| Climate warming is one of the main characteristics of global climate change.Climate warming is characterized by asymmetric warming,that is,nighttime temperature increases greater than daytime.The increase in atmospheric greenhouse gas concentration caused by human activities is the main reason for climate warming.Agricultural production is an important source of greenhouse gas methaane（CH4）and nitrous oxide（N2O）emissions.Rice and wheat are major food crops in China.How to reduce greenhouse gas emissions from rice and wheat fields under ensuring food security is an effective path for low-carbon production of rice and wheat to cope with climate change.Silicon fertilizer or biochar application significantly affected rice and wheat production and CH4 and N2O emissions,but the effect of silicon fertilizer and biochar under nighttime warming is still unclear.In this paper,the effects of biochar and silicon fertilizer on the growth,yield and CH4 and N2O emissions of rice and wheat under nighttime warming were studied by field simulation experiments.It is of great scientific significance to estimate the greenhouse gas emission intensity and global warming potential of rice-wheat rotation farmland.The field simulation experiment was carried out in the experimental field of Agricultural Meteorological Experiment Station of Nanjing University of Information Technology from November 2020 to November 2021.In this paper.a three-factor and three-level orthogonal experimental design was used The tested soil was a retention paddy soil,and the tested rice and wheat varieties were Nanjing 5055 and Sumai 188,respectively.Nighttime warming（19:00～6:00）was simulated by covering rice and wheat canopy with aluminum foil reflective film at night Three levels of warming were set:W0（normal temperature control,no covering aluminum foil film）,W1（covering 5 mm aluminum foil film）and W2（covering 11 mm aluminum foil film）.Three levels of biochar application were set as B0（no biochar application）,B1（10 t/ha biochar application）and B2（25 t/ha biochar application）;three levels of silicate fertilizer were set,namely,SiO（no silicate fertilizer）,Sil（200 kg/ha steel slag silicate fertilizer）and Si2（200 kg/ha mineral powder silicate fertilizer）.The main research results are as follows:（1）Nighttime warming effect and the growth of rice and wheatDuring the main growth periods of rice and wheat,the 5 mm reflective film and 11 mm reflective film under the passive warming system can increase the nighttime average temperature of rice canopy by 0.12℃ and 0.46℃,respectively,and increase the 5 cm soil layer by 0.12℃ and-1.47 ℃,and increase the wheat canopy by 0.44℃ and 0.14℃,respectively,and increase the 5 cm soil layer by 0.12℃ and 0.11℃.The application of biochar B1 and B2 increased the average temperature on rice canopy and 5 cm soil layer by 0.12℃,0 08℃ and 0.12 ℃.160℃,respectively,and increased wheat by 0.44℃,0.30℃and 0.12℃,0.01℃,respectively.Nighttime warming had inhibitory effect on plant height of rice,and significantly promoted plant height,leaf area index（LAI）and chlorophyll（SPAD）content of wheat.Application of biochar significantly increased plant height and LAI in rice,but also promoted wheat SPAD.Application of silicate fertilizer increased LAI and SPAD in rice and wheat.（2）Yield,yield composition and quality in rice and wheatNighttime warming significantly reduced the effective panicle number,grain number per panicle and yield（P<0.05）,with yield reduction rate was 19.66%-28.73%in rice,but it promoted the seed setting rate of rice,wheat yield and 1000-grain weight The application of biochar and silicate fertilizer could increase the yield in rice and wheat,mainly by promoting the grain number per panicle and seed setting rate.Night warming promoted the processing quality and nutritional quality in rice,but decreased the total starch and protein content in wheat Silicon fertilizer could improve rice processing quality,amylopectin and protein content,but had no significant effect on wheat protein content.Application of biochar could alleviate the adverse effects of nighttime warming on rice yield and nutritional quality The best economic and nutritional benefits in rice-wheat rotation were W1B2Si2（covering 5 mm reflective film at night,applying 25 t/ha biochar and 200 kg/ha mineral powder）and W1B1Si2（covering 5 mm reflective film at night,applying 10 t/ha biochar and 200 kg/ha mineral powder）.（3）Greenhouse gas emissions from rice and wheat fieldsNighttime warming,applying biochar and silicate fertilizer decreased the total warming potential（SGWP）and greenhouse gas emission intensity（GHGI）of CH4 and N2O.Biochar application had significant effects on - cumulative emissions from rice and wheat fields and N2O cumulative emission from rice field（P<0.05）.The total warming potential in rice field（SGWP）was significantly higher than that in wheat field,and CH4 cumulative emis sions played a dominant role in SGWP.The influence of the three factors on the total warming potential in rice field was in the order of B>Si>W,and the influence on the total warming potential in wheat field was in the sequence of Si>B>W.In overall consideration,the optimal treatment combination in this study was suggested as W1B2Si2,implying that applying 25 t/ha biochar and 200 kg/ha mineral powder will play a positive role in ensuring rice and wheat production and dealing with climate change under the background of climate warming. |
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