Scientific novel: Araucaria angustifolia branch may be converted into orthotropic trunk by grafting

Abstract

Grafting technique has been presented as an alternative for Araucaria angustifolia propagation. However, vegetative rescuing mature trees and obtaining large numbers of propagules is difficult, because the use of branch grafts has not been indicated due to its plagiotropic and morphogenic characteristic, generally resulting in undesired growth of the graft. So we aimed to describe the unpublished fact occurred in four plants of A. angustifolia grafted with grafts from primary branches that resulted in conversion to trunk. Plant growth and morphology were evaluated ten years after grafting. We verified vertical growth and organization of trunk and persistent branches with defined whorls, same to plants grafted with trunk grafts. Field tests with grafted plants using grafts obtained from the four plants resulted in same development pattern, proving the permanent morphogenic change and opening new perspectives for araucaria vegetative rescue and grafting. We concluded that trunciform shoots can be obtained by A. angustifolia grafting with plagiotropic primary branches. Despite the morphological clarity of trunciform shoots on grafted plagiotropic primary branches, it has not yet been possible to identify the causes of this reversion.

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“…In line with this, the branch type is also important in determining the developmental patterns of grafting. Araucaria angustifolia grafted with plagiotropic primary branches resulted in conversion to the trunk, represented by the vertical growth, organization of trunk, and persistent branches with defined whorls, in a similar developmental pattern to those grafted with trunk grafts (Constantino et al 2020).…”