| Global warming is an important environmental problem we are facing in agricultural production,and the asymmetric diurnal warming is one of the main characteristics of global climate change.Climate warming has increased the instability of agricultural production.Enhancing stability is an important measure to deal with climate change.Increasing biodiversity can increase system stability.Rice and winter wheat are the main food crops in China,and rice-wheat rotation is an important planting model in China.Nighttime warming effects on rice and winter wheat production,CH4and N2O emissions,and had an impact on the greenhouse effect.Intercropping can increase rice yield,but it is still unclear how it affects the emissions of CH4and N2O in paddy fields.Intercropping under nighttime warming,further carried out regional rice-wheat system comprehensive greenhouse effect assessment and emission reduction assessment,and improved agricultural production capacity to cope with global climate change.With two-factor randomized block design,field experiment was conducted to investigate intercropping effects on rice and winter wheat yield,CH4and N2O global warming potential and greenhouse gas emission intensity under nighttime warming,and performed at the Station of Agricultural Meteorology,Nanjing University of Information Science and Technology,Nanjing,China.The tested paddy soil was classified as a Typic Stagnic Anthrosol.Nighttime warming was designed with 2 levels,i.e.control（CK,control）and warming（NW,nighttime warming）;intercropping was designed with 3 levels,i.e.intercropping（IC）,main plant（MP）and secondrry plant（SP）.The rice intercropping was treated by transplanting at 3:1 ratio of main planting cultivar（Super cv.nanjing 9108）to secondary planting cultivar（Hybrid cv.shenliangyou 884）.The winter wheat intercropping was treated by transplanting at 3:1 ratio of main planting cultivar（Zhenmai12）to secondary planting cultivar（Sumai 188）.During the rice and winter wheat growing season,nighttime warming was treated by covering the rice canopy with an aluminum foil reflective film at night（19:00-6:00）.The main findings are listed as follows:（1）Growth and yield of rice and winter wheatNighttime warming significantly reduced the tiller number,plant height,above-ground biomass,below-ground biomass and yield of rice;nighttime warming significantly increased the tiller number,plant height,above-ground biomass and yield of winter wheat,but there were differences in different growth periods.Intercropping promoted the tiller number per plant,the plant height at heading stage-maturity stage,ear biomass,below-ground biomass and yield,but inhibited the plant height at rice tillering-joining stage,the biomass of stem and leaf;intercropping significantly increased the tiller number per plant,booting stage-maturity stage plant height,flowering stage-maturity stage stem,leaf biomass,ear biomass and yield,but decreased planting stage-joining stage biomass of stems and leaves at heading stage.（2）CH4and N2O emission in rice-wheat rotated soilNighttime warming and intercropping did not change the seasonal trend of rice-wheat CH4and N2O emission flux.Nighttime warming significantly increased the CH4and N2O emission fluxes and accumulated emissions in paddy soil,but there were differences in different growth periods.Nighttime warming significantly increased the CH4absorption flux,N2O emission flux,and cumulative N2O emissions from the wheat field soil during the jointing-flowering periods,but reduced the cumulative CH4emissions from the wheat field soil.Intercropping significantly increased the CH4,N2O emission fluxes and cumulative emissions from paddy soils.Intercropping significantly increased wheat field N2O emission flux,cumulative CH4and N2O emissions,but reduced wheat field soil CH4absorption flux.（3）Rice-wheat system global warming potential（GWP）and greenhouse gas emission intensity（GHGI）CH4GWP dominates the comprehensive warming potential of paddy fields,and nighttime warming and intercropping significantly increase the global warming potential of CH4and N2O.N2O warming potential is the main part of comprehensive warming potential in wheat field comprehensive warming potential.Nighttime warming increases the CH4absorption flux in the early growth stage and the CH4emission flux in the later growth stage,so the global warming potential is reduced,the N2O global warming potential is increased,and intercropping increased the wheat field’s comprehensive global warming potential.Paddy field global warming potential contribution is higher in integrated greenhouse effect of rice-wheat system.Nighttime warming and intercropping significantly increased the potential of rice-wheat comprehensive warming.The rice-wheat system GHGI is mainly concentrated in rice field GHGI.Nighttime warming increased the GHGI of rice fields and rice-wheat systems,while the GHGI of wheat fields decreased.Intercropping significantly enhanced the rice-wheat system GHGI.Intercropping significantly increased the yield of rice-wheat rotation crops,GHGI in rice fields,and reduced GHGI in wheat fields under nighttime warming. |
