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Soil carbon (C) responses to environmental change represent a major source of uncertainty in the global C cycle. Feedbacks between soil C stocks and climate drivers could impact atmospheric CO2 levels, further altering the climate. Here, we assessed the reliability of Earth system model (ESM) predictions of soil C change using the Coupled Model Intercomparison Project phases 5 and 6 (CMIP5 and CMIP6). ESMs predicted global soil C gains under the high emission scenario, with soils taking up 43.9 Pg (95% CI: 9.2–78.5 Pg) C on average during the 21st century. The variation in global soil C change declined significantly from CMIP5 (with average of 48.4 Pg [95% CI: 2.0–94.9 Pg] C) to CMIP6 models (with average of 39.3 Pg [95% CI: 23.9–54.7 Pg] C). For some models, a small C increase in all biomes contributed to this convergence. For other models, offsetting responses between cold and warm biomes contributed to convergence. Although soil C predictions appeared to converge in CMIP6, the dominant processes driving soil C change at global or biome scales differed among models and in many cases between earlier and later versions of the same model. Random Forest models, for soil carbon dynamics, accounted for more than 63% variation of the global soil C change predicted by CMIP5 ESMs, but only 36% for CMIP6 models. Although most CMIP6 models apparently agree on increased soil C storage during the 21st century, this consensus obscures substantial model disagreement on the mechanisms underlying soil C response, calling into question the reliability of model predictions.

Introduction: Plant growth-promoting rhizobacteria (PGPR) and elevated CO2 (eCO2) have demonstrated their individual potential to enhance plant yield and quality through close interaction with rhizosphere microorganisms and plant growth. However, the efficacy of PGPR under eCO2 on rhizosphere microbiome and, ultimately, plant yield and active ingredient accumulation are not yet fully understood. Methods: This study investigated how the medicinal plant Pseudostellaria heterophylla (P. heterophylla) and its rhizosphere microbes respond to PGPR (Bacillus subtilis and Pseudomonas fluorescens) at eCO2 (1,000 ppm). Results and Discussion: It was found that the yield and active ingredient polysaccharides accumulation in the tuber of P. heterophylla were significantly increased by 38 and 253%, respectively. This promotion has been associated with increased root development and changes in the indigenous microbial community. Metagenomics analysis revealed a significant reduction in pathogenic Fusarium abundance in the rhizosphere. Potential biocontrol bacteria Actinobacteria and Proteobacteria were enriched, especially the genera Bradyrhizobium and Rhodanobacter. The reshaping of the rhizosphere microbiome was accompanied by the upregulation of biological pathways related to metabolite biosynthesis in the rhizosphere. These modifications were related to the promotion of the growth and productivity of P. heterophylla. Our findings highlighted the significant role played by PGPR in medicinal plant yield and active ingredient accumulation when exposed to eCO2. [ABSTRACT FROM AUTHOR]

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]

The most important factor that affects the crop production in terms of nutritional content of foliar plants is the global climate change. Herbivore's growth, development, survival and geographical distribution all are determined by elevated CO2 and temperature. The interactions between herbivores and plants have changed due to increasing level of CO2 and temperature. The effect of high CO2 and temperature on grain legume plant which change in to plant physiology (e.g., nutritional content, foliage biomass) and how it change in herbivory metabolism rate and food consumption rate. Plant injury is determined by two factors viz. resistance and tolerance and both are influenced by greater CO2 and temperature. Legumes are an important source of food and feed in the form of proteins and also improve the soil environment. The repercussions of the abiotic factors mentioned above needs discussion among the scientific community. We may able to limit the negative repercussions of stated factors in future breeding projects by harnessing the practical favourable impacts and by including such influences of elevated CO2 and temperature on pulses productivity. The extensive research is necessary to overcome the negative effects of high CO2 and temperature on insect-plant interaction. [ABSTRACT FROM AUTHOR]

Napier grass is crucial in reducing greenhouse gas emissions by substituting non-renewable resources. When Napier grass is burned, the carbon dioxide (CO2) released is roughly equal to the amount absorbed during its growth, making it a potentially carbon-neutral energy source. This study investigates the impact of ratooning (repeated harvesting) on various aspects of Napier grass, including growth, physiology, biomass production, nutrient content, and chemical analysis. It also explored the interaction between elevated CO2 levels and ratooning. Two experiments were conducted over 12 months. Experiment 1 took place in an open field at the Faculty of Agriculture, Universiti Putra Malaysia (UPM), with two treatments: no ratooning and ratooning at three months after planting (MAP). Experiment 2 was conducted in an open field at UPM and a greenhouse at Tenaga National Berhad Research, Kajang, Selangor. Eight combination treatments were studied: (T1) 1-month elevated CO2 (MECO2) - no ratooned, (T2) 1 MECO2-R at 3 MAP, (T3) 2 MECO2-noR, (T4) 2 MECO2-R at 3 MAP, (T5) 5 MECO2-noR, (T6) 5 MECO2-R at 3 MAP, (T7) 12 MECO2-noR, and (T8) 12 MECO2-R at 3 MAP. The results indicated that, in Experiment 1, no ratooning was more favourable for all parameters compared to ratooning. In Experiment 2, a 1-month exposure to elevated CO2 showed better results compared to longer exposure periods. In conclusion, Napier grass performed better when not subjected to ratooning and exposed to short-term elevated CO2 levels. This research highlights the potential of Napier grass as a sustainable and carbonneutral energy source. [ABSTRACT FROM AUTHOR]

Global biogeochemical cycles have been widely altered due to human activities, potentially compromising the ability of plants to regulate their metabolism. We grew experimental herbaceous communities simulating the understory of eucalypt forests from southeastern Australia to evaluate the effects of elevated CO2 (400 vs. 650 ppm) and changes in soil resource availability (high-low water and high-low P) on the concentration of fourteen essential plant macro- and micronutrients, and their degree of coupling. Coupling was based on correlations among all elements in absolute value and a null modeling approach. According to the ancient nature of Australian soils, P addition was the main driver of changes in plant tissue chemistry, increasing the concentrations of P, Mg, Ca, and Mn and reducing the concentrations of C, N, S, Na, and Cu. Most treatment combinations showed coupled patterns of plant elements, particularly under ambient CO2. However, under elevated CO2, elements in plant tissues became more decoupled, which was interpreted as the result of a lack of enough supply of a range of elements to satisfy greater demands. Across treatments, P, Mn, and N were the least coupled elements, while K, Ca, and Fe were the most coupled ones. We provide evidence that plant element coupling was positively related to the concentration and coupling of elements measured in soils worldwide, suggesting that plant element coupling is conserved. Our results provide compelling evidence that evaluating the coupling of a representative range of chemical elements in plant tissues may represent a highly novel and powerful indicator of nutritional mismatches between demand and supply under specific environmental circumstances, including in a resource-altered global change context. [ABSTRACT FROM AUTHOR]

Accelerated senescence under elevated CO2 (eCO2) has not received sufficient attention, and its impact on the effect of CO2‐fertilization is unclear. To investigate the relationship between plant senescence and CO2 concentration, a pot experiment was conducted in four potato genotypes under low CO2 (LC), medium CO2 (MC) and high CO2 (HC) conditions. Nitrogen (N) uptake and cumulative transpiration were analysed to clarify whether eCO2‐induced senescence could be explained by low N uptake due to reduced transpiration. Compared to LC, the lifespan of potato plants under MC and HC was reduced by 3%–6% and 12%–32%, respectively, depending on the genotype. Biomass accumulation at full senescence was reduced when lifespan was shortened by approximately 5% and 10% under MC and HC, respectively. Cumulative transpiration was less affected by eCO2 during early developmental stages but decreased under eCO2 as plants aged. Plant water use decreased with a shortened lifespan under eCO2, but there was no reduction in N uptake, which was attributed to the high N uptake per unit of water used. The results of this study indicate that senescence in potato genotypes is non‐linearly related to CO2 concentration and cannot be explained by reduced N acquisition via reduced transpiration. The positive effect of CO2 fertilization can be reversed by accelerated senescence under eCO2. [ABSTRACT FROM AUTHOR]

Background: Food and nutritional security remain a major thrust area in the under developed and developing countries. These problems are exaggerated by the unprecedented challenges of climate change. Aims: The aim of this study was to assess the impact of climate change on grain quality of wheat and rice genotypes as well as their effect on soil aggregate fractions and aggregate associated carbon. Methodology: In the context, the present study was formulated by considering four predicted climate scenarios, namely, T0C0 (ambient condition), T0C1 (approx. 25% higher CO2), T1C0 (2°C higher temperature) and T1C1 (25% higher CO2 + 2°C higher temperature) and their impact on grain quality of wheat (HD2967, HD2733, DBW17, and HD3093) and rice (IR83376‐B‐B‐24‐2, IR84895‐B‐127‐CRA‐5‐1‐1, R Bhagwati, and IR64) genotypes as well as soil aggregate fractions and aggregate associated carbon. Results: The result revealed that T0C1 has a negative impact on grain nitrogen and protein content. On an average, nitrogen content in wheat and rice showed a decrease of about 15.55% (5.52%–25.32%) and 11.44% (3.33%–23.86%), respectively. Interestingly, the concurrent effect of elevated CO2 and temperature resulted in higher nitrogen and protein content as compared to other climate conditions. Further, P (P) content in the wheat and rice grains also improved under the elevated CO2 condition, whereas the content of potassium was not significantly influenced. Apart from major nutrients, micronutrients (Zn and Fe) were significantly influenced by climatic variables. The study revealed that grain Zn and Fe content of both the crops were reduced due to elevated CO2. The data on soil aggregate fractions revealed that elevated CO2 favors the formation of macro‐aggregate, whereas an increase in temperature favors micro‐aggregate fractions in the soil. Further, the elevation of CO2 also resulted in the accumulation of more carbon in the macro‐aggregates. Conclusion: We conclude that elevated CO2 and temperature cause specific changes in soil aggregate formation and grain nutrient quality. Based on molar ratio of P/Zn and P/Fe, we identified varieties of rice (IR83376‐B‐B‐24‐2) and wheat (HD2733) with higher bioavailability to address the nutritional security with changing climate in developing countries. [ABSTRACT FROM AUTHOR]

Summary Societal Impact Statement Summary Climate change continues to intensify the challenges of food production as agricultural systems face more variable and extreme weather. Coupled with increasing human population, growers must balance increasing crop yields with nutrient content to prevent global malnutrition. Photosynthetic diversity may permit some crops to tolerate climate change and elevated CO2 whilst maintaining both crop yield quantity and quality. This review examines how photosynthetic diversity interacts with crop production and nutritional stability under elevated CO2 and climate change, and highlights opportunities for photosynthetic diversity to inspire agricultural solutions.Innovative agricultural solutions are desperately needed to achieve food security for a growing human population amidst the imminent pressures of climate change that threaten more variable and extreme weather, placing additional pressures on already precarious agricultural systems. Not only are crop yields at risk under climate change but rising global atmospheric CO2 concentrations are concurrently driving a carbon dilution effect that threatens to reduce the nutritional quality of our crops to further global malnutrition. Plants using different photosynthetic metabolisms, however, experience these negative impacts to yield and nutrition to different degrees. Thus, photosynthetic diversity may offer solutions to combat malnutrition under climate change and elevated CO2 concentrations, whether that be through targeting existing resilient species for agricultural programmes or applying agricultural biotechnology to engineer photosynthetic diversity into existing crops. Here, we discuss how each major photosynthetic type is predicted to fare under elevated CO2 concentrations and climate change and explore agricultural opportunities to maintain both yield and nutrient stability. [ABSTRACT FROM AUTHOR]

Over 70% of soil organic carbon (SOC) is stored at a depth greater than 20 cm belowground. A portion of this deep SOC actively cycles on annual to decadal timescales and is sensitive to global change. However, deep SOC responses to global change likely differ from surface SOC responses because biotic controls on SOC cycling become weaker as mineral controls predominate with depth. Here, we synthesize the current information on deep SOC responses to the global change drivers of warming, shifting precipitation, elevated CO2, and land use and land cover change. Most deep SOC responses can only be hypothesized because few global change studies measure deep soils, and even fewer global change experiments manipulate deep soils. We call on scientists to incorporate deep soils into their manipulations, measurements, and models so that the response of deep SOC can be accounted for in projections of nature-based climate solutions and terrestrial feedbacks to climate change.

Elevated CO2 increases rice yields, and the response level varies across locations and genotypes. Previous analyses of genotypic variations from diverse Free-Air CO2 Enrichment (FACE) studies lacked specificity, limiting their applicability in simulating the responses of crop growth to elevated CO2. Using meta-analysis approach and the ORYZA (v3) model with historical and projected climatic data, this study evaluated the differences in the responses of rice ecotypes to elevated CO2 and identified adaptive measures. Meta-analytical findings indicated that Chinese inbred indica (indicai) and hybrid indica (indicah) rice exhibited comparable yield response rates (28.4% and 31.1%, respectively) to elevated CO2, surpassing those of Chinese japonica rice and Japanese indicai and japonica rice. Achieving higher adaptation to elevated CO2, exemplified by Chinese indicah rice, necessitates the consideration of balanced yield components, with individual contributions to yield responses ranging from 9.8% to 36.2%. This study highlighted the susceptibility of japonica rice to adverse effects of maximum temperatures on yield component responses to elevated CO2 compared to indicai or indicah rice. Strategic adjustments in sowing dates can enhance rice production under climate change, with high-response genotypes benefiting more from optimal sowing periods. Furthermore, for genotypes with less responsiveness to elevated CO2, augmenting nitrogen application in conjunction with sowing date adjustments was beneficial for yield optimization. This research not only advances our understanding of the diverse adaptation strategies of rice genotypes under varying climatic conditions but also enhances the precision of crop growth simulations by accounting for the varied responses to CO2 enrichment. These insights are pivotal for developing targeted breeding and management practices aimed at enhancing climate resilience in rice production.

The objective of this study was to assess the growth and biochemical responses of 23 wheat cultivars to different soil moisture levels (40% and 75% depletion of available soil water) and atmospheric CO2 concentrations (400 ± 50 and 700 ± 50 μmol mol−1). The findings showed that water scarcity stress lowered grain weight and shoot dry weight (ShDW) by decreasing leaf area (LA), Fv/Fm, chlorophyll, and carotenoid content, while increasing catalase activity (CAT), ascorbate peroxidase activity (APX), guaiacol peroxidase activity (GPX), 2,2-diphenyl-1-picrylhydrazyl scavenging capacity (DPPH), and leaf proline content (LPC). The effect of water deficit on the measured traits varied depending on the CO2 concentration. On average, the effect of water deficit stress on decreasing grain weight and LA, and increasing root dry weight (RDW), APX, LPC, and DPPH under ambient CO2 was greater than under elevated CO2. Furthermore, the impact of elevated CO2 on the studied traits was dependent on the soil moisture profile. Its effect on increasing ShDW and RDW was greater under control conditions, while its effect on decreasing APX, DPPH, Chla, Chlb, and Car content was greater under water deficit conditions. The effects of water stress and elevated CO2 were also found to be cultivar-specific. Principal component analysis revealed relationship among genotypes and traits. In summary, selecting wheat cultivars should be done separately for different CO2 and water conditions due to their varied responses. Cultivars #22 (Hidhab) and #16 (Sistan) perform well under ambient CO2 and control soil moisture, while #22 (Hidhab) and #5 (Karaj) show potential for adapting to different CO2 and soil moisture levels, resulting in significant grain weight. These cultivars hold promise for future research studies. Consequently, it is critical to consider atmospheric CO2 levels when designing breeding and yield improvement programs for wheat cultivars under changing climate conditions, as it affects their drought tolerance traits. [ABSTRACT FROM AUTHOR]

Nitrogen (N) loss is a significant source of water quality pollution in alluvial watersheds. However, the mechanisms linking N loss and elevated CO2 concentration (eCO2) are not well recognized. In this study, we comprehensively calibrated the SWAT model equipped with a dynamic CO2 input and response module to investigate the response mechanisms between multiform N losses and eCO2 in a representative large‐scale watershed. Results revealed nitrate loss under eCO2 exceeding 100% in some upstream zones under the SSP5‐8.5 scenario (P < 0.05) compared to the constant CO2 concentration. This was directly related to the great increase in hydrological variables, which were the carriers of N losses, and the intensive inputs of N fertilizer. Results also found that nitrate leaching was greater than the other two processes for future periods, peaking at 309.3%, as compared to the baseline period. The findings suggested reducing fertilizer inputs by 10%–20% was promising, especially for reducing nitrate loss through runoff and leaching by up to 17.7% and 12.2%. This study explored the mechanisms of increased N loss in response to eCO2 and provided scientific evidence for early warning and making decisions to improve water quality at a large watershed scale. [ABSTRACT FROM AUTHOR]

Nonstructural carbohydrates and antioxidants affect the yield of any plant. In this study, changes in nonstructural carbohydrates and antioxidant metabolism in leaf and spike, as well as their effects on grain yield, were examined in relation to elevated CO2 and nitrogen supply. For this, a wheat (Triticum aestivum) was grown at two levels of CO2, i.e., ambient 400 ppm (T1) and elevated 800 ppm (T2), with two levels of nitrogen supply, i.e., 0 gN (N1) and 1 gN (N2). In the sink, elevated CO2 and nitrogen caused a several-fold increase in glucose content. Fructose showed an increase of 53% and 60% in N2 treatment under both carbon levels. At the same time, sucrose content decreased by 112% and 100% with an increase in nitrogen doses under 400 ppm and 800 ppm. Higher N decreased the superoxide dismutase activity at ambient CO2, while higher N at elevated carbon levels increased the superoxide dismutase activity. Elevated CO2 decreased the catalase activity, while the peroxidases activity increased. In the spike, catalase activity increased at a higher N level. Grain yield was significantly enhanced at elevated CO2. The correlation analysis showed that catalase has a strong positive correlation with grain yield. The changes in nonstructural carbohydrates and antioxidant enzyme activities are associated with the altered leaf-spike relationship under N availability at high CO2 levels, which could be a key factor contributing to variable yield. Differential response of nonstructural carbohydrates and antioxidant enzymes in leaf and spike is responsible for changes in grain yield. [ABSTRACT FROM AUTHOR]

Rising CO2, global warming, and N deposition create challenging environmental conditions to vegetation. Since elevated CO2 and rising temperature are coupled with each other, it is important to understand their combined effects on plants. We investigated the growth and photosynthetic responses of yellow birch to five levels of nitrogen supply under the current (cCT: current CO2 and temperature) and the predicted future CO2 and temperature conditions (fCT: elevated CO2, current + 4℃ temperature). The results show that fCT and high N supply increased seedling growth but fCT reduced photosynthetic capacity (e.g., maximum rate of Rubisco carboxylation-Vcmax, maximum rate of photosynthetic electron transport-Jmax)) and foliar N concentration. However, the magnitude of the fCT effect declined with increases in N supply. Furthermore, the fCT treatment significantly reduced the Jmax/Vcmax ratio, indicating a possible shift of N allocation from Jmax to Vcmax in the photosynthetic machinery. This result suggests that the photosynthesis of yellow birch may be more limited by electron transport under the predicted future climate condition. Both low N supply and fCT significantly increased photosynthetic N use efficiency (PNUE) and there was a negative relationship between PNUE and photosynthetic capacity. In general, yellow birch grew better under fCT than cCT, particularly above-ground growth. [ABSTRACT FROM AUTHOR]

Vegetation responses to rising atmospheric CO2 levels can significantly affect water availability (defined as precipitation minus evapotranspiration (ET)). While this effect has long been recognized and assessed for the mean state, its influence on interannual variability, which is more closely associated with extreme events, has yet to be comprehensively quantified. In this study, our primary focus is to evaluate the impacts of ET by plant physiology (denoted as ETPhy) on the mean and interannual variability of water availability under elevated CO2 using multiple CO2 sensitivity experiments from the coupled model intercomparison project phase 6. We show that the contribution of vegetation physiological effects to the mean water availability varies among regions, while it consistently contributes to variability by about 33%. Considering CO2 physiological effects alone, ETPhy exerts a more significant influence on the mean state than on variability, particularly in humid regions. Consequently, ETPhy contributes less than 5% to the variability of water availability in humid regions under rising CO2, whereas it accounts for about 20% of the mean state. This distinction could be attributed to the different mechanisms governing the mean and variability of ETPhy. Specifically, evaporation from CO2 physiological forcing is the most critical contributor to the variability of ETPhy in most regions while showing minimal impacts on the mean state. Our findings identify the divergent effects of ETPhy on the mean state and interannual variability of water availability under elevated CO2, as important in future climate projections. Plain Language Summary: Rising atmospheric CO2 concentrations impacts on vegetation physiological processes are expected to change the evapotranspiration (ET) by plant physiology (denoted as ETPhy), allowing for altering the mean and the interannual variability of water availability (defined as precipitation minus ET). Using an ensemble of Earth system model simulations, this study reveals that the impacts of CO2 physiological effects on the mean of water availability are region‐specific, but with a nearly consistent contribution to its interannual variability. Combined with the impact of ETPhy on the mean and variability of water availability resulting from CO2 physiological forcing, ETPhy typically contributes less than 5% to the variability of water availability in humid regions under rising CO2, whereas it accounts for about 20% of the mean state. This discrepancy could arise from the different mechanisms governing the mean and variability of ETPhy. These results underscore the importance of accounting for the effects of ETPhy in response to increasing CO2 in altering the mean and the interannual variability of regional water resources. Key Points: The effects of CO2 vegetation responses contribute variably in space to mean annual water availability but uniformly to variabilityThe evapotranspiration (ET) from CO2 physiological forcing (ETPhy) shows more impacts on the mean of water availability than its variabilityThe evaporation from CO2 physiological forcing plays an important role in the variability of ETPhy but has weak effects on the mean [ABSTRACT FROM AUTHOR]

Summary: The oxygen isotope composition of cellulose (δ18O values) has been suggested to contain information on stomatal conductance (gs) responses to rising pCO2. The extent by which pCO2 affects leaf water and cellulose δ18O values (δ18OLW and δ18OC) and the isotope processes that determine pCO2 effects on δ18OLW and δ18OC are, however, unknown.We tested the effects of pCO2 on gs, δ18OLW and δ18OC in a glasshouse experiment, where six plant species were grown under pCO2 ranging from 200 to 500 ppm.Increasing pCO2 caused a decline in gs and an increase in δ18OLW, as expected. Importantly, the effects of pCO2 on gs and δ18OLW were small and pCO2 effects on δ18OLW were not directly transferred to δ18OC but were attenuated in grasses and amplified in dicotyledonous herbs and legumes. This is likely because of functional group‐specific pCO2 effects on the model parameter pxpex.Our study highlights important uncertainties when using δ18OC as a proxy for gs. Specifically, pCO2‐triggered gs effects on δ18OLW and δ18OC are possibly too small to be detected in natural settings and a pCO2 effect on pxpex may render the commonly assumed negative linkage between δ18OC and gs to be incorrect, potentially confounding δ18OC based gs reconstructions. [ABSTRACT FROM AUTHOR]

Ocean acidification and warming caused by elevated CO2 are urgent problems facing the marine ecological environment. With the strengthening of environmental governance in China, anthropogenic inputs of terrestrial phosphorus into the coastal ocean have drastically decreased, resulting in frequent phosphorus deficiency in seawater. These environmental factors in the future may affect algal growth, photosynthesis and yield. As an important economic macroalga suitable for large-scale cultivation, Gracilariopsis lemaneiformis is also potentially affected by the coupling of ocean acidification, warming and phosphorus deficiency. In this study, G. lemaneiformis was cultured outdoors under two pCO2 levels (LC, 400 μatm; HC, 1000 μatm), two temperatures (LT, 20 ℃; HT, 24 ℃) and two phosphorus concentrations (LP, 0.1 μmol L−1; HP, 10 μmol L−1) to investigate its growth and photosynthetic performance. The results showed that LP significantly decreased the relative growth rates (RGR) and the maximum photosynthesis rate (Pm) of G. lemaneiformis both under LC and HC conditions. Under P depletion condition, the effects of warming and ocean acidification on the growth and photosynthetic performance of G. lemaneiformis showed an opposite trend, that is, HC caused a decrease in the growth, Pm, maximum relative electron transfer rate (rETRmax) and light utilization efficiency (α) from the rapid light response curve of G. lemaneiformis, and HT improved these parameters. Under LP condition, HC significantly inhibited the RGR of G. lemaneiformis in the LT group but had no significant effect on RGR in the HT group. Additionally, under LP condition, HC insignificantly affected PE and PC contents in the LT group, but significantly reduced these contents in the HT group. These findings suggest that phosphorus deficiency results in a decline in the growth of G. lemaneiformis and, under LP condition, the inhibition effect of ocean acidification on the growth of G. lemaneiformis could be mitigated by warming. This study provides scientific guidance for the field cultivation and selective breeding of G. lemaneiformis in phosphorus-deficient seawater under global climate change. [ABSTRACT FROM AUTHOR]

Cassava (Manihot esculenta Crantz), an important tropical crop, is affected by extreme climatic events, including rising CO2 levels. We evaluated the short-term effect of elevated CO2 concentration (ECO2) (600, 800 and 1000 ppm) on the photosynthetic efficiency of 14 cassava genotypes. ECO2 significantly altered gaseous exchange parameters (net photosynthetic rate (P n), stomatal conductance (g s), intercellular CO2 (C i) and transpiration (E)) in cassava leaves. There were significant but varying interactive effects between ECO2 and varieties on these physiological characteristics. ECO2 at 600 and 800 ppm increased the P n rate in the range of 13–24% in comparison to 400 ppm (ambient CO2), followed by acclimation at the highest concentration of 1000 ppm. A similar trend was observed in g s and E. Conversely, C i increased significantly and linearly across increasing CO2 concentration. Along with C i, a steady increase in water use efficiency [WUEintrinsic (P n/ g s) and WUEinstantaneous (P n/ E)] across various CO2 concentrations corresponded with the central role of restricted stomatal activity, a common response under ECO2. Furthermore, P n had a significant quadratic relationship with the ECO2 (R 2 = 0.489) and a significant and linear relationship with C i (R 2 = 0.227). Relative humidity and vapour pressure deficit during the time of measurements remained at 70–85% and ~0.9–1.31 kPa, respectively, at 26 ± 2°C leaf temperature. Notably, not a single variety exhibited constant performance for any of the parameters across CO2 concentrations. Our results indicate that the potential photosynthesis can be increased up to 800 ppm cassava varieties with high sink capacity can be cultivated under protected cultivation to attain higher productivity. Cassava (Manihot esculenta Crantz) exhibited a positive response to elevated CO2 levels (ranging from 600 to 1000 ppm) compared to the ambient concentration of 400 ppm CO2. Most of the photosynthetic parameters showed steady improvement up to 800 ppm, followed by down-regulation at the highest concentration. The physiological water use efficiency of fourteen cassava varieties was enhanced at 1000 ppm due to restricted stomatal activity and reduced transpiration rate. [ABSTRACT FROM AUTHOR]

Nitrogen (N) is a limiting nutrient for primary productivity in most terrestrial ecosystems, but whether N limitation is strengthening or weakening remains controversial because both N sources and sinks are increasing in magnitude globally. Temperate marshes are exposed to greater amounts of external N inputs than most terrestrial ecosystems and more than in preindustrial times owing to their position downstream of major sources of human‐derived N runoff along river mouths and estuaries. Simultaneously, ecosystem N demand may also be increasing owing to other global changes such as rising atmospheric [CO2]. Here, we used interannual variability in external drivers and variables related to exogenous supply of N, along with detailed assessments of plant growth and porewater biogeochemistry, to assess the severity of N‐limitation, and to determine its causes, in a 14‐year N‐addition × elevated CO2 experiment. We found substantial interannual variability in porewater [N], plant growth, and experimental N effects on plant growth, but the magnitude of N pools through time varied independently of the strength of N limitation. Sea level, and secondarily salinity, related closely to interannual variability in growth of the dominant plant functional groups which drove patterns in N limitation and in porewater [N]. Experimental exposure of plants to elevated CO2 and years with high flooding strengthened N limitation for the sedge. Abiotic variables controlled plant growth, which determined the strength of N limitation for each plant species and for ecosystem productivity as a whole. We conclude that in this ecosystem, which has an open N cycle and where N inputs are likely greater than in preindustrial times, plant N demand has increased more than supply. [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]

IntroductionPlant growth-promoting rhizobacteria (PGPR) and elevated CO2 (eCO2) have demonstrated their individual potential to enhance plant yield and quality through close interaction with rhizosphere microorganisms and plant growth. However, the efficacy of PGPR under eCO2 on rhizosphere microbiome and, ultimately, plant yield and active ingredient accumulation are not yet fully understood.MethodsThis study investigated how the medicinal plant Pseudostellaria heterophylla (P. heterophylla) and its rhizosphere microbes respond to PGPR (Bacillus subtilis and Pseudomonas fluorescens) at eCO2 (1,000 ppm).Results and DiscussionIt was found that the yield and active ingredient polysaccharides accumulation in the tuber of P. heterophylla were significantly increased by 38 and 253%, respectively. This promotion has been associated with increased root development and changes in the indigenous microbial community. Metagenomics analysis revealed a significant reduction in pathogenic Fusarium abundance in the rhizosphere. Potential biocontrol bacteria Actinobacteria and Proteobacteria were enriched, especially the genera Bradyrhizobium and Rhodanobacter. The reshaping of the rhizosphere microbiome was accompanied by the upregulation of biological pathways related to metabolite biosynthesis in the rhizosphere. These modifications were related to the promotion of the growth and productivity of P. heterophylla. Our findings highlighted the significant role played by PGPR in medicinal plant yield and active ingredient accumulation when exposed to eCO2.

The article discusses a study that examines the factors contributing to tree mortality in tropical forests. The research finds that the traits of trees in current forests are more important for predicting changes in forest health than climate projections or rising CO2 levels. The study emphasizes the importance of understanding the trait composition of forests, particularly in tropical regions. The findings suggest that future forest health may depend more on existing traits than on climate change. The study also highlights the need for collaboration between field ecology and vegetation model development. [Extracted from the article]

This study aims to understand the combined impact of elevated CO2 and drought stress at flowering stage to explain the adaptation of bread wheat to future climate change scenarios. Four wheat genotypes with 24 replications of each were grown in two different greenhouses, maintaining 400 (ambient) and 800 (elevated) ppm levels of CO2. Irrigation was withheld at flowering to impose drought to 10 replications while 10 were allowed to grow normally. Daily water consumption was recorded until the pot-water of drought plants reached 10 % of the well-watered ones. This study was aided by the measurement of ecophysiology, phytohormones, and yield-related traits. In comparison to normal CO2, plants consumed the pot water quickly under elevated CO2. Further, the threshold value of the fraction of transpirable soil water, at which the relative transpiration is diverging from 1 was different at the two levels of CO2, and among genotypes. Drought significantly reduced plant water relations, gas exchange parameters, grain yield, and yield-related traits but enhanced osmotic adjustment, kernel abortion, and most of the phytohormones in leaves and spikes. Elevated CO2 though increased gas exchange parameters significantly under well-watered conditions but these parameters were significantly reduced under combined effect with drought and resultantly, lower yield-related traits were recorded. Moreover, we also identified a strong positive association between leaf trans-zeatin and a strong negative association of leaf and spike ABA and ACC with grain yield indicating that maintenance of a higher level of leaf trans-zeatin or lower levels of ABA and ACC can help plants to adapt better to the combination of elevated CO2 and drought.

Improved understanding of bacterial community responses to multiple environmental filters over long time periods is a fundamental step to develop mechanistic explanations of plant–bacterial interactions as environmental change progresses.This is the first study to examine responses of grassland root‐associated bacterial communities to 15 years of experimental manipulations of plant species richness, functional group and factorial enrichment of atmospheric CO2 (eCO2) and soil nitrogen (+N).Across the experiment, plant species richness was the strongest predictor of rhizobacterial community composition, followed by +N, with no observed effect of eCO2. Monocultures of C3 and C4 grasses and legumes all exhibited dissimilar rhizobacterial communities within and among those groups. Functional responses were also dependent on plant functional group, where N2‐fixation genes, NO3−‐reducing genes and P‐solubilizing predicted gene abundances increased under resource‐enriched conditions for grasses, but generally declined for legumes. In diverse plots with 16 plant species, the interaction of eCO2+N altered rhizobacterial composition, while +N increased the predicted abundance of nitrogenase‐encoding genes, and eCO2+N increased the predicted abundance of bacterial P‐solubilizing genes.Synthesis: Our findings suggest that rhizobacterial community structure and function will be affected by important global environmental change factors such as eCO2, but these responses are primarily contingent on plant species richness and the selective influence of different plant functional groups. [ABSTRACT FROM AUTHOR]

Coastal wetland communities provide valuable ecosystem services such as erosion prevention, soil accretion, and essential habitat for coastal wildlife, but are some of the most vulnerable to the threats of climate change. This work investigates the combined effects of two climate stressors, elevated temperature (ambient, + 1.7 °C, + 3.4 °C, and 5.1 °C) and elevated CO2 (eCO2), on leaf physiological traits of dominant salt marsh plant species. The research took place at the Salt Marsh Accretion Response to Temperature eXperiment (SMARTX) at the Smithsonian Environmental Research Center, which includes two plant communities: a C3 sedge community and a C4 grass community. Here we present data collected over five years on rates of stomatal conductance (gs), quantum efficiency of PSII photochemistry (Fv/Fm), and rates of electron transport (ETRmax). We found that both warming and eCO2 caused declines in all traits, but the warming effects were greater for the C3 sedge. This species showed a strong negative stomatal response to warming in 2017 and 2018 (28% and 17% reduction, respectively in + 5.1 °C). However, in later years the negative response to warming was dampened to < 7%, indicating that S. americanus was able to partially acclimate to the warming over time. In 2022, we found that sedges growing in the combined + 5.1 °C eCO2 plots exhibited more significant declines in gs, Fv/Fm, and ETRmax than in either treatment individually. These results are important for predicting future trends in growth of wetland species, which serve as a large carbon sink that may help mitigate the effects of climate change. [ABSTRACT FROM AUTHOR]

Aims: Elevated atmospheric CO2 (eCO2) and restricted iron (Fe) supply are known to impact plant growth and nutritional quality of food crops. However, studies aimed at understanding how eCO2 will interact with Fe deficiency are scarce. Changes in the nutritional status of the common bean (Phaseolus vulgaris L.) may significantly impact the nutritional status of populations that rely heavily on this crop. Methods: To understand the combined effects of eCO2 and Fe deficiency on mechanisms relevant to plant nutrient uptake and accumulation, common bean plants were grown under Fe sufficiency (Fe+, 20 mM Fe-EDDHA) and Fe deficiency (Fe-, 0 mM Fe-EDDHA) combined with eCO2 (800 ppm) or ambient CO2 (aCO2, 400 ppm) in hydroponics until maturity. Results: Elevated CO2, besides stimulating photosynthesis and stomatal closure, highly affected plant Fe metabolism: stimulated root ferric chelate reductase (FCR) activity by 6-fold and downregulated the expression of root FRO1 and IRT1 expressions by about 4-fold. In leaves, citrate and oxalate increased, but ferritin expression decreased by 9-fold. Such changes may have determined the differences on mineral accumulation patterns particularly the lower levels of Fe in roots (62%), leaves (38%) and seeds (50%). The combination of Fe deficiency and eCO2 doubled the effect of a single factor on FCR up-regulation, balanced the internal pH of Fe deficient plants, and resulted in the lowest Fe accumulation in all plant parts. Conclusions: These results suggest that eCO2 directly affects the Fe uptake mechanism of common bean plants, decreasing plant Fe content. [ABSTRACT FROM AUTHOR]

Herbivore performance can be impacted by elevated CO2 or insecticides. However, there is insufficient data on how invasive and native species are affected by these dual stresses. Frankliniella occidentalis and F. intonsa are economically important pests. We evaluated the direct effects of elevated CO2 on the sensitivity of thrips to spinetoram, and recorded their population fitness, as well as measured acetylcholinesterase (AChE) and cytochrome P450 (CYP450) activities in adults under short-term (3rd generation) and long-term (30th generation) exposures to these two stresses. Thrips' resistance to spinetoram was accelerated by elevated CO2, and was strongly displayed by F. occidentalis than by F. intonsa. In the 3rd generation, exposure to the two stresses significantly prolonged the longevity of adult F. occidentalis and increased its fecundity, sex ratio, and net reproductive rate (R0), whereas they only increased the fecundity of F. intonsa. Notably, the sex ratio of the former (2.15 ± 0.35) was significantly higher than that of the latter (0.65 ± 0.03). On the other hand, CYP450 activity in F. occidentalis was significantly lower than that of control. At the 30th generation, exposure to the two stresses reduced the population fitness of the two species. Additionally, the fecundity, sex ratio, R0, intrinsic rate of increase (r), and finite rate of increase (λ) of F. occidentalis were significantly higher than that of F. intonsa. Besides, AChE activities in both species were significantly lower than that of the control. We concluded that increased CO2 and spinetoram may hasten the displacement of the native species, F. intonsa by the invasive species, F. occidentalis in the future. [ABSTRACT FROM AUTHOR]

While the effect of CO2 enrichment on wheat (Triticum spp.) photosynthesis, nitrogen content or yield has been well-studied, the impact of elevated CO2 on metabolic pathways in organs other than leaves is poorly documented. In particular, glumes and awns, which may refix CO2 respired by developing grains and be naturally exposed to higher-than-ambient CO2 mole fraction, could show specific responses to elevated CO2. Here, we took advantage of a free-air CO2 enrichment experiment and performed multilevel analyses, including metabolomics, ionomics, proteomics, major hormones and isotopes in Triticum durum. While in leaves, elevated CO2 tended to accelerate amino acid metabolism with many significantly affected metabolites, the effect on glumes and awns metabolites was modest. There was a lower content in compounds of the polyamine pathway (along with uracile and allantoin) under elevated CO2, suggesting a change in secondary N metabolism. Also, cytokinin metabolism appeared to be significantly affected under elevated CO2. Despite this, elevated CO2 did not affect the final composition of awn and glume organic matter, with the same content in carbon, nitrogen and other elements. We conclude that elevated CO2 mostly impacts on leaf metabolism but has little effect in awns and glumes, including their composition at maturity. The specific impact of elevated CO2 on metabolic pathways in wheat (Triticum spp.) organs other than leaves is poorly documented. We addressed this aspect by taking advantage of a free-air CO2 enrichment experiment in durum wheat (Triticum durum). We found changes in polyamine and cytokinin metabolism under elevated CO2 in glumes and awns but no modifications in final composition at maturity. Elevated CO2 mostly impacts on leaf metabolism but has little effect on glumes and awns. [ABSTRACT FROM AUTHOR]

In this study, the SIMPLECrop model was applied to simulate maize biomass and yield in 2 crop seasons, Autumn - Winter 2020 (AW) and Winter - Spring 2020 - 2021 (WS), in Cho Moi district, An Giang province, Vietnam (10°23'47"N, 105°27'41"E). The research aimed to analyze the effects of climate variabilities, particularly increased temperature, on maize growth and yield. The growth period for the Winter - Spring 2020 - 2021 season was 67 days, which was 1 day longer than the AW season (Autumn - Winter 2020). Four cultivar parameters, namely Tsum, HI, I50A, and I50B, were employed for the calibration process to fine-tune the model. Sensitivity analysis using Morris and FAST methods revealed that RUE and Tbase had the highest sensitivity and significant impact on the SIMPLECrop model. These 2 parameters showed strong interactions and played a crucial role in influencing model outcomes. The evaluation of the model's performance resulted in RRMSE values ranging from 4.8 to 6.3 % and NSE values between 0.86 and 0.93, indicating good agreement between model predictions and observed data. Regarding the impact of temperature increase, a 5 °C temperature rise led to a reduction in stover biomass ranging from 5.2 % (Autumn - Winter 2020) to 19.3 % (Winter - Spring 2020 - 2021) and a decrease in yield by 11.3 % (Autumn - Winter 2020) and 27.0 % (Winter - Spring 2020 - 2021). Simulating an increase in CO2 concentration alone, varying from 50, 100, 150, 200 to 250 ppm, resulted in increased biomass and yield for maize. The most substantial increases were observed at 250 ppm CO2, with approximately 2.5 % higher biomass and 7.7 to 9.1 % greater yield. However, under more severe heat stress (5 °C increase), the positive effects of elevated CO2 were mitigated, resulting in a reduced increase in biomass and yield, approximately 3 - 5 %. These findings highlight the importance of considering temperature and CO2 interactions when assessing crop responses to climate variability. [ABSTRACT FROM AUTHOR]

Many governments have set ambitious targets for tree planting and increased woodland cover as a key part of actions to reach net‐zero carbon emissions by 2050. However, many uncertainties remain concerning how and where to expand tree cover, what species to plant, and how best to manage new plantations. Much contemporary forestry has been based on even‐aged monocultures, largely because of perceived advantages for timber production. However, in order to play a key role in climate change mitigation future forests will have to achieve timber production (and wider ecosystem service provision) alongside resilience to biotic and abiotic challenge. It is therefore crucial that appropriate informed decisions are made with regard to the structure, composition, and planning of future forests, in order to provide sustainable solutions that provide environmental, economic, and health benefits to society. Genetically diverse, mixed, and irregular forests, with their higher biodiversity and niche complementarity, are promising new forest configurations for regulating the water cycle, storing carbon, and delivering other goods and services. In the following discussion, we have used UK information to illustrate the benefits of mixed woodland versus monocultures and highlighted current issues related to government initiatives and policies for current and future forests. However, similar issues and problems are encountered globally. [ABSTRACT FROM AUTHOR]

CO2 levels are known to have an impact on plant development and physiology. In the current study, we have investigated the effect of elevated CO2 on flowering and its regulation through miRNA mediated sugar signaling. We also unraveled small RNA transcriptome of pigeonpea under ambient and elevated CO2 conditions and predicted the targets for crucial miRNAs through computational methods. The results have shown that the delayed flowering in pigeonpea under elevated CO2 was due to an imbalance in C:N stoichiometry and differential expression pattern of aging pathway genes, including SQUAMOSA PROMOTER BINDING PROTEIN-LIKE. Furthermore, qRT PCR analysis has revealed the role of miR156 and miR172 in mediating trehalose-6-phosphate dependent flowering regulation. The current study is crucial in understanding the responses of flowering patterns in a legume crop to elevated CO2 which showed a significant impact on its final yields. Also, these findings are crucial in devising effective crop improvement strategies for developing climate resilient crops, including pigeonpea. [ABSTRACT FROM AUTHOR]

Summary: Mosses hold a unique position in plant evolution and are crucial for protecting natural, long‐term carbon storage systems such as permafrost and bogs. Due to small stature, mosses grow close to the soil surface and are exposed to high levels of CO2, produced by soil respiration. However, the impact of elevated CO2 (eCO2) levels on mosses remains underexplored.We determined the growth responses of the moss Physcomitrium patens to eCO2 in combination with different nitrogen levels and characterized the underlying physiological and metabolic changes.Three distinct growth characteristics, an early transition to caulonema, the development of longer, highly pigmented rhizoids, and increased biomass, define the phenotypic responses of P. patens to eCO2. Elevated CO2 impacts growth by enhancing the level of a sugar signaling metabolite, T6P. The quantity and form of nitrogen source influences these metabolic and phenotypic changes. Under eCO2, P. patens exhibits a diffused growth pattern in the presence of nitrate, but ammonium supplementation results in dense growth with tall gametophores, demonstrating high phenotypic plasticity under different environments.These results provide a framework for comparing the eCO2 responses of P. patens with other plant groups and provide crucial insights into moss growth that may benefit climate change models. [ABSTRACT FROM AUTHOR]

Sweet potato is one of the important tropical tuber crops across the world. This review analyzes the studies on the climate resilience of sweet potato to various environmental parameters, the impact of climate change on its yield, and geographical suitability to exploit more about this crop and find out the knowledge gap in its existing research. Drought tolerance studies indicate the suitability of sweet potato in drought‐prone areas in terms of their survival rate, and their leaves can tolerate up to a wilting point of −1.3 MPa. The optimum night and daytime temperatures for sweet potato are 18°C and 28°C. There are 82 crop varieties available globally with heat‐stress tolerance without compromising the yield. The elevated atmospheric CO2 enhanced the growth and yield of sweet potato and increased the water use efficiency. The salinity tolerance of sweet potato is observed as 11 dS m−1, and it is superior to other major food crops. Sweet potato's ozone tolerance is higher than other crops (59 ppb). The impact studies on crop yield and geographical suitability also recommend its superiority to other major food crops with similar crop duration. As an outcome of this study, further research is needed to explore this crop as sweet potato can substitute for major food grain crops in developing countries regarding food, feed, medicine, and fuel. Research on value‐added products and their marketing is another area that needs immediate attention. Studies must exploit sweet potato leaves to ensure nutritional security in developing countries. The researchers also need to focus on developing climate‐resilient varieties to ensure a continuous supply of planting materials to needy people to ensure food security. This review also demands more studies on the modeling of sweet potato worldwide to issue crop yield forecasts and monitor the spatial distribution of its major pests worldwide. [ABSTRACT FROM AUTHOR]

Tree intrinsic water-use efficiency (iWUE) is a key characteristic of ecosystem functions central to the global cycles of carbon, water, and energy. Gas exchange and stable carbon isotope compositions have been widely used to assess iWUE. However, it remains unclear to what extent the iWUE estimates obtained using different approaches are comparable, particularly in combination with changes in temperature, precipitation, and experimental duration. Herein, the responses of different estimators of iWUE (as A/gs or through isotopic composition of leaves or tree rings) to elevated CO2 concentrations (eCO2) were assessed through a meta-analysis of 361 observations from 98 independent experiments. Our results show that (1) different proxies for iWUE provide inconsistent estimates of the response of iWUE to eCO2. (2) Throughout the growing season, the average response of gs to eCO2 was smaller than the single-point values estimated by gas exchange and the eCO2-induced reduction in gs was stronger for evergreen species than for deciduous species. (3) Precipitation, rather than temperature, significantly affected the responses of 13C-based estimates of iWUE to eCO2. (4) There was no significant response of leaf 13C-based iWUE estimates to eCO2. (5) The importance of photorespiration in elevated CO2 enhancement responses may be overestimated in evergreen species. [ABSTRACT FROM AUTHOR]

Elevated atmospheric CO2 concentration and precipitation change affect plants' survival and thriving. Phenotypic plasticity can show plants adaptability to varying environment. Physiological plasticity reflects plants capacity to open areas, and morphological plasticity reflects capacity to survive and grow. In this study, we simulated combined effects of elevated CO2 and precipitation change on the phenotypic plasticity of two Stipa species: Stipa grandis and Stipa breviflora. Our results indicated that plasticity of physiology was higher than plasticity of morphology under either ambient or elevated CO2 concentration in both Stipa species. S. breviflora showed higher plasticity index of physiological (PIp) and plasticity index of morphological (PIm) than S. grandis under elevated CO2 concentration. Therefore, we speculate that S. breviflora is more adaptable than S. grandis under high CO2 concentration in the future. Elevated atmospheric CO2 concentration and simultaneous precipitation change is advantageous to S. breviflora distribution expansion, nonetheless, the changing environments also favor the competitive ability of S. grandis. [ABSTRACT FROM AUTHOR]

Climate change is one of dominators driving the greening of vegetation worldwide, which is expected to enhance land carbon sink and mitigate global warming. The sensitivity of vegetation greenness to climate change is fluctuant and regulated by other environmental factors. However, the drivers and mechanisms behind remain unclear so far. Here, we hired long-term satellite-based vegetation index (NDVI), climatic variables, nitrogen deposition, and atmospheric CO2 records to investigate variations of greenness climatic sensitivity and its drivers across Eurasia. To obtain the timeseries of temperature (γNDVITEM) and precipitation sensitivity (γNDVIPRE), we applied multi-regression models and regressed temperature and precipitation on NDVI in each 9-year moving windows. The results showed that the area of vegetation greenness limited by low temperatures substantially shrunk, while the area of vegetation greenness limited by precipitation deficit increased during 1982–2015. Specifically, significantly decreasing γNDVITEM and γNDVIPRE accounted for 29.8% and 20.1%, respectively, while remarkably increasing γNDVITEM and γNDVIPRE accounted for about 18.2% and 24.5%, respectively, of the vegetated lands across Eurasia. Declining γNDVITEM was widely observed in most biomes, including tropical and subtropical moist broadleaf forests, temperate broadleaf and mixed forests, temperate coniferous forests, croplands, and deserts and xeric shrublands. Substantially increasing γNDVIPRE was merely found in montane grasslands and shrublands, and tropical and subtropical dry broadleaf forests, while decreasing γNDVIPRE and nonlinear regimes was widely proved in other biome types. Spatially, rather than elevated CO2 and nitrogen deposition, climate factors (temperature, precipitation, and radiation) jointly dominated γNDVITEM and γNDVIPRE variations across nearly 45% and 48% of Eurasia respectively. Our results uncovered the apparent pattern of greenness climate sensitivity changes across Eurasia and highlighted the necessity to unfold the underlying mechanisms based on plant physiology and traits.

Abstract In the region where heat stress has become evident, the elevation of air temperature could reduce yield of heat stress-susceptible crops, such as rice (Oryza sativa L.), which is a major food staple in Asia. In addition to air temperature, atmospheric CO2 is projected to be elevated in the future. To project rice yield in the future, it is necessary to clarify the responses of rice to concurrent elevations of air temperature and atmospheric CO2. In the present study, two japonica rice cultivars with different heat tolerance, Hinohikari (sensitive) and Nikomaru (tolerant), were grown in pots inside open-top chambers and exposed to elevated air temperature and/or CO2. The degrees of increase in the air temperature and CO2 concentration by the treatments were approximately 1 °C and 120 µmol mol−1 (ppm). The study was conducted in Nagasaki, Japan, where heat stress on rice has become evident. Elevated air temperature significantly decreased both whole-plant growth and grain yield. Elevated CO2 significantly increased the growth but significantly decreased the yield. The effects of elevated air temperature and elevated CO2 on growth and yield did not significantly differ between two cultivars. In both cultivars, the main cause of yield reduction by both treatments was reduction in spikelet fertility, which is typical heat stress on rice. The elevated CO2-induced reduction in spikelet fertility could be explained partially by high-temperature regime during flowering due to acceleration of heading and by increase in canopy temperature via stomatal closure in flag leaves. Because elevated air temperature and elevated CO2 treatments additively reduced spikelet fertility in both cultivars, concurrent elevations of air temperature and CO2 caused considerable reduction in grain yield.

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.

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.