Ginkgo biloba L., a relict species of the oldest extant genus among seed plants, is an economically important tree species. Ginkgo biloba has two industrial uses-seed/nut products and leaf extracts. Seed-use ginkgo involves harvesting of seeds from adult female plants. By contrast, leaf-use ginkgo involves harvesting of only leaves. Due to the abundant active compounds in ginkgo seedling leaves, 1–5-year-old ginkgo seedlings are typically used for G. biloba leaf extract (GbE), which is used for treatment of cardiovascular diseases, dementia, and dizziness. Therefore, ginkgo seedling is an important medicinal plant. Flavonoids are the main active constituents of GbE and more than 40 flavonoids have been isolated from ginkgo leaves, including flavanones, flavonols, flavones, and dihydroflavonols. In addition, the terpene lactones, including ginkgolides A, B, and C and bilobalide, are important pharmacological components of GbE Despite the high contents of active components (flavonoids and terpene lactones) in seedling leaves, leaf yield and primary/secondary metabolite accumulation of ginkgo seedlings according to planting density are unclear. Over the last few decades, improvements in planting density have been considered the main contributors to yield improvement per unit land area. Planting density influences yield by regulating plant growth, yield components, and photosynthesis. As density increases, resource allocation per plant decreases and plant-to-plant competition increases, thereby limiting per-plant yield potential. Although high planting density is detrimental to individual plant yield, increased density is used to maintain a sufficient number of seedlings per unit area and leads to a significant increase in leaf yield per unit area. There have been studies concerning the relationship between primary metabolite accumulation and planting density. A high planting density inhibits sucrose transport and starch accumulation in wheat grain. Reduced separation of apple trees increased the competition for light, reducing the total starch content. Similarly, the contents and types of secondary metabolites may be also affected by planting density. Secondary metabolites as important sources of bioactive components from medicinal plants, but few studies have examined secondary metabolite accumulation according to planting density. Here, we investigated the effect of different planting density on leaf yield and metabolite accumulation in leaf-use ginkgo and screened the suitable moderate planting density. Our findings will enable improvement of leaf yield and quality in ginkgo industrial plantations.

Regards,
Catherine
Journal Co-Ordinator
Annals of Biological Sciences