Reduction Methane Emission From Paddies Planted With SUSIBA2 Rice

Atmospheric methane(CH4)is one of most significant greenhouse gas next to CO2.It has 25 times the global warming potential of CO2.Rice paddy is one of important artificial source.Worldwide emission from rice has been extrapolated to be from 50 to 60 Tg per year,accounting for 15%in total CH4 emission.Emission from rice paddies has to be one of the important reasons leading to increasing CH4 concentration in atmosphere.SUSIBA2 rice is both high-starch content and low-methane emissions in new breeding.There are two ways of the allocation of photosynthates in rice——the seeds and CH4 emissions.SUSIBA2 rice has been added to a single transcription factor gene,barley SUSIBA2,favouring the allocation of photosynthates to aboveground biomass over allocation to roots.The altered allocation resulted in an increased biomass and starch content in seeds and stems,and suppressed methanogenesis,possibly through a reduction in root exudates.In a previous study,three field trials in China(Fu jian,Guang xi and Guangdong)demonstrated that the cultivation of SUSIBA2 rice was associated with a significant reduction in methane emissions.This study was conducted to gain the information about seasonal variation of CH4 emission from SUSIBA2 rice and the population variation between methanogens and methanotrophs,for indicating the mechanism of the reduction of CH4 emission from SUSIBA2 rice to accumulate experimental data.It was observed that the seasonal trend both of Nipp and SUSIBA2 rice are similar at all growth periods in different cropping seasons.CH4 emission from early rice paddies increased with growing vegetable periods and the maximum value was in mature period.CH4 emission from rice paddies in late cropping season were two peaks in the elongation-heading stage and the filling period respectively.CH4 emission from SUSIBA2 rice paddies was significantly lower compared with Nipp at all vegetable stages.The mitigation rate of CH4 from early rice paddies was(14.3±2.4)%～(76.6± 12.4)%,and that from late rice paddies was(12.4±3.4)%～(92.7±2.7)%.The maximum value of mitigation rate was in the riping stage and the filling stage,respectively.Six methanogens and two methanotrophs of soil at the roots in double cropping seasons were dectected,resulting that the abundant of methanogens and methanotrophs in SUSIBA2 rice was siginificantly lower than Nipp.The abundance reduction of Methanosaetaceae is highest in the root of SUSIBA2 rice.The decreasing trend of reduction gene abundance were Archaea、Methanomicrobiales、methanogens、Methanobacteriales.And Methytobacter/Methylosarcina was signigicantly lower than the other.There were measurements,statistics and comparison for phenotype of Nipp and SUSIBA2 rice in double cropping seasons.For early rice,SUSIBA2 rice significantly increased number of panicles,dry weight of aboveground,dry weight of filled grains and number of filled grains.For late rice,SUSIBA2 rice only significantly increased number of panicles.Dry weight of aboveground,dry weight of filled grains and number of filled grains were similar in the late experimental plots planted with SUSIBA2 rice and Nipp.This study shows that mitigation potential of CH4 emission from SUSIBA2 rice is not affected by growth periods and cropping seasons.Gene abundances of methanogens and methanotrophs were detected to testify reduction C content in SUSIBA2 rice roots.