Effect Of Straw Returning And Nitrogen Application On Rice Growth And Yield

In order to explore the difference of rice yield formation mechanism and nitrogen fertilizer utilization rate in rice production under the condition of straw returning to the field,a reasonable nitrogen fertilizer application model on rice production in the north.In this experiment,the rice variety Jijing 88 was used as the test material,and a field test was conducted at the Rice Test Base of Jilin Agricultural University in Changchun,Jilin Province from 2018 to 2019.The split-plot experiment design was adopted.The main plot was straw returning(S)and no-straw returning(S0);the sub-plot?was the treatment of nitrogen fertilizer applications.Total amount of nitrogen fertilizer was 200 kg/hm~2,with treatments of different?proportion of base?fertilizer: tillering fertilizer: panicle fertilizer were?7:2:1(N1),6:3:1(N2),5:3:2(N3),and 4:3:3(N4),with no N?application as control(CK).It was set to study the effects of each treatment on dry matter accumulation,rice yield,yield composition factors?and nitrogen utilization efficiency.The following results were drawn as follows:1.In terms of photosynthetic characteristics of rice,the results of the two-year experiment showed the highest leaf color value(SPAD value),the leaf area index and net photosynthetic rate of N1 treatment under the condition of returning straw to the field.Under the condition of returning straw in the physiological maturity stage,the leaf color value of N1 treatment was 5.57% to 75.00% higher than that of other treatments,and the leaf area index was 1.27% to 57.43% higher.The net photosynthetic rate of N1 treatment was 1.76%?7.57% higher than that of other treatments under the condition that the straw was returned to the field during the filling stage.The N1 treatment under the condition of returning straw effectively slowed down leaf senescence,increased the net photosynthetic rate of rice,and laid the foundation for dry matter accumulation in rice.2.In terms of dry matter accumulation,under the same nitrogen fertilizer application model,the dry matter accumulation amount of rice from the tillering stage to the jointing stage was lower than that of non-returning treatment,the dry matter accumulation of the population from jointing to heading stage was higher than that of non-return treatment,in the heading to maturity stage,the dry matter accumulation was higher in the stage with only high base fertilizer treatment(N1,N2)than in the non-return treatment.Under the condition of returning straw,the performance of different nitrogen fertilizer application showed that as the proportion of base fertilizer in the total nitrogen application decreased,the dry matter accumulation of the group from jointing to heading,heading to maturity stage gradually decreased,and the dry matter accumulation of rice population under N1 treatment the amount was the highest,and it was significantly different from N4 treatment.3.In terms of rice yield and yield components,returning straw combined with appropriate nitrogen fertilizer application effectively increased rice yield.The results of the two years of experiments tended to be consistent,and all showed that under the condition of returning straw,with the reduction of the proportion of base fertilizer to the total nitrogen application,the yield of rice gradually decreased.The highest were 10.75 t / hm~2 and 9.60 t / hm~2 respectively.The number of spikelets per panicle of rice was 3.15% to 31.36% higher than that of other straw return treatments,and the effective panicle number was 1.50% to 26.05% higher.SN1 treatment significantly increased the number of spikelets per panicle of rice,increased the effective panicle number and seed setting rate,and then improved the rice yield.4.In terms of nitrogen utilization rate,returning straw combined with appropriate nitrogen fertilizer application has effectively increased rice nitrogen accumulation,the apparent nitrogen utilization rate,nitrogen agronomic utilization rate,and nitrogen partial productivity.The average total nitrogen accumulation of straw returning treatment was higher than that of non-returning treatment.Under the condition of returning straw,the performance of different nitrogen fertilizer application showed that with the reduction of the proportion of total nitrogen applied by the base fertilizer,the nitrogen fertilizer utilization efficiency gradually decreased,the N1 treatment had the highest apparent utilization rate,agronomic utilization rate,and partial productivity,which were 4.84% to 58.46%,1.50 to 19.75 kg / kg,and 2.50 to 19.75 kg / kg higher than other treatments under the condition of returning straw,the difference between N1 treatment and N4 treatment was significant.