(2) Horizontal distribution of roots. Ginkgo has many roots and branches. The roots of ginkgo trees over 50 years old are concentrated in the range of 3~5 meters from the trunk, and the horizontal distribution range also expands with the growth of tree age. The horizontal lateral root of Ginkgo biloba is longer than the main root, which is generally 1.8~2.5 times the radius of crown width. The ancient ginkgo biloba in Dawu Township, Dongkou County, Hunan Province 1200 is 52 meters high, with a vertical distribution of more than 20 meters and a horizontal distribution of more than 500 meters, but the root clusters are mainly distributed 5-7 meters away from the trunk. The ratio of root width to crown width of Ginkgo biloba varies with tree age and site conditions. The ratio of root width to crown width of young trees is (1.4 ~1.7):1,and it is (0.99~ 1.2): 1 after entering full fruit stage. Because ginkgo root system is widely distributed, deep and loose soil should be chosen to build ginkgo forest.
(3) Vegetative growth characteristics of root system. Ginkgo root system began to germinate in late March and stopped growing in early February. The growth period is about 250 days, and its annual growth cycle has two growth peaks. The first growth peak is from late May to mid-July, about 60 days, which occurs at the same time as the growth peak of aboveground parts, and the tree has a great demand for nutrients. The second peak growth period is from mid-June 65438+ 10 to mid-June 165438+ 10, which is the slow growth period after seed harvesting and high-diameter growth. At this stage, the tree contains abundant nutrients, but its growth time is short, its photosynthetic capacity is weak, and its growth is very small.
It is a natural phenomenon that VAM fungi infect the root system in the soil of ginkgo forest land. Vaccination with VAM fungi can promote the growth of seedlings. Ginkgo VAM fungi can form a large number of intracellular hyphae, but few intercellular hyphae. After root infection, there are a lot of root hairs, which is a typical form of root absorption. The absorption root of Ginkgo biloba has good absorption ability only when it is infected by endogenous VAM fungi.
Ginkgo biloba root system has high water content and certain drought tolerance. However, if it germinates for a long time or is transported for a long distance, the root system will lose too much water, the mycorrhizal hyphae will dry up and the water absorption capacity of the root system will decrease, which will affect the survival rate of seedlings or the growth and development of young trees.