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Summary Growth of several first-generation seed orchard seedlots of Pinus radiata was compared with that of genetically unimproved routine seedlots at ages six to 15 years, in six seed source (yield) trials and eight progeny tests in New South Wales. The seed orchard seedlots were collected from three New South Wales, three interstate, and two overseas orchards, while the routine seedlots were mostly collected from final crop trees during first rotation clearfelling. At age 6–8 years, on average, stock from the eight seed orchards grew faster than the routines at all sites, with an overall mean gain of 8.5% for diameter and 19.9% for tree volume. Although there were some cases of seed orchard stock growing more slowly than routine stock, the great majority of samples tested were superior, i.e. 85% of the comparisons of diameter growth and 75% of comparisons of volume. In well over half of the comparisons, growth of stock from individual seed orchards exceeded that of the routines by at least 10%. The Tall... |
