关键词: 硝酸根离子选择微电极, 液泡, 再调动, 粳稻, 籼稻

Abstract: Remobilization of nitrate in leaf vacuoles of crops is closely related to nitrogen use efficiency of crop. Double-barrelled nitrate selective microelectrodes were used to measure the nitrate activity in leaf cytosol and leaf vacuoles of different rice cultivars in either nitrate supply or deprivation conditions. The results obtained are listed as follows. (1) The nitrate concentration in tissue of rice plants showed no significant changes during the period of nitrate supply, but it decreased gradually after deprivation of nitrate. (2) Different situations emerged in individual leaf cells where nitrate activity of vacuoles decreased significantly while the nitrate activity of cytosol was almost unchanged when nitrate was removed. (3) Nitrate activities in cytosol and in vacuoles in leaves of Yangdao6 were higher than those of Nongken57, moreover, nitrate released from the leaf vacuole of Yangdao 6 at different times of nitrate deprivation was faster than Nongken57. It is concluded that nitrate stored in leaf vacuoles serves as a buffer for nitrogen utilization in cytosol and thus can increase the nitrogen use efficiency in plant itself.

Key words: Double-barrelled nitrate-selective microelectrodes, Vacuole, Remobilization, Indica rice, Japonica rice