On the rate-limiting steps of nitrogen uptake in rice
1996
Kirk, G.J.D. | Solivas, J.L. (International Rice Research Inst., P.O. Box 933, 1099 Manila (Philippines). Soil and Water Sciences Div.)
Measurements of N uptake by rice plants growing in anaerobic soil and corresponding changes in soil solution NH4+ concentrations and the soil NH4+ diffusion coefficient, are used to calculate how root uptake properties influence soil N acquisition by rice. With root uptake parameters assigned value such that influx was maximal within realistic ranges, measured root length densities was less than those calculated indicating that diffusion of NH4+ to root surfaces and root uptake parameters limited N uptake rates. A sensitivity analysis showed that this would hold over a wide range of conditions. However, uptake of fertilizer broadcast into ricefield floodwater and absorbed by roots in the soil-floodwater interface is not likely to be limited by root uptake properties. Implications for rice plant types and N uptake efficiency are discussed
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