Pedosphere 17(3): 389--396, 2007
ISSN 1002-0160/CN 32-1315/P
©2007 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Root Exudates, rhizosphere Zn fractions, and Zn accumulation of ryegrass at different soil Zn levels |
XU Wei-Hong1 , LIU Huai2, MA Qi-Pu3 and XIONG Zhi-Ting4 |
1 College of Resources and Environmental Sciences, Southwest University, Chongqing 400716 (China). E-mail: redlx@swau.cq.cn
2 College of Plant Protection, Southwest University, Chongqing 400716 (China)
3 Soil Science and Plant Nutrition, University of Western Australia, Crawley WA 6009 (Australia)
4 College of Resources and Environmental Sciences, Wuhan University, Wuhan 430072 (China) |
| ABSTRACT |
| A glasshouse experiment was conducted using a root-bag technique to study the root exudates, rhizosphere Zn fractions, and Zn concentrations and accumulations of two ryegrass cultivars (Lolium perenne L. cvs. Airs and Tede) at different soil Zn levels (0, 2, 4, 8, and 16 mmol kg-1 soil). Results indicated that plant growth of the two cultivars was not adversely affected at soil Zn level≤8 mmol kg-1. Plants accumulated more Zn as soil Zn levels increased, and Zn concentrations of shoots were about 540μg g-1 in Aris and 583.9μg g-1 in Tede in response to 16 mmol Zn kg-1 soil. Zn ratios of shoots to roots across the soil Zn levels were higher in Tede than in Airs, corresponding with higher rhizosphere available Zn fractions (exchangeable, bound to manganese oxides, and bound to organic matter) in Airs than in Tede. Low-molecular-weight (LMW) organic acids (oxalic, tartaric, malic, and succinic acids) and amino acids (proline, threonine, glutamic acid, and aspartic acid, etc.) were detected in root exudates, and the concentrations of LMW organic acids and amino acids increased with addition of 4 mmol Zn kg-1 soil compared with zero Zn addition. Higher rhizosphere concentrations of oxalic acid, glutamic acid, alanine, phenylalanine, leucine, and proline in Tede than in Airs likely resulted in increased Zn uptake from the soil by Tede than by Airs. The results suggested that genotypic differences in Zn accumulations were mainly because of different root exudates and rhizosphere Zn fractions. |
| Key Words: plant Zn accumulation, rhizosphere Zn fractions, root exudates, ryegrass, soil Zn level |
| Citation: Xu, W. H., Liu, H., Ma, Q. P. and Xiong, Z. T. 2007. Root Exudates, rhizosphere Zn fractions, and Zn accumulation of ryegrass at different soil Zn levels. Pedosphere. 17(3): 389-396. |
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