Achievements in forest tree genetic improvement in Australia and New Zealand 7: maritime pine and Brutian pine tree improvement programs in Western Australia.

摘要

Maritime pine (Pinus pinaster) is an important plantation species in Western Australia. The area now planted is ~50 000 ha, but this will increase significantly because of the planned establishment of more than 150 000 ha in medium-rainfall areas of the wheat belt to reduce salinity while providing a commercial tree crop. A breeding programme was begun in 1957 in Western Australia to ameliorate defects in P. pinaster for plantation wood production on impoverished sands in high-rainfall areas of the Swan Coastal Plain. The priority was to improve stem straightness while maintaining dominant vigour; reducing branch angle and branch size were secondary requirements. Eighty-three progeny trials covering 160 ha with 186 100 trees were planted from 1965 to 1991, and 25 ha of clonal seed orchards were established. The programme has provided substantial gains in tree growth, and stem and branching form, since 1971. The new cultivar available for deployment to tree farms was ~80% more productive than the original stock, as well as being much straighter and smaller limbed. A second phase of the breeding programme started in 1996. This was designed to take the developed, diverse breeding population to new sites in medium-rainfall areas of the wheat belt, and to test the suitability of the genotypes available for deployment. Over the subsequent decade some 32 progeny trials testing 843 families with 81 380 progenies were established on an area of 55 ha. Tolerance to drought and strong apical dominance on fertile, medium-rainfall sites were identified as new traits important to the breeding objective. New seed orchards were developed for these major traits. Brutian pine (P. brutia) has the potential for high-evaporation, medium-low-rainfall areas because of its inherent ability to survive severe water stress and display apical dominance. The breeding of this species was stepped up in 1999 using old progeny trials at Yanchep as a base population. The objective was to improve the early growth and establishment of the species, and to examine its potential as a hybrid with P. pinaster.