Etiolation has been used successfully to improve rooting in cuttings of woody fruit-tree and ornamental species. The cuttings rooting is usually better when etiolation is used together with ringbarking or hormone application. Etiolation can be achieved through different forms by covering the stock plants in the field or in the greenhouse. The shoots can be rooted while they are still attached to the stock plant, by stooling or they are removed like cuttings. In this case, after the etiolated shoots have elongated enough, the shading is gradually reduced and an opaque band is wrapped around the base of the new shoot, thereby retaining its etiolated condition while the rest of the shoot turns green in the light. The process is not well understood, although is known that etiolation promove anatomical and physiological tissue changes which are correlated with ease of rooting. The changes include decreased of lignification and suberization of stem tissues, increased of undifferentiated parenchyma and decreased cell wall thickness. The light control of auxin metabolism is also changed, causing changes in phenolic substances content and in the activity of IAA-oxidase and rooting cofactors.
etiolation; vegetative propagation; rooting
