水稻成熟衰老期叶际及根际氮氧化物排放的光控机制

Impacts of Light Quality and Intensity on Nitrogen Oxide Gas Emissions of Rice Phyllosphere and Rhizosphere at Mature Aging Stage

为研究水稻成熟衰老期叶际及根际NOGs(nitrogen oxides gases,氮氧化物)排放的光控机制,在同步测定条件下,采用密闭箱法,研究了不同光质(黄、绿、白、红、蓝光)、光强〔0.00、(50.00±2.35)(75.00±2.32)(100.00±3.89)μmol/(m2·s)〕对水稻成熟衰老期叶际及根际NOGs排放的影响.结果表明:在相同氮源〔NH4NO3-N,ρ(N)为90 mg/L〕下,日间光强为(75.00±2.32)μmol/(m2·s)时,水稻成熟衰老期叶际N2O和NO的平均排放速率分别为18.09、0.39μg/(pot·h),二者排放量分别占各自总排放量的28.88%、30.78%;在(100.00±3.89)μmol/(m2·s)光强条件下,叶际N2O和NO的平均排放速率则分别为23.27、0.50μg/(pot·h),二者排放量分别占各自总排放量的36.74%、27.92%.在0.00^(100.00±3.89)μmol/(m2·s)日间光强下,水稻叶际及根际N2O和NO排放随随光强增加而增强,但不同光照条件下水稻叶际及根际均无明显的NO2净排放作用.在光强一致〔(20.00±0.48)μmol/(m2·s)〕条件下,同期黄、绿、白、红、蓝光处理的水稻叶际N2O平均排放速率分别为24.90、15.46、13.85、16.40和19.77μg/(pot·h),红、蓝光在抑制水稻叶际N2O及根际NO排放的同时,也促进了水稻根际N2O的排放.研究显示,水稻成熟衰老期叶际及根际NOGs排放均以N2O为主,叶际N2O的排放可以反映根际N2O的排放情况.光照越强,NOGs排放就越明显.适度控制日间光强并增加红、蓝光比例,可抑制N2O和NO排放.

In order to understand the contribution of mature aging rice plants to nitrogen oxides gas（ NOGs） emissions while parsing the light quality and intensity control mechanism,NOGs emissions from rice phyllosphere and rhizosphere and their relationship to light quality and intensity were investigated at mature aging stage. With controlled N and light conditions in a light-water incubator,with separation of the inner and outer chamber of the incubator,the experimentation strictly separated and sealed the phyllosphere in the inner chamber and the roots in the outer chamber with no effective harm occurring on the rice plants. For different weak light qualities（ e. g.,yellow,green,white,red and blue lights） and intensities（ e. g.,dark,0. 00; weak,（ 50. 00 ± 2. 35） μmol/（ m2·s）; moderate,（ 75. 00 ±2. 32） μmol/（ m2·s）; strong,（ 100. 00 ± 3. 89） μmol/（ m2·s））,using double-chamber method,a simultaneous leaf and root determination was designed to measure the source of NOGs emissions. The results showed that： under a constant nitrogen nutrient（ ρ（ N） = 90 mg/L,NH4NO3-N） when rice seedlings were treated with moderate（（ 75. 00 ± 2. 32） μmol/（ m2·s）） and strong light（（ 100. 00 ±3. 89） μmol/（ m2·s））,the average rates of N2 O and NO emission from rice phyllosphere were 18. 09,0. 39 μg/（ pot·h） and23. 27,0. 50 μg/（ pot·h）,respectively,accounting for 28. 88%,30. 78% and 36. 74%, 27. 92% of the total N2 O and NO evaporation loss for the whole rice plant. This result suggests that rice phyllosphere is an important source of N2 O and NO emissions in paddy fields at mature aging stage. More than 99% of NOGs release from rice phyllosphere and rhizosphere was N2 O,but no evident NO2 emission was detected under the same condition.Under a constant light intensity（ 20. 00 μmol/（ m2·s））,N2 Oemissions of rice phyllosphere in yellow,green,white,red and blue lights were 24. 90,15. 46,13. 85,16. 40 and 19. 78 μg/（ pot·h）,respectively. The N2 O emission of rice phyllosphere and NO emission of rice rhizosphere could be inhibited by red and blue light compared with the results for yellow light（ P 〈 0. 05）,but the N2 O emission of rice rhizosphere could be promoted by red and blue light synchronously under the same condition. There was no significant difference in NO emission of rice phyllosphere under different light qualities. Compared to green or yellow light,NO emission of rice rhizosphere decreased significantly under white,red and blue light. Both the N2 O and NO emissions of rice phyllosphere and rhizosphere could be promoted by moderate and strong light compared with the results for dark or weak illumination. In summary,the main NOGs release from rice phyllosphere and rhizosphere was N2 O. The higher the intensity of light was,the more NOGs the emissions. The N2 O emissions of phyllosphere could reflect the N2 O emissions of rhizosphere.By adjusting the composition of visible light to a modest technical measure of increasing the red and blue light proportions and synchronously controlling each light intensity,the light qualities and intensities could be always beneficial to inhibit N2 O and NOx（ NO,NO2） emissions of rice rhizosphere and phyllosphere at the mature aging stage.