Abstract: Phoebe bournei is an endangered but precious timber species. In a field pot experiment with “3414” incomplete orthogonal regression design, we examined the effects of N, P and K fertilizers on the nutrient uptake and utilization of one-year-old P. bournei rootnaked seedlings, with the aim to explore the interaction of nutrient elements and their effects on the growth ofP. bournei seedlings. The effects of different N, P, and K fertilizations on dry matter growth and nutrient element uptakes and utilization were examined. The results showed that appropriate N, P and K fertilization promoted dry matter, N, P and K uptakes and C fixation of P. bourni seedlings. All those variables showed the trend of first increasing and then decreasing with the increasing fertilization rate, with the maximum at T6 treatment (N, 0.532 g·plant^-1; P₂O₅, 0.133 g·plant^-1; K₂O, 0.356 g·plant^-1; N∶P₂O₅∶K₂O=1∶0.250∶0.669). Nitrogen fertilization had the strongest effect on the growth ofP. bournei seedlings, followed by K fertilization and P fertilization. Nitrogen fertilization promoted C fixation and dry matter growth by increasing N uptake, and further improved P and K uptakes. Phosphorus fertilization enhanced dry matter accumulation and nutrient uptake, but did not affect P utilization. Potassium fertilization mainly promoted seedlings growth by affecting P uptake and utilization. The NPK combined fertilization had the strongest positive effect on seedling growth, followed by twofactor fertilization and singlefactor fertilization. The NK fertilization was beneficial to nutrient uptake, while NP fertilization was beneficial to nutrient utilization. The T6 treatment was the best fertilization rate and proportion. By principal component and path analysis, we found that increasing utilization rate of N and K fertilizers and the C fixed amount which were subjected to the balance of P uptake and utilization, could promote the seedling growth. Therefore, N and K agronomic efficiency was the key index for the fertilization of P. bournei seedlings. P. bournei seedlings preferred N to P. The NPK fertilization was beneficial to the nutrient uptake and utilization of P. bournei seedlings, with the T6 treatment being the best one.

Key words: Phoebe bournei, balanced fertilization, nutrient element uptake, fertilizer utilization rate, biomass.