Effects Of Different Nitrogen Forms Treatments On The Physiological Characteristics Of Meconopsis Racemosa And Soil Rhizosphere Soil Ammonia Oxidation Microorganism

In this study,half-year-old seedlings of Meconopsis racemosa was used as the experimental material.Nitrate nitrogen,ammonium nitrogen,ammonium nitrate nitrogen and glycine were used for fertilization at concentrations of 20mmol/L and40mmol/L.we measured morphological indexes of seedlings such as plant height,vanne number,maximum leaf length,maximum leaf width,plant dry weight,fresh weight and photosynthesis and chlorophyll fluorescence parameters of seedlings and physical and chemical properties of soil such as soil p H,electrical conductivity(EC),ammonium nitrogen,nitrate nitrogen,total nitrogen content and Ammonia-oxidizing microbial abundance including AOA abundance and AOB abundance respectively after0d,20d,40d,60d.It is concluded the variation of the indexes under different concentrations of different nitrogen forms to provide a reference for Meconopsis racemosa seedling fertilization.The results are as follows:(1)The effect of different nitrogen forms on the phenotype of Meconopsis racemosa:The application of nitrogen fertilizers with different nitrogen forms can significantly promote the growth of plant height,leaf number,maximum leaf length,leaf width,and dry and fresh weight of Meconopsis racemosa seedlings(P<0.05).Nitrogen at a concentration of 20mmol/L is more effective than nitrogen at a concentration of 40mmol/L.The promoting effect on the phenotype of Meconopsis racemosa was the best with 20mmol/L ammonium nitrate nitrogen.Ammonium nitrogen under the single nitrogen form was more conducive to the increase of plant height,dry weight and fresh weight of leaves,while nitrate nitrogen was more conducive to the growth of leaf length and leaf width.Glycine had the weakest promoting effect on the phenotype,and high concentration of glycine inhibit the growth of Meconopsis racemosa seedlings.(2)The effect of different nitrogen forms on chlorophyll fluorescence parameters of Meconopsis racemosa:Except glycine,nitrogen fertilizers of other three nitrogen forms can significantly increase the Fm,Fv/Fm,Fv/Fo,Fm/Fo,q P and Y(II)of Meconopsis racemosa leaves,and reduce the NPQ of leaves(P<0.05),among which20mmol/L ammonium nitrate nitrogen has the strongest promoting effect.Glycine had inhibitory effects on Fv/Fm,Fv/Fo,and Fm/Fo,while the promoting effects of ammonium nitrogen and nitrate nitrogen in 40mmol/L were not significant.(3)The effect of different nitrogen forms on photosynthetic parameters of Meconopsis racemosa:Except glycine,nitrogen fertilizers with different nitrogen forms could significantly increase Pn,Gs and Tr of Meconopsis racemosa leaves,and decrease Ci of leaves(P<0.05).Compared with nitrogen forms,WUE is more influenced by nitrogen concentration,and nitrogen fertilizer of 40mmol/L can promote the increase of WUE.The effect of 20mmol/L ammonium nitrate nitrogen was the best among the four treatments,and the effect of ammonium nitrogen was better than nitrate nitrogen under single nitrogen form.(4)The effect of different nitrogen forms on the physical and chemical properties of cultivated soil:nitrogen fertilizers with different nitrogen forms can significantly improve soil EC,TN,NH₄⁺-N and NO₃^--N(P<0.05).40mmol/L can promote the change of p H and soil EC more than 20mmol/L.Ammonium nitrogen,nitrate nitrogen and ammonium nitrate nitrogen can significantly reduce soil p H,while glycine can promote the increase of soil p H.The accumulation effect of ammonium nitrogen on TN and NH₄⁺-N was better,while nitrate nitrogen was more beneficial to the accumulation of NO₃^--N in soil.(5)The effect of different nitrogen forms on ammonia-oxidizing microbial abundance of cultivated soil:The AOA abundance is always greater than AOB,and AOA abundance increase significantly over time(P<0.05),the AOB abundance increased first and then decreased over time,AOB/AOA decreased significantly over time(P<0.05),the different nitrogen forms of nitrogen fertilizer can promote the AOA and AOB abundance,the higher the concentration of nitrogen promote AOA abundance stronger.(6)Under different nitrogen forms,plant,soil and ammonia-oxidizing microorganisms are interrelated.Ammonium nitrogen and the soil physicochemical index have the greatest correlation with plant growth,while AOA abundance and amo A gene abundance have the greatest correlation with plant growth,which is positively correlated with fresh weight,dry weight,plant height and leaf number.The soil physical and chemical index most related to microbial abundance is soil EC,which is positively correlated with AOA abundance,total amo A gene abundance and AOB/AOA.