摘要： 旨在探讨光照和施氮量对水稻根、叶际N₂O排放的作用机制。采用水培方法，在小型光控培养箱内进行，将水稻（品种为培杂泰丰）地上部和地下部严格分隔在试验装置内室和外室条件下，用气相色谱法测定水稻根、叶际排放的N₂O量。首先进行了室内弱光（8：00-18：00，4 000 lx）、NH₄NO₃为氮源条件下，不同生育期（如分蘖期、开花结实期、成熟衰老期）的水稻在不同施氮量（低氮，30 mg/L；中氮，60 mg/L；高氮，90 mg/L））情况下的试验。在此基础上，进行了弱光（4 000 lx）、强光（8 000 lx）和自然光的不同光照条件下的脱氮（0 mg/L）、低氮（30 mg/L）、高氮（90 mg/L）试验。弱光试验条件下，低氮（30 mg/L）、中氮（60 mg/L）、高氮（90 mg/L）处理的水稻分蘖期叶际及根际N₂O排放通量分别为34.9，42.4，98.3 μg/（m² · h）和29.6，79.6，246.1 μg/（m² · h），随着施氮量增加，水稻根、叶际N₂O排放显著增强（P<0.05），且开花结实期及成熟衰老期试验亦获得相似的结果。在弱光（4 000 lx）、强光（8 000 lx）和自然光的不同条件下，脱氮（0 mg/L）、低氮（30 mg/L）、高氮（90 mg/L）处理的水稻开花结实期叶际平均N₂O排放通量分别为2.9，29.1，116.3 μg/（m² · h），23.6，40.1，120.1 μg/（m² · h）和10.9，26.2，131.3 μg/（m² · h），强光、自然光照下脱氮与低氮处理间水稻叶际N₂O排放差异不显著（P>0.05）。弱、强光及自然光条件下，脱氮、低氮、高氮处理的水稻根际N₂O排放通量分别为3.3，77.1，308.4 μg/（m² · h），14.1，45.6，182.4 μg/（m² · h）和19.3，44.9，224.6 μg/（m² · h），强光、自然光照下脱氮与低氮处理间水稻根际N₂O排放差异亦不显著（P>0.05）。弱光条件下，供氮范围内随着施氮量的增加，水稻根、叶界面N₂O排放通量随之增强；但对比弱光试验，相同供氮（1N、3N）水平条件下强光、自然光有抑制水稻根际N₂O排放作用，且强光、低氮（1N）的协同作用限制水稻根、叶际N₂O排放的效果显著。

关键词: 光照, 施氮量, 水稻, 叶际, 根际, N₂O, 排放

Abstract: This study aimed to clarify the effects of different N application rates and light intensities on N₂O emission flux in phyllosphere and rhizosphere of rice and its mechanism. The experiment was carried out by hydroponic method in a small light-controlled incubator, using rice variety Peizataifeng as the material, and the above-ground and underground parts of rice were strictly separated in the inner and outer chambers of the test device. The amount of N₂O emitted from the root and leaf interface of rice was determined by gas chromatography. First, we conducted the indoor low light (8:00-18:00, 4 000 lx) test using NH₄NO₃ as the nitrogen source, of which three N levels, low nitrogen (30 mg/L), medium nitrogen (60 mg/L) and high nitrogen (90 mg/L) at different developing stages were arranged. On this basis,we carried out the experiment under the conditions of low light (4 000 lx), strong light (8 000 lx) and natural light, including three N treatments:denitrification (0 mg/L), low nitrogen (30 mg/L) and high nitrogen (90 mg/L) at flowering and fruiting stages. The results showed that, under weak illumination (8:00-18:00, 4 000 lx), the mean rate of N₂O emission was 34.9, 42.4 and 98.3 μg/(m² · h) in rice phyllosphere, and was 29.6, 79.6, 246.1 μg/(m² · h) in rice rhizosphere, respectively, for treatments of 1N (30 mg/L), 2N (60 mg/L) and 3N (90 mg/L). With the increase of N rate, the amount of N₂O emission in rice phyllosphere and rhizosphere also increased (P<0.05), and the similar results were obtained at flowering/seeding stage and mature aging stage. The N₂O emission rate in the phyllosphere of 0N (0 mg/L), 1N (30 mg/L) and 3N (90 mg/L) was 2.9, 29.1 and 116.3 μg/(m² · h) for weak light treatment, was 23.6, 40.1 and 120.1 μg/(m² · h) for strong light treatment (8:00-18:00, 8 000 lx), and was up to 10.9, 26.2 and 131.3 μg/(m² · h) under natural light,condition, respectively. The N₂O emission rate in the rhizosphere of 0N (0 mg/L),1N (30 mg/L) and 3N (90 mg/L) was 3.3, 77.1 and 308.4 μg/(m² · h) for weak light treatment, was 14.1, 45.6, and 182.4 μg/(m² · h) for strong light treatment, and was 19.3, 44.9 and 224.6 μg/(m² · h) under natural light,condition, respectively. Under strong and natural light conditions, the N₂O emission rate in the rhizosphere of rice was not significant between 0 N (0 mg/L) and 1N (30 mg/L) treatments (P>0.05). Under weak light condition, the N₂O emission rate in the rhizosphere and phyllospher increased with the increase of N application amount. Under the same condition of N application (1N, 3N), the N₂O emissions in the rhizosphere of rice could be inhibited by stronger light and sunlight compared with the results of weak light treatment. It was suggested that the combination of strong light and low N level (1N) could inhibit the N₂O emissions in the rhizosphere and phyllosphere of rice.

Key words: Illumination, Nitrogen application rate, Rice, Phyllosphere, Rhizosphere, N₂O, Emissions

中图分类号: 

• S153.6

• X511