Realized gains in growth traits, stem quality and sawlog percentage of breeded seedsources of Acacia auriculiformis compared with a commercial seedlot after 15 - year planting in Quang Tri

Abstract

Genetic gain trial of Acacia auriculiformis at Dong Ha, Quang Tri was planted in August 2002, with 5 different seedsources, 5 replicates, 49 trees/plot. The different seedsources were SSO select, SPA select, SSO routine, natural provenances and commercial seedlot. At age of 15 years, the evaluation of this trial showed that growth and stem quality of different seedsources differed significantly (p < 0.05), except for stem axis persistence. SSO selectperformed the best seedlot, with MAI of 19.6 m3/ha/year. While the growth of SPA select, SSO routine and natural provenances were similarly, which yielded from 13.2 to 14.2 m3/ha/year. The commercial seedlot was the worst growth in the trial, only yielding 6.2 m3/ha/year. Realized gains in growth and stem quality, expressed as percent gain relative to commercial seedlot control, were 18.8% for total height, 27.9% for diameter, 61.7% of stem volume, 20.0 - 24.8% for the stem quality. Comparing the performances of natural-provenance seedlot, the SSO select had the realized gains of 6.0%; 16.7%, 28.4% and 5.5 - 16.2%, repectively. Of great concern for growers in Vietnam is the very poor performance of the commercial seedlot, which the growth and stem quality were reduced from 3.1 - 20.6%, compared to the naturalprovenance seedlot. Our research results also confirmed that if using SSO select to cultivate sawn-log plantations will be good achivement and highly effective after 15 - year planting and meet requirement of the program for restructuring forestry sector.