Breeding Eucalyptus Regnans—five Year Progress Report

SUMMARY The breeding programme at Traralgon aims to improve Eucalyptus regnans F. v. M. as a forest tree by increasing the rate of growth, improving wood quality, and increasing resistance to damage by fire. Improvement may be accomplished in three ways:—(1) provenance trials (to determine the best place to collect seed for afforestation in a given location), (2) selection of individual trees within the chosen provenance, and (3) hybrids with species with greater resistance to fire and the ability to grow on poor sites. The major part of the work has been the provenance trials which show continuous genetic variation with altitude on the south eastern side of Mount Erica, Victoria. Seed for the trials was collected in October 1959 from 68 trees on Mount Erica. with an average of 10 trees at each of seven altitudes from 1200 feet to 3250 feet. Studies were made of capsule size, germination, cotyledon area, and growth of seedlings in the nursery. Sixty-four open pollinated progenies were planted in a cubic lattice design in the Strzelecki Ranges at 1650 feet, and some smaller trials were planted at other places. Field measurements at two years of age and again at three years confirmed the trend shown in the nursery that seedlings from higher altitudes grew more slowly. Leaf shape also varied with altitude but survival of seedlings did not. A study of the relation of nursery measurements to field measurements showed promise of a technique for culling the slowest growing progenies in the nursery without the need for field planting all the progenies. An examination of growth rates of progenies from a given altitude showed that large dominant trees rarely produced the fastest growing seedlings, consequently trees selected for breeding should not be simply the largest individuals but rather the parents which give the best progeny in nursery and field trials. Experiments were commenced on the value for forestry of hybrids of E. regnans and some observations were made on seed production.