GENETIC VARIATION AMONG AND WITHIN PROVENANCES AND PROGENIES OF Corymbia maculata (Hook.) K. D. Hill and L. A. S. Johnson, IN PEDERNEIRAS, SP

Abstract

This study aimed to estimate genetic parameters and variation in a provenance-progeny test of C. maculate (ex Eucalyptus maculata Hook.), conducted at Pederneiras Experimental Station, in São Paulo Forest Institute. The test was based on 21 open-pollination progenies from provenance Woondum St. Forest and 17 from provenance Wondai St. Forest, both in Australia. A compact family block design was adopted consisting of ten blocks, six plants per straight-line plot and two outer border rows, with spacing 3 x 2 m. Traits assessed included diameter at breast height (DBH), height, volume, form and survival rate at age 4 and 21 years. Significant differences were detected only at age 4 between provenances for DBH and height and among progenies for DBH, height and volume. The coefficient of genetic variation was higher for all traits at age 21. The heritability coefficient at the progeny level ( 2 m h ) was also higher at age 21 and ranged from 0.21 for volume to 0.40 for height, indicating that genetic progress can be achieved through selection of the best progenies. Genetic correlations were high between traits within and between age categories, showing that potential genetic gains can be achieved through indirect, early selection. Results indicate that considerable gains can be made if high selection intensity is applied among and within progenies, with values ranging from 12.48% for height to 21.77% for volume.