开花结实期水稻叶际气态氮化物交换的初步研究

在气候箱及温室试验基础上, 用密闭箱法研究了开花结实期水稻叶际各种氮化物(NH₃、N₂O、NO和NO₂)的交换及其规律, 结果表明, (1)在气候箱控制、白昼有相对良好光照条件下, 开花结实期水稻未有显著净挥发NH₃效应；(2)同一时期水稻叶际NO平均交换速率白天15:00-18:00为-7.42 µg pot^-1 h^-1, 夜间20:00-23:00为-4.012 µg pot^-1 h^-1, 且有、无水稻完整植株处理间培养箱中抽出气流的NO浓度差异显著(P<0.05), 水稻表现有明显净吸收NO效应；随着环境空气NO浓度升高, 水稻NO吸收作用明显增强；(3)水稻有净吸收空气NO₂的明显效应, NO₂吸收速率相当于同时期白天和晚上水稻NO吸收速率的5.6%和3.9%；(4)在气候箱控制条件下, 白昼长时间适度光照(10 h, 165 µmol m^-2 s^-1)有抑制水稻N₂O挥发效应；在温室自然光暗条件下, 19:00一次日早9:00时段水稻平均N₂O挥发速率为5.04 µg pot^-1 h^-1, 有净挥发N₂O现象, 但白昼长时间光照条件下水稻未有从空气吸收N₂O的明显作用。从本试验结果看, 开花结实期水稻从空气中吸收的主要氮化物是NO, 向空气释放的主要氮化物是N₂O。

Preliminary Study on the Exchange of Gaseous Nitrogenous Compounds in Phyllosphere of Oryza sativa L. at Flowering and Seed Setting Stages

The exchange of gaseous nitrogenous compounds (NH₃, N₂O, NO, and NO₂) in phyllosphere of rice (Oryza sativa L.) at the flowering and seed setting stages was measured conducted with growth chamber and greenhouse. The results showed as follows: (1) There was no significant emission of NH₃ from rice leaves under the favorable illumination in growth chamber during the daytime. (2) There was the obvious uptake of NO by rice leaves; the mean exchange rate of NO in rice phyllosphere was -7.42 µg pot^-1 h^-1 from 15:00 pm to 18:00 pm and -4.012 µg pot^-1 h^-1 from 20:00 to 23:00 at night. Further more, there was the significant difference of NO content in air flux deflated from chamber between the treatments with and without rice plant (P<0.05), showing the obvious net NO absorption of rice leaves from the ambient air. As a result, the mean exchange rate of NO was significantly increased accordingly with the increasing of NO content in ambient air. (3) NO₂ was also obviously uptakedby rice plant, and the net absorption rates of NO₂ in rice phyllosphere were only about 5.6 % of net NO uptake in the day and about 3.9% of net NO uptake at night, respectively. (4) N₂O emission from leaves was inhibited evidently by long time of appropriate illumination (10 h, 165 µmol m^-2 s^-1) in growth chamber with light density regulated or in greenhouse without regulated light during daytime, but, there was obvious N₂O emission in rice phyllosphere under the weak light from 19:00 to 9:00 of next day without the control of light in greenhouse, with the mean exchange rate of 5.04 µg pot^-1 h^-1. However, with long time of appropriate light illumination, the net N₂O uptake was not occurred significantly in the course of N₂O exchange between rice plant and ambient air. It can be seen from the experimental results that one NO was the main one uptaked by rice leaves from air, and N₂O was the main one in gaseous nitrogenous compounds, released from leaves at the rice flowering and seed setting stages.