Growth of triploid and diploid acacia clones in three contrasting environments in Viet Nam

We assessed the growth and adaptability of triploid acacia clones in comparison with commercially planted diploid clones of the same taxa to age three years at three contrasting sites in north, central and south Viet Nam. Application of phosphorus fertiliser at planting gave a growth response only in the trial in central Viet Nam. One triploidAcaciahybrid (Acacia auriculiformisxmangium) clone was constantly the best performer in all sites, achieving mean annual increments at three years of 30.1, 26.6 and 32.1 m(3)ha(-1)in northern, central and southern Viet Nam, respectively. Two other triploid hybrid clones outperformed the diploid controls in southern Viet Nam. A single triploidA. auriculiformisclone and two diploid clones of this species grew much more slowly. TriploidAcaciahybrid clones had a lower incidence ofCorticium salmonicolor(pink disease) andCeratocystisdisease symptoms than did diploid hybrid clones. The wind-firmness of triploidAcaciahybrid clones was comparable with or better than the diploid hybrid clones. Triploid breeding offers a promising new pathway in the development of improvedAcaciaplanting material.