[M-IS14] Biogeochemistry

[MIS14-P06] Relationships between coumarin contents in the leaves of cherry-tree and geology, in Izu Peninsula, Japan

*Daisuke Endo¹, Atsushi Watanabe², Masahiro Suzuki³ (1.Izu Peninsula Geopark and Tourism Bureau, 2.Shizuoka Prefectural Nirayama Senior High School, 3.Numazu Industrial Technology Support Center)

Keywords:Izu Peninsula Geopark, Cerasus speciosa, high performance liquid chromatography, coumarin

Matsuzaki Town, located in the western part of the Izu Peninsula facing Suruga Bay, is surrounded by a beautiful and varied coastline and a rich natural environment, and the town's specialty, “Sakurabazuke” has a 70% share of the national production. The cherry-trees used for pickled cherry leaves are Cerasus speciosa, which grows wild in the mountains and coasts of this region. In the past, the leaves were harvested from trees growing in the mountains, but now they are grown in satoyama where are intensively managed and cultivated. Oshimazakura is generally said to be resistant to harsh environments such as sea breezes and strong winds, making it a tree species suited to the climate of the southwest coast of Izu, where seasonal winds from the west prevail in winter. Sakuraba pickles are made by bundling the collected leaves and salting them in special barrels for about six months before being shipped. According to experience among local producers, Oshimazakura is more popular among cherry-trees, cherry-trees from the southwest region of the Izu Peninsula such as Matsuzaki Town and Minamiizu Town are more popular, and cherry-trees picked from the mountains have a higher fragrance than those grown in the fields. In this study, we analyzed the content of coumarin, which is said to be the main component of the scent of cherry-tree leaves, in order to obtain data that supports these empirical rules. The leaves of 34 samples of cherry-trees, including Oshimazakura, collected from various locations on the Izu Peninsula were salted for approximately 3 months and the coumarin content was determined using high performance liquid chromatography (HPLC). The results revealed that the leaves of Oshimazakura, which grow naturally on the Jogasaki coast on the east coast of the Izu Peninsula, had the highest coumarin content per unit weight. This result differs from the producers' empirical rules, and it was found that the coumarin content of Oshimazakura in the southwest region of the Izu Peninsula is not simply high. The analysis also found a slight correlation between the growing environment of cherry-trees and coumarin content, with cherry-trees grown in upland fields having lower coumarin content. This confirms the producers' rule of thumb. Looking at the relationship between the coumarin content in cherry leaves and the geological environment, we found that the content tended to be lower in cherry-trees growing in areas with thicker soil and relatively better nutritional status, such as in fields.