Effects of Different Phosphorus-applying Levels on Seedling Growth and Camptothecin Accumulation in Camptotheca acuminata Seedlings

A potted experiment with controlled fertilization supply was conducted to study the effects of different phosphorus-applying levels (P₀, 0 kg P·hm^-2; P_L, 42 kg P·hm^-2; P_M, 84 kg P·hm^-2; P_H, 168 kg P·hm^-2) on the growth of seedlings and camptothecin (CPT) accumulation in C. acuminata seedlings. The experiment results showed that the height and dry weight of C. acuminata seedlings would increase when phosphorus-applying level increased. Under different levels of applying phosphorus, the dry weight of leaf, shoot and root of C. acuminata seedlings was significantly different (p < 0.05). The CPT content in leaf, shoot and root reached the highest level when phosphorus-applying level was P L. Compared with P₀, the CPT content in P_L increased significantly. The CPT amount in the whole seedling, leaf and shoot of C. acuminata increased gradually with the increase of phosphorus. But when phosphorus-applying level was higher than P_M, the increase of CPT amount was insignificant. The CPT amount in root reached the highest level when phosphorus-applying level was P_M. According to the results studied, proper deficient phosphorus stress could significantly enhance CPT content in C. acuminata seedlings. With a main objective to establish a C. acuminata seedling plantation for producing CPT, proper phosphorus level was P_M. CPT amount in seedlings was mainly decided by the accumulation of biomass of C. acuminata.