Effects Of Different Nitrogen Forms On Potato Growth And Soil Microecology

China is the largest potato producer in the world,the planting area and potato yield of China occupy first place in the world,while the average yield of China is lower than that of the world.In potato production,fertilization is an important measure to achieve high yield,especially nitrogen fertilizer.In orde to investigate the effects of different nitrogen forms on potato growth and soil microecology,this study used the potato variety"Xingjia"as the test material,and set up four nitrogen form treatments:CK(no nitrogen),Nitrate(potassium nitrate),Ammonium(ammonium sulfate),Amide(urea).The effects of different nitrogen forms on potato rhizosphere environment were studied from the perspective of soil bacterial community structure by using metagenomic sequencing technology,and then the indicators were evaluated comprehensively.The aim was to provide basis and data support for accurate application of nitrogen fertilizer in potato.The main results of this study were as follows:1.The effects of different nitrogen forms on potato growth,yield and qualityCompared with Ammonium and Amide treatments,Nitrate treatment can promote the growth of shoots and leaves more,and potato plant leaf area and dry matter quality are the largest.The tuber yield of Nitrate treatment was 2647.92 kg/666.7m~2,which was significantly higher than other treatments.Therefore,potatoes were considered to be nitrate-loving crops.The soluble sugar content,vitamin C content and nitrite content of potato tubers in Nitrate treatment were significantly higher than that of in other nitrogen treatments.The cadmium content of potato tubers was the highest in Ammonium treatment.2.The effects of different nitrogen forms on the soil physical-chemical properties and soil enzymes of potatoThe soil pH,available potassium content,and organic carbon content were the highest in Nitrate treatment,which was significantly higher than in other treatments.Different nitrogen forms have different effects on potato rhizosphere soil enzyme activity.Urease activity is highest in Amide treatment.Invertase activity is highest in Ammonium treatment.Catalase activity is highest in CK treatment.From the correlation analysis,it can be seen that the yield has a very significant positive correlation with soil urease,invertase and acid phosphatase.3.The effects of different nitrogen forms on soil bacterial diversity and community structure of potatoIn this study,16s sequencing analysis was performed on the soil bacterial community structure,and the results were as follows.(1)In Nitrate treatment,abundance and diversity of bacterial species were more than in other nitrogen treatment.According to the principal component analysis,the bacterial community structure of the Amide and Ammonium treatment soils were similar in the potato tuber expansion period and the potato starch accumulation period.The bacterial community structure of the Amide and Nitrate treatment soils were similar in the potato maturity period.(2)At the phylum level,the first three phyla with the highest abundance of dominant phyla in different nitrogen forms soil in the three periods of potato were Proteobacteria,Acidobacteria and Actinobacteria.Combining the three periods of potato,the oligotrophic bacteria"Acidobacteria"was more abundant in the Ammonium treatment soil than in other soils,and the eutrophic bacteria"Proteobacteria and Actinobacteria"were more abundant in the Nitrate treatment soil.It showed that the bacteria that prefered nutrient-rich soils were more abundant in Nitrate treatment soil.The potato soil fertility was higher in nitrate treatment.(3)At the genus level,ANOVA analysis was used to analyze the genus differences in different nitrogen treatments.Combining soil indicator bacterial species analysis and LEf Se analysis,bacterial genera that play a key role in each nitrogen treatment soil and can be used as indicator species were screened.Nitrate-treated soil included Sphingomonas,Pedobacter,Gemmatimonas,and Massilia.Ammonium-treated soil included Geobacter,Anaeromyxobacter,Nitrospira and MND1.Amide-treated soil contained Rhodoferax and Areimonas.(4)Different nitrogen forms had a significant effect on the C and N-related dominant functional genera in the soil.Nitrate treatment soil had more aerobic bacteria species than other treatments,and the relative abundance of aerobic bacteria Mesorhizobium with nitrogen fixation effect was higher than other treatments,which indicated that Nitrate treatment soil had more active metabolic capacity of organic and inorganic matter.The relative abundance of Nitrospira with aerobic nitrite oxidation effect,Geobacter with nitrate respiration effect in Ammonium treatment soil have higher than that of in other treatment soils.The relative abundance of Mizugakiibacter with nitrate respiration effect,Arenimonas with aerobic chemoheterotrophy effect and nitrate reduction effect in Amide treatment soil have higher than that of in other treatment soils.It showed that nitrite was easy to accumulate in the soil under the treatment of Ammonium and Amide,which was not conducive to the growth of potatoes.(5)According to the correlation between soil bacterial community and soil physical-chemical properties,OC and AN were the most significant physical-chemical factors that changed the structure of bacterial communities in the three periods of the potato.Rhodanobacter in soil was the most affected by soil physical and chemical factors.