Abstract: Cyclocarya paliurus, a multiple functional plant, has traditionally been used for drug formulations or ingredients of functional foods in China. Previous studies showed that the leaves of C. paliurus contain many physiologically active compounds (mainly triterpenoids) which were known to perform important physiological activity in human body. In the present study, a splitplot randomized design was used to examine the effects of shading (three levels) and provenance (three provenances) on triterpenoid content and triterpenoid accumulation over a growing season. Three shading levels were subjected to three light intensities, including 100% solar radiation (A1, without shading net), 30% of full solar radiation (A2, covered with one layer of shading net at 2 m height), and 12% of full solar radiation (A3, covered with two layers of shading net at 2 m height). Three provenances were Wufeng (B1) from Hubei Province, Yuanling (B2) from Hunan Province, and Muchuang (B3) from Sichuan Province. Our results showed that shading significantly affected the photosynthetic photon flux density, air temperature, and relative humidity, and thus significantly decreased the biomass accumulation. The highest biomass was detected in treatment A1B3. The interaction of shading and provenance significantly influenced the triterpenoid contents in leaves ofC. paliurus. The contents of cyclocaric acid B and arjunolic acid in provenances B1 and B2 were decreased in 30% light transmittance (A2) but increased in 12% light transmittance (A3). The highest contents of cyclocaric acid B and arjunolic acid were detected in 12% light transmittance. For provenance B3, however, the contents of cyclocaric acid B and arjunolic acid were positively correlated with increasing shading level. In addition, except for A2, the contents of cyclocarioside I in provenances B1 and B3 were decreased with thedeclined light intensity, with the variations ranging 0.20-0.27 mg·g^-1 and 1.33-2.52 mg·g^-1, respectively. Both the main and interactive effects of shading and provenance had significant influence on triterpenoid yield per plant. The highest yield of total triterpenoid and cyclocarioside I was detected in treatment A1B3, with the mean values of 2523.4 and 208.5 mg per plantrespectively, while the highest yields of cyclocaric acid B and arjunolic acid were found intreatment A2B3. The lowest yields of total and three individual triterpenoids were detected in A3 treatment. Overall, our results suggest a complex relationship between light environment,genotype and triterpenoid production, and highlight that selecting suitable provenance ofC. paliurus and optimizing cultivation system would be crucial for a high triterpenoid production.

Key words: cropland, grey relational analysis, potential acid, GIS