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The spatial extent of semi-arid hot regions is forecasted to grow through the twenty-first century, complicating restoration and reforestation plans. In arid and semi-arid climates, seedlings are more susceptible to transplant shock due to lower soil moisture throughout the year. Determining strategies to reduce seedling stress and improve survival post-planting will be paramount to continued reforestation efforts in a changing climate. We quantified seedling physiological, morphological, and field performance (mortality and growth) response for five species native to the semi-arid region of South Texas (Erythrina herbacea L., Celtis pallida Torr., Fraxinus berlandieriana DC, Malpighia glabra L., and Citharexylum berlandieri B.L Rob) to an antitranspirant (abscisic acid), drought, and elevated CO2. We examined post-treatment seedling gas exchange, non-structural carbohydrates, osmolality, root structure, and stomatal density and evaluated mortality and growth rate on a sample of the treatment population. For elevated CO2 and drought hardening treatments, seedling gas exchange, solute content, specific root length, and stomatal density varied by species, while abscisic acid strongly reduced transpiration and stomatal conductance in all species. However, these physiological and morphological differences did not translate to reduced mortality or improved growth rate due to high herbivory and above-normal precipitation after planting precluding seedlings from stress. We conclude that the simpler antitranspirant approach, rather than the more logistically challenging eCO2, has the potential to reduce drought-related transplant shock but requires more widespread testing. [ABSTRACT FROM AUTHOR]

Atmospheric elevated CO2 concentration (e[CO2]) decreases plant nitrogen (N) concentration while increasing water use efficiency (WUE), fertigation increases crop nutrition and WUE in crop; yet the interactive effects of e[CO2] coupled with two N-fertigation levels during deficit irrigation on plant gas exchange, root morphology and WUE remain largely elusive. The objective of this study was to explore the physiological and growth responses of ambient [CO2] (a[CO2], 400 ppm) and e[CO2] (800 ppm) tomato plant exposed to two N-fertigation regimes: (1) full irrigation during N-fertigation (FIN); (2) deficit irrigation during N-fertigation (DIN) under two N fertilizer levels (reduced N (N1, 0.5 g pot−1) and adequate N (N2, 1.0 g pot−1). The results indicated that e[CO2] associated with DIN regime induced the lower N2 plant water use (7.28 L plant−1), maintained leaf water potential (−5.07 MPa) and hydraulic conductivity (0.49 mol m−2 s−1 MPa−1), greater tomato growth in terms of leaf area (7152.75 cm2), specific leaf area (223.61 cm2 g−1), stem and total dry matter (19.54 g and 55.48 g). Specific root length and specific root surface area were increased under N1 fertilization, and root tissue density was promoted in both e[CO2] and DIN environments. Moreover, a smaller and denser leaf stomata (4.96 µm2 and 5.37 mm−2) of N1 plant was obtained at e[CO2] integrated with DIN strategy. Meanwhile, this combination would simultaneously reduce stomatal conductance (0.13 mol m−2 s−1) and transpiration rate (1.91 mmol m−2 s−1), enhance leaf ABA concentration (133.05 ng g−1 FW), contributing to an improvement in WUE from stomatal to whole-plant scale under each N level, especially for applying N1 fertilization (125.95 µmol mol−1, 8.41 µmol mmol−1 and 7.15 g L−1). These findings provide valuable information to optimize water and nitrogen fertilizer management and improve plant water use efficiency, responding to the potential resource-limited and CO2-enriched scenario. [ABSTRACT FROM AUTHOR]

Atmospheric CO2 levels have been increasing, and likewise, increasing drought events have been following increasing temperatures. There is very little literature on the effects of climate change factors on early-successional deciduous species used for ecological restoration. Thus, morphological and allometric variation in four coppiced early-successional deciduous species was examined in response to a 2 × 2 factorial of ambient CO2 (aCO2, 400 ppm) and elevated CO2 (eCO2, 800 ppm), as well as well-watered and drought treatments with 15%–20% and 5%–10% volumetric moisture content, respectively, grown in sandy soil with low soil nitrogen (N) under greenhouse conditions. The four species examined were as follows: green alder (Alnus viridis subsp. crispa (Ait.) Turrill), speckled alder (A. incana subsp. rugosa (Du Roi) R.T. Clausen), gray birch (Betula populifolia (Marshall)), and white birch (B. papyrifera (Marshall)), and all are from the same phylogenetic family, Betulaceae. Genus differences in morphological and growth traits were large, especially in response to the environmental treatments used. Alders upregulated all growth traits under eCO2 because of the strong coppicing sink effect and the additional foliar N provided by the actinorhizal ability of the genus, whereas birches remained the same or slightly decreased under eCO2. As a result, alders have a significantly greater foliar N than birches, with 2.8 and 1.0%, respectively. All species reduced growth under drought, and green alder had the greatest stem dry mass growth, followed by speckled alder and then the birches. Under drought, eCO2 not only mitigated the alder drought dry mass but, in fact, doubled the stem dm, whereas eCO2 only just mitigated the birches drought response. When corrected for size using stem height, alders allocated more to stem and leaf and less to root dry mass than birches. Atmospheric CO2 and soil moisture treatments changed organ biomass allocation. The tallest stem height was the best predictor of total (above and below) dry mass. With increasing atmospheric CO2, particularly on low nutrient sites, the results show alders are capable of sequestering far more carbon than birches. In addition, with more atmospheric CO2, alders can mitigate against drought conditions better compared to birches. [ABSTRACT FROM AUTHOR]

Atmospheric CO2 levels have been increasing, and these changes may result in differential adaptive responses in both genera and species and highlight the need to increase carbon sequestration. Ecophysiological and morphological responses of four early-successional deciduous species were examined under ambient CO2 (aCO2, 400 ppm) and elevated CO2 (eCO2, 800 ppm) treatments. The four species, all of which are used in restoration, were Alnus viridis subsp. crispa (Ait.) Turrill (green alder), A. incana subsp. rugosa (Du Roi) R.T. Clausen (speckled alder), Betula populifolia (Marshall) (gray birch), and B. papyrifera (Marshall) (white birch); all are from the same phylogenetic family, Betulaceae. We examined biochemical efficiencies, gas exchange, chlorophyll fluorescence, chlorophyll concentrations, foliar nitrogen (N), and growth traits. A general linear model, analysis of variance, was used to analyze the functional carbon efficiency and growth differences, if any, among genera, species, and provenances (only for growth traits). The alders had greater biochemical efficiency traits than birches, and alders upregulated these traits, whereas birches mostly downregulated these traits in response to eCO2. In response to eCO2, assimilation either remained the same or was upregulated for alders but downregulated for birches. Stomatal conductance was downregulated for all four species in response to eCO2. Intrinsic water use efficiency was greater for alders than for birches. Alders exhibited a consistent upregulation of stem dry mass and height growth, whereas birches were somewhat lower in height and stem dry mass in response to eCO2. Foliar N played an important role in relation to ecophysiological traits and had significant effects relative to genus (alders > birches) and CO2 (aCO2 > eCO2), and a significant genus × CO2 interaction, with alders downregulating foliar N less than did birches. Covariate analysis examining carbon efficiency traits in relation to foliar N showed clear functional responses. Both species in both genera were consistent in their ecophysiological and morphological responses to CO2 treatments. There was supporting evidence that assimilation was sink-driven, which is related to a plant organ's ability to continue to grow and incorporate assimilates. The alders used in this study are actinorhizal, and the additional available foliar N, paired with increased stem dry mass sink activity, appeared to be driving upregulation of the carbon efficiencies and growth in response to eCO2. Alders' greater carbon efficiencies and carbon sequestration in impoverished soils demonstrate that alders, as opposed to birches, should be used to accelerate ecological restoration in a world of increasing atmospheric CO2. [ABSTRACT FROM AUTHOR]

Transgenic Bt rice (abbr. Bt rice) has provided a powerful tactics to control the striped stemborer Chilo suppressalis as one key lepidopteran pest in the paddyfields of China. Globally rising carbon dioxide (i.e., CO2) concentration has been predicted to affect the Cry protein contents in plant tissues of Bt rice and thus might affect its control efficiency to target insect pests. To reveal the resistance ability and the corresponding mechanism of C. suppressalis to Bt rice during different growth stage under elevated CO2 (eCO2), we carried out this experiment to measure the Bt toxin contents in Bt rice stems grown under ambient CO2 (aCO2) (400 ppm) and eCO2 (800 ppm) at seedling, tillering and heading stages, and to observe the larval mortality and bioassay the activity of midgut protease and the expression levels of Bt-toxin-receptor genes, aminopeptidases (APNs) in C. suppressalis larvae. Compared with aCO2, eCO2 increased the Bt-toxin content of Bt rice at seedling stage (+6.66%), and decreased that at heading stages (−13.99%), and significantly reduced the Bt-toxin content at tillering stage (−15.21%). And the larval mortality of C. suppressalis was lower as reared with Bt rice stems during tillering stage grown under eCO2 in contrast to aCO2. In addition, eCO2 significantly increased the activity of total protease, tryptase-like enzyme and aminopeptidase of C. suppressalis larvae fed on Bt rice during seedling stage, and significantly reduced the activity of tryptase-like enzyme and aminopeptidase of C. suppressails larvae fed on Bt rice during tillering and heading stages respectively. Moreover, eCO2 significantly increased the expression level of APN1 and APN5 of C. suppressails larvae fed on Bt rice during seedling stage, and significantly reduced the expression level of APN5 of C. suppressalis larvae fed on Bt rice during tillering and heading stages respectively. In summary, the control efficiency of Bt rice to target insect pests under eCO2 showed a downward trend during tillering and heading stages, and especially during tillering stage. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa L.) is an important cereal crop worldwide due to its long domestication history. North-Eastern India (NEI) is one of the origins of indica rice and contains various native landraces that can withstand climatic changes. The present study compared NEI rice landraces to a check variety for phenological, morpho-physiological, and yield-associated traits under high temperatures (HTs) and elevated CO2 (eCO2) levels using molecular markers. The first experiment tested 75 rice landraces for HT tolerance. Seven better-performing landraces and the check variety (N22) were evaluated for the above traits in bioreactors for two years (2019 and 2020) under control (T1) and two stress treatments [mild stress or T2 (eCO2 550 ppm + 4 °C more than ambient temperature) and severe stress or T3 (eCO2 750 ppm + 6 °C more than ambient temperature)]. The findings showed that moderate stress (T2) improved plant height (PH), leaf number (LN), leaf area (LA), spikelets panicle−1 (S/P), thousand-grain weight (TGW), harvest index (HI), and grain production. HT and eCO2 in T3 significantly decreased all genotypes' metrics, including grain yield (GY). Pollen traits are strongly and positively associated with spikelet fertility at maturity and GY under stress conditions. Shoot biomass positively affected yield-associated traits including S/P, TGW, HI, and GY. This study recorded an average reduction of 8.09% GY across two seasons in response to the conditions simulated in T3. Overall, two landraces—Kohima special and Lisem—were found to be more responsive compared to other the landraces as well as N22 under stress conditions, with a higher yield and biomass increment. SCoT-marker-assisted genotyping amplified 77 alleles, 55 of which were polymorphic, with polymorphism information content (PIC) values from 0.22 to 0.67. The study reveals genetic variation among the rice lines and supports Kohima Special and Lisem's close relationship. These two better-performing rice landraces are useful pre-breeding resources for future rice-breeding programs to increase stress tolerance, especially to HT and high eCO2 levels under changing climatic situations. [ABSTRACT FROM AUTHOR]

Fusarium head blight (FHB) is a destructive fungal disease of wheat that causes significant economic loss due to lower yields and the contamination of grain with fungal toxins (mycotoxins), particularly deoxynivalenol (DON). FHB disease spread and mycotoxin contamination has been shown to worsen at elevated CO2, therefore, it is important to identify climate-resilient FHB resistance. This work evaluates whether wheat with the Fhb1 quantitative trait locus (QTL), the most widely deployed FHB resistance locus in wheat breeding programs, provides reliable disease resistance at elevated CO2. Near-isogenic wheat lines (NILs) derived from either a highly FHB susceptible or a more FHB resistant genetic background, with or without the Fhb1 QTL, were grown in growth chambers at ambient (400 ppm) and elevated (1000 ppm) CO2 conditions. Wheat was inoculated with Fusarium graminearum and evaluated for FHB severity. At elevated CO2, the NILs derived from more FHB-resistant wheat had increased disease spread, greater pathogen biomass and mycotoxin contamination, and lower rates of DON detoxification; this was not observed in wheat from a FHB susceptible genetic background. The Fhb1 QTL was not associated with increased disease severity in wheat grown at elevated CO2 and provided reliable disease resistance. [ABSTRACT FROM AUTHOR]

The extensive and uncontrolled utilization of rare earth elements, like europium (Eu), could lead to their accumulation in soils and biota. Herein, we investigated the impact of Eu on the growth, photosynthesis, and redox homeostasis in barley and how that could be affected by the future CO2 climate (eCO2). The plants were exposed to 1.09 mmol Eu3+/kg soil under either ambient CO2 (420 ppm, aCO2) or eCO2 (620 ppm). The soil application of Eu induced its accumulation in the plant shoots and caused significant reductions in biomass- and photosynthesis-related parameters, i.e., chlorophyll content, photochemical efficiency of PSII, Rubisco activity, and photosynthesis rate. Further, Eu induced oxidative stress as indicated by higher levels of H2O2 and lipid peroxidation products, and lower ASC/DHA and GSH/GSSG ratios. Interestingly, the co-application of eCO2 significantly reduced the accumulation of Eu in plant tissues. Elevated CO2 reduced the Eu-induced oxidative damage by supporting the antioxidant defense mechanisms, i.e., ROS-scavenging molecules (carotenoids, flavonoids, and polyphenols), enzymes (CAT and peroxidases), and ASC-GSH recycling enzymes (MDHAR and GR). Further, eCO2 improved the metal detoxification capacity by upregulating GST activity. Overall, these results provide the first comprehensive report for Eu-induced oxidative phytotoxicity and how this could be mitigated by eCO2. [ABSTRACT FROM AUTHOR]

We previously showed that chronic warming plus elevated carbon dioxide (eCO2) causes extreme upward bending of leaflets and petioles (i.e., hyponasty) in tomato (Solanum lycopersicum), which reduces growth. In that study, only two levels of CO2 (400, 700 ppm) and temperature (30, 37 °C) were tested in young vegetative plants, and the underlying mechanism for warming + eCO2 hyponasty was not investigated. In this study, warming + eCO2 hyponasty was evaluated in tomato across a range of temperatures and CO2 concentrations, and at multiple life stages. Based on their roles in thermal hyponasty, ethylene and auxin tomato mutants were examined, and light quality manipulated, to explore the mechanism for warming + eCO2 hyponasty. At eCO2 (800 ppm), the petiole angle increased roughly linearly with temperature from 30 to 38 °C. Under high temperature stress (38 °C), the petiole angle increased similarly at all eCO2 concentrations (600/800/1000 vs. 400 ppm). All life stages examined had an increased petiole angle in leaves developed during warming + eCO2, such that most leaves in juvenile plants exhibited hyponasty but only young growing leaves did so in adults. Auxin-insensitive mutants displayed a reduced petiole angle compared to auxin-sensitive, ethylene-sensitive, ethylene-insensitive, and non-mutant genotypes, indicating that auxin, but not ethylene, is likely a main component of this hyponastic response. Reduced far-red-to-red light plus increased blue light reduced petiole hyponasty compared to non-filtered white light during warming + eCO2. These results indicate that eCO2 affects the well-characterized thermal hyponastic response of leaves, which has implications for future plant responses to climate change. [ABSTRACT FROM AUTHOR]

The use of microbial metabolic limitation techniques has the potential to provide insights into carbon and nutrient cycling in an ecosystem under the influence of climate change. This study aimed to determine the characteristics and potential mechanisms of microbial metabolic limitation at the different growth stages of winter wheat (Triticum aestivum L.) in response to elevated CO2 concentrations, warming and drought. Winter wheat plants were grown in artificial climate chambers, and a set of treatments were employed, including two levels of CO2 concentration (400 and 800 μmol·mol−1), a temperature regime (the current ambient temperature and a temperature increase of 4 °C) and water conditions (80% and 60% of the field water capacity). The results showed that the soil microbes were mainly limited by C and P. Microbial C limitation significantly decreased by 26.7% and 36.9% at the jointing stage and significantly increased by 47.6% and 42.6% at the grain filling stage in response to elevated CO2 and warming, respectively. The microbial P limitation significantly decreased by 10.9–13.0% under elevated CO2 at the anthesis and grain filling stages, while it was not affected by warming. Both microbial C and P limitations were unaffected by drought. The growth stage, soil dissolved organic carbon (DOC) and available phosphorus (AP) were the key factors affecting microbial C limitation, and microbial P limitation was mainly affected by the soil microbial biomass carbon (MBC), phosphorus (MBP) and microbial C:P ratio. Thus, the soil microbial C and P limitations differed with growth stages and were primarily indirectly affected by the available nutrients in the soil and the properties of the microbial biomass, respectively. These findings are important for understanding the mechanisms underlying microbe-mediated C and nutrient cycles. Overall, this study provides guidance for soil nutrient management in an agroecosystem experiencing climate change. [ABSTRACT FROM AUTHOR]

To efficiently improve the productivity of strawberries under growing environmental change, the photosynthesis, root growth, and nitrogen allocation of strawberries (Fragaria × ananassa Duch. cv. Toyonoka) were investigated in a factorial design of CO2, temperature, and nitrogen supply. Elevated CO2 decreased the maximum CO2 assimilation rate (Amax), maximum CO2 carboxylation capacity per unit leaf area (Vcmax), and maximum CO2 carboxylation capacity per unit leaf mass (Vcm-m) by 20%, 24%, and 44%, respectively. Meanwhile, it reduced the SPAD value, maximal fluorescence level in the dark-adapted state (Fm), and maximal photochemical efficiency of PSII (Fv/Fm). Moreover, root branches, root number, root dry weight, and nitrogen-use efficiency were further increased in response to elevated CO2 under low nitrogen. When elevated CO2 was applied together with nitrogen nutrients, the Vcm-m and root nitrogen concentration (RNC) declined by 32% and 12%, respectively, but the total root dry weight (TRDW) increased by 88%. If the nitrogen nutrient was individually applied, the TRDW decreased by 16%, while the RNC increased by 21%. When the high temperature was individually applied, the TRDW increased by 104%, but the RNC decreased by 5%. Overall, elevated CO2 exacerbated photosynthetic down-regulation and significantly affected nitrogen redistribution among strawberry organs, reducing leaf nitrogen concentration and accelerating leaf senescence. However, it could increase seed quantity and improve its quality as well. In other words, under nitrogen-deficient conditions, elevated CO2 could improve the survival of offspring via the cost of the mother plant's growth capacity. [ABSTRACT FROM AUTHOR]

Unique plant functional traits (morpho-physio-anatomical) may respond to novel environmental conditions to counterbalance elevated carbon dioxide (eCO2) concentrations. Utilizing CO2, plants produce photoassimilates (carbohydrates). A mechanistic understanding of partitioning and translocation of carbon/photoassimilates into different plant parts and soils under ambient and eCO2 is required. In this study, we examine and present the intrinsic relationship between plant functional traits and eCO2 and seek answers to (i) how do plant functional traits (morpho-physio-anatomical features) affect C storage and partitioning under ambient and eCO2 in different plant parts? (ii) How do plant functional traits influence C transfer to the soil and rhizosphere services? Our study suggests that morpho-physio-anatomical features are interlinked, and under eCO2, plant functional traits influence the quantity of C accumulation inside the plant biomass, its potential translocation to different plant parts, and to the soil. The availability of additional photoassimilates aids in increasing the above- and belowground growth of plants. Moreover, plants may retain a predisposition to build thick leaves due to reduced specific leaf area, thicker palisade tissue, and higher palisade/sponge tissue thickness. eCO2 and soil-available N can alter root anatomy, the release of metabolites, and root respiration, impacting potential carbon transfer to the soil. [ABSTRACT FROM AUTHOR]

Experimental systems to simulate future elevated CO2 conditions in the field often have large, rapid fluctuations in CO2. To examine possible impacts of such fluctuations on photosynthesis, the intact leaves of the field-grown plants of five species were exposed to two-minute cycles of CO2 between 400 and 800 μmol mol−1, lasting a total of 10 min, with photosynthesis, stomatal conductance and PSII fluorescence measured at the end of each half-cycle and also 10 min after the end of the cycling. Prior to the cyclic CO2 treatments, the steady-state responses of leaf gas exchange and fluorescence to CO2 were determined. In four of the five species, in which stomatal conductance decreased with increasing CO2, the cyclic CO2 treatments reduced stomatal conductance. In those species, both photosynthesis and the photochemical efficiency of PSII were reduced at limiting internal CO2 levels, but not at saturating CO2. In the fifth species, there was no change in stomatal conductance with CO2 and no change in either photosynthesis or PSII efficiency at any CO2 level with CO2 cycling. It is concluded that in many, but not all, species, fluctuations in CO2 may reduce photosynthesis at low CO2, partly by decreasing the photochemical efficiency of photosystem II as well as by decreasing stomatal conductance. [ABSTRACT FROM AUTHOR]

Drought stress severely limits crop growth and yield. With the atmospheric CO2 constantly increasing, plants will be affected by multiple effects of drought and increased CO2 in the future. Abscisic acid (ABA) plays vital roles in plant stress tolerance, especially drought stress. However, little is known about the effects of elevated CO2 concentration (e[CO2]) and exogenous ABA in cucumber (Cucumis sativus L.) response to drought stress. In the present study, we investigated the effects of e[CO2] and exogenous ABA on the drought tolerance of cucumber seedlings under the simulated drought stress induced by 5% polyethylene glycol 6000. The experiment was a split-plot design, in which the main factor was CO2 concentrations; atmospheric and elevated CO2 concentrations (~400 and 800 ± 40 μmol mol−1, respectively). The subplot factor was the combinations of exogenous ABA and its synthesis inhibitor sodium tungstate (Na2WO4); deionized water (control), 20 μM ABA, 2 mM Na2WO4, and 2 mM Na2WO4 + 20 μM ABA, which were applied to plant leaves. The results showed that compared with exogenous ABA application only, e[CO2] combined with exogenous ABA significantly increased the biomass, chlorophyll content, and net photosynthetic rate (Pn) of cucumber seedlings under drought stress. Meanwhile, e[CO2] and exogenous ABA were more efficient in reducing the contents of reactive oxygen species and malondialdehyde, promoting the accumulation of proline, soluble sugar, soluble protein, free amino acid, ascorbic acid, and glutathione. The ratios of ascorbic acid/dehydroascorbic acid (ASA/DHA), glutathione/oxidized glutathione (GSH/GSSG), as well as the activities of antioxidant enzymes were increased. In conclusion, e[CO2] and exogenous ABA synergistically alleviated oxidative damage of drought stress on cucumber seedlings by increasing antioxidant enzyme activities and accelerating the ASA–GSH cycle in cucumber seedlings, which in turn improved the drought tolerance of cucumber seedlings, and provided theoretical and practical support for further studies on the alleviation of drought stress in protected horticulture. [ABSTRACT FROM AUTHOR]

Legumes are generally considered to be more responsive to elevated CO2 (eCO2) conditions due to the benefits provided by symbiotic nitrogen fixation. In response to high carbohydrate demand from nodules, legumes display autoregulation of nodulation (AON) to restrict nodules to the minimum number necessary to sustain nitrogen supply under current photosynthetic levels. AON mutants super-nodulate and typically grow smaller than wild-type plants under ambient CO2. Here, we show that AON super-nodulating mutants have substantially higher biomass under eCO2 conditions, which is sustained through increased photosynthetic investment. We examined photosynthetic and physiological traits across super-nodulating rdn1-1 (Root Determined Nodulation) and sunn4 (Super Numeric Nodules) and non-nodulating nfp1 (Nod Factor Perception) Medicago truncatula mutants. Under eCO2 conditions, super-nodulating plants exhibited increased rates of carboxylation (Vcmax) and electron transport (J) relative to wild-type and non-nodulating counterparts. The substantially higher rate of CO2 assimilation in eCO2-grown sunn4 super-nodulating plants was sustained through increased production of key photosynthetic enzymes, including Rieske FeS. We hypothesize that AON mutants are carbon-limited and can perform better at eCO2 through improved photosynthesis. Nodulating legumes, especially those with higher nitrogen fixation capability, are likely to out-perform non-nodulating plants under future CO2 conditions and will be important tools for understanding carbon and nitrogen partitioning under eCO2 conditions and future crop improvements. [ABSTRACT FROM AUTHOR]

Three genotypes of wheat grown at two CO2 concentrations were used in a drought experiment, where water was withheld from the pots at anthesis until stomatal conductance (gs) dropped below 10% of the control and photosynthesis (A) approached zero. The genotypes had different leaf area (Gladius < LM19 < LM62) and while photosynthesis and shoot growth were boosted by elevated CO2, the water use and drying rate were more determined by canopy size than by stomatal density and conductance. The genotypes responded differently regarding number of fertile tillers, seeds per spike and 1000 kernel weight and, surprisingly, the largest genotype (LM62) with high water use showed the lowest relative decrease in grain yield. The maximum photochemical efficiency of photosystem II (Fv/Fm) was only affected on the last day of the drought when the stomata were almost closed although some variation in A was still seen between the genotypes. A close correlation was found between Fv/Fm and % loss of grain yield. It indicates that the precise final physiological stress level measured by Fv/Fm at anthesis/early kernel filling could effectively predict percentage final yield loss, and LM62 was slightly less stressed than the other genotypes, due to only a small discrepancy in finalising the drying period. Therefore, Fv/Fm can be used as a proxy for estimating the yield performance of wheat after severe drought at anthesis. [ABSTRACT FROM AUTHOR]

Global climate changes are affecting organisms and their interactions in terrestrial and aquatic ecosystems, such as the increase in temperature and CO2 concentration. Herbivory interaction is a very important part of nutrient cycle and energy flow in freshwater ecosystem, and climate changes may directly or indirectly affect aquatic plants, aquatic herbivores and their interactions. In this study, we explored the effects of the rising temperature, elevated CO2 concentrations and herbivory by an herbivorous snail (Radix auricularia L.) on a submerged plant (Vallisneria natans L.). Our results showed that herbivory, temperature, and CO2 had specific effects on snail and plant growth, statistically there was only one interaction-a reduction in leaf number. Under different experimental conditions, snail herbivory always has negative effects on biomass accumulation and growth of V. natans. Moreover, the increases in temperature also inhibited its growth. Snail herbivory reduced the content of total carbon and total nitrogen of V. natans in all treatments, while the total phenols content increased. Our findings indicate that the rising temperature, elevated CO2 concentrations and herbivory have interactive effects on the growth and stoichiometry of submerged macrophytes, but further research is needed between aquatic plants and aquatic herbivores to aid prediction the impact of climate change on freshwater ecosystems. [ABSTRACT FROM AUTHOR]

Climate change elements including elevated atmospheric carbon dioxide (CO2) concentration and soil salinity significantly impact weed biology and management. In this study, we evaluated the performance of a highly invasive plant species, parthenium weed (Parthenium hysterophorus L.) grown at various soil salinity levels (ranging from 0 to 16 dS m−1) at two CO2 concentrations (ambient: 400 ppm and elevated: 700 ppm). The CO2 concentration and soil salinity individually affected various early growth attributes of parthenium weed. The interaction between CO2 and salinity was significant for chlorophyll index, stem dry weight and phenolics content. Parthenium weed plants grew taller (13%), achieved greater leaf area (28%) and produced more dry weight (24%) when raised under elevated as compared with the ambient CO2. Soil salinity had a dose-dependent, negative effect on various growth attributes, chlorophyll index, relative water content and phenolics content. Even the modest levels of salinity (4.2 to 4.6 dS m−1) caused 50% reduction in dry weights of leaves, roots and whole plants. Sodium ion (Na+) concentration peaked at the highest salinity level (16 dS m−1) as compared with the lower salinity levels (0 to 12 dS m−1). Overall, salinity had a negative effect on different growth variables but elevated CO2 improved growth and phenolics content regardless of the salt stress regime. Hence, parthenium weed could benefit from future atmospheric CO2 concentration and may invade some salt-affected areas. [ABSTRACT FROM AUTHOR]

Leaf chlorophyll pigment and macronutrient concentrations were quantified for four willow species (Salix cordata (COR), S. discolor (DIS), S. eriocephala (ERI) and S. interior (INT)) while growing under 2 × 2 factorial of ambient and elevated CO2 and well-watered and drought-stressed soil moisture treatments (Expt. 1). After the first year, we saw no difference in stem biomass between CO2 treatments. In the following year, a second experiment was conducted on a subset of well-watered willows as a 2 × 2 factorial of atmospheric CO2 and soil fertilization (FERT). For both years of Expt. 1, chlorophyll a, b, a + b (TCC) and carotenoids (CAR) significantly downregulated in response to elevated CO2 (eCO2) and upregulated in response to drought (DRT). In Expt. 2, FERT mitigated CO2 downregulation of TCC and CAR, and upregulated TCC and CAR. Across species, ERI had the greatest pigment concentrations followed by either COR or DIS. Except for one case, INT had the lowest pigment concentrations. A significant species x FERT interaction was due to magnitude effects. The CHLa:b ratio was not affected by CO2 or DRT but did increase in response to FERT. INT had the greatest CHLa:b ratio followed by DIS, then either ERI or COR. In the second year, TCC:CAR ratio decreased in response to eCO2 and increased in response to DRT and FERT. In Expt. 1, leaf N was the only nutrient to significantly downregulate in response to eCO2; whereas all other nutrient levels remained unchanged. In response to DRT, leaf N and Mg upregulated; whereas leaf P, K, and Ca were downregulated. In response to eCO2 in Expt. 2, again only leaf N downregulated; whereas all other nutrients remained unchanged. All leaf nutrients upregulated in response to FERT. Of the four species, INT had the greatest leaf N and K, and the lowest Ca. Species variation was important, but so to was clonal variation in response to change. Indeed, INT leaf chlorophyll and macronutrients are significantly different or segregated from the other three willow species and this may be related to the evolutionary origins of INT, and other species of the taxonomic section Longifoliae, in the arid southwest USA and Mexico. Furthermore, under low nutrient conditions, it may be necessary to fertilize the plants to see a biomass response to eCO2. [ABSTRACT FROM AUTHOR]

Elevated atmospheric CO2 (eCO2) and iron (Fe) availability are important factors affecting plant growth that may impact the proteomic profile of crop plants. In this study, soybean plants treated under Fe-limited (0.5 mM) and Fe-sufficient (20 mM) conditions were grown at ambient (400 μmol mol−1) and eCO2 (800 μmol mol−1) in hydroponic solutions. Elevated CO2 increased biomass from 2.14 to 3.14 g plant−1 and from 1.18 to 2.91 g plant−1 under Fe-sufficient and Fe-limited conditions, respectively, but did not affect leaf photosynthesis. Sugar concentration increased from 10.92 to 26.17 μmol g FW−1 in roots of Fe-sufficient plants and from 8.75 to 19.89 μmol g FW−1 of Fe-limited plants after exposure to eCO2. In leaves, sugar concentration increased from 33.62 to 52.22 μmol g FW−1 and from 34.80 to 46.70 μmol g FW−1 in Fe-sufficient and Fe-limited conditions, respectively, under eCO2. However, Fe-limitation decreases photosynthesis and biomass. Pathway enrichment analysis showed that cell wall organization, glutathione metabolism, photosynthesis, stress-related proteins, and biosynthesis of secondary compounds changed in root tissues to cope with Fe-stress. Moreover, under eCO2, at sufficient or limited Fe supply, it was shown an increase in the abundance of proteins involved in glycolysis, starch and sucrose metabolism, biosynthesis of plant hormones gibberellins, and decreased levels of protein biosynthesis. Our results revealed that proteins and metabolic pathways related to Fe-limitation changed the effects of eCO2 and negatively impacted soybean production. [ABSTRACT FROM AUTHOR]

Anthropogenic activities over the last century have caused rapid changes in environmental conditions through increasing CO2 emissions in the atmosphere that contribute to global warming. Moreover, the increased global average temperature is linked with changes in the precipitation rate and distribution, resulting in a negative impact on crop health and productivity. Plants in nature often experience combined stresses; therefore, they have developed adaptive mechanisms to cope with fluctuating environmental conditions. Thus, investigating plant responses under unfavorable environmental conditions will provide a better understanding of how crops can adapt and thereby assist in selecting climate-resilient crops that can withstand climate variability. This review highlights the main adaptive physiological and biochemical responses of crops grown under elevated CO2 (eCO2) and exposed to combined abiotic stresses (drought and heat). Moreover, the mitigation and limitation impact of elevated CO2 on plants under the combination of stress is discussed. [ABSTRACT FROM AUTHOR]

As multiple invaders often co-occur, understanding the interactions between different invasive species is important. Previous studies have reported on invasional meltdown and neutral and interference relationships between invasive species. However, interspecific interactions may vary with environmental change owing to the different responses of interacting invaders. To better understand the interaction of notorious invasive alien plants under CO2 enrichment and N deposition, the growth characteristics of common ragweed (Ambrosia artemisiifolia) and redroot pigweed (Amaranthus retroflexus) were studied when they were planted in monoculture (4Rag and 4Pig) or mixture (1Rag:3Pig, 2Rag:2Pig, 3Rag:1Pig) under four environmental treatments: elevated CO2, increased N, elevated CO2 + increased N and a control. Increased N positively affected almost all the traits (basal stem diameter, height, shoot biomass, root biomass and total biomass) of common ragweed, except for branch number and root-shoot ratio. But increased N only promoted redroot pigweed's height and basal stem diameter. interspecific competition promoted basal stem diameter and number of branches but decreased root biomass of common ragweed, and the basal stem diameter was significantly higher in 1Rag:3Pig and 2Rag:2Pig compared to the other two treatments. interspecific competition inhibited almost all the characteristics of redroot pigweed. The interaction between elevated CO2 and increased N also increased the biomass characteristics (shoot biomass, root biomass and total biomass) of common ragweed. However, elevated CO2 inhibited the root biomass of redroot pigweed. The results indicated that common ragweed was a superior competitor under conditions of elevated CO2 and increased N. Moreover, environmental change might strengthen the super-invasive plant common ragweed's competitive ability. [ABSTRACT FROM AUTHOR]

Due to climate change, the attainment of global food security is facing serious challenges in meeting the growing food demand. Abiotic stresses are the foremost limiting factors for agricultural productivity. However, not much information is available on the effect of multiple abiotic stresses on the morphological and biochemical aspects of kale and mustard. Therefore, an experiment was designed to study the effects of UV-B radiation, CO2 concentration, and high temperature on the growth, yield, and biochemistry of two Brassica species, namely B. oleracea L. var. acephala Winterbor F1 (hybrid kale) and B. juncea var. Green wave O.G. (mustard greens), which were grown under optimal nutrients and soil moisture conditions in soil–plant–atmosphere–research (SPAR) units. Two levels of UV-B radiation (0 and 10 kJ m−2 d−1), two concentrations of CO2 (420 and 720 ppm), and two different temperature treatments (25/17 °C and 35/27 °C) were imposed 12 days after sowing (DAS). Several morphological and biochemical parameters were measured at harvest (40 DAS) in both species. All the traits declined considerably under individual and multi-stress conditions in both species except under elevated CO2 levels, which had a positive impact. Marketable fresh weight decreased by 64% and 58% in kale and mustard plants, respectively, growing under UV-B treatment. A slight increase in the chlorophyll content was observed in both species under the UV-B treatment alone and in combination with high temperature and elevated CO2. Understanding the impacts of high temperature, CO2, and UV-B radiation treatments on leafy vegetables, such as kale and mustard, can help to improve existing varieties to enhance resilience towards environmental stresses while simultaneously improving yield, morphology, and biochemistry in plants. [ABSTRACT FROM AUTHOR]

Boreal bog plants adapted to cold and low available nutrient conditions might be strongly affected by global changes, including elevated CO2 (eCO2), warming (W), and increasing nitrogen (N) availability. Here, we examined responses of dark respiration (Rd) and net photosynthesis (Anet) in four dominant bog plants to five levels of short-term increases in both CO2 and temperature (CTI); and the effects of long-term (6 years) W and N addition on these responses. Results indicated that CTI increased Rd; meanwhile, the increase of these environmental variables decreased Anet in all these boreal bog plants. Long-term nitrogen addition simulated the increases of Rd and decreases of Anet in Trichophorum cespitosum. Long-term warming mitigated the increases of Rd in Andromeda glaucophylla and Gaylussacia bigeloviana, and the decrease of Anet in Gaylussacia bigeloviana. These findings highlight the importance of long-term warming and nitrogen addition in regulating responses of boreal bog plants to short-term CTI, suggesting the necessity to investigate the long-term effects of these environmental changes when projecting responses of boreal bog vegetation to global changes. [ABSTRACT FROM AUTHOR]

Triticum aestivum L. cv. Gazul is a spring wheat widely cultivated in Castilla y León (Spain). Potted plants were grown in a scenario emulating the climate change environmental conditions expected by the end of this century, i.e., with elevated CO2 and high temperature under two water deficit regimes: long (LWD) and terminal (TWD). Changes in biomass and morphology, the content of proline (Pro), ascorbate (AsA) and glutathione (GSH), and enzymatic antioxidant activities were analyzed in flag leaves and ears. Additionally, leaf gas exchange was measured. LWD caused a decrease in biomass and AsA content but an increase in Pro content and catalase and GSH reductase activities in flag leaves, whereas TWD produced no significant changes. Photosynthesis was enhanced under both water deficit regimes. Increase in superoxide dismutase activity and Pro content was only observed in ears under TWD. The lack of a more acute effect of LWD and TWD on both organs was attributed to the ROS relieving effect of elevated CO2. Gazul acted as a drought tolerant variety with anisohydric behavior. A multifactorial analysis showed better adaptation of ears to water deficit than flag leaves, underlining the importance of this finding for breeding programs to improve grain yield under future climate change. [ABSTRACT FROM AUTHOR]

Simple Summary: The changing climate scenario envisages elevated CO2 (eCO2) and drought in many parts of the world. Elevated CO2 is known to increase yields in C3 crops like rice and wheat, on the other hand, it does not cause a similar increase in C4 crops like maize and sorghum. Drought is known to reduce crop growth and yield. In this mini-review we discuss the combined effects of both eCO2 and drought which is typical of a climate change scenario. We try and explain how C3 and C4 crops are differentially affected by these two manifestations of climate change. We specifically show how eCO2 in addition to its known beneficial effects can also be effective in ameliorating the effects of drought in crops. We have critically analysed the current literature and have come up with some mechanistic explanations in terms of water relations, hormonal regulation, photosynthesis and growth, nutrient uptake, and enzyme dynamics. We present here how these processes operate across a range, from ecosystem to organismal level and from molecular to the whole plant level. The information presented will help researchers to devise strategies for adaptation in crops in agricultural systems. The changing dynamics in the climate are the primary and important determinants of agriculture productivity. The effects of this changing climate on overall productivity in agriculture can be understood when we study the effects of individual components contributing to the changing climate on plants and crops. Elevated CO2 (eCO2) and drought due to high variability in rainfall is one of the important manifestations of the changing climate. There is a considerable amount of literature that addresses climate effects on plant systems from molecules to ecosystems. Of particular interest is the effect of increased CO2 on plants in relation to drought and water stress. As it is known that one of the consistent effects of increased CO2 in the atmosphere is increased photosynthesis, especially in C3 plants, it will be interesting to know the effect of drought in relation to elevated CO2. The potential of elevated CO2 ameliorating the effects of water deficit stress is evident from literature, which suggests that these two agents are brothers in arms protecting the plant from stress rather than partners in crime, specifically for water deficit when in isolation. The possible mechanisms by which this occurs will be discussed in this minireview. Interpreting the effects of short-term and long-term exposure of plants to elevated CO2 in the context of ameliorating the negative impacts of drought will show us the possible ways by which there can be effective adaption to crops in the changing climate scenario. [ABSTRACT FROM AUTHOR]

Elymus repens (L.) Gould), Cirsium arvense (L.) Scop. and Sonchus arvensis L. are important arable creeping perennial weeds in Europe. These are clonal plants with subterranean reproductive organs (E. repens, rhizomes, the two dicots, horizontal creeping roots) sprouting from ramets. We tested the sprouting ability and early growth of ramet sprouts at temperatures typical for Nordic autumn climate and with different preconditions of the mother plant (time in autumn, mother plant age, climate change experiences of the mother plants (two experiments)). The species reacted differently, with S. arvensis not sprouting at all, and C. arvense ramets sprouting at higher temperatures than those of E. repens, which sprouted at all tested temperatures. Plant age affected only the ramet sprout biomass of E. repens. Climate change during mother plant growth only affected C. arvense, with the highest above-ground biomass of the sprouted ramets at an elevated temperature and ambient CO2. Testing earlier in autumn showed more sprouting and biomass for C. arvense and E. repens than testing later in the season. The observed temperature responses confirmed more and bigger sprouts with higher autumn temperatures. Controlling the sprouted ramets in autumn is easier for E. repens than for C. arvensis. Due to their low/no sprouting ability in autumn, the ramets of S. arvensis cannot be controlled in autumn. [ABSTRACT FROM AUTHOR]

Global climate change will modify plants in terms of growth and physiology. To better understand the consequences of this effect, the responses of the leaf water relations and nitrogen (N) use efficiency of barley and tomato plants to elevated CO2 (e[CO2], 800 ppm) combined with progressive drought stress at two levels of N supply (N1, 0.5 g N pot−1 and N2, 1.0 g N pot−1) were studied. The plants were grown in two separate phytotrons at ambient CO2 (a[CO2], 400 ppm) and e[CO2], respectively. The leaf physiological parameters as well as carbon (C) and N concentrations were determined; plant growth, water and N use efficiencies were evaluated. The results showed that e[CO2] increased photosynthesis and water use efficiency (WUE) while decreased specific leaf area (SLA) in both species, whereas N supply level differentially influenced WUE in barley and tomato plants. The abscisic acid (ABA)-induced stomatal closure during progressive soil drying varied between the two species where the stomatal conductance (gs) of barley plants was more sensitive to leaf ABA than tomato plants, though CO2 environment did not affect the response in both species. Compared to a[CO2], e[CO2] reduced plant transpiration rate (Tplant) in barley but not in tomato. e[CO2] increased the leaf C:N ratio ([C:N]leaf) in plants by enhancing leaf C concentration ([C]leaf) in barley and by dilution of leaf N concentration ([N]leaf) in tomato, respectively, but N2 substantially decreased [C:N]leaf, and thus, N treatment was the dominant factor controlling [C:N]leaf. Collectively, appropriate N supply may modulate the acclimation of plants to e[CO2] and soil water deficits. This study provides some novel insights into N management of different plant species for adapting to future drier and CO2-enriched environment. [ABSTRACT FROM AUTHOR]

Is there any relationship between plant nutrition and human health? The overall response to this question is very positive, and a strong relationship between the nutrition of plants and humans has been reported in the literature. The nutritional status of edible plants consumed by humans can have a negative or positive impact on human health. This review was designed to assess the importance of plant bioactive compounds for human health under the umbrella of sustainable agriculture. With respect to the first research question, it was found that plant bioactives (e.g., alkaloids, carotenoids, flavonoids, phenolics, and terpenoids) have a crucial role in human health due to their therapeutic benefits, and their potentiality depends on several factors, including botanical, environmental, and clinical attributes. Plant bioactives could be produced using plant tissue culture tools (as a kind of agro-biotechnological method), especially in cases of underexploited or endangered plants. Bioactive production of plants depends on many factors, especially climate change (heat stress, drought, UV radiation, ozone, and elevated CO2), environmental pollution, and problematic soils (degraded, saline/alkaline, waterlogged, etc.). Under the previously mentioned stresses, in reviewing the literature, a positive or negative association was found depending on the kinds of stress or bioactives and their attributes. The observed correlation between plant bioactives and stress (or growth factors) might explain the importance of these bioactives for human health. Their accumulation in stressed plants can increase their tolerance to stress and their therapeutic roles. The results of this study are in keeping with previous observational studies, which confirmed that the human nutrition might start from edible plants and their bioactive contents, which are consumed by humans. This review is the first report that analyzes this previously observed relationship using pictorial presentation. [ABSTRACT FROM AUTHOR]

Simple Summary: In recent years, the atmospheric CO2 concentration was increasing continuously, which has led to the change in the photosynthesis and chemical composition of rice plants. The growth and development of brown planthopper (BPH) Nilaparvata lugens are further affected. Plants release volatile organic compounds (VOCs) to mediate intra- and inter-specific interactions with other organisms in the surrounding environment. Therefore, here we aim to explore the effect of rice VOCs on the host selection ability of BPH under elevated CO2. Among the identified thirty-six rice VOCs, the contents of heptadecane, linalool and limonene from rice plants were significantly decreased under elevated CO2. Moreover, we found that the VOCs of rice damaged by BPH were also changed. Undecane, hexadecane, nonanal and 2,6-diphenylphenol from BPH-damaged rice plants under elevated CO2 were all significantly higher than those from healthy rice plants, which might lead to enhancement of the host selection ability of BPH, eventually aggravating the damage caused by BPH. However, the role of these VOCs in host selection ability of BPH is not clear, and more experiments are needed to verify their function. It is predicted that plant volatile organic compounds (VOCs) are affected by the atmospheric CO2 levels rising globally, which further affects the interaction between plants and herbivorous insects, especially the host selection behavior of herbivorous insects. In this study, the effects of elevated CO2 on the host-selection behavior of the brown planthopper (BPH) Nilaparvata lugens, and the emission of VOCs from the healthy and BPH-damaged rice plants were studied simultaneously to make clear the population occurrence of BPH under global climate change. Compared with ambient CO2, elevated CO2 significantly increased the host selection percent of BPH for the healthy (CK) and BPH-damaged rice plants, and the host selection percent of BPH for the BPH-damaged rice plants was significantly higher than that for the healthy rice plants under elevated CO2, which might be regulated by the transcription levels of OBP1, OBP2 and CSP8 in BPH due to the upregulated transcriptional levels of these three genes of BPH under elevated CO2. In addition, we analyzed and quantified the emission of VOCs in rice plants grown under ambient CO2 and elevated CO2 by GS-MS. A total of 36 VOCs from rice plants were identified into eight categories, including alkanes, alkenes, alcohols, aldehydes, ketones, esters, phenols and aromatic hydrocarbons. Elevated CO2 significantly decreased the contents of heptadecane, linalool and limonene from rice plants compared with ambient CO2. Besides, the contents of linalool, phytol, decanal, 1-methyldecalin and 2,6-diphenylphenol from BPH-damaged rice plants under ambient CO2, and undecane, hexadecane, nonanal and 2,6-diphenylphenol from BPH-damaged rice plants under elevated CO2 were all significantly higher than those from healthy rice plants. The percentage composition of phenols was positively correlated with the host selection rate of BPH. Our study indicates that elevated CO2 is beneficial to promote the host selection ability of BPH for rice plants damaged by BPHs due to the changed plant VOCs. [ABSTRACT FROM AUTHOR]

Extensive stolon development and growth are superior traits for rapid establishment as well as post-stress regeneration in stoloniferous grass species. Despite the importance of those stoloniferous traits, the regulation mechanisms of stolon growth and development are largely unknown. The objectives of this research were to elucidate the effects of the reallocation of soluble sugars for energy reserves and endogenous hormone levels for cell differentiation and regeneration in regulating stolon growth of a perennial turfgrass species, creeping bentgrass (Agrostis stolonifera L.). Plants were grown in growth chambers with two CO2 concentrations: ambient CO2 concentration (400 ± 10 µmol mol−1) and elevated CO2 concentration (800 ± 10 µmol mol−1). Elevated CO2 enhanced stolon growth through increasing stolon internode number and internode length in creeping bentgrass, as manifested by the longer total stolon length and greater shoot biomass. The content of glucose, sucrose, and fructose as well as endogenous IAA were accumulated in stolon nodes and internodes but not in leaves or roots under elevated CO2 concentration. These results illustrated that the production and reallocation of soluble sugars to stolons as well as the increased level of IAA in stolon nodes and internodes could contribute to the enhancement of stolon growth under elevated CO2 in creeping bentgrass. [ABSTRACT FROM AUTHOR]

Coastal wetlands are dynamic ecosystems that exist along a landscape continuum that can range from freshwater forested wetlands to tidal marsh to mudflat communities. Climate-driven stressors, such as sea-level rise, can cause shifts among these communities, resulting in changes to ecological functions and services. While a growing body of research has characterized the landscape-scale impacts of individual climate-driven stressors, little is known about how multiple stressors and their potential interactions will affect ecological functioning of these ecosystems. How will coastal wetlands respond to discrete climate disturbances, such as hurricane sediment deposition events, under future conditions of elevated atmospheric CO2? Will these responses vary among the different wetland communities? We conducted experimental greenhouse manipulations to simulate sediment deposition from a land-falling hurricane under future elevated atmospheric CO2 concentrations (720 ppm CO2). We measured responses of net primary production, decomposition, and elevation change in mesocosms representing four communities along a coastal wetland landscape gradient: freshwater forested wetland, forest/marsh mix, marsh, and mudflat. When Schoenoplectus americanus was present, above- and belowground biomass production was highest, decomposition rates were lowest, and wetland elevation gain was greatest, regardless of CO2 and sediment deposition treatments. Sediment addition initially increased elevation capital in all communities, but post-deposition rates of elevation gain were lower than in mesocosms without added sediment. Together these results indicate that encroachment of oligohaline marshes into freshwater forested wetlands can enhance belowground biomass accumulation and resilience to sea-level rise, and these plant-mediated ecosystem services will be augmented by periodic sediment pulses from storms and restoration efforts. [ABSTRACT FROM AUTHOR]

Assimilation to the internal CO2 (ACi) response curve and gas exchange parameters were quantified for four North American willows ((Salix cordata (COR), S. discolor (DIS), S. eriocephala (ERI), and S. interior (INT)) grown in a 2 × 2 factorial of atmospheric CO2 and soil moisture treatments to see how they would respond to climate change factors. After the first year of greenhouse growth under said treatments, we saw no difference in the aboveground stem biomass between CO2 treatments. Thus, in the second year, a second experiment on a subset of well-watered, coppiced willows was conducted in a 2 × 2 factorial of atmospheric CO2 and soil fertilization (FERT) treatments. In both experiments, the maximum rate of carboxylation (Vcmax) significantly declined for all four species in response to elevated CO2 (eCO2). In response to a drought treatment (DRT), Vcmax declined, except for INT, which increased Vcmax. In both experiments, INT had the greatest Vcmax, maximum rate of electron transport (Jmax), and triose phosphate utilization, followed by COR and ERI, with DIS having the lowest values. FERT resulted in a strong increase in assimilation (A) and stomatal conductance (Gwv) by 92 and 119%, respectively. Gwv is the primary driver and A is a minor driver of water use efficiency (WUE) under DRT. FERT mitigated the Vcmax and A downregulation in eCO2, but eCO2 did not mitigate the DRT downregulation effect. Differences between INT and the other three willows in a number of adaptive traits and responses related to drought may reflect the evolutionary origins of INT and the taxonomic group Longifoliae in the arid southwest USA and Mexico. [ABSTRACT FROM AUTHOR]

Simple Summary: Global warming caused by the increase in atmospheric CO2 concentration is becoming a major environmental issue. Lipaphis erysimi is one of the most damaging pests of cruciferous crops worldwide, and L. erysimi has strong adaptability to the environment and reproductive capacity. The age-stage, two-sex life table is currently used by many researchers in place of the traditional age-specific life table, providing many details such as fitness and potential damage. In this study, the individual fitness and population dynamics parameters of three successive generations of L. erysimi were analyzed using the age-stage, two-sex life table. The results show that a high CO2 concentration had a cumulative effect on the survival rate and fecundity of L. erysimi, and elevated CO2 had a negative effect on the individual fitness parameters of L. erysimi. The life expectancy (exj) is significantly lower in elevated CO2 than that in ambient CO2 treatment in the three successive generations, indicating that L. erysimi was more sensitive to CO2 concentration and the life of L. erysimi was shortened under elevated CO2. Additionally, we can find that elevated CO2 has a short-term effect on the population parameters, including the intrinsic rate of increase (r) and finite rate of increase (λ) in L. erysimi. Through the data from this experiment, we believe that the individual and population fitness of L. erysimi will be decreased under elevated CO2, which indicates that the damage caused by L. erysimi may be reduced in the future with increasing CO2 levels. To assess the effect of elevated CO2 on the development, fecundity, and population dynamic parameters of L. erysimi, the age-stage, two-sex life table was used to predict the individual fitness and population parameters of three successive generations of L. erysimi in this study. The results show that a significantly longer total pre-adult stage before oviposition (TPOP) was observed in the third generation compared with the first generation of L. erysimi under the 800 μL/L CO2 treatment. The fecundity is significantly lower in the 800 μL/L CO2 treatment than that in the 400 μL/L CO2 treatment in the third generation of L. erysimi, which indicates that elevated CO2 had a negative effect on the individual fitness parameters of L. erysimi. Additionally, the life expectancy (exj) is significantly lower under the 800 μL/L CO2 treatment than that under the 400 μL/L CO2 treatment in the three successive generations. A significantly higher intrinsic rate of increase (r) and finite rate of increase (λ) were found in the second generation compared with those in the first and third generations of L. erysimi under the 800 μL/L CO2 treatment. Moreover, significantly lower r and λ were observed under the 800 μL/L CO2 treatment compared with those under the 400 μL/L and 600 μL/L CO2 treatments in the first generation of L. erysimi, which indicates that elevated CO2 has a short-term effect on the population parameters (r and λ) of L. erysimi. Our experiment can provide the data for the comprehensive prevention and control of L. erysimi in the future with increasing CO2 levels. [ABSTRACT FROM AUTHOR]

CO2 is currently a growth-limiting resource for plants with C3 metabolism, and elevated CO2 also often reduces stomatal conductance, reducing plant water stress. Increased photosynthesis and improved water status might be expected to result in increased leaf size. It is therefore unexpected that leaf size is in some cases reduced in plants grown at elevated CO2, and also unexpected that elevated CO2 applied only during darkness can increase leaf size. These experiments compared leaf size responses to day and/or night elevated CO2 in six cultivars of Phaseolus vulgaris grown with either constant or varying temperature in controlled environment chambers. Diverse responses of leaf size to elevated CO2 were found among the cultivars, including increased leaf size with elevated CO2 applied only during darkness in some cultivars and temperature regimes. However, leaf size responses to elevated CO2 and cultivar differences in response were unrelated to differences in leaf water potential or turgor pressure. [ABSTRACT FROM AUTHOR]

Potential global climate change-related impacts on crop production have emerged as a major research priority and societal concern during the past decade. Future changes, natural and human-induced, projected in the climate have implications for regional and global crop production. The simultaneous occurrence of several abiotic stresses instead of stress conditions is most detrimental to crops, and this has been long known by farmers and breeders. The green leafy vegetables of the Brassicaceae family have especially gained attention due to their many health benefits. However, little information is available about abiotic stress's effects on Brassica vegetables' growth and development. An experiment was conducted on two Brassica species: B. oleracea L. var. acephala WINTERBOR F1 (hybrid kale) and B. juncea var. GREEN WAVE OG (mustard greens). Seven treatments were imposed on the two brassica species in soil–plant–atmosphere–research (SPAR) units under optimum moisture and nutrient conditions, including a control treatment (optimal temperature and UV-B conditions at ambient CO2 levels), and six treatments where stresses were elevated: CO2, UV-B, temperature (T), CO2+UV-B, CO2+T, and CO2+UV-B+T. Above- and below-ground growth parameters were assessed at 26 d after sowing. Several shoot and root morphological and developmental traits were evaluated under all the treatments. The measured growth and development traits declined significantly under individual stresses and under the interaction of these stresses in both the species, except under elevated CO2 treatment. All the traits showed maximum reductions under high IV-B levels in both species. Leaf area showed 78% and 72% reductions, and stem dry weight decreased by 73% and 81% in kale and mustard, respectively, under high UV-B levels. The increased CO2 concentrations alleviated some deleterious impacts of high temperature and UV-B stresses. The results of our current study will improve our understanding of the adverse effects of environmental stresses on the early-season growth and development of two Brassica species. [ABSTRACT FROM AUTHOR]

Elevated carbon dioxide (EC) can increase the growth and development of different C3 fruit crops, which may further increase the nutrient demand by the accumulated biomass. In this context, the current investigation was conceptualized to evaluate the growth performance and nutrient uptake by tomato plants under elevated CO2 (EC700 and EC550 ppm) and temperature (+2 °C) in comparison to ambient conditions. Significant improvement in the growth indicating parameters like leaf area, leaf area index, leaf area duration and crop growth rate were measured at EC700 and EC550 at different stages of crop growth. Further, broader and thicker leaves of plants under EC700 and EC550 have intercepted higher radiation by almost 11% more than open field plants. Conversely, elevated temperature (+2 °C) had negative influence on crop growth and intercepted almost 7% lower radiation over plants under ambient conditions. Interestingly, earliness of phenophases viz., branch initiation (3.0 days), flower initiation (4.14 days), fruit initiation (4.07 days) and fruit maturation (7.60 days) were observed at EC700 + 2 °C, but it was statistically on par with EC700 and EC550 + 2 °C. Irrespective of the plant parts and growth stages, plants under EC700 and EC550 have showed significantly higher nutrient uptake due to higher root biomass. At EC700, the tune of increase in total nitrogen, phosphorus and potassium uptake was almost 134%, 126% and 135%, respectively compared to open field crop. This indicates higher nutrient demand by the crop under elevated CO2 levels because of higher dry matter accumulation and radiation interception. Thus, nutrient application is needed to be monitored at different growth stages as per the crop needs. [ABSTRACT FROM AUTHOR]

Elevated CO2 (eCO2) has been reported to cause mineral losses in several important food crops such as soybean (Glycine max L.) and common bean (Phaseolus vulgaris L.). In addition, more than 30% of the world's arable land is calcareous, leading to iron (Fe) deficiency chlorosis and lower Fe levels in plant tissues. We hypothesize that there will be combinatorial effects of eCO2 and Fe deficiency on the mineral dynamics of these crops at a morphological, biochemical and physiological level. To test this hypothesis, plants were grown hydroponically under Fe sufficiency (20 μM Fe-EDDHA) or deficiency (0 μM Fe-EDDHA) at ambient CO2 (aCO2, 400 ppm) or eCO2 (800 ppm). Plants of both species exposed to eCO2 and Fe deficiency showed the lowest biomass accumulation and the lowest root: shoot ratio. Soybean at eCO2 had significantly higher chlorophyll levels (81%, p < 0.0001) and common bean had significantly higher photosynthetic rates (60%, p < 0.05) but only under Fe sufficiency. In addition, eCO2 increased ferric chelate reductase acivity (FCR) in Fe-sufficient soybean by 4-fold (p < 0.1) and in Fe-deficient common bean plants by 10-fold (p < 0.0001). In common bean, an interactive effect of both environmental factors was observed, resulting in the lowest root Fe levels. The lowering of Fe accumulation in both crops under eCO2 may be linked to the low root citrate accumulation in these plants when grown with unrestricted Fe supply. No changes were observed for malate in soybean, but in common bean, shoot levels were significantly lower under Fe deficiency (77%, p < 0.05) and Fe sufficiency (98%, p < 0.001). These results suggest that the mechanisms involved in reduced Fe accumulation caused by eCO2 and Fe deficiency may not be independent, and an interaction of these factors may lead to further reduced Fe levels. [ABSTRACT FROM AUTHOR]

The identification of the key components in the response to drought stress is fundamental to upgrading drought tolerance of plants. In this study, biochemical responses and leaf gas exchange characteristics of fig (Ficus carica L.) to water stress, short-term elevated CO2 levels and brassinolide application were evaluated. The ‘Improved Brown Turkey’ cultivar of fig was propagated from mature two- to three-year-old plants using cuttings, and transferred into a substrate containing 3:2:1 mixed soil (top soil: organic matters: sand). The experiment was arranged as a nested design with eight replications. To assess changes in leaf gas exchange and biochemical responses, these plants were subjected to two levels of water stress (well-watered and drought-stressed) and grown under ambient CO2 and 800 ppm CO2. Water deficits led to effects on photosynthetic rate, stomatal conductance, transpiration rate, vapour pressure deficit, water use efficiency (WUE), intercellular CO2, and intrinsic WUE, though often with effects only at ambient or elevated CO2. Some changes in content of chlorophyll, proline, starch, protein, malondialdehyde, soluble sugars, and activities of peroxidase and catalase were also noted but were dependent on CO2 level. Overall, fewer differences between well-watered and drought-stressed plants were evident at elevated CO2 than at ambient CO2. Under drought stress, elevated CO2 may have boosted physiological and metabolic activities through improved protein synthesis enabling maintenance of tissue water potential and activities of antioxidant enzymes, which reduced lipid peroxidation. [ABSTRACT FROM AUTHOR]

This research investigated the effects of continuous elevated CO2 (20%, (v/v)) application or a 3 day CO2 pretreatment followed by modified atmosphere (MA) or micro-perforated (MP) packaging on the postharvest quality of asparagus. The combination of CO2 pretreatment with MA packaging (Pre-MA) inhibited the yellowing of asparagus and fresh weight loss (FWL), whereas stem firmness slightly increased with all elevated CO2 treatments. CO2 pretreatments increased antioxidant activity in the stem, but not in the tip, in contrast to the continuous flow CO2 (Flow-CO2) treatment. The phenolic and flavonoid contents increased in the elevated CO2 pretreatments and Flow-CO2 treatment. The elevated CO2 treatments, especially Flow-CO2, inhibited the development of microorganisms, and the treated asparagus did not decay. Pre-MA and Flow-CO2 treatments were more effective in maintaining the visual quality and retarding the off-odor of asparagus. Furthermore, significant correlations between sensory quality characteristics and physiological-biochemical attributes were recognized; three principal components were extracted and they explained 86.4% of asparagus characteristics. The results confirmed the importance of visual quality, off-odor, firmness, color parameters, SSC and total phenolic content. In conclusion, elevated CO2 pretreatment followed by MA packaging (Pre-MA) was beneficial for extending asparagus cold storage shelf life, and Flow-CO2 was the best treatment for inhibiting postharvest decay. [ABSTRACT FROM AUTHOR]

Arbuscular mycorrhizal fungi (AMF) and elevated CO2 (eCO2) have been effectively integrated to the agricultural procedures as an ecofriendly approach to support the production and quality of plants. However, less attention has been given to the synchronous application of AMF and eCO2 and how that could affect the global plant metabolism. This study was conducted to investigate the effects of AMF and eCO2, individually or in combination, on growth, photosynthesis, metabolism and the functional food value of Thymus vulgare. Results revealed that both AMF and eCO2 treatments improved the photosynthesis and biomass production, however much more positive impact was obtained by their synchronous application. Moreover, the levels of the majority of the detected sugars, organic acids, amino acids, unsaturated fatty acids, volatile compounds, phenolic acids and flavonoids were further improved as a result of the synergistic action of AMF and eCO2, as compared to the individual treatments. Overall, this study clearly shows that co-application of AMF and eCO2 induces a synergistic biofertilization impact and enhances the functional food value of T. vulgare by affecting its global metabolism. [ABSTRACT FROM AUTHOR]

Featured Application: The effect of CO2 leaks from CCS on plant root systems was investigated; morphological characteristics of maize roots degraded by 19.16–44.73%; fewer fine roots in a root system was the main response to CO2 leakage; and empirical evidence is essential to explaining plant responses to CO2 leakage. To assess the environmental risks of carbon capture and storage (CCS) due to underground CO2 leakage, many studies have examined the impact on plant growth; however, the effect of leaked CO2 on root morphology remains poorly understood. This study simulated the effects of CO2 leakage from CCS on maize (Zea mays L.) root systems through pot experiments—one control treatment (no added CO2) and two elevated soil CO2 treatments (1000 g m−2 d−1 and 2000 g m−2 d−1). Compared with the control, root length, root surface area, and root volume were reduced by 44.73%, 34.14%, and 19.16%, respectively, in response to CO2 treatments with a flux of 2000 g m−2 d−1. Meanwhile, the fine root length in CO2 treatments with a flux of 1000 g m−2 d−1 and 2000 g m−2 d−1 were reduced by 29.44% and 45.88%, respectively, whereas no obvious difference in regard to coarse roots was found. Understanding changes in plant root morphology in this experiment, especially the decrease in the fine root length, are essential for explaining plant responses to CO2 leakage from CCS. [ABSTRACT FROM AUTHOR]

Intraspecific variation in crop responses to global climate change conditions would provide opportunities to adapt crops to future climates. These experiments explored intraspecific variation in response to elevated CO2 and to high temperature during anthesis in Chenopodium quinoaWild. Three cultivars of quinoa were grown to maturity at 400 ("ambient") and 600 ("elevated") μmol·mol-1 CO2 concentrations at 20/14 °C day/night ("control") temperatures, with or without exposure to day/night temperatures of 35/29 °C ("high" temperatures) for seven days during anthesis. At control temperatures, the elevated CO2 concentration increased the total aboveground dry mass at maturity similarly in all cultivars, but by only about 10%. A large down-regulation of photosynthesis at elevated CO2 occurred during grain filling. In contrast to shoot mass, the increase in seed dry mass at elevated CO2 ranged from 12% to 44% among cultivars at the control temperature. At ambient CO2, the week-long high temperature treatment greatly decreased (0.30 × control) or increased (1.70 × control) seed yield, depending on the cultivar. At elevated CO2, the high temperature treatment increased seed yield moderately in all cultivars. These quinoa cultivars had a wide range of responses to both elevated CO2 and to high temperatures during anthesis, and much more variation in harvest index responses to elevated CO2 than other crops that have been examined. [ABSTRACT FROM AUTHOR]

Legumes match the nodule number to the N demand of the plant. When a mutation in the regulatory mechanism deprives the plant of that ability, an excessive number of nodules are formed. These mutants show low productivity in the fields, mainly due to the high carbon burden caused through the necessity to supply numerous nodules. The objective of this study was to clarify whether through optimal conditions for growth and CO2 assimilation a higher nodule activity of a supernodulating mutant of Medicago truncatula (M. truncatula) can be induced. Several experimental approaches reveal that under the conditions of our experiments, the nitrogen fixation of the supernodulating mutant, designated as sunn (super numeric nodules), was not limited by photosynthesis. Higher specific nitrogen fixation activity could not be induced through short- or long-term increases in CO2 assimilation around shoots. Furthermore, a whole plant P depletion induced a decline in nitrogen fixation, however this decline did not occur significantly earlier in sunn plants, nor was it more intense compared to the wild-type. However, a distinctly different pattern of nitrogen fixation during the day/night cycles of the experiment indicates that the control of N2 fixing activity of the large number of nodules is an additional problem for the productivity of supernodulating mutants. [ABSTRACT FROM AUTHOR]

The Dietary Guidelines for Americans recommends giving priority to nutrient-dense foods while decreasing energy-dense foods. Although both flax (Linum usitatissimum) and sorghum (Sorghum bicolor) are rich in various essential minerals, their ionomes have yet to be investigated. Furthermore, previous studies have shown that elevated CO2 levels could reduce key nutrients in crops. In this study, we analyzed 102 flax and 108 sorghum varieties to investigate their ionomic variations (N, P, K, Ca, Mg, S, B, Zn, Mn, Fe, Cu, and Mo), elemental level interactions, and nutritional value. The results showed substantial genetic variations and elemental correlations in flax and sorghum. While a serving size of 28 g of flax delivers 37% daily value (DV) of Cu, 31% of Mn, 28% of Mg, and 19% of Zn, sorghum delivers 24% of Mn, 16% of Cu, 11% of Mg, and 10% of Zn of the recommended daily value (DV). We identified a set of promising flax and sorghum varieties with superior seed mineral composition that could complement breeding programs for improving the nutritional quality of flax and sorghum. Overall, we demonstrate additional minerals data and their corresponding health and food security benefits within flax and sorghum that could be considered by consumers and breeding programs to facilitate improving seed nutritional content and to help mitigate human malnutrition as well as the effects of rising CO2 stress. [ABSTRACT FROM AUTHOR]