperatures (15℃ and 30℃) was conducted to evaluate Mg uptake kinetics. A 45 days’ hydroponic experiment (two Mg levels: 0, 1.0 mmol/L) was conducted to compare Mg uptake and utilization efficiency.
Results The uptake kinetics results showed that Mg uptake rate at 15℃ was higher than that at 30℃. The Mg uptake rate of three tomato cultivars at two temperatures was ‘Gailiangmaofen’ > ‘Jinpengchaoguan’ > ‘Zhongza No.9’. There were significant differences in the maximum uptake rate (Imax) and the affinity coefficient (Km) among the three tomato cultivars, and the two parameters of the three tomato cultivars was ‘Gailiangmaofen’ > ‘Jinpengchaoguan’ > ‘Zhongza No.9’. The Mg uptakes among three tomato cultivars in the 45 day experiment were significantly different in the two Mg levels. Mg uptake of ‘Jinpengchaoguan’ was significantly lower than those of ‘Jinpengchaoguan’ and ‘Zhongza No.9’, and there was no significant difference between ‘Jinpengchaoguan’ and ‘Zhongza No.9’.
Conclusions Growth temperature affects the uptake rate of Mg, but does not change the uptake characteristics of different cultivars. ‘Zhongza No.9’ and ‘Jinpengchaoguan’ show a high Mg uptake potential at low Mg supply level, while ‘Gailiangmaofen’ does not.
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