| Ratooning rice refers to the use of rice piles harvested after the first season of rice,through scientific fertilizer and water management measures,so as to make the dormant buds with low nodes germinate,grow into rice plants until they reach panicle maturity,and then harvest rice for another season.As a new planting mode,it is of great significance to adjust China's agricultural structure,guarantee food security and adapt to global climate change.At present,there have been in-depth studies on the law of nutrient demand,fertilization period and nitrogen fertilizer operation of ratooning rice at home and abroad,but most of the studies ignored the effect of ratooning rice planting process on greenhouse gas emission in rice field.To this end,this study carried out a two-year field experiment in Zhefu village,Jianli county,Jinzhou city,Hubei province in 2018 and 2019.Two groups of experiments were carried out on the regenerated rice LY 6326:reduced fertilization with nitrification inhibitor and slow release fertilizer.A total of eight processing:CK?no fertilizer control?,FF?farmers high yield and fertilizer?and DF1?reducing fertilizer treatment 1?,DFD1?reducing fertilizer treatment 1 and nitrification inhibitors?,DF2?reducing fertilizer treatment 2?,DFD2?reducing fertilizer treatment 2 and nitrification inhibitors?,SRF1?special slow-release fertilizer I processing?,SRF2?special slow-release fertilizer II processing?,research on ratooning rice yield and its component,ratooning rice growth and the influence of the paddy greenhouse gas emissions.The main results are as follows:?1?CH4 emission of LY 6326 was mainly concentrated in the first season,2 emission flux peaks appeared at tillering stage and booting stage,and CH4 emission flux in the regenerative season was relatively low.The peak emission of N2O in the whole growth period mainly occurred during each fertilization and water drying.Compared with FF treatment,the cumulative emissions of CH4 and N2O treated by DF1,DFD1,DF2 and DFD2were reduced by 5.94%?14.34%and 12.88%?32.65%respectively.The lower the fertilizer application,the lower the cumulative emissions of CH4 and N2O.At the same fertility level,the addition of DMPP reduced the generation of CH4 and N2O by 4.66%?6.05%and 2.83%?18.85%,respectively.The treatment of SRF1 and SRF2 also reduced the CH4 emission from the rice field to 51 kg/hm2?86 kg/hm2,with a decrease of 10.20%?24.38%,and a decrease of 0.15 kg/hm2?0.31 kg/hm2,with a decrease of 10.20%?23.49%.?2?Compared with FF treatment,weight loss treatment and slow-release fertilizer treatment reduced global warming potential?GWP?by 262 kg CO2-eq./hm2?1320 kg CO2-eq./hm2 and 1364 kg CO2-eq./hm2?2185 kg CO2-eq./hm2,respectively,with a decrease of4.31%?19.81%and 20.47%?35.96%.The greenhouse gas emission intensity?GHGI?was reduced by 1.95%?13.47%and 19.98%?35.00%,respectively,after weight loss treatment and slow-release fertilizer treatment.?3?Compared with FF treatment,DF1 fertilization reduced by 0.6%?1.6%and 1.6%?4.5%in two years,respectively,showing no significant difference.In the middle of 2019,the output of DF2 and DFD2 treatments was reduced by 8.6%and 7.1%,respectively,compared with that of FF treatments.Among them,the difference in the yield components of the first rice was mainly manifested in the number of effective panicle,and the four weight loss treatments were 11.60%,9.94%,24.31%and 24.86%lower than the FF treatments,respectively.The difference of yield components in the regeneration season was mainly manifested in the number of effective panicle and total grains per panicle,among which,the number of effective panicle and total grains per panicle treated by DF2 and DFD2 were significantly different from those treated by FF,DF1 and DFD1.SRF1 and SRF2 were reduced by 0.4%?1.2%?2018?and 0.53%?+0.53%?2019?respectively compared with FF treatment,with no significant difference.The difference in yield components of the first rice under the special slow-release fertilizer treatment was mainly manifested in the effective panicle number.Compared with FF treatment,SRF1 and SRF2treatments significantly increased the effective panicle number,but reduced the seed setting rate and 1000-grain weight.Compared with FF treatment,SRF1 treatment significantly increased the number of effective panicle,but had little impact on the other three yield components.SRF2 treatment reduced the number of effective panicle and the total number of grains per panicle,but increased the seed setting rate and 1000-grain weight.?4?Compared with FF treatment,plant height and tiller number under DF1 and DFD1treatments were slightly reduced,but no significant difference was found.However,DF2 and DFD2 treatments significantly reduced the plant height and tiller number.SRF1 and SRF2 treatments had little effect on tillering stage,but the plant height and tiller number were increased at full panicle stage and mature stage.?5?In the experiment of weight loss,the number and area of vascular bundles between panicle and neck decreased with the increase of weight loss gradient.In the experiment of slow release fertilizer,the number and area of vascular bundles between the two slow release fertilizers were increased to a certain extent compared with FF treatment.?6?Under the condition of weight loss experiment,the contribution rate of stem sheath NSC output in the first season to panicle weight was 10.00%?13.94%.Compared with FF treatment,the transfer volume,transfer rate and contribution rate of stem sheath NSC under DF1 and DFD1 treatment were significantly higher.However,DF2 and DFD2 treatments were lower than FF treatments;The contribution rate of NSC output to ear was between26.65%and 41.45%.In the special slow-release fertilizer test,the contribution rates of stem sheath and leaf NSC output to ear under SRF1 and SRF2 treatments were 12.20%,13.24%,1.19%and 1.06%,respectively,lower than those under FF treatment,while the contribution rates of NSC output of regenerated stem sheath and leaf were 38.85%,33.14%,2.15%and2.62%,respectively,higher than those under FF treatment.To sum up,DF1,DFD1 treatment and slow-release fertilizer formula treatment can significantly reduce greenhouse gas emissions and global warming potential without significantly reducing rice yield.In addition,compared with the high-yielding fertilization treatment of farmers,the reduced amount of fertilization:N decreased by 13.00%,P2O5decreased by 16.67%,and K2O decreased by 8.33%.Slow release fertilizer:N increased by3.62%,P2O5 decreased by 26.67%,K2O decreased by 10.00%,and the number of fertilization times was reduced from 5 times to 3 times.These light and simple cultivation measures can meet the development requirements of China's new rice production model of high quality,high efficiency,green,light and simplified,and can be used as a feasible optimal rice cultivation technology model in the middle and lower reaches of the Yangtze river. |
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