Abstract

VALLEJOS, Jonathan; BADILLA, Yorleny; PICADO, Félix  and  MURILLO, Olman. Agron. Costarricense [online]. 2010, vol.34, n.1, pp.105-119. ISSN 0377-9424.

Plus trees selection and incorporation in tree improvement programs. A revised methodology for plus tree evaluation and superiority determination on the basic of its phenotypical attributes, as part of a breeding program, is presented. The methodology is based on a phenotypical evaluation of each candidate and its best four neighboring trees, in a 10 to 15 m radius. The field evaluation allows the establishment of a register for each plus tree candidate, with records for commercial volume and a joint criterium called tree quality. Aspects of intensity selection (i); number of trees selected per farm; age of selection; character selection; dominant bud as a better selection criteria in hardwoods, among others, are thoroughly revised. With the hope of avoiding type I selection errors (selected trees which are not truly genetically superior) and type II selection errors (trees that are truly genetically superior, but not selected), the selection method is revised by comparison with the best 4 neighboring trees, and by the establishment of 2 lists of candidate plus trees. List A is for these plus tree which was determined in field as superior in volume as well as in quality. List B is for these plus tree which may show some doubts, and found phenotypically superior only in volume or only in quality. This method allows the production of several statistics and interpretation possibilities. It helps in the initial definition of the commercial breeding population from the whole breeding population. An example based on real data from one of our teak (Tectona grandis) breeding programs, as part of the tree improvement cooperative GENFORES, is shown in detail.

Keywords : Plus tree; tree breeding; selection differential; teak; Tectona grandis.

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