Toriki (English spelling) layerage

Japanese: 取木 - とりき（英語表記）layerage

A propagation method in which new roots are sprouted from a part of a plant's trunk or branch to create an independent individual, a type of vegetative propagation. Unlike grafting, in which the trunk or branch that will become the parent plant is cut from the parent plant and then rooted, layering involves directly rooting the trunk or branch and then dividing or cutting it. This method is suitable for propagating plants that are difficult to root by grafting or have thick trunks that are difficult to handle, and can be propagated while being enjoyed as ornamental plants in pots, but it is difficult to propagate many at once.

[Yasuo Hori]

method

(1) Mounding method (laying method) This is a commonly used method in which a branch growing above ground level is bent sideways, held down with wire or weights, and soil is piled on top of it to allow roots to sprout. Rooting can be sped up by ring-barking or making a cut in the part of the branch to be layered. This is used for clumped wintersweet and climbing roses. (2) High-layering method This is a method of layering a branch as it is while it is growing, and is used especially for trees with thick trunks or branches or trees that cannot be bent to the ground. A ring of 5-10 mm of bark is removed from the part to be layered (ring-barking), and if any sap comes out, it is wiped off thoroughly, and the part is wrapped in sphagnum moss or keto soil into a ball, wrapped around the outside in vinyl, and both ends are tied together. It is kept from drying out until roots sprout. This is often used for pomegranates, maples, cherry trees, rubber trees, and crape myrtles. The reason for removing the bark is to prevent the carbohydrates and other nutrients produced in the leaves from migrating to the roots, and to encourage the roots to accumulate. After the roots have grown, once several roots have been seen from the outside, they are cut below the bark and the sphagnum moss is completely removed before planting.

The best time to layer is from May to June when the plant is in its active phase. For deciduous trees, April just before germination is best. Rooting varies by tree species, taking from as fast as three months to as long as nearly a year.

Other methods of layering include (1) the advance method, in which the tip of the branch is buried in the soil; (2) the centipede method, in which a well-grown branch is curved and undulated; and (3) the shumoku method, in which a branch is laid straight down and roots are sprouted from each node, but these methods are not commonly used.

[Yasuo Hori]

The method of layering
©Shogakukan ">

The method of layering

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

植物の幹や枝の一部分から新しく発根させ、独立した個体をつくる増殖法で、栄養繁殖の一種である。母体となる幹や枝を、親株から切り取ってから発根させる挿木と異なり、取木は直接発根させたのち、分割または切り取るものである。挿木で発根しにくいものや、幹が太く扱いにくいものの繁殖法として適し、また鉢植えなどで観賞しながら殖やすことができるが、一度に多数殖やすことはむずかしい。

［堀　保男］

方法

（1）盛土法（伏せ込み法）　一般に用いられる方法で、地際より伸びている枝を横に曲げ、針金または重石(おもし)で押さえ、さらにその上に土を盛り発根させる。盛土する枝の部分に環状剥皮(はくひ)か切り目を入れると発根が早まる。株立ちしたロウバイ、つるバラなどに利用される。（2）高取法　生育中の枝をそのまま取木する方法で、とくに幹や枝が太い場合や地面に曲げられない状態の木に利用される。取木する部分の樹皮を5～10ミリ環状に除去（環状剥皮）し、樹液が出たらよくふき取り、その部分をミズゴケまたはケト土などで団子状にくるみ、外側をビニルなどで包んで両端を結束する。発根するまで乾燥しないよう管理する。ザクロ、カエデ類、サクラ、ゴム、サルスベリなどによく用いられる。除皮処理の理由は、葉で形成された炭水化物などの養分が根部のほうに移行するのを抑え、蓄積させることで発根を促すためである。なお、発根後は、根が外から数本確認できたら剥皮した下側で切断し、またミズゴケは完全に取り除いてから植え付ける。

　取木の時期は植物が活動期に入った5～6月が適期である。また落葉樹では発芽直前の4月が適するものもある。発根は樹種により差があり、早いもので3か月、遅いものでは1年近くかかる。

　取木の方法としては、ほかに〔1〕枝の先端を土中に埋める先取法、〔2〕よく伸びた枝を湾曲にし、波状に起伏させた百足(むかで)取法、〔3〕枝を真横に倒し各節部から発根させる撞木(しゅもく)取法などがあるが、一般にはあまり利用されない。

［堀　保男］

取木の方法

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