Pedosphere 8(4): 367--376, 1998
ISSN 1002-0160/CN 32-1315/P
©1998 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Kinetics of nitrogen and potassium uptake by various rice cultivars at different nitrogen levels from purple soil |
| WANG Zheng-Yin, XU Wei-Hong, YAO Jian-Xiang and LUO De-Yong |
| Collage of Resources and Environmental Science, Southwest Agricultural University, Chongqing 400716 (China) |
| ABSTRACT |
| A pot experiment was conducted to study the effect of nitrogen fertilizer on nitrogen and potassium uptake by four rice cultivars. Results showed that the quadratic parabola relationship between biomass of rice and nitrogen levels was observed, with the maximum biomass at the nitrogen level of 150 mg kg-1. The rates of nitrogen and potassium uptake by the four rice cultivars depended on growth stage and rice cultivar with the maximum rate of N in Shanyou-63 and maximum rate of K in Kaiyou-5 (hybrid rice), respectively. The kinetics of nitrogen and potasssium uptake by rice plant could be quantitatively described by the following equations: y = a + blogt, y = ab + t1/2 and y = ae-bt. The b value in the equations was correlated significantly to the rates of nitrogen and potassium uptake (NR and KR, r = 0.901**~0.990**), suggesting that the b value could be used to distinguish the index of nitrogen and potassium uptake capacity of rice. The maximum values of nitrogen uptake by plant (b value) and apparent recovery of fertilizer nitrogen were observed in Shanyou-63, and the minimum value in Eryou-6078. However, the capacity of potassium uptake (b value) by Kaiyou-5 ranked first and that by Shanyou-63 second. There was a significant linear relationship between nitrogen level and nitrogen uptake by rice, but a quadratic parabola relationship was found between nitrogen level and patassium uptake by rice. The application of nitrogen fertilizer decreased the ratios of potassium to nitrogen uptake by rice plant. The greatest reduction in the ratio was observed at high nitrogen level, and the least reduction was found in Kaiyou-5 and Shanyou-63 due to their greater ability to absorb potassium. |
| Key Words: kinetic equation, nitrogen fertilzer, potassium nutrition, rice |
| Citation: Wang, Z. Y., Xu, W. H., Yao, J. X. and Luo, D. Y. 1998. Kinetics of nitrogen and potassium uptake by various rice cultivars at different nitrogen levels from purple soil. Pedosphere. 8(4): 367-376. |
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