POTENTIAL AND NICHES FOR INTER-SPECIFIC HYBRIDS WITH PINUS RADIATA IN NEW ZEALAND

In New Zealand there are currently 1.59 million hectares of plantation Pinus radiata D.Don. Further expansion of the plantation resource in this country may have to occur outside the most suitable growing regions, while some existing plantation areas may undergo significant climatic changes. Therefore, species alternatives that have additional climatic and site tolerances need to be found. In addition, although P. radiata is fairly versatile, its intrinsic wood quality clearly limits product quality. Inter-specific hybrid combinations might provide a wider range of opportunities for wood quality improvement and disease resistance. This could be particularly important for biotic threats such as pitch canker (Fusarium circinatum Nirenberg & O’Donnell). Some hybrids have already been produced and, even though these inter-specific crosses have shown lower viability and in some cases lower post-germination viability than intra-specific crosses, the benefits from introducing new attributes or increasing the range of attributes could still be worth pursuing. However, hybrids also have higher developmental costs in crossing and propagation such that greater complexity in breeding strategy may be required than with their pure-species counterparts. Therefore, pine hybrids in New Zealand need to be targeted to specific outcomes of high value. These priorities are most likely climatic (site- and climatechange related), biotic (extending the current plantation area into drought-, frost-, and snow-prone environments), and risk mitigation against the accidental introduction of biotic threats.