Study On The Effects Of Topping Pruning On The Biomass,Taxol,and 10-DAB Of Annual Branches Of Taxus × Media

Taxus × media is a new variety of Taxus introduced artificially in China.Recently,with the successful selection and promotion of new domestic varieties with high-content Taxus and the cultivation,Taxus × media Rehder has lost market competitiveness.This study was conducted to improve the accumulation of paclitaxel and 10-DAB in the branches of Taxus × media Rehder,based on the pruning method of tea tree,with four cutting-top pruning heights(1.0 m,1.2 m,1.4 m,1.6 m)and four pruning times(February,May,August,and November),using 15-year-old Taxus × media Rehder as the material.The experiment was conducted in February,May,August,and November.Sampling and determination of annual branch biomass,paclitaxel,and 10-DAB content were carried out to analyze the dynamic changes of annual branch growth and major medicinal components to determine the effects of top pruning on annual branch biomass,paclitaxel,and 10-DAB content,and the accumulation of single plants,which would provide theoretical and technical support for the production and management of the medicinal material forest of Taxus × media Rehder.The main findings were as follows:(1)Annual branches started to sprout from March and their biomass increased month by month after top-cut pruning;paclitaxel and 10-DAB contents showed a significant decreasing trend from March to August,which was consistent with the control(unpruned).(2)Top-cut pruning had a highly significant effect on the biomass of annual branches,while the most significant effect was the top-cut pruning at 1.4 m in May,whose biomass of annual branches reached 136.61 g/plant in May,219.43 g/plant in June,and 322.58g/plant in December,all higher than that of other prunings and the control during the same period.(3)The effect of top-cut pruning on the content of paclitaxel and 10-DAB was insignificant,both showing a high level first and then a low level,with the highest level in March at 0.058% for paclitaxel and 0.100% for 10-DAB,and then decreasing with the increase of month,reaching a stable level of 0.020% for both components after August.(4)Top-cut pruning had significant effects on the accumulation of paclitaxel and10-DAB monoculture,especially in May when the top-cut pruning was done at 1.4 m.The highest value of paclitaxel accumulation was 89.97 mg/plant and 10-DAB monoculture accumulation was 94.35 mg/plant in the following year after pruning.In conclusion,top-cutting pruning had a highly significant effect on the biomass of annual branches of Taxus × media Rehder,while the effects on paclitaxel and 10-DAB content were insignificant.