Seasonal Variation of Chemical Compositions of Insect-resistant Pinus massonania Needles

The chemical compositions were separated from needles of insect-resistant clones of Pinus massonania by solvent extraction combined with steam-distillation. Relative content and structure of the chemical compositions were analyzed and identified. The results showed that 74 components were detected, of which 45 were identified. Major compositions were monoterpenes, sesquiterpenes and alcohols. There were significant differences in the relative contents of the chemical compositions in different seasons. The chemical composition changeed with the seasons showed different trends. Contents of monoterpenes variation showed significant and positive correlation with each other. Monoterpenes contents variation showed significantly negative correlation relationship with sesquiterpenes.