Effects Of Nitrogen Fertilizer Management On Yield,Nutrient Uptake And Quality Of Rice In Saline-alkaline Soil

With the breeding of saline-alkaline resistant rice varieties and the popularization of cultivation techniques,the planting area of rice is expanding continuously in saline-alkaline soil.In order to improve the yield of rice in saline-alkaline soil,farmers often apply more nitrogen fertilizer than conventional paddies,and the applying nitrogen fertilizer period is uncertain,which limits the stable yield and sustainable development in saline-alkaline soil to some extent.Therefore,in this study,Kenjing 7 and Kenjing 8,were used to investigate the effects of N fertilizer management on yield,nutrient absorption,and quality of rice in soda saline-alkaline soil.The plants were assigned to the following five treatment groups: no N fertilizer,farmers conventional,balanced,reduced,and postponed N fertilizer management.In order to provide theoretical basis for high yield and quality rice cultivation in soda saline-alkaline soil.The main results were as follows:1.Compared with N1,N2 increased the panicle and spikelets per panicle of the two varieties,and the actual yield was significantly increased by 11.11 %.The seed setting rate and 1000-grain weight of N3 increased by 4.08 % and 2.76 % respectively,and the actual yield was significantly increased by 5.54 %.Spikeles per panicle in different grain positions showed medium grain > superior grain > inferior grain,and the seed setting rate and 1000-grain weight showed superior grain > medium grain > inferior grain.2.The panicle length and single panicle weight were the highest under N2,followed by N3,and both of them were higher than N1.N2 and N3 also increased the number of primary and secondary branches in each part,and the results of N4 were opposite.The number of the primary branches was as follows: lower position> middle position > upper position,while secondary branches showed: middle position > lower position > upper position.3.Compared with N1,N2 and N3 increased leaf area index,net photosynthetic rate,stomatal conductance and transpiration rate at full heading stage and filling stage,as well as the population dry matter weight of full heading stage,filling stage,mature stage and dry matter output,output rate and conversion rate of each organ,and all the above indexes had great influence under N2.4.The accumulation of N,P and K in above-ground plants was the highest with N2,which was significantly increased by 35.39 %,27.38 % and 26.21 %,respectively,compared with N1,followed by N3,which was significantly increased by 12.97 %,12.67 % and 10.39 %,respectively.N2 and N3 also increased the N(P,K)transfer volume,apparent transfer rate,transfer contribution rate of leaves and stems,and nitrogen uptake efficiency,nitrogen agronomic utilization rate,nitrogen contribution rate and nitrogen partial productivity,and reduced the soil nitrogen dependence rate.5.N2 and N3 raised brown rice percentage,milled rice percentage and head rice percentage,but reduced chalky grain rate,chalkiness and phytic acid content,also improved the protein and 17 amino acids and Cu,Mn,Fe,Na,Ca and K content,improved the grinding quality,appearance quality and nutritional quality.N2 increased the completeness and starch content,and decreased cooking and eating quality.N3 reduced amylose content,increased amylopectin and total starch content,and improved the cooking and eating quality.N4 reduced the grinding,appearance and cooking quality,but improved the nutritional quality of rice.