Provenance and progeny variation in growth and frost tolerance of Casuarina cunninghamiana in California, USA.
Field trials of Casuarina cunninghamiana, including 130 open-pollinated families from 13 provenances in New South Wales, Australia, were established in 1987 at five field sites, in provenance trials designed to determine genetic variation between and within provenances, measure the degree of planting site × genotype interaction, and assess the relative frost hardiness of provenances. Three main sites, Anderson, Davis and Woodland, had a common design (132 seedlots, 10 families × 13 provenances plus 2 bulked provenance seedlots) with spacing mainly 108 m × 1.8 m. Two additional sites were also established: Palermo, to evaluate growth with waste water irrigation, and Oregon House, to test relative frost tolerance. Based on height and volume growth and survival at 60 months after planting (data are for the three main sites only, due to frost damage at the 2 supplemental sites), significant genetic variation was observed both between and within provenances. Significant differences among provenances were also observed in frost injury rating following the occurrence of mid-winter temperatures as low as -13°C. The results of this study indicate that the growth and frost tolerance of C. cunninghamiana in California can be improved by proper choice of provenance and selection within provenances.