Early testing for improving growth under water shortage in Eucalyptus globulus Labill.

Abstract

Aim of study: We aimed at identifying differences in the response to water shortage between Eucalyptus globulus clones. Area of study: Field trials were established in SW Spain. Material and methods: Potted plants from six clones were grown in a greenhouse for 35 days under two watering regimes. Two clones were F0 genotypes and the other four were F1 (hybrid) genotypes, including one inbred clone. Differences in stomatal conductance, hydraulic traits, growth and specific leaf area (SLA) were analyzed. Main results: Water shortage decreased SLA, growth in height and leaf area and leaf-specific hydraulic conductivity (KLmax). We measured the highest growth in F1 genotypes and the lowest in the clone in which SLA was lowest. The inbred clone showed the highest growth reduction under water shortage. There was substantial hysteresis between leaf water potential (Y) and native embolism, most probably a result of combined cavitation and refilling. High losses of hydraulic conductance were compatible with high stomatal conductances. Maximum values of stomatal conductance decreased with the soil water content estimated from predawn Y and were lowest in the inbred clone, showing less plasticity and a diminished ability to cope with high temperatures, which could explain its poor development under field conditions. Research highlights: Soil water content and predawn Y appeared as critical factors controlling stomata closure, while stomatal conductance and SLA could be useful to predict differences in growth and survival from early trials.