Influence of genotypes and environmental factors on leaf triterpenoid content and growth of Cyclocarya paliurus

Cyclocarya paliurus, an economically valuable tree species, has traditionally been used as a nutraceutical food or medicine in China. However, limited information is available on its genotype selection and cultivation under a wide range of environmental conditions for growth and targeted health-promoting substances. We studied the effects of genotype and environment, and their interaction on leaf triterpenoid content and tree growth for 12 genotypes of C. paliurus grown at four sites. We quantified the correlation between leaf triterpenoid accumulation and tree growth. The contents of cyclocaric acid B, cyclocarioside I, and arjunolic acid ranged from 0.06 to 3.89, 0 to 3.71, and 0.65 to 8.86mgg(-1), respectively. Three individual triterpenoids were primarily influenced by genotype (variation ranged from 53.7 to 68.0%), while environment accounted for most of the variation in total triterpenoid content and tree growth (71.3-89.5%). Most tested environmental parameters were significantly correlated to total triterpenoid content, but not to the contents of the individual triterpenoids measured. Growth in tree height and diameter at breast height were significantly negatively correlated with total triterpenoid content but were non-significantly correlated with individual triterpenoid contents. We conclude that genotypic selection, manipulation of environmental conditions, and implementation of appropriate silvicultural operations would be important strategies for increasing the accumulation of health-promoting phytochemicals.