Growth and yield traits of Tripterygium wilfordii

Key words: 
• botany /
• Tripterygium wilfordii /
• production trait /
• root system biomass /
• growth law /
• correlation

Abstract: Growth and yield traits of Tripterygium wilfordii，used for the traditional Chinese medicine： Radix et Rhizoma Tripterygii，were studied to provide a theoretical basis for improved growing stock and resource utilization. The 55 2-year-old seedlings and 62 3-year-old seedlings were measured. A correlation analysis was used to determine the relationship between whole root yield and 1） root system biomass；2） branch fresh weight；3） branch number；4） main branch thickness and length；and 5） number，thickness，and length of the main root system. Results showed that the biomass ratio of the aerial to the underground parts was 1.0 ∶ 1.7 ~ 2.0. However，with increased plantings，the number of main roots decreased. Strong correlations（P＜0.01） were noted between fresh weight of the whole root and branch fresh weight （r2 = 0.854 5，r3 = 0.869 2. The subscript 2 means 2-year-old seedlings，and 3 means 3-year-old seedlings，same as below），branch number （r2 = 0.691 5，r3 = 0.489 9），branch thickness（r2 = 0.504 4，r3 = 0.358 5），branch length（r2 = 0.509 7，r3 = 0.444 8），number of main root systems（r2 = 0.686 5，r3 = 0.444 2），thickness of the thickest root （r2 = 0.614 7，r3= 0.383 7），and length of the longest root （r2 = 0.571 0，r3= 0.631 1）. Thus，for T. wilfordii，since branch fresh weight followed by branch number had the most positive influence on fresh weight of the underground root，they could be used to forecast biomass of the root system. When selecting the best planting stock，the main factor to consider would be the fresh weight and number of branches，as well as the thickness of the thickest root and the length of the longest root.［Ch，4 tab. 12 ref.］