Effects of NaCl and silicon on ion distribution in the roots, shoots and leaves of two alfalfa cultivars with different salt tolerance
Wang, X.S.(China Agricultural Univ., Beijing) | Han, J.G.
The effects of exogenous NaCl and silicon on ion distribution were investigated in two alfalfa (Medicago sativa. L.) cultivars: the high salt tolerant Zhongmu No. 1 and the low salt tolerant Defor. The cultivars were grown in a hydroponic system with a control (that had neither NaCl nor Si added), a Si treatment (1 mmol/L Si), a NaCl treatment (120 mmol/L NaCl), and a Si and NaCl treatment (120 mmol/L NaCl + 1 mmol/L Si). After 15 days of the NaCl and Si treatments, four plants of the cultivars were removed and divided into root, shoot and leaf parts for Nasup(+), Ksup(+), Casup(2+), Mgsup(2+), Fesup(3+), Mnsup(2+), Cusup(2+) and Znsup(2+) content measurements. Compared with the NaCl treatment, the added Si significantly decreased Nasup(+) content in the roots, but notably increased Ksup(+) contents in the shoots and leaves of the high salt tolerant Zhongmu No.1 cultivar. Applying Si to both cultivars under NaCl stress did not significantly affect the Fesup(3+) Mgsup(2+) and Znsup(2+) contents in the roots, shoots and leaves of Defor and the roots and shoots of Zhongmu No.1, but increased the Casup(2+) content in the roots of Zhongmu No.1 and the Mnsup(2+) contents in the shoots and leaves of both cultivars, while it decreased the Casup(2+) and Cusup(2+) contents of the shoots and leaves of both cultivars under salt stress. Salt stress decreased the Ksup(+), Casup(2+), Mgsup(2+) and Cusup(2+) contents in plants, but significantly increased Znsup(2+) content in the roots, shoots and leaves and Mnsup(2+) content in the shoots of both cultivars when Si was not applied. Thus, salt affects not only the macronutrient distribution but also the micronutrient distribution in alfalfa plants, while silicon could alter the distributions of Nasup(+) and some trophic ions in the roots, shoots and leaves of plants to improve the salt tolerance.
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