Authors: Gutiérrez, Diego; Gutiérrez, Elena; Pérez, Pilar; Morcuende, Rosa; Verdejo, Angel L.; Martinez-Carrasco, Rafael

Source: Physiologia Plantarum, Volume 137, Number 1, September 2009 , pp. 86-100(15)

Publisher: Wiley-Blackwell

Abstract:

A study was conducted over 2 years to determine whether growth under elevated CO₂ (700 μmol mol⁻¹) and temperature (ambient + 4 °C) conditions modifies photochemical efficiency or only the use of electron transport products in spring wheat grown in field chambers. Elevated atmospheric CO₂ concentrations increased crop dry matter at maturity by 12-17%, while above-ambient temperatures did not significantly affect dry matter yield. In measurements with ambient CO₂ at ear emergence and after anthesis, growth at elevated CO₂ concentrations decreased flag leaf light-saturated carbon assimilation. The quantum yield of electron transport (φ_PSII) measured at ambient CO₂ and higher irradiances increased at ear emergence and decreased after anthesis in plants grown at elevated CO₂. At higher light intensities, but not in low light, photochemical quenching (qP) decreased after growth in elevated CO₂ conditions. Growth under CO₂ enrichment increased dark- (Fv:Fm) and light-adapted (Fv′:Fm′) photochemical efficiencies, and decreased the chlorophyll a:b ratio, suggesting an increase in light-harvesting complexes relative to PSII reaction centres. A relatively higher decrease in carbon assimilation than the decrease in φ_PSII pointed to a sink other than CO₂ assimilation for electron transport products at defined growth stages. With higher light intensities, warmer temperatures increased φ_PSII and Fv′:Fm′ at ear emergence and decreased φ_PSII after anthesis; in ambient—but not elevated—CO₂, warmer temperatures also decreased qP after anthesis. CO₂ fixation increased or did not change with temperature, depending on the growth stage and year. We conclude that elevated CO₂ decreases the carbon assimilation capacity, but increases photochemistry and resource allocation to light harvesting, and that elevated levels of CO₂ can mitigate photochemistry inhibition as a result of warm temperatures.

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1399-3054.2009.01256.x

Affiliations: 1: Institute of Natural Resources and Agrobiology of Salamanca, CSIC, Apartado 257, E-37071 Salamanca, Spain

Publication date: 2009-09-01

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