Water is the main limiting factor for the development of agricultural species and forest species. In Chile more than 3⁄4 of the land surface corresponds to arid and semiarid areas.
Several studies have shown that species of the genus Eucalyptus, have a wide potential in the tolerance to limited rainfall. For this reason, we evaluate the effect of water availability in some responses of three species of Eucalyptus: Eucalyptus globulus, Eucalyptus camaldulensis and Eucalyptus cladocalyx.
The plants were subjected to three levels of water availability, defined as: no stress, moderate stress and severe stress. The plants were kept under semi-controlled environments and responses were evaluated during two cycles of drying at the end of each cycle, plants were rehydrated for one week. The results indicate that E. camaldulensis had higher physiological plasticity with respect to the values of stem water potential, stomatal conductance, photosynthesis (with E. cladocalyx) and chlorophyll fluorescence.
The availability of water treatments are applied in a first phase, lasting five weeks, then recover with watering plants for a week, then re-apply for water restriction treatments for nine weeks. Finally, we apply a week of recovery with irrigation.
The study includes 90 eucalyptus plants, 30 species, which are arranged in a factorial design of five blocks at random. The major constraint observed in Eucalyptus camaldulensis and Eucalyptus cladocalyx with water restriction, is of type stomatal directly influence photosynthesis, internal CO2 concentration and stomatal conductance. In E. globulus, meanwhile, is metabolic.
This experiment allowed us to confirm that E. camaldulensis and E. cladocalyx tolerate water deficit, being entitled to be located in areas with low water availability, such as semi-arid and arid areas of Chile.
Milla Moreno, E. 2010. Hydric stress and its influence in tree physiology, looking at three species of Eucalyptus spp. Thesis. Faculty of Forestry, University of Chile. Santiago, Chile. 60 p.