Abstract

BUSTILLOS-AGUIRRE, César Virgilio; VARGAS-HERNANDEZ, J. Jesús; LOPEZ-UPTON, Javier  and  RAMIREZ-VALVERDE, Gustavo. Repeatability of Genetic Parameters for Branching Traits in Pinus patula Progenies. Madera bosques [online]. 2018, vol.24, n.1, e2411131.  Epub Mar 09, 2018. ISSN 2448-7597.  https://doi.org/10.21829/myb.2018.2411131.

Due to their effect on wood quality, branching traits have an important economic impact in forest plantations. The potential for including these traits in a tree-breeding program depends on their heritability and their genetic relationships with productivity of trees. The objective of the study was to estimate the repeatability of genetic parameters for branching traits in Pinus patula progenies at 7 years and 10 years of age, and their genetic relationship with growth rate of trees. Branching (number of whorls, branch number, diameter and angle, and branching defects) and growth (stem height, diameter and volume) traits were evaluated in 84 open-pollinated families. The data obtained was used to estimate heritability as well as genetic, phenotypic and age-age correlations of traits. Genetic control of branching traits varied from null to moderate (0.00 ≤ h2 i ≤ 0.23; 0.00 ≤ h2 f ≤ 0.42), but it was stable at both ages. Branching traits with genetic variation showed a favorable genetic structure with growth traits. Number of whorls and adjusted branch diameter had a negative correlation (-0.60 ≤ rg ≤ -0.01), and branch angle a positive correlation (0.14 ≤ rg ≤ 0.47) with growth rate. Repeatability of genetic structure for all branching and growth traits was high, in terms of age-age correlations (0.58 ≤ rg ≤ 0.94; 0.83 ≤ rpf ≤ 1.00) and the correlation coefficient between the matrices of genetic and phenotypic correlations at both ages (r ≥ 0.86). Individual or family selection to increase productivity in this population would also improve branching traits on trees (fewer whorls and thin branches with wider angle), and thus wood quality.

Keywords : branch angle; wood quality; genetic correlation; branch size; heritability; selection response.

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