Effects Of Combined Application Of Nitrogen,Phosphorus And Potassium On Growth And Fertilizer Utilization Efficiency Of Cerasus Humilis In Sandy Area

As a potential high-quality desert economic forest species,Prunus humilis has many characteristics such as high calcium and drought resistance.It is an important variety for the development of sand industry in desertification control area.However,in the fragile sandy environment,under the background of weak research on fertilization and cultivation of Prunus humilis,due to the lack of understanding of its fertilizer demand law in the process of introduction,this greatly limits the efficient cultivation management and large-scale promotion of Prunus humilis in sandy areas.According to the two-year formula fertilization scheme,the two-year formula fertilization scheme of ultra-high phosphorus in Yulin was selected as the research object,and the two-year formula fertilization scheme of ultra-high phosphorus in Yulin was set as the research object.Therefore,Among them,the sequence of different nitrogen fertilizer treatments from low to high is N-（0kg/hm²）,N1（43kg/hm²）,N2（240kg/hm²）,N3（437kg/hm²）,N+（480kg/hm²）.The sequence of different phosphorus fertilizer treatments from low to high is P-（0kg/hm²）,P1（16kg/hm²）,P2（90kg/hm²）,P3（164kg/hm²）,P+（180kg/hm²）.The sequence of different potassium fertilizer treatments from low to high is K-（0kg/hm²）,K1（20kg/hm²）,K2（110kg/hm²）K3（200kg/hm²）,K+（220kg/hm²）,CK without fertilization was used as the blank control group,a total of 16 groups were treated.In order to study the response characteristics of physiological growth,photosynthetic characteristics and nutrient utilization of European plum under different nitrogen,phosphorus and potassium fertilization gradients,and by fitting the correlation equation model between different fertilization rates and yield,find out the best fertilization amount and the best NPK ratio,so as to clarify the fertilizer demand characteristics of European plum cultivation in sandy area,and put forward the effective nitrogen,phosphorus and potassium fertilization formula suitable for European plum cultivation in sandy area.The main results are as follows:（1）There were significant differences in the effects of different application rates of nitrogen,phosphorus and potassium on the growth indexes of European plum.In the treatment of different nitrogen fertilizer application rates,the maximum horizontal and vertical crown width of N+was 56.89cm and 56.78cm respectively,with an increase of 83.52%and 78.05%compared with CK,and the maximum plant height was 50.44cm,with an increase of 81.57%compared with CK;When the fertilization treatment was P3,the transverse and longitudinal crown width and plant height were the highest,reaching 47.25cm,46.17cm and 50.25cm respectively;The crown width and plant height at K3 were significantly different from other treatments in the same group.The plant biomass of Prunus humilis treated with N+was the highest,reaching356.81g/plant,about 4 times that of CK.The results showed that the combination of N+P3K3 had the best effect on the growth of Prunus humilis.（2）The effects of different application rates of nitrogen,phosphorus and potassium on the photosynthetic characteristics of Prunus humilis were not consistent.The chlorophyll SPAD value of Prunus humilis reached the highest at N3,which was44.10.The average increase of leaf chlorophyll content under different potassium fertilizer application was about 49.82%compared with CK without fertilization.The highest intercellular CO₂concentration was 332.83μmol.mol^-1when the fertilization amount was N2,the highest stomatal conductance was 0.35mol·m^-2s^-1at N+,and the net photosynthetic rate at K+was 1.92 times that of CK,5.28μmol·m^-2s^-1higher than that at K1,up to 13.78μmol·m^-2s^-1,the transpiration rate increased significantly with the increase of potassium fertilizer,and there was a significant difference between K2and other treatments,as high as 2.88mmol·m^-2s^-1;The instantaneous water use efficiency of N2 was significantly different from that of other treatments,which was1.2 times higher than that of CK,and the highest was 1.98μmol.mol^-1,up to1.84μmol.mol^-1at K1,the highest instantaneous water use efficiency at P2 was1.69μmol.mol^-1the instantaneous water use efficiency of Prunus humilis increased first and then decreased under different application rates of nitrogen,phosphorus and potassium.The analysis showed that N3P2K2 proportional fertilization combination had a significant effect on the physiological characteristics of European plum.（3）The total nitrogen contents of leaves and fruits of Prunus humilis were17.06g/kg and 8.78g/kg respectively at N3.The distribution characteristics of nitrogen content in tissues and organs of Prunus humilis were leaf>root>fruit>stem;When the amount of fertilizer was P+,the maximum phosphorus content in leaves was1.18g/kg,which was about 3.71 times that of CK without fertilizer,and the maximum absorption amount P3 of fruits was 2.98g/kg.The sensitivity of phosphorus absorption of European plum was fruit>leaf>rhizome;When the fertilization amount was K+,the total potassium content of leaves and fruits was the highest,reaching 15.53g/kg and 7.81g/kg respectively.The analysis showed that the distribution characteristics of potassium accumulation in tissues and organs were leaf>fruit>root>stem.The nitrogen use efficiency of root and stem of Prunus humilis was as high as 1.93%and 3.88%when the amount of fertilizer was N2;The phosphorus fertilizer utilization rate of leaves reached 10.36%at P1,and the components of roots,stems and leaves showed the law of P1>P2>P3 with the increase of phosphorus application.The phosphorus fertilizer utilization rate of fruits reached 20.71%on average,which was significantly higher than that of other components of European plum;The average utilization rates of potassium fertilizer in leaves and fruits of Prunus humilis were 23.38%and 32.91%respectively.The results showed that the nutrient absorption efficiency of European plum was the best under N2P1K2 proportional fertilization.（4）Combined with the comprehensive analysis of yield and different fertilization rates of nitrogen,phosphorus and potassium,the optimal fertilization rate and optimal fertilization ratio of nitrogen,phosphorus and potassium were obtained,in which the fruit yield of European plum reached the best when the application rates of nitrogen,phosphorus and potassium were 505.28kg/hm²-513.24kg/hm²,106.38kg/hm²-132.61kg/hm²and 89.97kg/hm²-119.44kg/hm²respectively,that is,N:P₂O₅:K₂O=4.7:1.1:1.So as to provide scientific basis and technical reference for high-quality and high-yield cultivation of Cerasus humilis in sandy area.