Measurement of NH4+ activity in leaf cells of rice using double-barreled NH4+ selective microelectrode.

This paper reported the manufacture method,working principle and operating method of double-barreled NH_4~+ selective microelectrode.An apparent difference of NH_4~+ selective microelectrode from other microelectrodes(such as H~+ and NO_3~- microelectrode) is the interference of K~+.These microelectrodes showed a typical log linear response to NH_4~+ from 0.01-100 mmol/L in the presence of 72 mmol/L K~+,with a slope of 48～58 mV.The detect limit was below 10~(-3) mmol/L.The results showed that the microelectrode was more sensitive and selective to NH_4~+ and could be used on the NH_4~+ measurement.Intracellular measurement of NH_4~+ activity in leaf cells of rice using the double-barreled NH_4~+ selective microelectrode showed that NH_4~+ activity fell into two main populations,one was in the cytoplasm with the NH_4~+ concentrations of 2.58-9.37 mmol/L and the other one was in the vacuole with the NH_4~+ concentrations of 11.36- 25.20 mmol/L.Tissue NH_4~+ of rice leaf mainly comes from that of the vacuole.Tissue NH_4~+ concentrations of rice leaf using a continuous-flow auto analyzer were 11.12 mmol/L.NH_4~+ selective microelectrode offered technical support for the study of the assimilation and utilization of NH_4~+ in rice.