单 位：
云南农业大学资源与环境学院;云南省烟草农业科学研究院;云南省烟草公司;昆明学院农学院云南省都市特色农业工程技术研究中心中国科学院昆明动物研究所昆明学院;昆明学院
摘 要：
【目的】稻田生态系统是N_2O的重要排放源,本研究旨在探讨氮素形态和光照对水稻根际、叶际N_2O排放作用及其机制。【方法】试验采用水培方法,在小型光控培养箱内进行,供试作物为水稻。将水稻地上部和地下部严格分隔在试验装置内室和外室,用气相色谱法测定水稻根、叶界面排放的N_2O量。首先进行了弱光(8:00~18:00,4000 Lux;18:00~22:00,0 Lux)和供氮量一致条件下(N 90 mg/L),NO_3~–-N、NH_4NO_3和NH4+-N 3种氮素形态对水稻根、叶界面N_2O排放的影响的试验。在此基础上,进行了不同光照条件下[弱光(8:00~18:00,4000 Lux;18:00~22:00,0 Lux)、强光(8:00~18:00,8000 Lux;18:00~22:00,0 Lux)和自然光]不同氮素形态对水稻根、叶界面N_2O排放的影响的试验。【结果】1)相同供氮水平、弱光条件下,NO_3~–-N、NH_4NO_3、NH4+-N处理的水稻分蘖期叶际及根际N_2O排放速率分别为6.37、5.03、0.46μg/(pot·h)和16.30、15.71、1.31μg/(pot·h),开花结实期及成熟衰老期亦获得相似的结果。NO_3~–-N、NH_4NO_3处理水稻根际、叶际N_2O排放量显著高于NH4+-N(P<0.05)。2)弱光照条件下,NO_3–-N、NH_4NO_3和NH4+-N处理的水稻开花结实期叶际N_2O平均排放速率分别为10.47、3.70、0.26μg/(pot·h),强光照条件下分别为20.83、10.82、2.08μg/(pot·h),两种光照条件下3种氮源处理之间N_2O平均排放速率差异显著,自然光照条件下NO_3~–-N与NH_4NO_3处理间水稻叶际N_2O排放差异不显著。3)在弱光条件下,NO_3~–-N、NH_4NO_3和NH4+-N处理的水稻根际N_2O排放速率分别为27.76、5.19、0.30μg/(pot·h),强光条件下分别为32.83、16.41、1.27μg/(pot·h),自然光条件下分别为16.49、20.21、1.74μg/(pot·h)。NH_4NO_3处理水稻根际N_2O排放随光照增强而增加,自然光条件下NO_3~–-N与NH_4NO_3处理间水稻根际N_2O排放差异不显著,但弱光条件下差异显著;4)叶际N_2O排放速率(Y)与根际N_2O排放速率(X)间呈极显著正相关,Y=1.963+0.444X(R~2=0.661,P<0.01)。【结论】不论光照条件强弱,供应NO_3~–-N均显著提高水稻根、叶界面的N_2O-N排放,NH_4NO_3次之。光照越强,排放就越明显。叶际N_2O排放可以反映出根际的排放,因此,水稻施肥应尽量选用铵态氮肥,避免使用硝态氮以及含有硝态氮的肥料。
译 名：
N_2O emissions from rice phyllosphere and rhizosphere when supplied with different nitrogen forms and light intensities
作 者：
XU Sheng-guang;GAO Zhao-hua;LIN Li;CHEN Ze-bin;CHEN Wu-rong;LI Bing;YU Lei;Yunnan Urban Agricultural Engineering and Technological Research Center, Kunming University;College of Resources and Environment, Yunnan Agricultural University;Kunming Institute of Zoology, Chinese Academy of Sciences;
关键词：
nitrogen forms;;rice;;phyllosphere;;rhizosphere;;N2O emission
摘 要：
【Objectives】 Paddy ecosystem is an important source of N_2 O emission, this paper is aimed to clarify the effects of different nitrogen forms under different light intensities on N_2 O emission from rice phyllosphere andrhizosphere and the mechanism of these effects. 【Methods】Hydroponic methods with rice were adopted in small incubators in which the light was controlled. The incubators were separated into inner and outer chambers and the above-ground part of rice was completely sealed in the inner chamber and the roots in the outer chamber The N_2 O emissions from rice phyllosphere and rhizosphere were measured by gas chromatography method. It was firstly studied about the effects of three N forms(NO_3~–-N, NH_4NO_3-N, NH_4~+N) on N_2 O emission of rice phyllosphere and rhizosphere under weak light(8:00–18:00, 4000 Lux) and same N applications(90 mg/L)Then the experiments were conducted to further study the effects of different N forms on N_2 O emission from rice phyllosphere and rhizosphere under different light intensities(weak light, 8:00–18:00, 4000 Lux;18:00–22:00, 0 Lux; strong light, 8:00–18:00, 8000 Lux, 18:00–22:00, 0 Lux and natural sunlight respectively). 【Results】 1) Under NO_3~–-N, NH_4NO_3 and NH_4~+N with weak light, the mean rates of N_2 O emission from phyllosphere and rhizosphere were 6.37, 5.03 and 0.46 μg/(pot·h), respectively, and 16.30, 15.71 and 1.31 μg/(pot·h), respectively, during rice tillering stage, and similar results were obtained during rice flowering, seeding and mature aging stages under the same conditions. 2) Under weak light, the N_2 O emissions from rice phyllosphere treated with NO_3~–-N, NH_4NO_3 and NH_4~+N were 10.47, 3.70 and 0.26 μg/(pot·h)respectively, and 20.83, 10.82 and 2.08 μg/(pot·h) with strong light, respectively, during flowering and seeding stages. There were significant differences in N_2 O emissions among the three N forms under these two ligh intensities, but no significant difference in N_2 O emissions between NO_3~–-N and NH_4NO_3 under the sunlight. 3)Under NO_3~–-N, NH_4NO_3 and NH_4~+N with the weak light during flowering and seeding stages, the N_2 O emissions of rice rhizosphere were 27.76, 5.19 and 0.30 μg/(pot·h), respectively. Under the strong light, the N_2 O emission rates were 20.83, 10.82 and 2.08 μg/(pot·h), respectively, and 16.49, 20.21 and 1.74 μg/(pot·h), respectively under the sunlight. The N_2 O emission from rhizosphere was high with high light intensity under NH_4NO_3. No significant difference was observed in the N_2 O emission between NO_3~–-N and NH_4NO_3 under sunlight, but did under weak light. 4) There was a significantly positive linear regression relationship between N_2 O emission from rice phyllosphere(Y) and rhizosphere(X)(Y = 1.963 + 0.444 X, R~2 = 0.661, P < 0.01). 【Conclusions】The N_2 O emissions from rice phyllosphere and rhizosphere can be increased significantly by NO_3~–-N, followed by NH_4NO_3 The N_2O emissions is also increased with the increase of light intensity. The N_2 O emissions of phyllosphere can reflect the N_2 O emissions of rhizosphere. Therefore, while applying N fertilizers, ammonium fertilizers should be preferentially used and nitrate nitrogen and fertilizers containing nitrate nitrogen should be avoided.
