Effects Of Nitrogen Fertilizer Management On Nitrogen Utilization,Quality And Grain Yield Of Rice Under Drill Seeding

In order to study the effects of nitrogen fertilizer management on the yield,quality and growth characteristics of rice under drill seeding,this experiment,after two years,chose rice variety 702 in the first year,with 4 nitrogen application rates(190kg/hm2,215kg/hm2,240kg/hm2,265kg/hm2)and 3 fertilization ratios(bottom fertilizer: tiller fertilizer: jointing fertilizer =0:7:3,3:5:2,5:5:0).In the second year,rice varieties tonghe836 and shennongdao 546 were selected,with three fertilizer rates(161.5kg/hm2,190kg/hm2,218.5kg/hm2)and three fertilizer ratios(base fertilizer:(seed fertilizer + tiller fertilizer): jointing fertilizer: panicle fertilizer =5:5:0:0,4:3:2:1,0:5:3:2).Rice yield and its components,rice quality,nitrogen uptake and utilization,lodging traits,photosynthetic characteristics,dry matter accumulation and population growth were studied.1.Effects of nitrogen fertilizer management on rice yield and its components in dry direct seedingThe maximum yield in 2018 was 8.68t/hm2,which appeared in NF2(215kg/hm2)nitrogen application rate FF2(3:5:2)fertilization ratio.The maximum annual output of 2019 is 10.20t/hm2,which appears under NS2(190kg/hm2)nitrogen application rate FS2(4:3:2:1)fertilization ratio.In two years,the nitrogen application rate of dry direct seeding rice was 190kg/hm2,and the fertilization ratio was forward,middle and rear stable: base fertilizer(seed fertilizer + tiller fertilizer): jointing fertilizer: panicle fertilizer 4:3:2:1 was the best nitrogen application combination.The effective panicle number was consistent with the yield and was positively correlated with the yield,and the grain number per panicle,seed setting rate and 1000-grain weight were less affected by nitrogen application.2.Effects of nitrogen fertilizer management on rice quality in dry direct seeding riceThe application of nitrogen fertilizer can affect the processing quality,appearance quality,nutrition quality and taste value of rice.The processing quality of dry direct seeding rice was improved after nitrogenous fertilizer was applied.The brown rice rate,milled rice rate and whole milled rice rate of each variety increased first and then decreased with the increasing of nitrogen application,which was the best under the nitrogen application rate of 190kg/hm2.Chalky grain rate and chalkiness increased obviously.With the increase of nitrogen application and amylose content decreased protein content also increased.The increase of nitrogen fertilizer will reduce the taste value.Proper nitrogen fertilizer can improve the processing quality,appearance quality,nutritional quality and taste value of dry direct rice,but this experiment shows that the treatment without base fertilizer can reduce the rice quality.In the first year,NF1(190kg/hm2)-FF2(3:5:2)and NS2(190kg/hm2)-FS2(4:3:2:1)were the best nitrogen fertilizer combinations for dry direct seeding rice quality.3.Effects of nitrogen management on nitrogen absorption and utilization in dry direct seeding riceNitrogen fertilizer management can affect the nitrogen absorption and utilization efficiency of dry rice.After proper application of nitrogen fertilizer,the accumulation of nitrogen in different parts of dry direct seeding rice tended to increase,and appropriate nitrogen fertilizer would also promote the accumulation of nitrogen in different parts of rice.Under the ratio of 3:5:2 and 4:3:2:1 fertilization,the accumulation of nitrogen in different parts of rice was higher.The increased application of nitrogen fertilizer reduced the nitrogen utilization efficiency of each variety and increased the productivity of the partial factor of nitrogen fertilizer,while the utilization rate of nitrogen fertilizer increased first and then decreased with the increase of nitrogen application.The nitrogen use efficiency,nitrogen agronomic use efficiency,nitrogen fertilizer slant factor productivity and nitrogen fertilizer use efficiency were higher under the ratio of 3:5:2 and 4:3:2:1.Nitrogen uptake and utilization efficiency is the best combination of nitrogen application at 190kg/hm2 with 4:3:2:1 or 3:5:2 fertilization.4.Effects of nitrogen fertilization on lodging traits of rice in direct seeding during droughtThe yield resistance of dry direct seeding rice decreased with the increase of nitrogen application,while the lodging index increased with the increase of nitrogen application.The yield resistance was the largest and lodging index was the smallest under the treatment of NF1(190kg/hm2)and NS1(161.5kg/hm2).In terms of fertilization ratio,FF2(3:5:2)and FS2(4:3:2:1)had the highest yield and the lowest lodging index.5.Effects of nitrogen fertilization on photosynthetic characteristics and population growthNitrogen fertilization had a great influence on the photosynthetic characteristics of dry rice.The net photosynthetic rate of rice was improved by increasing nitrogen application,but the net photosynthetic rate of rice was affected by too much nitrogen application.The two varieties had the highest net photosynthetic rates under the nitrogen application ratio FS2(4:3:2:1)with NS2(190kg/hm2).The leaf area index(lai)of the two varieties increased first and then decreased with the increase of nitrogen application,and the lai was highest when the nitrogen application rate of NS2(190kg/hm2)was FS2(4:3:2:1).The population transmittance of dry rice could be decreased by increasing nitrogen fertilizer.The SPAD value of dry direct seeding rice was the highest under FS2 fertilization ratio(4:3:2:1)under NS2(190kg/hm2)nitrogen application rate.In general,the photosynthetic characteristics of nitrogen application combinations with NS2(190kg/hm2)and FS2(4:3:2:1)were the best.