Water scarcity imposes huge reductions in crop yield and is one of …

• Abstract
• Introduction
• Revising the constraints to photosynthesis and the regulatory systems operating under water deficits
• Applications to water-saving agriculture
• Conclusions
• References
• Table 1
• Table 2
• Figures

Full irrigation (FI) Deficit irrigation (DI) Partial root-zone drying (PRD) Non-irrigated (NI) Afield (µmol m–2 s–1) 16.3–10.0 13.3–11.3 14.6–8.3 12.5–3.3 gs field (mol m–2 s–1) 0.30–0.28 0.23–0.19 0.19–0.15 0.13–0.07 Acontrolled (µmol m–2 s–1) 13.3±0.5 12.0±1.1 11.5±0.9 9.5±0.9 gs controlled (mol m–2 s–1) 0.35±0.04 0.33±0.05 0.25±0.05 0.14±0.01 pd (MPa) –0.10 to –0.18 –0.14 to –0.44 –0.14 to –0.30 –0.22 to –0.64 Sap flow (g h–1 m–2) 402–356 275–196 145–130 109–101 Berries 13 C () –26.3±0.17 –25.9±0.28 –23.7±0.07 –22.4±0.69 Leaf area (m2 per vine) 6.3±0.26 4.9±0.15 4.3±0.21 3.6±0.18 Exposed clusters (%) 9.8±2.8 12.9±3.2 16.8±3.5 22.8±3.8

Maximum and minimum values of leaf net photosynthetic rates (A_field) and stomatal conductance (g_{s field}) measured at midday, from mid-June to mid-September 2000, in the grapevine cultivar Moscatel, under different irrigation treatments, FI, DI, PRD, and NI. A_controlled and g_{s controlled} measured under controlled conditions of light (1200 µmol m^–2 s^–1) and temperature (25 °C) at the end of August (mean values ± SE). Maximum and minimum values of leaf predawn water potential (_pd) for the same period as above and for sap flow measurements done during August. Discrimination of ¹³C in the berries, measured at harvest, in September (mean values ± SE). Leaf area per vine measured at harvest and percentage of sun-exposed cluster at maturation (mean values ± SE). (Data from Souza et al., 2003; Santos et al., 2003).