Variation characteristics of the contents of nitrogen, phosphorus and potassium in the soil and leaves of Psidium guajava L. during the reproductive growth period

【Objective】To study variation characteristics of the contents of nitrogen，phosphorus and potassium in the soil and leaves of different guava（Psidium guajava L.）varieties during the reproductive growth period，so as to provide a theoretical basis for the differential fertilization management of different guava varieties.【Method】The contents of nitrogen，phosphorus and potassium in orchard soil and leaves of three guava varieties，Hongxiang 1，Caihong and Pearl，were determined. The relationship between soil nutrients and leaf nutrients was analyzed by correlation analysis and variance decomposition method.【Result】The trends of orchard soil pH change in Hongxiang 1，Caihong and Pearl guava during reproductive growth period were different，and the orchard soil pH in Caihong guava first decreased and then increased； Hongxiang 1 and Pearl guava showed an upward-downward-upward trend，but the pH of orchard soil of the three varieties was the lowest in the second expansion period. Among them，the orchard soil pH of Caihong and Pearl guava was significantly lower than that of other reproductive growth periods（P<0.05，the same below），and Hongxiang 1 had no significant difference（P>0.05）. The content of nitrogen，phosphorus and potassium in leaves showed a downward trend，and there was a significant difference between the middle fruit stage and the secondary expansion stage. This process was the period of maximum nutrient demand in the reproductive growth period. Among the soil nutrients，during the second expansion period of guava，the content of nitrogen，phosphorus and potassium in the soil of Caihong and Pearl guava orchards was the highest. Except for the alkali-hydrolyzable nitrogen in the soil of Pearl guava orchard，the other nutrients were significantly different from other reproductive growth periods. This phenomenon was not observed in Hongxiang 1. The results of correlation analysis showed that there was a negative correlation between soil phosphorus and leaf nutrition in Hongxiang 1，Caihong and Pearl guava orchards. Different growth stages and soil phosphorus content were the common factors affecting guava leaf nutrition，soil nitrogen was the individual difference factor of Hongxiang 1 leaf nutrition，and soil potassium was the individual difference factor of Caihong and Pearl.【Conclusion】Soil phosphorus is the key soil nutrient factor limiting the nutrients of guava leaves in the subtropical area. Different varieties of guava have similarities and differences in nutrient absorption. Attention should be paid to the differences in nutrient requirements caused by different varieties of guava in field management，and orchard fertilization schemes of different guava varieties should be optimized.