Salt secretion in Rhodes grass (Chloris gayana Kunth) under conditions of excess magnesium(Plant Nutrition)

概要

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Rhodes grass (Chloris gayana Kunth) is known to be a salt-tolerant grass, and its tolerance is related to the presence of salt glands that secrete excess salts transported into the leaves. The salt glands of Rhodes grass reportedly have a high ability to secrete Na^+, but their ability to secrete Mg^<2+> remains unclear. In the present study, we examined salt secretion via the salt glands under conditions of excess Mg^<2+> using both whole plants and detached leaves of Rhodes grass. MgCl_2 treatment significantly increased Mg^<2+> secretion, but the extent of secretion remained relatively minor. MgCl_2 treatment significantly increased K^+ secretion, and the increase in K^+ secretion was more than 50-fold higher than the increase in Mg^<2+> secretion. The increase in K^+ secretion caused by MgCl_2 treatment was inhibited by the application of ion transport inhibitors. Inhibition of K^+ secretion amplified the increase in leaf sap osmolality caused by MgCl_2 treatment. These results indicate that: (1) salt glands of Rhodes grass have a low ability to secrete Mg^<2+>, (2) salt glands of Rhodes grass substitute K^+ secretion for Mg^<2+> secretion under conditions of excess Mg^<2+>, (3) substitutive K^+ secretion may play a role in the alleviation of osmotic changes caused by Mg^<2+> accumulation.
社団法人日本土壌肥料学会の論文