Total Nonstructural Carbohydrate Concentration Research Articles

Halophytic succulence is a driver of the leaf non-structural carbohydrate contents in plants in the arid and hyper-arid deserts of northwestern China.

Non-structural carbohydrates (NSC), primarily sugars and starch, play a crucial role in plant metabolic processes and a plant's ability to tolerate and recover from drought stress. Despite their importance, our understanding of NSC characteristics in the leaves of plants that thrive in hyper-arid and saline environments remains limited. To investigate the variations in leaf NSC across different species and spatial scales, and to explore their possible causes, we collected 488 leaf samples from 49 native plant species at 115 sites in the desert area of northwestern China. The contents of soluble sugars (SS), starch, and total NSC were then determined. The average contents of SS, starch, and total NSC were 26.99, 60.28, and 87.27mg g-1 respectively, which are much lower than those reported for Chinese forest plants and global terrestrial plants. Herbaceous and woody plants had similar NSC levels. In contrast, succulent halophytes, a key component of desert flora, showed significantly lower leaf SS and total NSC contents than non-succulent plants. We observed a strong negative correlation between leaf succulence and SS content, suggesting a role of halophytic succulence in driving multi-species NSC pools. Environmental factors explained a minor portion of the spatial variation in leaf NSC, possibly due to the narrow climatic variation in the study area, and soil properties, particularly soil salinity, emerged as more significant contributors. Our findings increase the understanding of plant adaptation to drought and salt stress, emphasizing the crucial role of halophytic succulence in shaping the intricate dynamics of leaf NSC across diverse plant species in arid and hyper-arid environments.

The underlying mechanisms by which boron mitigates copper toxicity in Citrus sinensis leaves revealed by integrated analysis of transcriptome, metabolome and physiology.

Both copper (Cu) excess and boron (B) deficiency are often observed in some citrus orchard soils. The molecular mechanisms by which B alleviates excessive Cu in citrus are poorly understood. Seedlings of sweet orange (Citrus sinensis (L.) Osbeck cv. Xuegan) were treated with 0.5 (Cu0.5) or 350 (Cu350 or Cu excess) μM CuCl2 and 2.5 (B2.5) or 25 (B25) μM HBO3 for 24wk. Thereafter, this study examined the effects of Cu and B treatments on gene expression levels revealed by RNA-Seq, metabolite profiles revealed by a widely targeted metabolome, and related physiological parameters in leaves. Cu350 upregulated 564 genes and 170 metabolites, and downregulated 598 genes and 58 metabolites in leaves of 2.5μM B-treated seedlings (LB2.5), but it only upregulated 281 genes and 100 metabolites, and downregulated 136 genes and 40 metabolites in leaves of 25μM B-treated seedlings (LB25). Cu350 decreased the concentrations of sucrose and total soluble sugars and increased the concentrations of starch, glucose, fructose and total nonstructural carbohydrates in LB2.5, but it only increased the glucose concentration in LB25. Further analysis demonstrated that B addition reduced the oxidative damage and alterations in primary and secondary metabolisms caused by Cu350, and alleviated the impairment of Cu350 to photosynthesis and cell wall metabolism, thus improving leaf growth. LB2.5 exhibited some adaptive responses to Cu350 to meet the increasing need for the dissipation of excessive excitation energy (EEE) and the detoxification of reactive oxygen species (reactive aldehydes) and Cu. Cu350 increased photorespiration, xanthophyll cycle-dependent thermal dissipation, nonstructural carbohydrate accumulation, and secondary metabolite biosynthesis and abundances; and upregulated tryptophan metabolism and related metabolite abundances, some antioxidant-related gene expression, and some antioxidant abundances. Additionally, this study identified some metabolic pathways, metabolites and genes that might lead to Cu tolerance in leaves.

The rates of starch depletion and hydraulic failure both play a role in drought-induced seedling mortality

Key messageThe elapsed times to deplete starch concentrations and to reach a null hydraulic safety margin were related to tree seedling mortality under experimental drought. Starch concentration showed an accelerated decline across all species during the early stages of dehydration, while the concentrations of soluble sugars and total nonstructural carbohydrates remained stable. Concomitant carbohydrate depletion and hydraulic failure drive seedling mortality under drought.ContextCurrent upsurges of drought events are provoking impacts on tree physiology, resulting in forest mortality. Hydraulic dysfunction and nonstructural carbohydrate (NSC) depletion have been posited as the main mechanisms leading to plant mortality under drought.AimsThis study explores the dynamics of the two mortality-inducing processes during drought stress using an experimental approach with 12 evergreen tree species.MethodsSeedlings were subjected to drought until 100% mortality was observed. Midday (ΨMD) and predawn (ΨPD) water potentials, xylem pressure leading to a 50% loss of hydraulic conductivity (Ψ50), along with NSC concentrations in different organs (leaves, stems, and roots) were measured regularly during drought.ResultsTotal NSC concentrations and soluble sugar pools did not decline during drought. However, starch pools showed strong reductions early during drought stress as ΨPD decreased, and the time leading to starch depletion emerged as a strong mortality predictor. Ψ50 alone did not provide an accurate estimate of mortality, while the elapsed time to reach a null hydraulic safety margin (ΨMD—Ψ50 = 0) was related to seedling mortality.ConclusionAdopting a dynamic approach by estimating the times to consume both starch reserves and hydraulic safety margins is highly relevant to improve predictions of tree mortality under the current context of increasing global drought.

External aluminium supply regulates photosynthesis and carbon partitioning in the Al-accumulating tropical shrub Melastoma malabathricum.

Aluminium (Al) is toxic to most plants, but recent research has suggested that Al addition may stimulate growth and nutrient uptake in some species capable of accumulating high tissue Al concentrations. The physiological basis of this growth response is unknown, but it may be associated with processes linked to the regulation of carbon assimilation and partitioning by Al supply. To test alternative hypotheses for the physiological mechanism explaining this response, we examined the effects of increasing Al concentrations in the growth medium on tissue nutrient concentrations and carbon assimilation in two populations of the Al-accumulator Melastoma malabathricum. Compared to seedlings grown in a control nutrient solution containing no Al, mean rates of photosynthesis and respiration increased by 46% and 27%, respectively, total non-structural carbohydrate concentrations increased by 45%, and lignin concentration in roots decreased by 26% when seedlings were grown in a nutrient solution containing 2.0 mM Al. The concentrations of P, Ca and Mg in leaves and stems increased by 31%, 22%, and 26%, respectively, in response to an increase in nutrient solution Al concentration from 0 to 2.0 mM. Elemental concentrations in roots increased for P (114%), Mg (61%) and K (5%) in response to this increase in Al concentration in the nutrient solution. Plants derived from an inherently faster-growing population had a greater relative increase in final dry mass, net photosynthetic and respiration rates and total non-structural carbohydrate concentrations in response to higher external Al supply. We conclude that growth stimulation by Al supply is associated with increases in photosynthetic and respiration rates and enhanced production of non-structural carbohydrates that are differentially allocated to roots, as well as stimulation of nutrient uptake. These responses suggest that internal carbon assimilation is up-regulated to provide the necessary resources of non-structural carbohydrates for uptake, transport and storage of Al in Melastoma malabathricum. This physiological mechanism has only been recorded previously in one other plant species, Camellia sinensis, which last shared a common ancestor with M. malabathricum more than 120 million years ago.

In Situ Sucrose Injection for Alteration of Carbohydrate Reserve Dynamics in Grapevine

Inconsistent yield of subtropical table grape across seasons is often associated with low carbohydrate reserves during flowering. In an attempt to increase TNC and thus yield, sucrose was injected into treated trunks during periods of high carbohydrate demand (i.e., between budburst and flowering). Total non-structural carbohydrate (TNC) concentration dynamics were assessed in the grapevine root and trunk tissues of both control and treated vines. In the control (untreated) vines, the TNC concentration in root and trunk tissues was 13.5% and 7.5% w/dw at leaf fall and 7.2% and 3.7% w/dw at flowering, respectively. This decrease in carbohydrate reserve was estimated at ~500 g/vine and is associated with the re-establishment of the plant canopy in early spring. Carbohydrate reserves remained stable or rose slightly between flowering and harvest and recovered between crop harvest and leaf fall. In treated vines, a constantly pressurised low-pressure in situ trunk injection system (69 kPa) with 5% w/v sucrose solution over 45 days from budburst (to flowering), in each of the two seasons, delivered a widely variable amount of sucrose into each vine with variation ascribed to the amount of internal dead wood in the trunk. In the best circumstances, an average of 150 g sucrose/vine/season was injected, and sucrose-injected vines had higher trunk TNC reserve (4.1% compared to 3.6% w/dw in the control) at flowering. A δ13C (‰) analysis confirmed the presence of injected sucrose in the shoot at flowering. However, the correlation between the amount of loaded sucrose and δ13C in young shoot tissue was poor, indicative of variable partitioning patterns. Inflorescence number per vine and berry yield were markedly higher in sucrose-injected vines, but differences were not significant given the high variation between vines. The addition of KCl to the sucrose solution and use of the healthy vines are recommended to increase sucrose loading using the injection method to address inconsistent yielding of subtropical table grape.

Growth and non-structural carbohydrates response patterns of Eucommia ulmoides under salt and drought stress.

Salinity and droughts are severe abiotic stress factors that limit plant growth and development. However, the differences and similarities of non-structural carbohydrates (NSCs) responses patterns of trees under the two stress conditions remain unclear. We determined and compared the growth, physiology, and NSCs response patterns and tested the relationships between growth and NSCs concentrations (or pool size) of Eucommia ulmoides seedlings planted in field under drought and salt stress with different intensities and durations. We found that drought and salt stress can inhibit the growth of E. ulmoides, and E. ulmoides tended to enhance its stress resistance by increasing proline concentration and leaf thickness or density but decreasing investment in belowground biomass in short-term stress. During short-term drought and salt stress, the aboveground organs showed different NSCs response characteristics, while belowground organs showed similar change characteristics: the starch (ST) and NSCs concentrations in the coarse roots decreased, while the ST and soluble sugar (SS) concentrations in the fine roots increased to enhance stress resistance and maintain water absorption function. As salt and drought stress prolonged, the belowground organs represented different NSCs response patterns: the concentrations of ST and SS in fine roots decreased as salt stress prolonged; while ST in fine roots could still be converted into SS to maintain water absorption as drought prolonged, resulting in an increase of SS and a decrease of ST. Significant positive relationships were found between growth and the SS and total NSCs concentrations in leaves and branches, however, no significant correlations were found between growth and below-ground organs. Moreover, relationships between growth and NSCs pool size across organs could be contrast. Our results provide important insights into the mechanisms of carbon balance and carbon starvation and the relationship between tree growth and carbon storage under stress, which were of great significance in guiding for the management of artificial forest ecosystem under the context of global change.

Understory seedlings of Quercus mongolica survive by phenological escape

Understanding understory seedling regeneration mechanisms is important for the sustainable development of temperate primary forests in the context of increasingly intense climate warming events. The poor regeneration of dominant tree species, however, is one of the biggest challenges it faces at the moment. Especially, the regeneration of the shade-intolerant Quercus mongolica seedling is difficult in primary forests, which contrasts with the extreme abundance of understory seedlings in secondary forests. The mechanism behind the interesting phenomenon is still unknown. This study used in-situ monitoring and nursery-controlled experiment to investigate the survival rate, growth performance, as well as nonstructural carbohydrate (NSC) concentrations and pools of various organ tissues of seedlings for two consecutive years, further analyze the understory light availability and simulate the foliage carbon (C) gain in the secondary and primary forest. Results suggested that seedlings in the secondary forest had greater biomass allocation aboveground, height and specific leaf area (SLA) in summer, which allowed the seedling to survive longer in the canopy closure period. High light availability and positive C gain in early spring and late autumn are key factors affecting the growth and survival of understory seedlings in the secondary forest, whereas seedlings in the primary forest had annual negative carbon gain. Through the growing season, the total NSC concentrations of seedlings gradually decreased, whereas those of seedlings in the secondary forest increased significantly in autumn, and were mainly stored in roots for winter consumption and the following year's summer shade period, which was verified by the nursery-controlled experiment that simulated autumn enhanced light availability improved seedling survival rate and NSC pools. In conclusion, our results revealed the survival trade-off strategies of Quercus mongolica seedlings and highlighted the necessity of high light availability during the spring and autumn phenological periods for shade-intolerant tree seedling recruitment.

Effects of mepiquat chloride and plant population density on leaf photosynthesis and carbohydrate metabolism in upland cotton

BackgroundMepiquat chloride (MC) application and plant population density (PPD) increasing are required for modern cotton production. However, their interactive effects on leaf physiology and carbohydrate metabolism remain obscure. This study aimed to examine whether and how MC and PPD affect the leaf morpho-physiological characteristics, and thus final cotton yield. PPD of three levels (D1: 2.25 plants·m−2, D2: 4.5 plants·m−2, and D3: 6.75 plants·m−2) and MC dosage of two levels (MC0: 0 g·ha−2, MC1: 82.5 g·ha−2) were combined to create six treatments. The dynamics of nonstructual carbohydrate concentration, carbon metabolism-related enzyme activity, and photosynthetic attributes in cotton leaves were examined during reproductive growth in 2019 and 2020.ResultsAmong six treatments, the high PPD of 6.75 plants·m−2 combined with MC application (MC1D3) exhibited the greatest seed cotton yield and biological yield. The sucrose, hexose, starch, and total nonstructural carbohydrate (TNC) concentrations peaked at the first flowering (FF) stage and then declined to a minimum at the first boll opening (FBO) stage. Compared with other treatments, MC1D3 improved starch and TNC concentration by 5.4% ~ 88.4%, 7.8% ~ 52.0% in 2019, and by 14.6% ~ 55.9%, 13.5% ~ 39.7% in 2020 at the FF stage, respectively. Additionally, MC1D3 produced higher transformation rates of starch and TNC from the FF to FBO stages, indicating greater carbon production and utilization efficiency. MC1D3 displayed the maximal specific leaf weight (SLW) at the FBO stage, and the highest chlorophyll a (Chl a), Chl b, and Chl a + b concentration at the mid-late growth phase in both years. The Rubisco activity with MC1D3 was 2.6% ~ 53.2% higher at the flowering and boll setting stages in both years, and 2.4% ~ 52.7% higher at the FBO stage in 2020 than those in other treatments. These results provided a explanation of higher leaf senescence-resistant ability in MC1D3.ConclusionIncreasing PPD coupled with MC application improves cotton yield by enhancing leaf carbohydrate production and utilization efficiency and delaying leaf senescence.

Shrubs have a greater influence on the nonstructural carbohydrates of desert mosses along precipitation decreased

Biological soil crusts and the mosaic distribution of vascular plants have become an important landscape feature on the desert surface owing to limited water. The desert shrub, as one of the best-known vascular plants, exerts a notable influence on multiple facets, encompassing the growth and development of biological soil crusts as well as the coverage, biomass, physiology, and biochemical properties of mosses. Therefore, to comprehend how plants react and adapt to drought conditions, it is necessary to investigate the concentration and allocation patterns of nonstructural carbohydrates (NSCs). Nevertheless, the phenomenon still remains unclear whether the influence of shrubs on biological soil crusts follows any pattern concerning the alteration in precipitation gradients on a broader spatial scale. In this investigation, Syntrichia caninervis was gathered from two distinct microenvironments within the Gurbantunggut Desert spanning the gradient of natural precipitation. The aim was to examine the reaction of NSCs within S. caninervis to the presence of shrubs under varying precipitation circumstances. The amount of total NSCs and their components in S. caninervis were determined by the shrub effect, mean annual precipitation (MAP), and mean annual temperature (MAT). The presence of shrubs led to a remarkable rise in the content of fructose, starch, and total NSCs in S. caninervis, but a decline in the ratio of soluble sugar to starch. Nonetheless, variations were observed in the overall NSCs content, the individual constituents of NSCs, and the proportion of soluble sugars to starch within S. caninervis across diverse microenvironments and sampling locations. The content of total NSC and its components, as well as the ratio of soluble sugar to starch, substantially increased with a decrease in MAP (negative correlation) in S. caninervis. Conversely, they significantly decreased as MAT decreased (positive correlation). With the amplifying MAP, the disparities in these parameters (total NSC content, its components, and the ratio of soluble sugar to starch) between two distinct microhabitats diminished gradually, whereas these disparities progressively intensified with rising mean annual temperature (MAT). The outcomes derived from the structural equation model (SEM) underscored the direct and indirect influence of climate and the presence of shrubs influenced the content of NSCs directly or indirectly by enhancing soil nutrients. As a conclusion, the impact of shrub presence, followed by mean annual precipitation (MAP), had the most notable effect on NSCs in S. caninervis. Consequently, despite the observed spatial pattern in NSCs content, shrubs emerged as the most critical factor, in speaking of their effect continuous raising with the declining MAP. These findings provide new insights into the mechanisms of NSCs distribution and stress resistance in desert moss in different microhabitats.

Estimation of the Total Nonstructural Carbohydrate Concentration in Apple Trees Using Hyperspectral Imaging

The total nonstructural carbohydrate (TNC) concentration is an important indicator of the growth period and health of fruit trees. Remote sensing can be applied to monitor the TNC concentration in crops in a non-destructive manner. In this study, hyperspectral imaging from an unmanned aerial vehicle was applied to estimate the TNC concentration in apple trees. Partial least-squares regression, ridge regression, and Gaussian process regression (GP) were used to develop estimation models, and their effectiveness using selected key bands as opposed to full bands was evaluated in an effort to reduce computational costs and improve reproducibility. Nine key bands were identified, and the GP-based model using these key bands performed almost as well as the models using full bands. These results can be combined with previous studies on estimating the nitrogen concentration to provide useful information for more precise nutrient management to improve the yield and quality of apple trees.

Local adaptation to aridity in a widely distributed angiosperm tree species is mediated by seasonal increase of sugars and reduced growth.

Trees in dry climates often have higher concentrations of total non-structural carbohydrates (NSC=starch + soluble sugars) and grow less than conspecifics in more humid climates. This pattern might result from growth being more constrained by aridity than the carbon (C) gain, or reflect local adaptation to aridity, since NSC fuel metabolism and ensure adequate osmoregulation through the supply of soluble sugars (SS), while low growth reduces water and C demands. It has been further proposed that C allocation to storage could come at the expense of growth (i.e., a growth-storage trade-off). We examined whether NSC and growth reflect local adaptation to aridity in Embothrium coccineum (Proteaceae), a species with an exceptionally wide niche. To control for any influence of the phenotypic plasticity on NSC and growth, we collected seeds from dry (500mmyear-1) and moist (> 2500mmyear-1) climates and grew seedlings in a common garden experiment for 3years. We then compared NSC and SS concentrations and pools (i.e., total contents), and the biomass of seedlings at spring, summer, and fall. Seedlings from the dry climate had significantly lower biomass and similar NSC concentrations and pools than seedlings from moist climate, suggesting that reduced growth in arid environments does not result from a prioritization of C allocation to storage but it confers advantages under aridity (e.g., lower transpiration area). Across organs, starch and NSC decreased similarly in seedlings from both climates from spring onward. However, root and stem SS concentrations increased during the growing season, and these increases were significantly higher in seedlings from the dry climate. The greater SS accumulation in seedlings from the dry climate compared to those from the moist climate demonstrates ecotypic differentiation in the seasonal dynamics of SS, suggesting that SS underlie local adaptation to aridity. (298 words).

Effect of Rootstock on Vineyard Establishment Using Green-Growing Benchgrafts

Demand for vine plant material has increased drastically due to the ongoing expansion of viticulture, and recent widespread replanting efforts. Nurseries and growers are turning to green-grafted vines to meet demand. Unfortunately, most vineyard establishment studies have centered around dormant benchgrafted vines. Thus, little is known regarding the specific establishment trends of green-growing benchgrafts. This study aimed to explore the role rootstock selection has in green-growing benchgraft establishment and development over the first four years post-planting. Vitis vinifera L. cv. Sauvignon blanc was grafted onto multiple rootstocks of varying parentage, including ‘101-14MGT’ (V. riparia × V. rupestris), ‘1103P’ (V. berlandieri × V. rupestris), ‘110R’ (V. berlandieri × V. rupestris), ‘420A MGT’ (V. berlandieri × V. riparia), and ‘Teleki 5C’ (V. berlandieri × V. riparia). The experimental site was organized using a completely randomized design (n = 12) with all vines managed to industry-standard cultural practices. Vines grafted onto 1103P had the largest average trunk diameter (p = 0.0012) and circumference (p < 0.0001) at 22.2 mm and 7.57 cm, respectively. Vines grafted onto 110R had the second-largest trunk circumference at 6.65 cm. Vines grafted onto 110R had the largest concentration of total non-structural carbohydrates at planting at 1.47 g/L, followed by 1103P at 1.25 g/L (p < 0.0001). Total non-structural carbohydrate concentrations in the trunk during dormancy was the highest in 110R at 16.0% total dry weight (p = 0.0008). The larger trunk size and more extensive carbohydrate reserves suggest that green-growing benchgrafts using 110R or 1103P have a higher capacity and likelihood of establishment success.

Short and long-term acclimation to water status at leaf and plant level of fungus-tolerant genotypes

Today’s viticulture faces the double challenge of reducing chemical input while adapting plant material to future climate conditions. Adopting fungus disease-tolerant varieties appears to be a long-term solution as long as they are performant under abiotic constraints, such as drought. This study aimed to study the effects of water deficit (WD) and characterise the different strategies adopted to cope with drought in six new fungus disease-tolerant varieties selected by INRAE compared to Syrah. During five consecutive seasons (2018 to 2022), a gradient of WD was applied in field conditions and monitored through vine predawn water potential measurements. Grape development was non-destructively tracked by imaging to determine the arrest of berry phloem unloading. All variables were collected at the single plant level. The impacts of WD on leaf gas exchange and intrinsic water use efficiency (WUEi), vegetative development and yield components were assessed, as well as the genotypic sensitivity to WD at the leaf, vegetative and reproductive levels. All variables were negatively impacted by WD, except for intrinsic water use efficiency and total non-structural carbohydrate concentrations. Genotypes were differently impacted by WD at the physiological and vegetative levels, while no genotype-dependent response was observed for most reproductive variables. Generally, genotypes with the highest potential (highest intercept) in a certain variable were also the most sensitive to water deficit (higher slope). The most sensitive genotype regarding physiological and reproductive variables was G5, which showed higher reductions in berry weight, photosynthesis and WUEi, contrasting with Syrah, 3159B and Floreal. In this study, we observed a diversity of strategies to cope with WD in the long term, where some genotypes opted to reduce most variables (G5 and Artaban) or to maintain functioning at higher levels (Syrah and 3176N). Others displayed mixed responses: either reducing vegetative growth more than yield (3159B) or vice-versa (G14).

Dynamic variation of non-structural carbohydrates in branches and leaves of temperate broad-leaved tree species over a complete life history

The composition of non-structural carbohydrates (NSC), one of the photosynthetic products of plants, reflects the survival strategy of a plant. Although several studies have investigated variation of NSC content in woody plants over a set time scale, few studies have considered the dynamic variation of NSC over a continuous life history. In this study, the leaves, new twigs, and old branches of seven temperate broad-leaved tree species (diffuse-porous species:Betula platyphylla,Betula costata,Tilia amurensis,Acer pictumsubsp.mono; ring-porous species:Ulmus davidianavar.japonica,Ulmus laciniata,Fraxinus mandshurica) were observed at three life history stages (seedling, sapling, and mature tree) to measure the dynamic changes of NSC and its influencing factors throughout the entire life cycles of these species. The results showed that life history, wood type, and environmental factors (soil nitrogen and phosphorus content, soil pH) significantly affected the NSC content in leaves and branches (including both new twigs and old branches). As plants grew, the NSC content in the leaves and branches generally showed an upward trend, meaning the total non-structural carbohydrate (TNC) content and soluble sugar (SS) content increased significantly, and the starch (ST) content was relatively stable. Lastly, there was no significant difference in NSC content between the canopy layers of mature trees. This indicates that the influence of life stage on NSC content in leaves and branches of plants may be dominated by genetics instead of being regulated by light factors.

Global patterns of mobile carbon partitioning in mountain trees in response to elevation

Non-structural carbohydrate (NSC), a major substrate of primary metabolism, has been implicated in mediating cold-induced termination of tree growth, particularly in the alpine environment. Despite its functional significance, NSC pattern as well as its partitioning between sugar and starch in response to elevation across the globe remains unclear. Here, we compiled data from 67 studies encompassing 90 elevational transects worldwide and conducted a meta-analysis to evaluate the responses of NSC (including sugar, starch, and total NSC concentrations) as well as sugar:starch ratio in mountain trees to increasing elevation at organ scale. Our results showed that declining temperature with increasing elevation promoted NSC accumulation in aboveground organs, but did not affect the sugar:starch ratio in all organs analysed, implying that the remarkably significant role of NSC in both short-term cellular metabolism and long-term recalcitrant storage. Trees grown within warmer mountain regions (i.e., regions with relatively higher mean temperature during the growing season) stored more NSC in leaf in response to elevation than those grown within colder mountain regions. We also found that the observed increasing pattern of NSC with elevation occurred only in treeline tree species but not in non-treeline trees (i.e., tree taxa that do not reach the alpine treeline). Additionally, a significant negative effect of elevation on NSC revealed an unbalanced carbon supply in the roots of angiosperms tree species, indicating that the growth inhibition of belowground organ with increasing elevation occurred mainly in angiosperms rather than in gymnosperms. Our findings suggest that a sugar-starch partitioning pattern, which remains essentially stable over a wide range of climates and functional type species, predominately modulates the balance of carbon assimilates between supply and demand in responding to cold stress in the mountain trees worldwide.

Interannual dynamics of stemwood nonstructural carbohydrates in temperate forest trees surrounding drought

Interactions between water and carbon dynamics underlie drought-related tree mortality. While whole-tree water relations have been shown to play a key role in the response to and recovery from drought, the role of nonstructural carbohydrates (NSC) and how their storage and allocation changes surrounding drought events deserves further attention and is critical for understanding tree survival. Here, we quantified in situ NSC responses of temperate forest trees to the 2016 drought in the northeastern United States. Sugar and starch concentrations were measured in the stemwood of five tree species from 2014 to 2019, which allowed us to monitor NSCs in relation to climatic conditions before, during, and after the natural drought. We found that immediately following the drought, measured stemwood NSC concentrations decreased. However, NSC concentrations rebounded quickly within three years. Notably, trees allocated proportionally more to starch than to sugars following the 2016 drought. In winter 2017, starch comprised 45% of total stemwood stores, whereas starch made up only 1–2% in other years. Further, we modeled and assessed the climatic drivers of total NSC concentrations in the stem. Variation in total NSC concentrations was significantly predicted by the previous year’s temperature, precipitation, and standardized precipitation-evapotranspiration index (SPEI), with stemwood concentrations decreasing following hotter, drier periods and increasing following cooler, wetter periods. Overall, our work provides insight into the climatic drivers of NSC storage and highlights the important role that a tree’s carbon economy may play in its response and recovery to environmental stress.

The synergistic effect of hydraulic and thermal impairments accounts for the severe crown damage in Fraxinus mandshurica seedlings following the combined drought-heatwave stress

Drought combined with extreme heatwaves has been increasingly identified as the important trigger of worldwide tree mortality in the context of climate change; nonetheless, our understanding of the potential hydraulic and thermal impairments of hot droughts to trees and the subsequent post-recovery process remains limited. To investigate the response of tree water and carbon relations to drought, heatwave, and combined drought-heatwave stresses, three-year-old potted seedlings of Fraxinus mandshurica Rupr., a dominant tree species in temperate forests of northeast China, were grown under well-watered and drought-stressed conditions and exposed to a rapid, acute heatwave treatment. During the heatwave treatment with a maximum temperature exceeding 40 °C for two days, the leaf temperature of drought-stressed seedlings was, on average, 5 °C higher than that of well-watered counterparts due to less effective evaporative cooling, indicating that soil water availability influenced leaf thermoregulatory capacity during hot extremes. Consistently, more pronounced crown damage, as shown by 13 % irreversible leaf scorch, was found in seedlings under the drought-heatwave treatment relative to sole heatwave treatment, alongside the more severe stem xylem embolism and leaf electrolyte leakage. While the heatwave treatment accelerated the depletion of non-structural carbohydrates in drought-stressed seedlings, the increase of branch soluble sugar concentration in response to heatwave might be related to the requirement for maintaining hydraulic functioning via osmoregulation under high dehydration risk. The coordination between leaf stomatal conductance and total non-structural carbohydrate content during the post-heatwave recovery phase implied that plant-water relations and carbon physiology were closely coupled in coping with hot droughts. This study highlights that, under scenarios of aggravating drought co-occurring with heatwaves, tree seedlings could face a high risk of crown decline in relation to the synergistically increased hydraulic and thermal impairments.

Intra- and Interspecific Variability of Non-Structural Carbohydrates and Phenolic Compounds in Flowers of 70 Temperate Trees and Shrubs

(1) The focus on floral functional traits and their variability has been significantly lower than when compared to other plant organs. Here, we focused on the variability of four novel floral chemical traits. We aimed to assess the level of interspecific variability of total non-structural carbohydrates (TNC) and total phenolic compounds (TPh) in the flowers of woody species. (2) We collected data on 70 species of temperate trees and shrubs. We also assessed the intraspecific level of variability by collecting flowers from the high-light and low-light parts of the crown. (3) We found a phylogenetic signal in the variability of starch and TPh. We did not observe statistically significant differences or biologically significant trends between the high-light and low-light parts of the crown. We detected a low impact of light availability on the intraspecimen variability of the TNC and TPh contents. (4) Low intraspecimen variability allows for a more reliable extrapolation of measurements in cases of interspecific comparisons and can be used to better describe the reproductive strategies of different woody species.

The Dynamics of Non-Structural Carbohydrates in Different Types of Bamboo in Response to Their Phenological Variations: Implications for Managing Bamboo Plantations

Non-structural carbohydrate (NSC) dynamics in different bamboo types underlie the different management practices of bamboo plantations. The changes in moisture, soluble sugars, and starch content in response to phenological variations in different types of bamboo were measured to reveal the NSC dynamics in different bamboo forests for high yield. It was reported for the first time that new leaves of monopodial bamboo started sprouting after the completion of branching, while sympodial bamboo extended new leaves and branches simultaneously. NSC accumulation for shooting lasted about eight months for monopodial bamboo but only a short interval of two to three months for sympodial bamboo. The moisture content in different types of bamboo showed a similar trend of increasing from March to July and then decreasing until the coming January. From March to May, particularly in March, irrigation was required for the shooting of monopodial bamboo, whereas the shoot buds in sympodial bamboo showed sprouting, branching, and leafing. Total NSCs in different bamboo types remained relatively high in March, gradually decreased to the lowest in July, and then increased continuously until the coming January. Average soluble sugar and starch contents showed the same trend as the total NSCs in different types of bamboo. During the period from March to July, large amount of photoassimilates were required for shooting and height growth and then for branching and leafing in monopodial bamboo. Abundant photoassimilates were also required for branching, leafing, and shoot bud differentiation, as well as for subsequent shoot germination in sympodial bamboo. Thus, fertilizer application to both monopodial and sympodial bamboo plantations should be scheduled in early May and late July. Given the moisture, soluble sugar, starch, and total NSC content, January was the best season for harvesting monopodial bamboo for high production and future growth, whereas for sympodial bamboo, November was the best season.

马尾松幼苗根系和光合碳供应对土壤性质变化和温室气体排放的驱动作用

PDF HTML阅读 XML下载 导出引用 引用提醒 马尾松幼苗根系和光合碳供应对土壤性质变化和温室气体排放的驱动作用 DOI: 10.5846/stxb202008012004 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点研发计划(2017YFC0505503)；国家自然科学基金面上项目(31370627) Root input and photosynthetic carbon supply effect on soil properties and greenhouse gases release of Pinus massoniana seedling Author: Affiliation: Fund Project: The National Key Technologies R&D Program of China 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:森林植被受全球气候变化、森林经营活动及病虫害等多种干扰,导致林地光合碳供应水平及根系输入量发生变化。在此背景下,土壤性质及土壤温室气体排放的响应及其机理是预测森林碳汇功能变化及森林可持续经营的重要依据。以2年生马尾松盆栽苗为对象,通过单株/盆和3株/盆栽植密度控制根系输入量、通过环割和截干控制光合碳向地下的供应能力,模拟森林植被干扰导致的根系输入量及光合碳供应变化对土壤理化性质、微生物群落结构及温室气体排放的影响。结果表明,苗木根系非结构性碳水化合物(TNC)含量和氮含量比单株/盆低;3株/盆的土壤速效氮含量比单株/盆低,土壤革兰氏阳性菌、厌氧菌、放线菌及丛枝菌根真菌丰富度均比单株/盆显著增加,3株/盆的土壤二氧化碳(CO2)排放速率较高,但土壤氧化亚氮(N2O)排放速率差异不显著。无论是单株/盆还是3株/盆,环割和截干处理后,根系生物量、根系长度及表面积均比对照显著下降;根系TNC含量显著下降。土壤和根系氮含量都有增加趋势;土壤微生物生物量碳(SMBC)含量降低,而土壤微生物生物量氮(SMBN)则提高。环割和截干后,土壤中各种微生物组成丰富度均有下降趋势,土壤CO2排放速率显著下降,土壤N2O排放速率则显著提高。根系输入量及光合碳供应对土壤细菌和真菌含量均有显著影响,土壤细菌含量与根系生物量、SMBC和SMBN显著正相关;土壤真菌含量与土壤温度显著负相关,与根系生物量、SMBC和SMBN显著正相关。相关分析表明,土壤CO2排放通量与土壤温度、土壤湿度及根系生物量显著正相关,与土壤硝态氮显著负相关;土壤N2O排放通量与土壤温度和土壤湿度显著正相关。以上研究表明,根系输入量与地上光合碳供应共同作用,改变土壤理化性质及微生物环境,进而影响土壤温室气体排放。 Abstract:Forest vegetation is affected by climate change, forest management activities, and diseases and pests, which can lead to changes in photosynthetic carbon supply, root input of forest land, composition of soil microbial community, and soil greenhouse gases emission. These changes and their underlying mechanisms are the basis for modelling change of forest ecological functions and for managing forest scientifically. Here, we studied level of root input of 2-year-old potted seedlings of Pinus massoniana under two densities, single-plant/pot and 3-plants/pot, and under two disturbance treatments, ring-barking and stem-severing to stop carbon transport to the root system. We aimed to simulate the effects of changes in root input and photosynthetic carbon supply on soil physical and chemical properties, microbial community structure and greenhouse gas emission under various conditions. Our results showed that the total nonstructural carbohydrate (TNC) and nitrogen in seedling roots were lower in 3-plants/pot treatment than in single-plant/pot treatment. The content of soil available nitrogen in 3-plants/basins was lower than that in single-plant/pot. In contrast, richness of soil Gram-positive bacteria, anaerobic bacteria, actinomycetes and arbuscular mycorrhizal fungi were higher in 3-plants/pot treatment than in single-plant/pot treatment. Further, the emission rate of soil carbon dioxide (CO2) was higher in 3-plants/pot treatment than in single-plant/pot treatment. Planting density had no significant effects on emission rate of soil nitrous oxide (N2O). Both the ring-barking and stem-severing treatments decreased the root biomass, root length, root surface and root TNC content in both single-plant/pot and 3-plants/pot treatments. Both the ring-barking and stem-severing treatments increased the content of nitrogen in soil and roots, the content of soil microbial biomass nitrogen (SMBN), and emission rate of soil N2O, but decreased the content of soil microbial biomass carbon (SMBC), the richness of soil microbial and the emission rate of soil CO2. Root biomass input and photosynthetic carbon supply have significant effect on soil bacterial and fungal contents. Soil bacterial contents were positively correlated with root biomass, SMBC and SMBN. Soil fungal content was negatively correlated with soil temperature, positively correlated with root biomass, SMBC and SMBN. Correlation analysis showed that soil CO2 emission flux was positively correlated with soil temperature, soil humidity and root biomass, while negatively correlated with soil nitrate nitrogen; soil N2O emission flux was positively correlated with soil temperature and soil humidity. The results suggest that root input and photosynthetic carbon supply work together to change soil physical and chemical properties and microbial environment, thus contribute to changes in the emissions rate of soil greenhouse gases. 参考文献 相似文献 引证文献