PROBLEM TO BE SOLVED: To provide a method and a plant growth agent which can promote infection and growth of mycorrhizal fungi to a plant, and can grow the plant with improved efficiency.SOLUTION: A plant growth agent is given which can be carried on a plant root and allows mycorrhizal fungi to adhere thereto and in which its size is at least one of μm order, nm order, or pm order, and its structure is at least one of multicellular structure, fiber structure, spiral structure, cylindrical structure, tunnel structure, layer structure, and nest structure, or these structures are mixed. The following steps are performed using the plant growth agent: an application step in which the plant growth agent is applied to the plant root or a cultivation place of the plant a rootlet guiding step in which the plant is grown under the situation where rooting is enabled and a rootlet is guided from the plant root and a mycorrhizal fungi inoculation step in which the mycorrhizal fungi is inoculated into the rootlet of the plant during the rootlet guiding step or after the rootlet guiding step.SELECTED DRAWING: NoneCOPYRIGHT: (C)2017,JPO&INPIT【課題】菌根菌の植物への感染及び増殖をさらに促進し、従来よりも植物を効率よく育成することができる方法及び植物育成剤を得る。【解決手段】植物の根に担持されることが可能且つ菌根菌が付着可能であって、少なくともμmオーダー、nmオーダー、又はpmオーダーのいずれか1つの大きさで且つ少なくとも多孔質構造、繊維質構造、螺旋構造、筒状構造、トンネル構造、層状構造、又は、入れ子構造のいずれか1つの構造からなる植物育成剤を含む、あるいはそれらの構造物が混在する植物育成剤を、植物の根又は植物の栽培箇所に施用する施用工程と、植物を発根可能な状況下で生育させ、植物の根から細根を誘導する細根誘導工程と、細根誘導工程中又は細根誘導工程後に、植物の細根に菌根菌を接種させる菌根菌接種工程を行う。【選択図】なし
