© 2007 Heron Publishing—Victoria, Canada
Clonal variation in crown structure, absorbed photosynthetically active radiation and growth of loblolly pine and slash pine
Veronica I. Emhart (1–3), Timothy A. Martin (1), Timothy L. White (1) and Dudley A. Huber (1)
1. School of Forest Resources and Conservation, University of Florida, P.O. Box 110410, Gainesville, FL 32611, USA / 2. Corresponding author (vemhart@infor.cl) / 3. Present address: Instituto Forestal, Casilla 109-C, Concepción, Chile / Received December 19, 2005; accepted April 14, 2006; published online December 1, 2006
Summary
Crown structure, absorbed photosynthetically active radiation (APAR) and growth were analyzed in 300 replicated loblolly (Pinus taeda L.) and slash pine (Pinus elliottii Engelm. var. elliotti) clones to: (1) quantify genetic variation in crown structural traits, growth and APAR at the species, family and clonal
levels; and (2) estimate within-family genetic and environmental influences on measured variables. Species and family-within-species
differences were found in some growth traits, crown size, leaf area, APAR and branch angle. Loblolly pine developed larger
crowns, exposed more leaf area with an acute angle, and intercepted more radiation than slash pine. Significant differences
among clones within-family were found for stem volume and crown architecture. Loblolly pine and slash pine within-family,
individual-tree broad-sense heritabilities ranged from 0.00 to 0.41 for growth and crown structural traits and most were between
0.10 and 0.25 when estimated from a combined analysis across families. Genetic correlations of crown size, leaf area and APAR
with volume increment generally ranged from 0.60 to 0.75. This knowledge of the genetic interactions among growth and crown
structural traits improves our understanding of how crown morphology affects light interception and stand development, and
ultimately how these attributes can be incorporated in the selection of families or clones for the development of new crop
tree ideotypes.
Keywords:
crown architecture, intercepted radiation, Pinus taeda, Pinus elliottii var. elliottii, quantitative genetics.
