Early growth, biomass allocation and physiology in three Eucalyptus nitens populations under different water regimes

Abstract

Potted seedlings of three populations of Eucalyptus nitens were either watered up to field capacity or subjected to several substrate water limitations. Water limitation was established automatically through pressure transducer microtensiometers and watering regimes were maintained after sowing for 3 months in a greenhouse. Increasing water deficits affected germination of E. nitens seeds, but maintaining adequate substrate surface humidity seemed more important for improving germination. Soil water deficits affected biomass accumulation, foliage and growth of juvenile potted E. nitens plants. The proportion of dry matter allocated to roots was not affected by watering regimes. Moreover, for each population, watering regime had no effect on the ratio of stem and leaves to total biomass. Population differences were not observed in stomatal conductance and transpiration rate. Likewise the interaction between population and water treatment was not significant for gas exchange. However, responses in photosynthesis and water-use efficiency were found among the populations.