UTILITY OF GENOTYPE X ENVIRONMENT INTERACTIONS

With increasing knowledge about how nutrient and water availability affect tree growth, and with new techniques of genetic manipulation becoming known, it seems appropriate to ask whether the two can be combined. Is it possible or worthhile to produce genotypes tailored for specific nutrient or water conditions? Interactions between genotypes and the environments in which they grow have frequently been shown to be statistically significant for a wide range of tree species in many environments. However, the practical importance of the interactions is highly questionable as additional genetic gains to be had through using the interactions are very small in relation to the overall gains themselves. Interactions seem very large for seedling experiments in glasshouse trials, but are much less in field trials even when the environments are extensively modified by fertilizers. For the genotypes to be matched to environments, those environments must be well-defined and repeatable. Sites where there are specific problems tend to be well-defined and repeatable. Matching genotypes to such sites may provide a useful solution to those problems. The genotypes may be produced as seed from crosses or as clones from tissue culture or, more conventially, from stem cuttings. Selection in vitro for particular traits requires a level of knowledge about the traits generally absent for forest trees. When the ways in which diseases or poor adaptation effect trees are better known, such selection may become practicable. We do not believe it is practicable at present for diseases or for nutrient or water relations. © 1990.