The influence of temperature and genotype on the growth and stomatal morphology of southern beech, Nothofagus cunninghamii (Nothofagaceae)

Abstract

Nothofagus cunninghamii (Hook.) Oerst. clones of five different genotypes from Mt Field National Park, Tasmania, were grown in controlled environment cabinets at daytime temperatures of 23 and 18°C. These temperatures approximate summer conditions in Tasmania at sea level and at about 700 m a.s.l., respectively. There was a significant effect of both temperature and genotype on plant height, but there was no interaction of these terms. Temperature also had a significant influence on plant leaf area and biomass. Plants grown at 23°C were significantly larger and allocated more biomass to leaf tissue than did those grown at 18°C. Importantly, temperature had no impact on the size of leaves, whether expressed as average weight per leaf or area per leaf, but these variables were strongly affected by genotype. Specific leaf area, stomatal density and stomatal index did not vary with either temperature or genotype. These results have implications for our understanding of altitudinal impacts on plant morphology and also for the interpretation of the fossil record, since temperature has little impact on leaf characters in this species.