Field evaluation of in vitro-induced tetraploid and diploid Centella asiatica (L.) urban.
Centella asiatica - a medicinal plant that produces high-value active triterpenoids - is in increasing demand by the pharmaceutical and cosmetic industries. The aim of this study was to field-test one induced tetraploid and three diploid C. asiatica lines for the selection of high-quality plants with high phytomass and triterpenoid content and to determine their optimal harvesting time. All tested C. asiatica were micropropagated using an established protocol. One-month-old plantlets were acclimatized for the field experiment. The plants were grown in a randomized complete block design (RCBD) with three replications, ten plantlets per replication, and the experimental bed site was 0.6 × 1.0 m. Growth parameters, phytomass and the amounts of four active triterpenoids were evaluated. All lines exhibited the highest growth, yields and triterpenoids at 4 months after cultivation. The tetraploid line showed significantly better characteristics, i.e., larger leaf area, leaf width, petiole length, and greater yields, than diploid lines. Dry weight per cultivated area (77.53±3.07 g/m2) and total triterpenoids (15.38±0.76% dry weight) were increased significantly in tetraploid plants of C. asiatica. Furthermore, the harvesting time had an effect on the yield and triterpenoid content (P<0.001). In all tetraploid and diploid lines, the yields and triterpenoid content per cultivated area reached their maximum at 4 months after planting. Our results demonstrated that polyploidy induction is a beneficial tool that can be used to improve the medicinal value of C. asiatica.