Abstract

Water is the main limiting factor for poplar plantations in the Mediterranean zone of central Chile. Overall, water requirements in these plantations may be estimated using climatic and soil moisture data. However, irrigation strategies can be improved if growth and plant water status are considered. The aim of this study was to assess the growth (diameter increments) and leaf-level physiology (xylem water potential (Psi(x)) and stomatal conductance (g(s))) responses of two Populus x canadensis clones ('I-214' and 'I-488') to different irrigation frequencies. The study was carried out during three growing seasons in commercial plantations located in the Maule Region, central Chile. Three irrigation frequencies were evaluated: an over-irrigation frequency (21 days) (T1); a standard irrigation frequency used operationally in the area (28 days) (T2) and a deficit irrigation frequency (35 days) (T3), while the watering time was held constant for all treatments. Although both clones belong to the same interspecific cross, they differed in their growth and physiological responses to water deficit. Compared with 'I-214', 'I-488' was more sensitive to lower irrigation frequencies (higher water restriction), which decreased the diameter increments, the water potential and stomatal conductance. The results suggest that the use of physiological and climatic information may improve water management on commercial poplar plantations.