Influence of provenance and shade on biomass production and triterpenoid accumulation in Cyclocarya paliurus

Cyclocarya paliurus is a well-known multiple function tree species and has been used for ingredients in functional foods and drug formulations in China. A split-plot randomized design was used to grow three provenances at three different shade levels and effects of provenance and shading on growth and triterpenoid accumulation were assessed. Shading caused significant variation in photosynthetic photon flux density, air temperature and relative humidity, and moreover influenced total triterpenoid content in leaves. However, contents of cyclocaric acid B, cyclocarioside I, and arjunolic acid in the leaves were mainly affected by provenance. A significant seasonal variation of triterpenoid contents was observed in the leaves and the highest content appeared in September. Two-way analysis of variance revealed a significant provenance effect, shading effect and integrated effect between provenance and shading on biomass production. The highest accumulation of total triterpenoid and cyclocarioside I per plant was achieved in Muchuan provenance without shading, while the biggest accumulations of cyclocaric acid B and arjunolic acid were observed in Muchuan provenance with one-layer shading net. The data obtained suggest a complex relationship between environment, genotype and triterpenoid production but highlight that selecting suitable provenance of C. paliurus and optimizing cultivation system would be crucial for a high triterpenoid production.