Pedosphere 5(2): 115--126, 1995
ISSN 1002-0160/CN 32-1315/P
©1995 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Phosphate distribution and movement in soil-root interface zone: Ⅰ. The influence of transpiration rate |
| XU Ming-Gang, ZHANG Yi-Ping and SUN Ben-Hua |
| Department of Soil Science, Northwestern Agricultuml University, Yangling, Shaanxi 712100 (China) |
| ABSTRACT |
| The experiments were conducted in the artificial climate laboratory using 32P labelled soil and soil-root plane system to investigate phosphate distribution and its movement in the soil-root interface zone and their relations with phosphate uptake by plant as well as transpiration rate (atmosphere humidity). It was found that although the phosphate in the soil-root interface zone was of depletive distribution as a function C/Co = axbC/Co is the relative content of fertilizer phosphate in a distance from the root surface x, a and b are the regression constants), and a relative accumulation zone of phosphate within 0.5 mm near the root surface was often observed especially in the heavier texture soils because of root phosphate secretion. The depletion intensity of phosphate in the soil-root interface zone was in agreement with the phosphate uptake by plants under two humidities very well. However, the effects of air humidity on characteristics of the phosphate distribution near wheat or maize root surface were different. Wheat grew better under lower atmosphere humidity while maize, under higher humidity, which caused a more intensive uptake and thus a stronger depletion of phosphate in the rhizosphere. Moreover, the depletion intensity was greater by the bottom or the middle part of wheat roots and by the top or the middle part of maize roots. The depletive distribution of phosphate in the rhizosphere soil and the relative contribution of phosphate diffusion to plant, which was more than 98% in the cultural experiments, indicated that diffusion was a major process for phosphorus supply to plants. |
| Key Words: phosphate distribution, soil-root interface zone, transpiration rate |
| Citation: Xu, M. G., Zhang, Y. P. and Sun, B. H. 1995. Phosphate distribution and movement in soil-root interface zone: Ⅰ. The influence of transpiration rate. Pedosphere. 5(2): 115-126. |
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