Study On The Best N, P, K Fertilization For Increasing The Sugar And Reducing The Acid And Nitrogen Absorption With Operation Mechanism About Huangguogan

With Huangguogan which at Shimian as materials in this experiment,under the condition of field experiment,studied the effects of different N,P,K fertilization levels on fruit quality,yield of Huangguogan and soil enzyme in the key phenophase(the period of germination.the period of first physiological fruit drop,fruit rapid swelling stage.color turning stage);discussed the difference about Ndff value in fruits and leaves during the summer shoot growing stage.fruit rapid swelling stage, color turning stage and the difference about Ndff value,the distribution rate of 15N,the comprehensive utilization of nitrogen fertilizer in different parts of the tree during the maturity under the two modes of key phenophase and rule fertilization (the period of germination,the period of first physiological fruit drop),the results of the study were as follows:(1) The right amount of N,P,K fertilizer could improve the fruit quality of Huangguogan significantly,effects of treatment 22 which was N3PiK.3(the period of germination fertilized urea 1.00 Kg, super phosphate 0.39 Kg, potassium sulfate 0.72 Kg; the steady fruit stage fertilized urea 0.25 Kg, super phosphate 0.13 Kg,potassium sulfate1.08 Kg; the fruit rapid swelling stage fertilized urea 1.00 Kg, super phosphate 0.52 Kg, potassium sulfate 1.44 Kg; the color turning stage fertilized urea 0.25 Kg, super phosphate 0.26 Kg, potassium sulfate 0.36 Kg)improved the fruit quality better,the results as that:contents of total sugar from 8.85 g/100ml to 12.05 g/100ml,promoted 36.2%;contents of total acid from 1.26 g/100ml to 0.91 g/100ml,reduced 27.8%;contents of Vc from 15.32 mg/110ml to 15.1mg/100ml, had little influence;contents of TSS from 10.8%to 12.5%,promoted 15.7%.(2) Contents of total sugar was significantly positive correlation with activity of urease, catalase, protease,these correlation coefficients respective were 0.357,0.461,0.433;contents of Vc was significantly passive correlation with activity of urease,the correlation coefficient was -0.377.Therefore,it could be used the contents of total sugar to evaluate the activity of soil urease, catalase, protease and the contents of Vc to evaluate the activity of soil urease in the fruit during the maturity of Huangguogan.(3) In the three key periods of fruit rapid swelling stage,color turning stage and maturity,the Ndff value of citrus fruit in the key phenophase fertilization mode was notable bigger than that in rule fertilization mode,it indicated that more nitrogen could be turned and distributed into the fruit and finished the structuring about fruit organ more better in the key phenophase fertilization mode;the Ndff value of fruit was bigger and bigger during the four phenophase in the key phenophase fertilization mode,that indicated the rate which fruit absorbed the 15N was bigger and bigger as phenophase went on.(4) In the mature period,the distribution rate of 15N were both highest in fruit in the two modes,among them,the distribution rate of 15N in fruit that in the key phenophase fertilization mode was 50.2%,which was notable higher than 45.7% that in the rule fertilization mode,the utilization rate of 15N about citrus tree in the key phenophase fertilization mode was 35.7%,which was notable higher than 27.8% that in the rule fertilization mode,the result showed that citrus tree could absorb and utilize nitrogen more fully in the key phenophase fertilization mode.