一些真菌侵入苗木的根部组织后,建立的一种联合共生体叫做菌根。真菌可从土壤中为苗根输送水分及矿物质等营养成分;苗根则给真菌供应碳水化合物,所以菌根与苗木的生长发育有着密切的关系。许多树种的幼苗期皆有菌根,它形成根系中非木质化时的侧根末梢。林区常见的松树、桦树、柳树等都是外生菌根,即通过外表皮细胞间隙侵 Some fungi invade the roots of seedlings after the establishment of a joint symbiont called mycorrhiza. Fungus can transport nutrients such as moisture and minerals from the soil to the seedling roots; while the seedling roots supply carbohydrates to the fungi, so mycorrhiza has a close relationship with the growth and development of seedlings. Many tree species have mycorrhizal seedlings, which form the non-lignified lateral root tips of the root system. Common pine forest, birch, willow and other ectomycorrhizal, that is, through the outer epidermal cell gap invasion