Study On Nitrogen Metabolism Of Blueberry

In this experiment,blueberry cultivars‘Northland’and‘Spartan’were taken as the research objects,leaf,new shoot,annual branch,biennial branch and root system of fruit were used as test materials,total nitrogen,total protein,soluble protein,free amino acid content,glutamic-pyruvic transaminase,glutamic-oxalacetic transaminase and glutamine synthetase activities were determined,to study the annual cycle variation rule of nitrogen absorption and utilization in blueberry,and the effects of different nitrogen application rates on the growth and develop-ment of blueberry and nitrogen metabolism,using ¹⁵N tracer method,to study the absorption and utilization of different nitrogen sources in various organs of blueberry plant,to explore the requirement of blueberry for nitrogen fertilizer,it is expected to provide reference for rational application of nitrogen fertilizer and improvement of nitrogen fertilizer use efficiency in production,the results of the study are as following:1、The contents of total nitrogen,total protein,soluble protein,free amino acid and the activities of glutamic-pyruvic transaminase,glutamic oxalacetic transaminase and glutamine synthetase in leaves and shoots in the annual cycle of‘Northland’blueberry showed a trend of first increasing and then decreasing,the contents of total nitrogen,total protein,soluble protein,free amino acid and the activities of glutamic-pyruvic transaminase,glutamic-oxalacetic transa-minase and glutamine synthetase in roots and branches were firstly decreased and then increased,the contents of total nitrogen,total protein,soluble protein and free amino acid in fruit showed a trend of gradual increase,the activities of glutamic-pyruvic transaminase and glutamic-oxalac-etic transaminase first decreased and then increased,the activity of glutamine synthetase first decreased,then increased and then decreased.Metabolic activities of roots and branches of‘Northland’blueberry were weakened during dormant period,the content of various indicators decreased;after germination,the nitrogen content in leaves and shoots increased gradually,the total nitrogen content reached the maximum of 2.89%and 2.23%before and after May 2,respectively,the activity of glutamine synthetase in leaves reached the highest at this time,the soluble protein content reached the highest of 2.82 mg/g and 2.35 mg/g before and after May 20,respectively,at this time,nitrogen mainly acts on leaves and shoots,the contents of total nitrogen and total protein in root,phloem and xylem decreased continuously,the root total nitrogen content decreased to the lowest 1.32%around June 5,the total nitrogen content in phloem and xylem decreased to 1.18%and 1.05%around July 10,respectively;the nitrogen content in the fruit increased gradually after growth,in addition to the nutrients stored in the tree body,the nutrients provided by the leaves during photosynthesis are also supplied,therefore,the peak values of glutamic-pyruvic transaminase and glutamic-oxalacetic transaminase activities in leaves before and after July 10;then nutrients from the leaves begin to flow back into the tree and its roots,the nitrogen content in leaves decreased,nutrients gradually increase in the tree,store nutrients for the next year’s tree growth.2、Compared with no ammonium sulfate,treatment with nitrogen 20 g/plant,it can signif-icantly increase the plant height,stem diameter and bud quantity of‘Spartan’blueberry,at the same time,the content of total nitrogen,total protein,soluble protein,free amino acid,glutamic-pyruvic transaminase,glutamic-oxalacetic transaminase,glutamine synthetase activity of blueb-erry was the best,promote blueberry nitrogen metabolism.Nitrogen application of 40 g/plant could inhibit the activities of nitrogen metabolismrelated enzymes to a certain extent.At the same time,during the whole growing period,the nitrogen metabolism of blueberry showed a trend of increasing firstly and then decreasing,nitrogen metabolism was the highest at fruit ripening stage.3、In the annual cycle,the distribution of‘Northland’blueberry nitrogen in various organs of the tree was leaf>fruit>shoot>root system>phloem>xylem,the distribution of‘Spartan’blueberry nitrogen in various organs of the tree was leaf>fruit>shoot>root system>branch.4、Application of NH₄⁺-N and NO₃^--N fertilizer in blueberry production process can increase the biomass of blueberry,however,the NH₄⁺-N fertilizer effect is more durable and the fertilizer utilization rate is higher.At young fruit stage,nitrogen mainly acted on leaves,and at fruit maturity,nitrogen was gradually transferred to storage organs such as roots and branches.Nitrogen distribution rate of blueberries treated with NO₃^--N increased at young fruit stage,when NO₃^--N fertilizer was applied at fruit ripening stage,the root shoot ratio of plants decreas-ed,root growth was inhibited to some extent,longterm application of NO₃^--N fertilizer is disad-vantageous to the growth of blueberry root system.It is suggested that in the actual production process,depending on the growth of the blueberry to determine the amount of fertilizer and fertilizer time,in order to better improve the blueberry nitrogen utilization rate,to achieve high quality and high yield effect.