Experimental drought is well documented to induce a decline in photosynthetic capacity. However, if given time to acclimate to low water availability, the photosynthetic responses of plants to low soil moisture content may differ from those found in short-term experiments.
Zhou et al. compared Eucalyptus taxa and tested whether plants respond by modifying the functional relationships between photosynthetic traits and water stress, and whether species of contrasting habitat differ in their degree of acclimation. Under prolonged partial drought, E. occidentalis from a xeric habitat modifies the relationships and it is able to continue active transpiration and photosynthesis down to a much lower soil water potential (−3.9 MPa) relative to riverside Eucalyptus taxa.
Zhou, S.-X., Medlyn, B. E., & Prentice, I. C. (2015). Long-term water stress leads to acclimation of drought sensitivity of photosynthetic capacity in xeric but not riparianEucalyptusspecies. Annals of Botany, 117(1), 133–144. http://dx.doi.org/10.1093/aob/mcv161