Root characteristics of several Pinus radiata genotypes growing on different sites in Gippsland

Summary The effect of genotype, site and season in the expression of root characteristics such as fine root length, proportion of active roots, short root density and per cent mycorrhiza, were studied on six Pinus radiata families growing on four different sites. Genetic differences occurred between the families in the expression of root characteristics. There was a strong family × site interaction indicating that particular genotypes may express their root characteristics differently in different environments. There were significant differences in the expression of root characteristics between different sampling times. However, generally there was no significant family × season interaction. This suggests that assessment and selection for root parameters could be carried out in any season as long as soil conditions at the time are suitable for expression of variation between genotypes. However significant site × family × season interactions suggest that sampling times need to be chosen carefully for propo...