GENETIC-PARAMETERS AND BREEDING VALUE PREDICTIONS FOR EUCALYPTUS NITENS WOOD FIBER PRODUCTION TRAITS

A base breeding population of 13,000 trees from about 300 Eucalyptus n itens families of open-pollinated origin in 6 provenances of native fo rest stands, was established in 8 tests, analyzed for genetic paramete rs and used for breeding value and gain prediction. Traits considered were basal area (BA), basic density (BD), and kraft pulp yield (PY) in 4- to 8-yr-old trees. Measurement of PY, whether taken as individual trees (PYI) or composites (PYC), were considered as the same trait, si nce the average Type B genetic correlation (r(Bg)) between PYI and PYC was 0.94. Trees with the ''early-adult form'' typically from the Erri nundra provenance appeared to have the poorest PY, averaging 1 to 3% p oints lower than all the other provenances. This provenance was exclud ed from detailed genetic analyses. Significant differences among the o ther five provenances were found for all traits. Four provenances were reasonably similar, but northern New South Wales was estimated to be lowest for BA and PY, and highest for ED. Single-site biased heritabil ities (h(b)(2)) varied substantially from site to site, and averaged 0 .32 +/- 0.05 for BA, 0.43 +/- 0.09 for BD, 0.37 +/- 0.08 for PY. Herit ability estimates from combined-site analyses were 0.19 for BA, 0.42 f or ED, and 0.37 for PY. Genotype x environment (g x e) interaction was estimated using r(Bg). For BD and PY, r(Bg) was 0.94, indicating no m ajor g x e. Moderate g x e interactions were detected for SA, with r(B g) at 0.60. Genetic correlation between BA and PY, and between ED and PY were favorable, but between BA and ED was unfavorable (genetic corr elation = 0.24, 0.41 and -0.24 respectively).