Comparison of rhizosphere impacts of two wheat genotypes differing in phosphorus utilization efficiency

摘要

Yan, H., Liu, W., Liu, X., Li, G. and Zhang, S. 2010. Comparison of rhizosphere impacts of two wheat genotypes differing in phosphorus utilization efficiency. Can. J. Plant Sci. 90: 311-317. Exploitation of high phosphorus (P) use efficiency genotypes of crops and understanding their rhizosphere P activation mechanisms is essential to development of beneficial management practices for sustainable agricultural production. A pot experiment was carried out to investigate the differences in changes of pH, phosphatase activity, and water-soluble P in the rhizosphere soil and crop growth and P content of two constrasting wheat genotypes (P-efficient, Xiaoyan54, and P-inefficient, Jing411) in a calcareous soil supplied with three rates (0, 50, and 100 mg kg(-1) soil, which are coded as P-0, P-50 and P-100, respectively) of fertilizer P. Results showed that root biomass, root/shoot ratio and efficiency index of Xiaoyan54 were significantly higher than those of Jing411 at the same P level. In addition, the roots of Xiaoyan 54 absorbed significantly more P than the roots of Jing 411, except for the P-50. The dry weight of shoot biomass was similar between the two wheat genotypes. Wheat biomass and P content in shoot, root and the total for both genotypes increased for P supplied treatments, compared with those without P supply. The rhizosphere acidification capacity of Xiaoyan54 was greater than Jing411 without P addition. However, Xiaoyan54 acidified rhizosphere soil at a larger distance than Jing411 at high P fertilization. The phosphatase activity did not differ between the two genotypes, regardless of the location in the rhizosphere. Soil applied with high P decreased the phosphatase activity for the root surface soil only. Water-soluble P concentration in rhizosphere and the bulk soil were similar for Xiaoyan54 and Jing411, and increased as increasing P levels. Xiaoyan54's large root biomass and strong acidification ability might be the main mechanisms contributing to high P uptake under P-deficient conditions.