ABSTRACT
This chapter describes the principles of water transport and its importance, followed by a discussion of the effect of water stress on tree performance and the main physiological strategies that trees use to cope with this stress. It reviews the molecular mechanisms that trees use to cope with water stress, with illustrations of how those mechanisms can be manipulated to induce drought tolerance. Osmotic adjustment is generally accepted as a mechanism for plant adaptation to drought. Biotic stressors can act on any of the tree compartments in parallel with the abiotic stressors of reduced moisture or humidity and elevated temperatures. The dynamics of water and carbon fluxes depend on the duration of the drought, tree drought responses and biotic stressors. Carbon metabolism is linked to whole-plant hydraulic functions, and both carbon and turgor should be prioritized in research into drought-resistance strategies.
