【摘要】 【目的】研究不同氮（N）、磷（P）和钾（K）施肥量和施肥方式影响闽楠叶片光合特性、内含物含量，酶活性及植株养分吸收量，揭示施肥调控光合碳固定机制，为闽楠壮苗培育和科学施肥提供理论依据。【方法】采用“3414”田间试验方法，分析不同N、P和K施肥处理对闽楠幼苗光合色素含量、光合作用参数、叶片内含物及相应酶活性的影响；通过极差分析，筛选最佳的氮磷钾施肥方式；通过逐步回归分析、相关分析和通径分析，构建施肥调控光合碳固定途径。【结果】1) N、P、K施肥提高闽楠叶片光合色素含量，光合、蒸腾和水分利用能力，抑制叶片可溶性糖，可溶性蛋白和丙二醛含量，提高叶片硝酸还原酶、谷氨酰胺合成酶和酸性磷酸酶活性，抑制多酚氧化酶活性，进而提高叶片淀粉含量，促进碳固定。在光合碳固定中，叶片酸性磷酸酶、水分利用效率和淀粉含量是调控的关键点。2) N元素增强硝酸还原酶活性，提高叶绿素a含量，增强水分利用效率，促进碳固定。3) P元素提高叶绿素b含量，降低丙二醛含量，保护细胞完整性，提高碳同化效率，但对于光合产物碳代谢无显著影响。4) K元素提高叶绿素a和b含量，增大气孔导度，提高气孔CO₂和水分利用效率，提高淀粉含量，促进光合碳固定。5)在N、P、K配施下，N,P和K吸收量最大，与酸性磷酸酶呈极显著相关，最有利于光合碳固定；其次为N、P配施，最差的为单施磷肥，以T6(N:0.532 g·plant^-1, P₂O₅:0.133 g·plant^-1, K₂O:0.356 g·plant^-1)处理效果最好。【结论】施肥后，闽楠幼苗吸收N、P和K,加大叶片气孔通气，显著提高气孔导度和蒸腾速率，提高水分利用效率，增强闽楠幼苗的净光合速率，促进光合产物的输出，提高蛋白质合成，在酸性磷酸酶的作用下调控碳代谢，产生淀粉，为其生长提供物质和能量。更多还原

【Abstract】 【Objective】In this paper, the effects of different fertilization rates and models of nitrogen（N）, phosphorus（P） and potassium（K） on photosynthetic characteristics, organic compound content and enzyme activities in leaves, and nutrients of Phoebe bournei seedlings were investigated, to reveal the mechanism of photosynthetic carbon fixation regulated by fertilization, which would provide a theoretical basis for the cultivation of strong seedlings and scientific fertilization of P. bournei.【Objective】The “3414” field experiment was conducted to analyze the effects of different N,P,K fertilization treatments on photosynthetic pigment contents, photosynthetic indexes, leaf organic compound content and enzyme activities of P. bournei seedlings. The range analysis method was used to screen the best N,P,K fertilization model. The stepwise regression, correlation and path analysis method were used to construct the photosynthetic carbon fixation pathway regulated by fertilization.【Result】1) N,P,K fertilization increased the photosynthetic pigment content, photosynthesis, transpiration and water use capacity, reduced the contents of soluble sugars, soluble protein and malondialdehyde（MDA）, increased the activities of nitrate reductase（NR）, glutamine synthetase（GS） and acid phosphatase（ACP）, inhibited polyphenol oxidase（PPO） activity, increased leaf starch content, and then promoted leaf carbon fixation of P. bournei seedlings. In the photosynthetic carbon metabolism, ACP, WUE and starch content were the key regulation points. 2) N element enhanced NR activity, increased chlorophyll a content, water use efficiency, and leaf carbon fixation of P. bournei seedlings. 3) P element increased chlorophyll b content, decreased MDA content, protected cell integrity, and improved carbon assimilation efficiency, but had no significant effect on the metabolism of photosynthate of P. bournei seedlings. 4) K element increased the contents of chlorophyll a and b, stomatal conductance, stomatal CO₂ and water use efficiency, starch content, and leaf carbon fixation of P. bournei seedlings. 5) Under the combined application of N, P and K fertilizer, the absorption of N, P and K was the most, which was significantly correlated with ACP activities, and was the most beneficial to photosynthetic carbon fixation, followed by the combined application of N and K fertilizer, and the smallest was single application of P fertilizer. The treatment effect of T6(N: 0.532 g·plant^-1, P₂O₅: 0.133 g·plant^-1, K₂O: 0.356 g·plant^-1) was the best. 【Conclusion】After fertilization, P. bournei seedlings absorb N, P and K element, thereby increase the stomata ventilation, significantly improve the stomatal conductance, transpiration rate, and water use efficiency, increase net photosynthetic rate, photosynthetic product, and protein synthesis. Under the action of ACP enzyme, fertilization regulates carbon metabolism, and promotes the production of starch which can provide material and energy for growth of P. bournei seedlings.更多还原