开花结实期水稻叶际气态氮化物交换的初步研究

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

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-7.42μgpot-1h-1,夜间20:00—23:00为-4.012μgpot-1h-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(10h,165μmolm-2s-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5.04μgpot-1h-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。

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 -7.42μg pot^-1h^-1 from 15：00 pm to 18：00 pm and --4.012μg pot^-1h^-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 uptaked by 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^-1h^-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.