Journal of Food, Agriculture and Environment
Vol 10,
Issue 3&4,2012
Online ISSN: 1459-0263
Print ISSN: 1459-0255
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Difference between NH4+ and NO3- uptake kinetics of different rice (Oryza sativa L.) grown hydroponically
Author(s):
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
Abstract: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-.
Keywords: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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