The Effect of Applying Different Types of Fertilizers on the Growth and Leaf Quality of Cyclocarya paliurus

To study the effects of different types of fertilizer on the growth and leaf quality of Cyclocarya paliurus in ecologically vulnerable areas, and provide sustainable soil improvement strategies for targeted cultivation of C. paliurus plantations. Taking 2-year-old C. paliurus seedling as the test material, and the experiment was conducted in the field conditions, six different fertilizers were set up, and the growth indicators, photosynthesis indicators, mineral elements and secondary metabolites content of different treatments were measured at two leaf harvesting months in April and June, respectively. The differences between different fertilization treatments were compared by one-way ANOVA, and the best fertilization method was comprehensively evaluated by principal component analysis. The results show that compared with the CK, the application of different fertilizers promoted the growth of C. paliurus trees, and all indicators were the highest in T₅ treatment; the net photosynthetic rate, transpiration rate and stomatal conductance of all treatment groups increased over time and were all significantly higher than those of CK (P<0.05), and the intercellular CO₂ concentration of CK was the highest at 275.00 μmol/(m²·s); the calcium, potassium and phosphorus element contents of the leaves in T₁ treatment were the highest, and the magnesium content of T₄ treatment was the highest. Compared with April, the mass elements content in leaves except magnesium increased in June, and the contents of copper, zinc, nickel, and iron elements increased with the progression of treatment time, with the highest zinc, nickel, and iron contents in T₅. The water-soluble polysaccharides and total triterpenes content of T₅ leaves were the highest, while the total flavonoids content of T₄ leaves was the highest. The correlation analysis of various indicators showed that, except for magnesium and manganese elements, the growth indicators of tree bodies, the photosynthesis indicators of leaves, and the contents of mineral elements and secondary metabolites were all significantly positively correlated. Principal component analysis evaluated that T₅ had the best overall characteristics and ranked first. In conclusion, if the harvest time is set in April and June in the poor soil areas of Hunan Province, T₅ (compound fertilizer + water-soluble fertilizer containing amino acids) fertilization treatment is more conducive to the growth and development of C. paliurus and the accumulation of mineral elements and secondary metabolites in leaves.