Moderate heat stress prevented the observed biomass and yield stimulation caused by elevated CO in two well-watered wheat cultivars.

Heat stress (HS) under well-watered conditions was not detrimental to leaf photosynthesis or yield but modified the elevated CO response of photosynthesis and yield in two contrasting wheat cultivars. Climate change is increasing the frequency of extreme events such as heat waves, adversely affecting crop productivity. While positive impacts of elevated carbon dioxide (eCO) on crop productivity are evident, the interactive effects of eCO and environmental stresses are still unclear.

Does Elevated [CO] Only Increase Root Growth in the Topsoil? A FACE Study with Lentil in a Semi-Arid Environment.

Atmospheric carbon dioxide concentrations [CO] are increasing steadily. Some reports have shown that root growth in grain crops is mostly stimulated in the topsoil rather than evenly throughout the soil profile by e[CO], which is not optimal for crops grown in semi-arid environments with strong reliance on stored water. An experiment was conducted during the 2014 and 2015 growing seasons with two lentil () genotypes grown under Free Air CO Enrichment (FACE) in which root growth was observed non-destructively with mini-rhizotrons approximately every 2-3 weeks.

Early vigour in wheat: Could it lead to more severe terminal drought stress under elevated atmospheric [CO ] and semi-arid conditions?

Early vigour in wheat is a trait that has received attention for its benefits reducing evaporation from the soil surface early in the season. However, with the growth enhancement common to crops grown under elevated atmospheric CO concentrations (e[CO ]), there is a risk that too much early growth might deplete soil water and lead to more severe terminal drought stress in environments where production relies on stored soil water content. If this is the case, the incorporation of such a trait in wheat breeding programmes might have unintended negative consequences in the future, especially in dry years.

A reduced-tillering trait shows small but important yield gains in dryland wheat production.

Reducing the number of tillers per plant using a tiller inhibition (tin) gene has been considered as an important trait for wheat production in dryland environments. We used a spatial analysis approach with a daily time-step coupled radiation and transpiration efficiency model to simulate the impact of the reduced-tillering trait on wheat yield under different climate change scenarios across Australia's arable land. Our results show a small but consistent yield advantage of the reduced-tillering trait in the most water-limited environments both under current and likely future conditions.

Carbon sink strength of nodules but not other organs modulates photosynthesis of faba bean (Vicia faba) grown under elevated [CO ] and different water supply.

Photosynthetic stimulation by elevated [CO ] (e[CO ]) may be limited by the capacity of sink organs to use photosynthates. In many legumes, N -fixing symbionts in root nodules provide an additional sink, so that legumes may be better able to profit from e[CO ]. However, drought not only constrains photosynthesis but also the size and activity of sinks, and little is known about the interaction of e[CO ] and drought on carbon sink strength of nodules and other organs.

Author Correction: Increasing CO threatens human nutrition.

An Amendment to this paper has been published and can be accessed via a link at the top of the paper.

Effect of heat wave on N fixation and N remobilisation of lentil (Lens culinaris MEDIK) grown under free air CO enrichment in a mediterranean-type environment.

The stimulatory effect of elevated [CO ] (e[CO ]) on crop production in future climates is likely to be cancelled out by predicted increases in average temperatures. This effect may become stronger through more frequent and severe heat waves, which are predicted to increase in most climate change scenarios. Whilst the growth and yield response of some legumes grown under the interactive effect of e[CO ] and heat waves has been studied, little is known about how N fixation and overall N metabolism is affected by this combination.

Elevated CO2 alleviates the negative impact of heat stress on wheat physiology but not on grain yield.

Hot days are becoming hotter and more frequent, threatening wheat yields worldwide. Developing wheat varieties ready for future climates calls for improved understanding of how elevated CO2 (eCO2) and heat stress (HS) interactively impact wheat yields. We grew a modern, high-yielding wheat cultivar (Scout) at ambient CO2 (aCO2, 419 μl l -1) or eCO2 (654 μl l-1) in a glasshouse maintained at 22/15 °C (day/night).

Elevated [CO ] effects on crops: Advances in understanding acclimation, nitrogen dynamics and interactions with drought and other organisms.

Future rapid increases in atmospheric CO concentration [CO ] are expected, with values likely to reach ~550 ppm by mid-century. This implies that every terrestrial plant will be exposed to nearly 40% more of one of the key resources determining plant growth. In this review we highlight selected areas of plant interactions with elevated [CO ] (e[CO ]), where recently published experiments challenge long-held, simplified views.

The water use dynamics of canola cultivars grown under elevated CO are linked to their leaf area development.

The 'CO fertilisation effect' is often predicted to be greater under drier than wetter conditions, mainly due to hypothesised early season water savings under elevated [CO] (e[CO]). However, water savings largely depend on the balance between CO-induced improvement of leaf-level water use efficiency and CO-stimulation of transpiring leaf area. The dynamics of water use during the growing season can therefore vary depending on leaf area development.

Elevated [CO2] mitigates the effect of surface drought by stimulating root growth to access sub-soil water.

Through stimulation of root growth, increasing atmospheric CO2 concentration ([CO2]) may facilitate access of crops to sub-soil water, which could potentially prolong physiological activity in dryland environments, particularly because crops are more water use efficient under elevated [CO2] (e[CO2]). This study investigated the effect of drought in shallow soil versus sub-soil on agronomic and physiological responses of wheat to e[CO2] in a glasshouse experiment. Wheat (Triticum aestivum L.

Water availability moderates N fixation benefit from elevated [CO ]: A 2-year free-air CO enrichment study on lentil (Lens culinaris MEDIK.) in a water limited agroecosystem.

Increased biomass and yield of plants grown under elevated [CO ] often corresponds to decreased grain N concentration ([N]), diminishing nutritional quality of crops. Legumes through their symbiotic N fixation may be better able to maintain biomass [N] and grain [N] under elevated [CO ], provided N fixation is stimulated by elevated [CO ] in line with growth and yield. In Mediterranean-type agroecosystems, N fixation may be impaired by drought, and it is unclear whether elevated [CO ] stimulation of N fixation can overcome this impact in dry years.

Benefits of increasing transpiration efficiency in wheat under elevated CO for rainfed regions.

Higher transpiration efficiency (TE) has been proposed as a mechanism to increase crop yields in dry environments where water availability usually limits yield. The application of a coupled radiation and TE simulation model shows wheat yield advantage of a high-TE cultivar (cv. Drysdale) over its almost identical low-TE parent line (Hartog), from about -7 to 558 kg/ha (mean 187 kg/ha) over the rainfed cropping region in Australia (221-1,351 mm annual rainfall), under the present-day climate.

Prescreening in large populations as a tool for identifying elevated CO-responsive genotypes in plants.

Elevated atmospheric CO2 concentration (e[CO2]) can stimulate the photosynthesis and productivity of C3 species including food and forest crops. Intraspecific variation in responsiveness to e[CO2] can be exploited to increase productivity under e[CO2]. However, active selection of genotypes to increase productivity under e[CO2] is rarely performed across a wide range of germplasm, because of constraints of space and the cost of CO2 fumigation facilities.

The relationship between transpiration and nutrient uptake in wheat changes under elevated atmospheric CO.

The impact of elevated [CO ] (e[CO ]) on crops often includes a decrease in their nutrient concentrations where reduced transpiration-driven mass flow of nutrients has been suggested to play a role. We used two independent approaches, a free-air CO enrichment (FACE) experiment in the South Eastern wheat belt of Australia and a simulation study employing the agricultural production systems simulator (APSIM), to show that transpiration (mm) and nutrient uptake (g m ) of nitrogen (N), potassium (K), sulfur (S), calcium (Ca), magnesium (Mg) and manganese (Mn) in wheat are correlated under e[CO ], but that nutrient uptake per unit water transpired is higher under e[CO ] than under ambient [CO ] (a[CO ]). This result suggests that transpiration-driven mass flow of nutrients contributes to decreases in nutrient concentrations under e[CO ], but cannot solely explain the overall decline.

The proportion of nitrate in leaf nitrogen, but not changes in root growth, are associated with decreased grain protein in wheat under elevated [CO].

The atmospheric CO concentration ([CO]) is increasing and predicted to reach ∼550ppm by 2050. Increasing [CO] typically stimulates crop growth and yield, but decreases concentrations of nutrients, such as nitrogen ([N]), and therefore protein, in plant tissues and grains. Such changes in grain composition are expected to have negative implications for the nutritional and economic value of grains.

Barley yellow dwarf virus infection and elevated CO alter the antioxidants ascorbate and glutathione in wheat.

Plant antioxidants ascorbate and glutathione play an important role in regulating potentially harmful reactive oxygen species produced in response to virus infection. Barley yellow dwarf virus is a widespread viral pathogen that systemically infects cereal crops including wheat, barley and oats. In addition, rising atmospheric CO will alter plant growth and metabolism, including many potential but not well understood effects on plant-virus interactions.

The concentration of ascorbic acid and glutathione in 13 provenances of Acacia melanoxylon.

Climate change can negatively affect sensitive tree species, affecting their acclimation and adaptation strategies. A common garden experiment provides an opportunity to test whether responses of trees from different provenances are genetically driven and if this response is related to factors at the site of origin. We hypothesized that antioxidative defence systems and leaf mass area ofAcacia melanoxylonR.

Elevated atmospheric [CO2 ] can dramatically increase wheat yields in semi-arid environments and buffer against heat waves.

Wheat production will be impacted by increasing concentration of atmospheric CO2 [CO2 ], which is expected to rise from about 400 μmol mol(-1) in 2015 to 550 μmol mol(-1) by 2050. Changes to plant physiology and crop responses from elevated [CO2 ] (e[CO2 ]) are well documented for some environments, but field-level responses in dryland Mediterranean environments with terminal drought and heat waves are scarce. The Australian Grains Free Air CO2 Enrichment facility was established to compare wheat (Triticum aestivum) growth and yield under ambient (~370 μmol(-1) in 2007) and e[CO2 ] (550 μmol(-1) ) in semi-arid environments.

Expression patterns of C- and N-metabolism related genes in wheat are changed during senescence under elevated CO2 in dry-land agriculture.

Projected climatic impacts on crop yield and quality, and increased demands for production, require targeted research to optimise nutrition of crop plants. For wheat, post-anthesis carbon and nitrogen remobilisation from vegetative plant parts and translocation to grains directly affects grain carbon (C), nitrogen (N) and protein levels. We analysed the influence of increased atmospheric CO2 on the expression of genes involved in senescence, leaf carbohydrate and nitrogen metabolism and assimilate transport in wheat under field conditions (Australian Grains Free Air CO2 Enrichment; AGFACE) over a time course from anthesis to maturity, the key period for grain filling.

Intraspecific variation in leaf growth of wheat (Triticum aestivum) under Australian Grain Free Air CO Enrichment (AGFACE): is it regulated through carbon and/or nitrogen supply?

Underlying physiological mechanisms of intraspecific variation in growth response to elevated CO2 concentration [CO2] were investigated using two spring wheat (Triticum aestivum L.) cultivars: Yitpi and H45. Leaf blade elongation rate (LER), leaf carbon (C), nitrogen (N) in the expanding leaf blade (ELB, sink) and photosynthesis (A) and C and N status in the last fully expanded leaf blade (LFELB, source) were measured.

Elevated CO2 decreases both transpiration flow and concentrations of Ca and Mg in the xylem sap of wheat.

The impact of elevated atmospheric [CO2] (e[CO2]) on plants often includes a decrease in their nutrient status, including Ca and Mg, but the reasons for this decline have not been clearly identified. One of the proposed hypotheses is a decrease in transpiration-driven mass flow of nutrients due to decreased stomatal conductance. We used glasshouse and Free Air CO2 Enrichment (FACE) experiments with wheat to show that, in addition to decrease in transpiration rate, e[CO2] decreased the concentrations of Ca and Mg in the xylem sap.

Rising CO2 concentration altered wheat grain proteome and flour rheological characteristics.

Wheat cv. H45 was grown under ambient CO2 concentration and Free Air CO2 Enrichment (FACE; e[CO2], ∼550 μmol CO2 mol(-1)). The effect of FACE on wheat grain proteome and associated changes in the flour rheological properties was investigated.

Increasing CO2 threatens human nutrition.

Dietary deficiencies of zinc and iron are a substantial global public health problem. An estimated two billion people suffer these deficiencies, causing a loss of 63 million life-years annually. Most of these people depend on C3 grains and legumes as their primary dietary source of zinc and iron.