Editing Tree breeding (section)

{{Short description|Aspect of forestry/silviculture}}
'''Tree breeding''' is the application of genetic, reproductive biology and economics principles to the genetic improvement and management of forest trees. In contrast to the selective breeding of livestock, arable crops, and horticultural flowers over the last few centuries, the breeding of trees, with the exception of fruit trees, is a relatively recent occurrence.

[[File:Grafts.jpg|thumb|Pinus radiata grafts in preparation for the establishment of a seed orchard in New Zealand]]
[[File:Isolation bags.jpg|thumb|Isolation bags for controlled pollination in a Pinus radiata seed orchard.]]

A typical forest tree breeding program starts with selection of superior [[phenotype]]s (plus trees){{clarify|date=August 2024}} in a natural or planted forest, often based on growth rate, tree form and site adaptation traits. This application of [[Selection methods in plant breeding based on mode of reproduction#Mass selection|mass selection]] improves the mean performance of the forest. Offspring is obtained from selected trees and grown in test plantations that act as genetic trials. Based on such tests the best genotypes among the parents can be selected. Selected trees are typically propagated either by seeds or by [[grafting]], and [[seed orchard]]s are established when the preferred output is improved seed. Alternatively, the best genotypes can be directly propagated by cuttings or [[in vitro|in-vitro]] methods and used directly in clonal plantations. The first system is frequently used for pines and other conifers, while the second is typical in some broadleaves (poplars, eucalypts and others). The objectives of a tree breeding program range from yield improvement and adaptation to particular conditions, to pest- and disease-resistance, wood properties, etc. Currently,{{when|date=August 2024}} tree breeding is starting to take advantage of the fast development in plant genetics and genomics.