Comparing Wood Density, Heartwood Proportion and Bark Thickness of Diploid and Triploid Acacia Hybrid Clones in Vietnam

Abstract

Selected triploid Acacia hybrid (A. mangium × A. auriculiformis) clones grow at similar rates to commercial diploid Acacia hybrid clones planted widely in Vietnam. We compared wood properties at age 3.8 years of two promising triploid clones and two commercial diploid clones grown at Tan An, south Vietnam and Cam Hieu, central Vietnam, using discs from five trees per clone sampled at five heights above ground from 1.3 to 7.5 m. Heartwood proportions were calculated from disc diameters and heartwood-sapwood boundaries. Basic densities of triploid and diploid clones were similar at Tan An (434-491 kg m-3 at breast height). At Cam Hieu, where tree growth was slower, all densities were lower, and the triploid clones had lower densities than the diploid clones (359 and 378 compared with 407 and 447 kg m-3). Heartwood proportions at breast height (45 and 47%) and bark thickness (4.5 and 4.6 mm at breast height) of the two triploid clones were higher than those of the diploid clones (25 and 31%, and 3.7 and 3.7 mm respectively) at Tan An but triploids and diploids did not differ in these traits at Cam Hieu. Implications for wood processing and product value are considered.

Physical and Mechanical Properties of Fast Growing Polyploid Acacia Hybrids (A. auriculiformis × A. mangium) from Vietnam

“…As shown in Table 2, the basic densities of AA-4x and AM-4x were significantly different from those of BV10 and BV16; however, the basic densities of X101, X102, and AH-4x did not differ from those of BV10 and BV16. The wood density of Acacia hybrids was previously reported by PV et al [30] They showed that the basic density of diploid and triploid Acacia hybrids was 0.36-0.49 g/cm 3 , and their mean values for diploid and triploid hybrids in southern Vietnam are consistent with our results. They also showed that Acacia hybrids from the same clone at the same age planted in southern Vietnam had similar basic densities.…”

“…Thus, the ratio of heartwood-sapwood may explain the difference in EMC between clones. In previous research, triploid Acacia had a higher proportion of heartwood than diploid Acacia when the plants were of equal age (3.8 years) and from similar locations [30]. Thus, the EMC of clones may be higher when the ratio of heartwood increases.…”

Breeding Polyploid Varieties of Acacia: Reproductive and Early Growth Characteristics of the Allotetraploid Hybrid (Acacia mangium × A. auriculiformis) in Comparison with Diploid Progenitors

“…The potential for superior growth and wood properties and reduced fertility and consequent weediness of triploid hybrid acacias is now well established [47][48][49], and the findings presented here encourage the adoption of this methodology for further breeding. The chromosomal instabilities, including aneuploidy, which we have identified make it unlikely that we can use forward selection based on simple quantitative genetic predictions, and further research is required to optimize the breeding strategy.…”

Effect of Genetic Gain in Diameter and Wood Density on Advanced Generation Breeding Strategy of Acacia Mangium in Indonesia

“…Wood density is one of the important wood characteristics which is commonly regarded as a key trait in determining wood quality as it strongly correlates with other wood properties and end products (Zobel & Buijtenen 1989, Bon et al 2020. Selection is the main activity in a breeding programme for improving targeted traits, such as wood density.…”