Absorption and Distribution of Na+ and Some Ions in Seedlings of Metroxylon vitiense H. Wendl. ex Benth. & Hook. f. under Salt Stress

Na+, K+, Ca2+, Mg2+ and Cl- concentrations in different plant parts and some physiological characteristics under NaCl treatment in solution culture were determined to investigate the salt resistance of Metroxylon vitiense (H. Wendl.) H. Wendl. ex Benth. & Hook. f. that belongs to the same genus as sago palm (M. sagu Rottb.). Seedlings at the 11th to 13th leaf stages were used for the treatment of 342mM (2%) NaCl for 31 days in a phytotron at 30°C and 75% relative humidity under natural sunlight in mid-summer in central Japan. The Na+ and Cl- concentrations increased in the roots, petioles and leaflets with the NaCl treatment, while, the K+ concentration did not change in the top parts. The Ca2+ and Mg2+ concentrations increased in the leaflets, especially at lower and higher leaf positions, respectively. Leaf emergence and dry matter weight of the top parts were not affected by the NaCl treatment, whereas the transpiration rate decreased. It was, therefore, considered that salt avoidance to maintain the water status in the leaves by restricting the transpiration is important for the salt resistance of M. vitiense. The changes in the Ca2+ concentration can be considered to play a role in adequate absorption of K+, which would enable the plant to maintain osmotic adjustment in the leaflets.