Effects of nitrogen, phosphorus and potassium ratio of fertilization on the growth and development and fruit quality of Psidium guajava L.

【Objective】To explore the effects of nitrogen，phosphorus and potassium ratio of fertilization on the growth and development and fruit quality of Psidium guajava，so as to provide a theoretical basis for the appropriate fertilization of P. guajava.【Method】Using the method of matrix container cultivation，three groups of nutrient solutions with different nitrogen，phosphorus and potassium ratios were set up，which were treatment A（high nitrogen，low phosphorus and medium potassium，10∶6∶13），treatment B（low nitrogen，medium phosphorus and high potassium，6∶7∶16）and treatment C（low nitrogen，low phosphorus and high potassium，8∶4∶15）. With compound fertilizer as the control，the effects of different nitrogen，phosphorus and potassium ratios on the nutritional growth，reproductive growth and fruit quality of P. guajava cultivated in matrix container were analyzed.【Result】Effects of fertilizers of different nitrogen，phosphorus and potassium ratios on the nutritional growth of P. guajava were different. Treatment A and C were better than CK in terms of the growth of trunk diameter increase，the length and diameter of primary and secondary branches and leaf area. Treatment B had no significant difference with CK（P>0.05，the same below）. The mineral content of leaves treated with nutrient solution was significantly higher than that of CK（P<0.05）. Compared with CK，the content of nitrogen，calcium，magnesium，boron and zinc in leavesin treatment A increased by 12.50%，115.25%，61.53%，13.29% and 14.01% respectively. In terms of reproductive growth，the flowering branch rate，fruit setting rate，single fruit weight and single plant yield of treatment A increased by 4.53%，10.85%，7.41% and 29.49% respectively compared with CK，while other treatments had no significant difference with CK. In terms of fruit quality，the contents of soluble solid，soluble sugar，reducing sugar and VC in treatment A were increased by 22.42%，16.54%，15.09% and 8.27% respectively compared with CK，while there was no significant difference between other treatments and CK.【Conclusion】In conclusion，the fertilization treatment of increasing potassium and reducing phosphorus on the basis of high nitrogen effectively promotes the vegetative growth of P. guajava plants and increases P. guajava yield，and plays a certain role in the improvement of fruit soluble solids，soluble sugar and other quality indicators. It is suggested that the fertilization ratio of P. guajava in southern Fujian is N∶P₂O₅∶K₂O=10∶6∶13.