Effect of phosphorus on growth and total alkaloids of Sophora flavescens

A pot experiment was conducted to study the effect of phosphorus (P) on growth, total alkaloids concentration and total alkaloids yield of Sophora flavescens. Four levels of P2O5 were set up: 0(Control), 15, 30, 60 mg/kg using single superphosphate (P2O512%) fertilizer. Results showed that stem height, root fresh weight, root dry weight, chlorophyll (Chl) concentration, total alkaloids concentration and total alkaloids yield of Sophora flavescens increased significantly with P application. The 30 mg/kg P2O5 applied produced significantly higher ether root fresh weight (45.5 g/plant) and root dry weight (23.1 g/plant) than control and 60 mg/kg P2O5 applied. It also increased the root fresh and dry weight by 23.5% and 18.5% compared with the control respectively. The 30 and 15 mg/kg P2O5 applied did not differ significantly in root fresh and dry weight. Both root dry weight /root fresh and dry weight / total plant dry weight decreased with phosphorus application. Phosphorus had significant positive effect on root diameter. Root diameter was the highest at 30 mg/kg P2O5 application and it increased by 14％compared with the control. The percentage of xylem diameter increased with P application, while the percentage of root bark depth decreased. The 15 mg/kg P2O5 applied produced significantly higher ether Chl concentration, total alkaloids concentration and total alkaloids yield than control and 60 mg/kg P2O5 applied. Compared to the control, Chl concentration, total alkaloids increased by 17.1％ and 34.8% compared with the control, respectively. The total alkaloids yield of per plant increased by 56.3％. At the condition of our experiment, the highest root dry weight and total alkaloids were observed at P2O5 application 30 and 15 mg/kg, respectively. For the high total alkaloids concentration, the suitable P2O5 rate is 15 mg/kg.