•Two wheat cultivars were grown at elevated CO2, under six environmental conditions.•Elevated CO2 effect on grain protein, Zn, Mg and Na were varied with environmental conditions.•Found no clear ...relationship of relative effects of eCO2 on grain protein with any of the environmental indices tested.•Relative effects of eCO2 on grain yield and protein were strongly correlated.•These findings suggest that primary factor determine grain protein concentration under eCO2 is yield dilution.
Bread wheat (Triticum aestivum L. cv. Yitpi and cv. Janz) was grown under field conditions in the Australian Grains Free-Air CO2 Enrichment (AGFACE) facility. Ambient CO2 (aCO2, ∼384μmolmol−1) and elevated CO2 (eCO2, ∼550μmolmol−1) were combined with two soil water levels (rain-fed and irrigated) and two times of sowing (TOS) in three consecutive years to provide six environments (2007-TOS1, 2007-TOS2, 2008-TOS1, 2008-TOS2, 2009-TOS1, 2009-TOS2). Grain samples were assessed for a range of physical, nutritional and dough rheological properties. The effect of eCO2 on thousand grain weight (TGW) was significantly different in each growing environment: TGW was significantly increased under eCO2 only at 2007-TOS2 (by 5%), 2009-TOS1 (by 5%) and 2009-TOS2 (by 15%) but not significantly changed under other conditions. The magnitude of reduction of grain protein concentration at eCO2 differed among the growing environments but was highly correlated with the percentage yield stimulation under eCO2 (r2=0.91) suggesting that grain protein concentration under eCO2 was diluted by increased yield. Across all treatments, grain nutrient concentration was significantly reduced by eCO2 for Fe (3.9%, 6.2%), Cu (2.2%, 3.4%), Zn (5.9%, 5.7%), Ca (5.6%, 7.3%), Mg (5.6%, 5.8%), Na (21.2%, 30.4%), S (4.4%, 4.4%), P (4.1%, 3.2%) in cv. Yitpi and Janz, respectively. Effects of eCO2 on grain Zn, Mg and Na concentrations were dependent on the growing environment. Relative reduction of grain S, Fe, Mg, Zn, P at eCO2 were significantly correlated with grain yield stimulation at eCO2. Reductions of these nutrients under eCO2 were not fully explained by biomass dilution as the relationships differed for each nutrient. Under eCO2, flour yield of cv. Janz was increased but that of cv. Yitpi was not changed. Even though grain protein concentrations of both cultivars were similar at eCO2, bread volume as inferred indirectly by dough rheology parameters was 12% greater for cv. Janz (185±5cm3) than cv. Yitpi (162±4cm3) at eCO2. This disparity may be related to the compositional changes in wheat flour protein at eCO2, suggesting that future breeding and adaptation strategies to improve the grain quality under eCO2 should consider the prevailing hydro-thermal 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 CO2 concentrations (eCO2), 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. We used selected data from cultivars with proven expression of high and low early vigour from the Australian Grains Free Air CO2 Enrichment (AGFACE) facility, and complemented this analysis with simulation results from two crop growth models which differ in the modelling of leaf area development and crop water use. Grain yield responses to eCO2 were lower in the high early vigour group compared to the low early vigour group, and although these differences were not significant, they were corroborated by simulation model results. However, the simulated lower response with high early vigour lines was not caused by an earlier or greater depletion of soil water under eCO2 and the mechanisms responsible appear to be related to an earlier saturation of the radiation intercepted. Whether this is the case in the field needs to be further investigated. In addition, there was some evidence that the timing of the drought stress during crop growth influenced the effect of eCO2 regardless of the early vigour trait. There is a need for FACE investigations of the value of traits for drought adaptation to be conducted under more severe drought conditions and variable timing of drought stress, a risky but necessary endeavour.
Using selected data from the Australian Free Air CO2 enrichment project complimented by simulation results we found a trend toward a lower response to eCO2 with high vigour lines. We hypothesised high early vigour lines under eCO2 would respond with a greater increase in leaf area which would lead to more severe drought stress post‐anthesis, thus reducing the grain yield response to eCO2. Dynamics of water use however rather suggested early saturation of radiation intercepted reduced the response.
The atmospheric CO2 concentration (CO2) is increasing and predicted to reach ∼550ppm by 2050. Increasing CO2 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. This study addresses two mechanisms potentially accountable for the phenomenon of elevated CO2-induced decreases in N: N uptake per unit length of roots as well as inhibition of the assimilation of nitrate (NO3−) into protein are investigated and related to grain protein. We analysed two wheat cultivars from a similar genetic background but contrasting in agronomic features (Triticum aestivum L. cv. Scout and Yitpi). Plants were field-grown within the Australian Grains Free Air CO2 Enrichment (AGFACE) facility under two atmospheric CO2 (ambient, ∼400ppm, and elevated, ∼550ppm) and two water treatments (rain-fed and well-watered). Aboveground dry weight (ADW) and root length (RL, captured by a mini-rhizotron root growth monitoring system), as well as N and NO3− concentrations (NO3−) were monitored throughout the growing season and related to grain protein at harvest. RL generally increased under eCO2 and varied between water supply and cultivars. The ratio of total aboveground N (TN) taken up per RL was affected by CO2 treatment only later in the season and there was no significant correlation between TN/RL and grain protein concentration across cultivars and CO2 treatments. In contrast, a greater percentage of N remained as unassimilated NO3− in the tissue of eCO2 grown crops (expressed as the ratio of NO3− to total N) and this was significantly correlated with decreased grain protein. These findings suggest that eCO2 directly affects the nitrate assimilation capacity of wheat with direct negative implications for grain quality.
Within the Australian Grains Free Air CO2 Enrichment (AGFACE) research program, several facilities were established at different field sites near the towns of Horsham (36.752 S, 142.114 E; 127 m ...elevation), and Walpeup (35.121 S, 142.005 E; 94 m elevation) in the state of Victoria Australia from 2007 – 2017. These included: TraitFACE, SoilFACE, WalpeupFACE, VegeFACE, and NFACE. These facilities were designed to answer a range of research questions to understand the impacts of elevated CO2 (eCO2) on crop physiology and production. To this end, FACE ‘rings’ (octagons) were built to elevate atmospheric CO2 to 550 µmol/mol expected by 2050. These rings were open structures allowing crops to grow freely, without enclosures. Each side of an octagonal ring was individually controlled by a ring-side controller that injected CO2 over crops as per the control program. Infrared Gas Analysers (IRGAs) placed at ring centres sampled air continuously from 10 cm above the crop canopy, while CO2 was injected at a height 15 cm above the crop canopy. Infrared Gas Analysers (IRGAs) measured atmospheric CO2 concentration (CO2) during the cropping season and provided feedback to the controller to maintain ring-centre CO2 at 550 µmol/mol. The CO2 data were collected from the centre of each FACE ring from 2007 until 2017. The CO2 within a ring was measured each second using calibrated IRGAs. Wind direction and speed were monitored continuously at 2 m above the soil surface at the centre of each ring. These measurements were also collected at the centres of a couple of ambient experimental areas (control – no rings) using the same IRGA and wind sensors. A wireless ethernet local area network (LAN) and a Visual Basic program were used to monitor and transmit data from the individual rings and control areas for data logging. Data at every 4th second and one-minute average (A_MN_CO2) from each ring were logged to daily files, and only A_MN_CO2 data were combined into a seasonal cumulative file. All data recorded during the IRGA warmup period and due to equipment malfunction were removed from cleaned data files. Only A_MN_CO2 data from the rings are uploaded in the Mendeley Data Repository for this article because these data are principally used by scientists and researchers. Data columns in an individual clean file are labelled with abbreviated column names and each file includes: 1) RING, 2) DATE, 3) TIME, 4) A_MN_CO2, 5) REGULAT, 6) WIND_SPD, 7) WIND_DIR and 8) RING_SEC. A limited amount of data (2007 CO2 data at ring centres from 8 TraitFACE rings) was published previously 1.
Frost damage to broadacre crops can cause up to an 85% loss in productivity. Although growers have few options for crop protection from frost, a rapid method for assessing frost-induced sterility ...would allow for timely management decisions (e.g., cutting for hay and altering marketing strategies). Spectral mixture analysis (SMA) has shown success in mapping landscape components and was used with hyperspectral data collected on the canopy, heads, and leaves of wheat at different sites to determine if this could quantify frost damage. Spectral libraries were assembled from canopy components collected from local field sites to generate spectral libraries for SMA from which a series of fraction sets was derived. The frost (Fr) fraction was then used to estimate final yield as a means of measuring frost damage. The best-fitting Fr fractions to yield were derived from the same data set as the source Fr spectra, and these ranged over R2 = 0.58–0.75 at the canopy scale. It was clear that spectral signatures need to be collected at scale to assess frost damage. While Fr fractions were able to estimate yield there was no “universal” endmember set from which a Fr fraction could be derived. The normalized difference vegetation index (NDVI) was not able to estimate frost damage consistently. Future work requires determining whether there is a “universal” set of endmembers and a minimum set of targeted wavebands that could lead to multispectral instruments for frost assessment for use in ground and aerial sensors.
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. Our climate scenarios show that whilst elevated CO2 (eCO2) alone might limit the area where the reduced‐tillering trait is advantageous, the most likely climate scenario of eCO2 combined with increased temperature and reduced rainfall consistently increased the area where restricted tillering has an advantage. Whilst long‐term average yield advantages were small (ranged from 31 to 51 kg ha−1 year−1), across large dryland areas the value is large (potential cost‐benefits ranged from Australian dollar 23 to 60 MIL/year). It seems therefore worthwhile to further explore this reduced‐tillering trait in relation to a range of different environments and climates, because its benefits are likely to grow in future dry environments where wheat is grown around the world.
Reducing the number of tillers per plant using a tiller inhibition 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.
•Elevated CO2 did not generally accelerate senescence.•Elevated CO2 influenced gene expression in N-, C-metabolism and transport.•CO2 effect differs between pre-senescence and during ...senescence.•Change in expression pattern is consistent with greater grain N-sink strength.
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. Wheat grown under CO2 enrichment had lower N concentrations and a tendency towards greater C/N ratios. A general acceleration of the senescence process by elevated CO2 was not confirmed. The expression patterns of genes involved in carbohydrate metabolism, nitrate reduction and metabolite transport differed between CO2 treatments, and this CO2 effect was different between pre-senescence and during senescence. The results suggest up-regulation of N remobilisation and down-regulation of C remobilisation during senescence under elevated CO2, which is consistent with greater grain N-sink strength of developing grains.
The complexities behind the mechanisms associated with virus-host-vector interactions of vector-transmitted viruses, and their consequences for disease development need to be understood to reduce ...virus spread and disease severity. Climate has a substantial effect on viruses, vectors, host plants and their interactions. Increased atmospheric carbon dioxide (CO
) is predicted to impact the interactions between them. This study, conducted under ambient and elevated CO
(550μmolmol
), in the Australian Grains Free Air Carbon Enrichment facility reports on natural yellow dwarf virus incidence on wheat (including Barley/Cereal yellow dwarf viruses (B/CYDV)). A range of wheat cultivars was tested using tissue blot immunoassay to determine the incidence of four yellow dwarf virus species from 2013 to 2016. In 2013, 2014 and 2016, virus incidence was high, reaching upwards of 50%, while in 2015 it was relatively low, with a maximum incidence of 3%. Across all years and most cultivars, BYDV-PAV was the most prevalent virus species. In the years with high virus incidence, a majority plots with the elevated levels of CO
(eCO
) were associated with increased levels of virus relative to the plots with ambient CO
. In 2013, 2014 and 2016 the recorded mean percent virus incidence was higher under elevated CO
when compared to ambient CO
by 33%, 14% and 34%, respectively. The mechanism behind increased yellow dwarf virus incidence under elevated CO
is not well understood. Potential factors involved in the higher virus incidence under elevated CO
conditions are discussed.
Abstract
After an initial wave of coronavirus disease 2019 (COVID-19) in Haiti in summer 2020 (primarily lineage B.1), seropositivity for anti-severe acute respiratory syndrome coronavirus 2 ...(SARS-CoV-2) immunoglobulin G (IgG) was ~40%. Variant P.1 (gamma) was introduced in February 2021, with an initially limited introduction followed by exponential local dissemination within this unvaccinated population with prior exposure to earlier SARS-CoV-2 lineages.
This study presents an explanatory biophysical model developed and validated to simulate seed coat colour traits including CIE L*, a*, and b* changes over time for stored lentil cultivars PBA ...Hallmark, PBA Hurricane, PBA Bolt, and PBA Jumbo2 under diverse storage conditions. The model showed robust performance for all cultivars, with R2 values ≥ 0.89 and RMSE values ≤ 0.0019 for all seed coat colour traits. Laboratory validation at 35 °C demonstrated a high agreement (Lin’s Concordance Correlation Coefficient, CCC ≥ 0.82) between simulated and observed values of all colour traits for PBA Jumbo2 and strong agreement (CCC ≥ 0.81) for PBA Hallmark in brightness (CIE L*) and redness (CIE a*), but not in yellowness (CIE b*). At 15 °C, both cultivars exhibited moderate to weak agreement between simulated and observed values of all colour traits (CCC ≤ 0.47), as very little change was recorded in the observed values over the 360 days of storage. Bulk storage system validation for PBA Hallmark showed moderate performance (CCC ≥ 0.46) between simulated and observed values of all colour traits. Modelling to simulate changes in seed coat colour traits of lentils over time will equip growers and traders to make informed managerial decisions when storing lentils for long periods.
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