Abstract:

【Objective】This study aimed to provide a reference for nutrient diagnosis and balanced fertilization of Liangping pomelo orchards.【Method】The nutritional status of pomelo leaves of 18 representative orchards in the Liangping pomelo core production area was studied using diagnosis and recommendation integrated system (DRIS); the N, P, K, Ca, Mg, Zn, Fe, Cu, and Mn contents of pomelo leaves were determined during fruit expansion period, and the diagnosis standard of leaf nutrition was put forward.【Result】The average content of P, K, Mg, Cu in the leaves of high-yielding orchards was higher than that of low yield garden, and N, Ca, Zn, Fe, Mn were lower than that of low yield garden.According to the range of mineral nutrient content in leaves from high-yielding pomelo orchards, the appropriate values of mineral nutrient elements in Liangping pomelo leaves during fruit expansion period were as follows: N, (22.12 ± 2.53) g/kg; P, (0.77 ± 0.20) g/kg; K, (16.50 ± 4.67) g/kg; Ca, (29.13 ± 6.12) g/kg; Mg, (3.92 ± 0.89) g/kg; Zn, (18.45 ± 3.07) mg/kg; Fe, (128.26 ± 34.00) mg/kg; Cu, (20.66 ± 5.68) mg/kg; and Mn, (20.98 ± 9.70) mg/kg. The order of nutrient requirement was different in different orchards; high-yielding pomelo orchards were relatively deficient in K, Mg, Fe, Mn, and Cu, whereas low-yielding pomelo orchards were relatively deficient in K, Mg, Fe, and Mn. The imbalanced index of nutrition in low-yielding pomelo orchards was higher than that in high-yielding pomelo orchards, which indicated that the imbalance of nutrition proportion was more serious in low yield pomelo garden, which was one of the reasons for the low yield of pomelo tree in low yield garden.【Conclusion】K, Mg, and Fe deficiencies are common in Liangping pomelo orchards, especially in low-yielding pomelo orchards. The results suggest that pomelo orchards should be appropriately supplemented with K, Fe, and Mg trace element fertilizer to improve their production potential.

Key words: Liangping pomelo, mineral nutrition, nutrition diagnosis, diagnosis recommendation integrated system(DRIS)