Fruit oil contents of the genus Quercus (Fagaceae): A comparative study on acorns of subgenus Quercus and the Asian subgenus Cyclobalanopsis

Abstract

Seed oils are an essential energy reserve for germination and early seedling development for many species. yet quantification is still relatively rare beyond the main crops. The genus Quercus. (Fagaceae), consisting of subgenera Quercus and Cyclobalanopsis, is widespread throughout the Northern Hemisphere: however. fruit / acorn oil content of the Asian distributed subgenus Cyclobalanopsis is not well documented. We quantified fruit oil contents in eight species from the subgenus Cyclobalanopsis (from China) and ten species from the subgenus Quercus (from both China and Europe) by supercritical fluid extraction with carbon dioxide. The majority of fruits were highly viable with a germination of over 50%. Fruit oil content of subgenus Cyclobalanopsis was significantly lower than that of subgenus Quercus and across IS species studied moisture content of the storage tissue (cotyledons) was negatively related to fruit oil content. Our oil content data were combined with that from the literature, resulting in a total of 57 species, and mapped on the current phylogeny for Quercus to reveal the highest fruit oil contents associated with sect. Lobatae.