Detection and prediction of heterosis in Eucalyptus globulus

Significant specific combining ability effects (SCA) for two year growth were detected in a factorial of Eucalyptus globulus ssp. Globulus. This factorial was established across 5 locations in Australia and involved crossing between and within two provenances (King Island and Taranna) in addition to crossing males from both provenances to a single female from south Flinders Island. We attempted to predict heterosis using genetic distance between parents calculated using RAPD markers. We isolate DNA from all 8 females and 19 out of 26 male parents. Data were collected from 99 different RAPD bands. Sixty-six out of the 99 RAPD bands scored were polymorphic. A UPGMA dendrogram based on Nei's distance resulted in parents within provenance being clustered together in all but one case. The degree to which genetic distance predicted heterosis was statistically significant but accounted for less than 5% of the variation in SCA, and mainly reflected the greater genetic differentiation between parents involved in interprovenance crossing. SCA effects within provenances were unpredictable.