Growth and form of Guadalupe and Cedros Island provenances of Pinus radiata in low rainfall environments

Abstract

Half-sib families of ‘elite’ Guadalupe and Cedros Island radiata pine provenances identified by Boardman and McGuire (1997) are tested along with routine genetically improved seed orchard material and an Australian Capital Territory developed Guadalupe hybrid at three sites in the Mid-to-Upper South East of South Australia.  A comprehensive assessment of growth and form traits were undertaken at nine years of age and results from this assessment forms the basis of this report.

This trial is one of the very few trials in the world to test Guadalupe and Cedros Pinus radiata provenance material in low rainfall environments.  The Mexican island P. radiata provenances were also tested in a non-limited resources environment which is a high (I-II) site quality site (Lewis, Keeves & Leech 1976).  Low rainfall P. radiata data in general is scarce, particularly when sourced from regions down to 400-450 mm mean annual rainfall (MAR).  This trial provides performance information at nine years of age in such a region and also provides an indication to the production of over 3 000 ha of P. radiata on private land within the Upper South East of South Australia north of Comaum.

Assessment of the trial at nine years of age has not identified superior P. radiata families for growth and/or form traits from the material tested.  Routine, genetically improved P. radiata did not perform better than the Guadalupe and Cedros Island half-sib ‘elite’ selections at all sites including the non-limiting resource site of Reedy Creek.  Volume production of the routine material was only 75-81% of the top performer at each site.  The results of the form assessments indicate that the Mexican island’s excellent natural form traits together with ‘elite’ selection and first generation crossing produces progeny with form equal to material produced from mature breeding programs.


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