光照对分蘖期水稻叶际及根系-培养液体系 N2O 和 NOX（NO，NO2）排放的影响

[目的]该研究探讨光照对分蘖期水稻根、叶界面N2O和NOX排放的作用及其机制。[方法]试验在水培控氮、小型光控培养箱控光和同步测定条件下，探讨了不同光质、光强及光控处理对分蘖期水稻叶际及根系-培养液体系 N2O和 NOX 排放的影响。[结果]①在相同氮源(NH4NO3-N,90 mg/L)、日间光照为6000、8000 lx条件下，分蘖期平均水稻叶际 N2O和NO排放速率分别为27.08、32.33μg/(pot·h)和0.114、0.057μg/(pot·h),分别占 N2O和 NO总排放的57.38%、58.65%和9.65%、4.52%，水稻叶际是N2O的重要排放源；②在光强(1600 lx)一致条件下，LED黄、绿、白、红、蓝光处理的平均水稻叶际N2O 排放速率分别为6.83、9.40、9.73、2.82和4.08μg/(pot·h)，光 X强较高的红(3000 lx)、蓝光(2500 lx)处理能同步抑制分蘖期水稻根、叶界面N2O的挥发(P<0.01)，LED红、白光有促进日间水稻叶际NO排放的作用，LED蓝光则有同步抑制水稻根、叶界面 NO挥发的作用效果，但不同光控处理下水稻根、叶界面均无明显的NO2净排放作用；③0~8000 lx 范围内随着光照增强，水稻根部NO及根、叶界面 N2O排放同步增加，但高光强(6000~8000 lx)下水稻叶际 NO排放显著大幅下降(P<0.01)。[结论]水稻根、叶界面均以N2O挥发为主；试验供氮水平下适度控制日间光强并同步增加红光、蓝光比例的技术，能同步抑制水稻根、叶界面氮氧化物的排放。

Effect of Light Quality and Intensity on N2O and NOX(NO,NO2)Emissions from Rice Phyllosphere and Roots at Tillering Stage in a Liquid Culture Medium System

Objective] N2O and NOX (NO, NO2) are important nitrogen oxides gases (NOGs) in paddy fields, and rice plants play important roles in NOG emissions in paddy fields. However, the source of NOG emissions from rice phyl osphere and roots and their relationship to light quality and intensity stil remain unclear. In this study, the relationship between light quality, intensity and N2O, NOX (NO, NO2) emis-sions from rice phyl osphere and roots at til ering stage was investigated to clarify the contribution of rice plants to N2O and NOX (NO, NO2) emissions and analyze the mechanism of light control, aiming at providing a scientific basis for revealing how light-control technology affects NOG emissions from rice at til ering stage in paddy fields. [Method] In this study, nitrogen content was control ed by a hydroponic system. A smal electric incubator was used for light control. A simultaneous deter-mination was designed to investigate the effect of different weak light qualities (yel-low, green, white, red and blue lights) and intensities (dark, 0 lx; very weak, 2 000 lx; weak, 4 000 lx; moderate, 6 000 lx; strong, 8 000 lx) on N2O and NOX emis-sions from rice phyl osphere and roots at til ering stage in a liquid culture medium system. N2O concentration in air samples was determined by gas chromatography within 12 h, and NOX (NO, NO2) concentration was analyzed using 42i NO- NO2-NOX gas analyzer. [Result] The results showed that: (1) Under a constant nitrogen condition (NH4NO3-N, 90 mg/L) when rice seedlings were treated with moderate (6 000 lx) and strong (8 000 lx) light, the average emission rate of N2O and NO from rice phyl osphere at til ering stage was 27.08, 32.33 μg/(pot·h) and 0.114, 0.057 μg/(pot·h), respectively, accounting for 57.38%, 58.65% and 9.65%, 4.52% of the total release of N2O and NO from the whole rice plant, respectively. It implicated that rice phyl o-sphere is an important source of N2O emission at til ering stage in paddy fields. (2) When rice seedlings were treated with yel ow, green, white, red and blue LED lights under a constant light intensity (1 600 lx), the average emission rate of N2O from rice phyl osphere was 6.83, 9.40, 9.73, 2.82 and 4.08 μg/(pot·h), respectively. Com-pared with green and yel ow LED lights, N2O emission from rice phyl osphere and roots at til ering stage was inhibited markedly by red (3 000 lx) and blue (2 500 lx) LED lights (P<0.01). In addition, NO emission from rice phyl osphere was enhanced significantly by white and red LED lights, while NO emissions from rice phyl osphere and roots were inhibited by blue light synchronously. Nevertheless, no evident NO2 emission from rice phyl osphere and roots was detected under the same condition. (3) Within the range of 0-8 000 lx, NO and N2O emissions from rice roots and N2O emission from rice phyl osphere increased with the enhancement of light intensi-ty. In contrast, NO emission from rice phyl osphere was inhibited remarkably by moderate (6 000 lx) and strong (8 000 lx) light (P<0.01). [Conclusion] Rice seedlings mainly exhibited net emissions of NO2 from the phyl osphere and roots. N2O and NOX (NO, NO2) emissions from rice phyl osphere and roots at til ering stage could be inhibited by adjusting the composition of visible light (synchronously increasing the proportions of red and blue lights) and appropriately control ing day-time light intensity.