Following joint seed collections of Casuarina cunninghamiana between CSIRO, Australia, and the International Tree Crops Institute in 1985 (see FGRI No. 15:51–54), provenance trials were established at five sites in California. Although C. cunninghamiana has proven to be a successful species in California, it has not been earlier systematically tested in the State (mainly planted for windbreaks, fuelwood, erosion control and amenity purposes).
The objectives of the provenance trials are to (i) determine the amount of genetic variation within and between provenances; and (ii) select superior provenances and individuals on the basis of growth, form and frost tolerance.
Trial seedlots
Most of the 132 seedlots included in the trials are open-pollinated seedling families from 13 provenances (10 seed trees each), from New South Wales (Australia). One provenance from the northern portion of the species range in Queensland (Mareeba) and one high elevation provenance from New South Wales (Blue Hole), are included in the trials as bulked seedlots. There are three primary testing sites for all 132 seedlots (bulked provenance seedlots).
The trials were established in March/April 1987; trees will be irrigated throughout the project.
Survival percent, height and diameter at breast height, will be measured annually at each site. Towards the end of the trial (1994 or later), tree form will be scored and wood samples will be collected for density and combustion testing.
The work is being carried out by the International Tree Crop Institute 2 through a non-profit association (the Casuarina Improvement Association), in close collaboration with the Forestry Tree Improvement Programme of California.
In addition to the C. cunninghamiana provenance trials, some supplemental research on herbicide screening and Frankia inoculation has been done in cooperation with the University of California at Davis. A field planting of artificially inoculated seedlings was established near one of the main (uninoculated) trial plots. Six months after planting, the mean heights of artificially inoculated seedlings were significantly greater than those without inoculation, in five out of the six provenances tested.
Field trials of Casuarina glauca are planned for 1989. It is proposed to test the effect of Frankia inoculation and phosphorus fertilizer on the growth of C. glauca in both saline and non-saline environments.
Additional information on the above trials can be found in the references listed below. The International Tree Crop Institute is interested in exchanging information and genetic materials with others involved in Casuarina research and development, with special reference to Casuarina cunninghamiana and C. glauca). For further information, please contact the author of this article (see footnote 1).
References
Merwin, M.L. 1987 Casuarina Field Trials in California. Nitrogen-Fixing Tree Research Reports 5:29–30 (available as above).
Merwin, M.L. 1988 Update on provenance trials of Casuarina cunninghamiana at the International Tree Crops Institute. Nitrogen Fixing Tree Research Reports 6:52–53 (available from the Nitrogen-Fixing Tree Association (NFTA), P.O. Box 680, Waimanalo, Hawaii 96795, USA).
