Genetic divergence among slash pine second generation progenies at an early age

Abstract

The objective of this study was to estimate the genetic divergence among slash pine open-pollinated progenies at an early age. Two progeny tests were established in a randomized complete block design, single-tree plots planted in March, 2009, in a 3 x 3.0 m spacing. One test was planted in Ribeirão Branco, São Paulo State, involving 44 progenies in 40 blocks. The other one was planted in Ponta Grossa, Paraná State, with 24 progenies in 32 blocks. Growth and form traits were assessed five years after planting. Genetic divergence was estimated by using the Mahalanobis distance method. Two hierarchical grouping methods were compared: UPGMA and Tocher optimization. Both of these showed similar results and identified five and ten groups, respectively in Ribeirão Branco and Ponta Grossa tests. In order to avoid losses in genetic gain in subsequent generations, crosses should be restricted to individuals belonging to families in divergent groups.