Effects of shading and fertilization on the growth and photosynthetic physiological characteristics of Heptacodium miconioides cuttings

In order to investigate the effects of two conventional management practices shading and fertilization on the growth of Heptacodium miconioides cuttings after field planting, two-year-old rooted cutting was used as the experimental material. A two-factor completely randomized block design was adopted, with two light environments: no shading (full sunlight, L₀) and shading (60% shading intensity, L₁), and three fertilizer treatments with different N, P, and K ratios were applied: high-phosphorus compound fertilizer (N-P₂O₅-K₂O = 15-15-15, total nutrients ≥ 45%, N₁₅), high-potassium fertilizer (N-P₂O₅-K₂O = 19-6-22, total nutrients ≥ 47%, N₁₉), and a no-fertilizer control (N₀). The study examined the effects of different treatments on the photosynthetic pigments, photosynthetic characteristics, chlorophyll fluorescence parameters, non-structural carbohydrates and growt of the transplanted cuttings. The results showed that the net photosynthetic rate (P_n), minimum fluorescence under light (F_o'), effective photochemical quantum yield of PSII (F_v'/F_m'), photochemical quenching coefficient (q_P), soluble sugar content, starch content, NSC and ground diameter growth of L₁ treatment were significantly lower than those of L₀ treatment. The P_n of the two groups of fertilization treatments was higher than that of N₀ treatment, and the soluble sugar content, starch content, NSC and ground diameter growth of leaves were significantly higher than those of N₀ treatment. The P_n, NSC and ground diameter growth of N₁₉ treatment were 17.87 % and 13.06 %, 21.93 % and 22.35 %, 25.59 % and 24.48 % higher than those of N₀ treatment in L₀ and L₁ light environments, respectively, which were better than those of N₁₅ treatment. In conclusion, under the experimental conditions of this study, 60% shading intensity was unfavorable for the growth of transplanted H. miconioides cuttings. Fertilization partially alleviated the adverse effects of shading, with the N₁₉ treatment exhibiting superior growth-promoting effects. Therefore, for field reintroduction or landscaping applications near the experimental site, ambient shading should preferably be maintained below 60%. For fertilizer application, compound fertilizer with higher potassium content (N-P₂O₅-K₂O = 19-6-22, total nutrients ≥ 47%) is more suitable.