Root morphological changes in response to low phosphorus concentration in eucalypt species

Eucalypt seedlings differently modulate root morphology in response to phosphorus availability, with changes in the length or density of root hairs being more common that changes in root length. Phosphorus (P) is an essential nutrient for plant growth and development and thus can restrict biomass accumulation when it is at low levels in the soil. Eucalypts cover large areas of planted forests in the world, including regions with naturally low P availability. This study was conducted to evaluate the morphological changes in the roots of seedlings of five eucalypt species: Eucalyptus acmenoides, E. globulus, E. grandis, E. tereticornis and Corymbia maculata in response to low P concentration. Seedlings were grown in pots with vermiculite and received a nutrient solution of low (25 μM), and sufficient concentration (500 μM) of P. Root hair length and density were evaluated in secondary root segments, and the production of plant biomass and P concentration in the shoots were determined. The species modulated root morphology differently in response to P limitation. E. tereticornis showed the lowest plasticity of these morphological traits in response to P concentration. The total root length increased in some species, but changes in the length and/or density of root hairs were the commonest response to low P concentration. P concentrations in the shoots and biomass production were not related to increase of root length or root hair density and length.