title: Acclimation of Biochemical and Diffusive Components of Photosynthesis in Rice, Wheat, and Maize to Heat and Water Deficit: Implications for Modeling Photosynthesis.
abstract: The impact of the combined effects of heat stress, increased vapor pressure deficit (VPD) and water deficit on the physiology of major crops needs to be better understood to help identifying the expected negative consequences of climate change and heat waves on global agricultural productivity. To address this issue, rice, wheat, and maize plants were grown under control temperature (CT, 25°C, VPD 1.8 kPa), and a high temperature (HT, 38°C, VPD 3.5 kPa), both under well-watered (WW) and water deficit (WD) conditions. Gas-exchange measurements showed that, in general, WD conditions affected the leaf conductance to CO2, while growth at HT had a more marked effect on the biochemistry of photosynthesis. When combined, HT and WD had an additive effect in limiting photosynthesis. The negative impacts of the imposed treatments on the processes governing leaf gas-exchange were species-dependent. Wheat presented a higher sensitivity while rice and maize showed a higher acclimation potential to increased temperature. Rubisco and PEPC kinetic constants determinedin vitroat 25°C and 38°C were used to estimate Vcmax, Jmax, and Vpmaxin the modeling of C3and C4photosynthesis. The results here obtained reiterate the need to use species-specific and temperature-specific values for Rubisco and PEPC kinetic constants for a precise parameterization of the photosynthetic response to changing environmental conditions in different crop species.
authors.affiliation: Plant Biology and Crop Science, Rothamsted ResearchHarpenden, UK; Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes BalearsPalma, Spain.
authors.forename: Juan A
authors.initials: JA
authors.lastname: Perdomo
authors.affiliation: Lancaster Environment Centre, Lancaster University Lancaster, UK.
authors.forename: Elizabete
authors.initials: E
authors.lastname: Carmo-Silva
authors.affiliation: Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears Palma, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Hermida-Carrera
authors.affiliation: Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears Palma, Spain.
authors.forename: Jaume
authors.initials: J
authors.lastname: Flexas
authors.affiliation: Research Group on Plant Biology under Mediterranean Conditions, Universitat de les Illes Balears Palma, Spain.
authors.forename: Jeroni
authors.initials: J
authors.lastname: Galmés
keywords: C3; C4; crops; high temperature; photosynthesis; water deficit