Pedosphere 8(4): 289--296, 1998
ISSN 1002-0160/CN 32-1315/P
©1998 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Effect of silicon on leaf ultrastructure, chlorophyll content and photosynthetic activity of barley under salt stress
LIANG Yong-Chao
Department of Plant Nutrition, College of Natural Reaources and Environmental Science, and Ministry of Agriculture Key Laboratory of Crop Growth and Regulation, Nanjing Agricultural University, Nanjing 210095 (China)
      Two contrasting cultivars of barley (Hordeum vulgare L.): Kepin No.7 (salt sensitive), and Jian 4 (salt tolerant) were grown in a hydroponics system with 2 NaCl levels: 60 mmol NaCl L-1 and 120 mmol NaCl L-1, and 3 Si levels: 0 mmol Si L-1, 0.5 mmol Si L-1 and 1.0 mmol Si L-1 (as silicic acid). Compared with the plants treated with 60 mmol NaCl L-1 alone, the leaf chlorophyll contents of plants treated with salt and Si increased significantly for salt-sensitive cultivar at tillering stage, but for salt-tolerant cultivar, the addition of Si resulted in an obvious increase in the leaf chlorophyll content of plants exposed to 120 mmol NaCl L-1. However, this Si-enhancement of leaf chlorophyll content was also observed in the salt-tolerant plants at jointing stage, but not in the salt-sensitive plants. Moreover, leaf chlorophyll content was consistently higher for the salt-tolerant cultivar than for the salt-sensitive cultivar irrespective of salt and/or Si treatment. Compared with the plants treated with salt alone, net CO2 assimilation rate in plant leaves increased significantly for both cultivars when treated with salt and Si. The addition of Si to the salt treatment was found to improve the cell ultrastructure of leaves. Under salt stress condition, the double membranes of chloroplasts disappeared, but membrane integrity was markedly improved in the salt treatment supplemented with Si. Silicon was also found to ameliorate the damage to the ultrastructure of chloroplast granae which appeared to be disintegrated and vague in salt treatments without added Si. The results support previous work which showed that Si decreases the permeability of plasma membranes of salt-stressed barley, thus mitigating salt damage.
Key Words:  barley, photosynthesis, salt, silicon, ultrastructure
Citation: Liang, Y. C. 1998. Effect of silicon on leaf ultrastructure, chlorophyll content and photosynthetic activity of barley under salt stress. Pedosphere. 8(4): 289-296.
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