Influence of water stress on photosynthetic characteristics in barley plants under ambient and elevated CO₂ concentrations

Abstract

We evaluated the combined effects of elevated CO 2 and water availability on photosynthesis in barley. Soil and plant water content decreased with water stress, but less under elevated CO 2 concentration (EC) compared with ambient CO 2 concentration (AC). During water stress, stomatal conductance, carboxylation rate, RuBP regeneration, and the rate of triose phosphate utilisation (TPU) were decreased but less when plants grew under EC. Drought treatments caused only a slight effect on maximum photochemical efficiency (variable to maximum fluorescence ratio, F v /F m ), whereas the actual quantum yield (Φ PS2 ), maximum electron transport rate (J max ) and photochemical quenching (qP) were decreased and the non photochemical quenching (NPQ) was enhanced. Under water deficit, the allocation of electrons to CO 2 assimilation was diminished by 49 % at AC and by 26 % at EC while the allocation to O 2 reduction was increased by 15 % at AC and by 12 % at EC.Additional key words: climate change, drought, electron transport allocation, Hordeum vulgare, photochemical efficiency, quantum yield.

Evaluation of Spring Wheat (20 Varieties) Adaptation to Soil Drought during Seedlings Growth Stage

“…It is known that soil drought occurring over several days can cause both stomatal and non-stomatal inhibition of photosynthesis. With a sudden decrease in water supply to plants, the stomata closed resulting in rapid reduction of water losses in the transpiration process and increased diffusion resistances to CO 2 [21]. The process of photosynthesis is very sensitive to changes in water supply to leaves and responds quickly to water deficit [4,22].…”

Adaptation of Boreal Field Crop Production to Climate Change

“…In elevated CO 2 , photosynthesis was, surprisingly, also stimulated more under drought than under well watered conditions, and photorespiration decreased. The electron transport chain and utilization of ATP and NADPH were stimulated by elevated CO 2 , thus making them more tolerant to water deficit, and photoinhibition decreased (Robredo et al, 2010). Fig.…”

“…Elevated CO 2 can override some of the yield decreasing effects of drought. The water status of barley (Hordeum vulgare L.) under drought conditions was better under elevated CO 2 than in ambient CO 2 , on account of the decrease in stomatal conductance under elevated CO 2 (Robredo et al, 2010). In elevated CO 2 , photosynthesis was, surprisingly, also stimulated more under drought than under well watered conditions, and photorespiration decreased.…”

“…Even though assimilation is stimulated, partitioning is not, and yield increases are sink-limited unless additional N is supplied . Elevated CO 2 concentration has also been shown to attenuate the effects of water deficit and to improve the efficiency of water use at both the leaf and canopy scale by maintaining the stomatal conductance, carboxylation rate and RuBP (Ribulose-1,5-bisphosphate) regeneration (Robredo et al, 2010). When the photosynthesis is limited by RuBP regeneration capacity, the increase in photosynthesis results mostly from decrease in photorespiration .…”

Abiotic Stress Diagnosis via Laser Induced Chlorophyll Fluorescence Analysis in Plants for Biofuel

“…One of the main crops currently being proposed as a diesel/kerosene substitute or extender, is Jatropha curcas (Linnaeus) (Openshaw 2000, Francis et al, 2005. Water stress studies have been already carried out in several plant species, seeking for responses of different mechanisms in leaves under water distress (Theisen, 1988;Chappelle et al, 1984;Dahn et al, 1992;Broglia, 1993;Munns, 2002;Marcassa et al, 2006;Abou Kheira & Atta, 2009;Maes et al, 2009;Caires et al, 2010;Robredo et al, 2010;Patane & Cosentini, 2010;Tushar et al, 2010;Silva et al, 2010). In this section, the effect of water deficit in jatropha plants is investigated using chlorophyll fluorescence spectroscopy.…”