Methods of Plus Tree Selection for Raising First-generation Population for a Tree Breeding Programme

Tree Breeding is emerging as an important part of all afforestation/reforestation programmes to develop genetically improved planting stock. The objective of a tree breeding programme may be to increase productivity, to improve the quality of forest products, to develop resistance against insect-pests and to adapt the species to unfavourable conditions. The first step in a breeding programme is to select plus trees based on the objectives of any breeding programme. Plus trees are selected among the base populations consisting of either uneven-aged or even-aged stands/plantations. The breeder should make efforts to select even-aged stands, preferably plantations, for making more purposeful selections. A plus tree is selected either by comparing phenotypic values of a candidate tree with those of base population (comparison methods) or evaluating a candidate tree on the basis of its score values (individual tree methods). The comparison methods include comparison tree method, base value method and regression method. Under individual tree methods either the sumtotal of scores or independent culling or selection indices are used to select a plus tree. Comparison tree method has been recorded to be the easy and effective method of plus tree selection. A simplified presentation and the comparative significance of these methods have been discussed.