Journal of Food, Agriculture and Environment

Vol 10, Issue 3&4,2012
Online ISSN: 1459-0263
Print ISSN: 1459-0255

Difference between NH4+ and NO3- uptake kinetics of different rice (Oryza sativa L.) grown hydroponically


Yun Lian 1, Mingxia Chen 2, Farooq Shah 1, Qiang Wang 1, Yutiao Chen 1, Kehui Cui 1, Lixiao Nie 1, Jianliang Huang 1*

Recieved Date: 2012-06-07, Accepted Date: 2012-10-05


To investigate the uptake kinetic difference between NH4+ and NO3- when both of them are present together, a set of 23 rice varieties with different nitrogen use efficiencies was grown hydroponically. Maximum uptake rate per pot (Vm), Michaelis-Menten constant (Km) and maximum uptake rate per dry weight of root (Vmax) for NH4+ and NO3- were determined at two N-levels, i.e. N 10 mg L-1 (N10) and 40 mg L-1 (N40), and growth stages (40 and 58 days after sowing referred as DAS40 and DAS58). The results showed that Vm and Vmax for NH4+ of all tested varieties were greater than for NO3- at both N-levels and stages, while greater Vm for NH4+ than for NO3- was ascribed to greater Vmax. Similarly, most of the varieties had greater Km for NH4+ than for NO3- at both N-levels and stages, however, the number of varieties which had higher Km for NH4+ than for NO3- was 21 at N10, and 14 and 19 under N40 at 40 and 58 DAS, respectively. The relationship between Vm and Km for NH4+ was significantly negative. The greater Vm can be mainly attributed to large root system at higher N level, e.g. dry weight of root (DWR) contributed approximately 70% to Vm for NH4+ and NO3- at N40, while at lower N level (N10) the higher Vm is mainly ascribed to the presence of more transporters for NH4+ than for NO3-, though the affinity for NH4+ of rice was less than for NO3-. All these results indicate that rice plant possesses higher uptake ability for NH4+ than for NO3-, and can adapt to high and low NH4+ habitats simultaneously. These findings may provide new insights to improve the uptake efficiency of rice for NH4+ and NO3- through improved Vmax and by considering the large root system and lower Km for NH4+ and NO3-.


Ammonium, nitrate, kinetics, absorption, Vm,  Km, Vmax,  rice (Oryza sativa L.)

Journal: Journal of Food, Agriculture and Environment
Year: 2012
Volume: 10
Issue: 3&4
Category: Agriculture
Pages: 437-442

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