采用L2⁵(5³)正交实验设计设置不同氮、磷和钾肥施用量及配比[单株施用量分别为CO(NH2 )2 2. 0、4. 0、 6.0、8. 0 和10. 0 g,  Ca(H₂ PO₄ )2 4. 0、6. 0、8. 0、10. 0 和12. 0 g,KCl 0. 6、1. 2、1. 8、2. 4 和3. 0 g],并设置不同复合肥施用量(单株施用量分别为10、20、30、40 和50 g),比较了施肥后第1 至第3 个月木棉(Bombax ceiba Linn.)幼苗叶片光合指标[包括净光合速率(Pn)、水分利用效率(WUE)、PSII最大光化学效率(Fv / Fm ) 和叶绿素相对含量(SPAD)]和幼苗生长指标(包括株高增长量、地径增长量和叶面积增长量)的变化。结果表明:总体来看,不同施肥处理组木棉幼苗叶片的Pn 和WUE 值升高,幼苗的株高增长量、地径增长量和叶面积增长量增加,但不同施肥处理对叶片Fv / Fm和SPAD 值的影响较小;复合肥对叶片光合生理特性和幼苗生长的影响也较小。在施肥后的第1 至第3 个月,单株施用量氮肥4. 0 或6. 0 g,磷肥4. 0 或8. 0 g,钾肥1. 2、1. 8 或3. 0 g 处理组幼苗叶片的Pn 和WUE 值显著高于对照(不施肥)和大多数处理组;单株施用量氮肥4. 0 或6. 0 g、磷肥4. 0 ~12. 0 g、钾肥1. 2 ~3. 0 g 处理组幼苗的株高增长量、地径增长量和叶面积增长量也均较高。综合分析结果显示:氮肥对木棉幼苗光合生理特性及生长的影响最大,钾肥次之,磷肥最小。综合考虑Pn 值、WUE 值、株高增长量、地径增长量和叶面积增长量,木棉苗期的适宜单株施肥量为N 1. 84 或2. 76 g、P2 O5 0. 72 ~2. 16 g 和K2 O 0. 72 ~1. 80 g。

Different applying amounts and proportions of nitrogen, phosphorus and potassium fertilizers [applying amount per plant of 2. 0, 4. 0, 6. 0, 8. 0 and 10. 0 g CO(NH₂)₂, 4. 0, 6. 0, 8. 0, 10. 0 and 12. 0 g Ca(H₂ PO₄ )₂, 0. 6, 1. 2, 1. 8, 2. 4 and 3.0 g KCl, respectively]were set up by L25 (5³ ) orthogonal experimental design, and different applying amounts of compound fertilizer (applying amount per plant of 10, 20, 30, 40 and 50 g, respectively) were also set up, changes in photosynthetic characteristics indexes [including net photosynthetic rate (Pn), water use efficiency (WUE), the maximum photochemical efficiency of PSII(Fv / Fm) and chlorophyll relative content (SPAD)]of leaf and seedling growth indexes (including increments of height, ground diameter and leaf area) of Bombax ceiba Linn. seedling after fertilization from the first to the third month were compared. The results show that in general, Pn and WUE values of leaf of B. ceiba seedling in different fertilization treatments increase, and increments of seedling height, ground diameter and leaf area increase, but effects of different fertilization treatments on Fv / Fm and SPAD values of leaf are small. Effect of compound fertilizer on leaf photosynthetic characteristics and seedling growth is also small. After fertilization from the first to the third month, Pn and WUE values of leaf of seedling in treatment groups with applying amount per plant of 4. 0 or 6. 0 g nitrogen fertilizer, 4. 0 or 8. 0 g phosphorus fertilizer, 1. 2, 1. 8 or 3. 0 g potassium fertilizer are significantly higher than those in the control (no fertilizer) and most treatment groups. Increments of height, ground diameter and leaf area of seedlings in treatment groups with applying amount per plant of 4. 0 or 6. 0 g nitrogen fertilizer, 4. 0-12. 0 g phosphorus fertilizer, 1. 2-3. 0 g potassium fertilizer are also high. The result of comprehensive analysis indicates that effect of nitrogen fertilizer on photosynthetic characteristics and growth of B. ceiba seedling is the largest, that of potassium fertilizer takes the second place, and that of phosphorus fertilizer is the smallest. Comprehensively considering on Pn value, WUE value and increments of height, ground diameter and leaf area, the suitable applying amount per plant at seedling stage of B. ceiba is 1. 84 or 2. 76 g N, 0. 72-2. 16 g P₂ O₅ and 0. 72-1. 80 g K₂O.