Effect Of ?–PGA On ¹⁵N Uptake And Drought Tolerance Of Peach Trees

At present,nitrogen fertilizer abuse is a common problem in fruit production in China.In order to obtain higher yield and benefit,fruit farmers continue to increase the input of nitrogen fertilizer.Excessive application of nitrogen fertilizer not only causes waste of resources,but also causes serious water and soil pollution.In addition,in China,especially in arid and semi–arid areas,water shortage has always been one of the most important factors limiting agricultural production.Even in areas with heavy rainfall,seasonal drought problem is common.?–Polyglutamic acid is a kind of biologically active polymeric macromolecular substance,which is widely used in medicine,environmental protection,food and other fields.At present,research on several crops has found that it is beneficial to soil water and fertilizer retention and crop growth.But the application on fruit trees needs further research.Therefore,this experiment takes this as the starting point,uses the isotopic labeling method to take the1-year-old peach potted seedling as the test material,the base fertilizer is urea 3 g(15N is labeled 0.4 g),potassium dihydrogen phosphate 3 g,set CK as the control,T1,T2,T3respectively add polyglutamic acid 10,80,150 mg,to explore the influence of different concentration of?-polyglutamic acid on Peach plant growth and nitrogen absorption and utilization,to explore polyglutamic acid The results are as follows:1.Application of medium and high amounts of?–PGA can significantly increase soil urease and catalase activities and soil alkaline nitrogen content,increase soil conductivity and redox potential.Application of medium and high levels of?–PGA can promote peach seedling root growth,especially fine roots.Compared with the control,the total length of roots,branches,root tips,crosses,and total root surface area of medium–dose?–PGA peach seedlings increased by 51.95%,40.53%,30.72%,35.21%,and 45.23%,respectively.Medium and high levels of?–PGA can significantly increase the plant net photosynthetic rate,chlorophyll SPAD value,and dry matter accumulation.It can be seen that?–polyglutamic acid can improve the soil environment,promote root development,and promote the growth of young peach trees.2.Application of medium and high levels of?–PGA can significantly improve root vigor,nitrate reductase,aspartate aminotransferase,and alanine aminotransferase activities of peach seedlings,and enhance nitrogen metabolism.Application of medium and high amounts of?–PGA improves nitrogen absorption and utilization rate and nitrogen residual rate and reduced nitrogen loss rate in peach seedlings.Compared with the control,nitrogen absorption and utilization rate increased by 27.80%and 27.07%,nitrogen retention rate increased by 14.00%and 19.04%,respectively.Nitrogen loss rate significantly reduced by16.43%and 19.49%,respectively.It can be seen that the application of?–PGA can improve the physical and chemical properties of soil in the root zone,increase the nitrogen absorption and utilization rate of plants,increase the residual rate of soil nitrogen,and reduce the rate of nitrogen loss.3.In the sand culture experiment,under the same drought conditions,compared with control,under 150ml 0.1g L–1 polyglutamic acid treatment,the water content in the quartz sand matrix and the water content increased significantly.Compared with control,photosynthetic rate and chlorophyll SPAD value significantly increased,transpiration rate significantly decreased,leaf proline,total soluble sugar and free amino acid increased by18.85%,1.47%and 22.01%respectively after five days of treatment,and increased by29.39%,10.12%and 26.93%after ten days of treatment.The CAT,POD,and SOD activities of peach seedlings increased by 5.91%,10.89%,and 4.41%after ten days of treatment.It can be seen that exogenous addition of?–polyglutamic acid can increase the water content of the substrate and maintain the absorption of the root system..In addition,it can adapt to the environment by increasing the accumulation of osmotic adjustment substances and reducing the transpiration rate.By increasing the activity of CAT,POD,and SOD to reduce the content of superoxide free radicals to alleviate cell damage.