Non-structural Carbohydrate Content Research Articles

Effects of elevated atmospheric CO2 concentration on nonstructural carbohydrates and grain quality of maize.

We used open-top chambers (OTCs) to simulate the conditions of elevated atmospheric CO2 concentration at the Changwu State Key Agro-Ecological Experimental Station of the Loess Plateau. There were three treatments, CK (maize grown under field conditions with natural atmospheric CO2 concentration), OTC (maize grown in the open-top chamber under natural atmospheric CO2 concentration), and OTCe (maize grown in the open-top chamber under elevated atmospheric CO2 concentration of 700 μmol·mol-1).We explored the responses of non-structural carbohydrate (NSC) and grain quality (soluble sugar, starch and crude protein) of spring maize to elevated CO2 at different growth stages, aiming to provide scientific basis for revealing the adaptation mechanism of maize to elevated CO2. The results showed that the effects of elevated CO2 on NSC content and accumulation in maize varied across organs and growth periods. Elevated CO2 promoted the activation and redistribution of NSC in leaves, stems and roots during reproductive growth period, and significantly increased the amount of NSC conversion to the grains (ATMNSC), as well as the conversion rate to the grains (ARNSC) and the contribution to the grains (ACNSC) in leaves, stems and roots. Compared with CK, the warming effect of OTC inhibited the activation and redistribution of NSC in stems and roots, but promoted the activation and redistribution of NSC in leaves, significantly increased the ATMNSC, ARNSC, and ACNSC of maize leaves. Elevated CO2 did not affect the contents of soluble sugar, starch, and crude protein in maize grains.

海拔高度对中国沙棘水碳代谢和生长的影响——以关帝山区为例

PDF HTML阅读 XML下载 导出引用 引用提醒 海拔高度对中国沙棘水碳代谢和生长的影响——以关帝山区为例 DOI: 10.5846/stxb202111193260 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 山西省重点研发计划项目（201903D221051）；山西省自然科学基金项目（2019D211360）；北方功能油料树种培育与研发山西省重点实验室（201805D111010） Effects of altitude on water and carbon metabolism and growth of hippophae rhamnoides in Guandi Mountain Author: Affiliation: Fund Project: 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:海拔是影响中国沙棘自然分布和生长的的重要环境因子，水分代谢和碳代谢的平衡是植物存活和生长的基础，研究海拔对中国沙棘的水碳代谢和生长的影响有利于全面了解中国沙棘对海拔高度的适应性及其生理机制。以山西西部关帝山地区野生中国沙棘为研究对象，测定了海拔1100-2100 m的中国沙棘雌株在6月和8月的小枝正午水势、枝条导水损失率、枝条导管直径和导管密度、光合作用、不同部位非结构性碳水化合物（NSC）浓度，同时测定了不同海拔沙棘的株高和冠幅。结果表明：随着海拔的升高，6月和8月的土壤含水量均呈增加趋势；小枝正午水势先升高后降低；枝条导水损失率在6月先降低后升高；随着海拔的升高沙棘的导管直径没有显著性变化，但导管密度、枝条最大比导水率、叶面积呈现先升高后降低的趋势。随着海拔的升高6月和8月光合速率均呈增加趋势；根和叶NSC含量没有较大幅度变化；随着海拔高度的增加中国沙棘树高和冠幅均呈现先增加后降低的趋势。以上结果表明：低海拔（1100-1300 m）和高海拔（1900-2100 m）中国沙棘生长均受到一定程度的抑制，在低海拔主要受干旱胁迫的影响，高海拔对中国沙棘的生长的抑制作用体现在低温引起的水分状况变差、生长季缩短和低温抑制树木的生长。 Abstract:Altitude is an important environmental factor that affects Chinese seabuckthorn (Hippophae rhamnoides L. subsp. sinensis Rousi) distribution and growth. The balance of water metabolism and carbon metabolism is the basis of plant survival and growth. Studies about the effect of altitude on water-carbon metabolism and growth of Chinese seabuckthorn will contribute to fully understanding its adaptability and physiological mechanism to altitude. In this study, wild Chinese seabuckthorn growing in Guandi Mountain area of western Shanxi Province was used as the study object. Twig water potential, branch percentage loss of conductivity (PLC), photosynthesis and nonstructural carbohydrate (NSC) concentration of female seabuckthorn plants at elevation1100 m to 2100 m were measured in June and August, and plant height and crown width were also measured at different elevations. The results showed that with the elevation increasing, the soil water content increased in both June and August, and the midday twig water potential increased first and then decreased. The branch PLC decreased first and then increased in June.With the increase of altitude, the branch vessel diameter did not change significantly, but the vessel density, branch maximum specific water conductivity and leaf area increased first and then decreased. And the net photosynthetic rate increased in June and August. There was no significant change of NSC content in both roots and leaves. With the increase of altitude, both tree height and crown width increased first and then decreased. The above results suggested that the growth of seabuckthorn was inhibited to some extent at both low altitude (1100-1300 m) and high altitude (1900-2100 m). Seabuckthorn at low altitude was mainly affected by drought stress. And the growth inhibition at high altitude was reflected in the poor water status resulting from low temperature, shortened growing season and the inhibition of low temperature on tree growth. 参考文献 相似文献 引证文献

Divergent responses of Picea crassifolia Kom. in different forest patches to climate change in the northeastern Tibetan Plateau

Global climate changes have significantly affected tree growth and forest structures and functions in some arid and semi-arid regions, which are becoming warmer and wetter. Due to natural factors such as climate and terrain, some tree species may form different forest patches at the edges of their distribution areas. However, how forest patches of various sizes respond to climate change is unclear. In this study, we collected 203 tree cores from six different sizes of forest patches at the edge of the distribution area of Picea crassifolia Kom. in the northeast Tibetan Plateau. And we used the dendrochronology method to study the response of tree growth and resilience in different forest patches to climate change from 1961 to 2020. We simultaneously measured the contents of non-structural carbohydrates (NSC), total nitrogen and total phosphorus of tree needles. Our results showed that the growth of trees in small- and medium-size forest patches (0.8–18.6 ​ha) has increased significantly. The early growing season (May–July) minimum temperature was the most important climate factor driving the growth of small- and medium-sized patch trees. The early growing season maximum temperature was the most important climate factor that inhibited the growth of trees in the largest patches (362.8 ​ha). The growth of individual trees in medium forest patches was better and the correlation with annual minimum temperature, maximum temperature, precipitation, actual evapotranspiration, and palmer drought severity index was stronger. The higher NSC content, stronger photosynthesis, and higher nitrogen utilization efficiency in leaves might be one of the reasons for the better growth of trees in moderate forest patches. In extreme drought years, as the forest patch area increased, the overall trend of tree growth resistance showed a unimodal pattern, with the highest at a forest patch area of 7.1 ​ha, while the overall trend of tree growth recovery was opposite. Therefore, we should strengthen the management of trees in large forest patches to cope with climate change.

Biomass, carbohydrate, and leakage conductance in buds of six ornamental tree species subjected to a “false spring” in Northeast China

Information is highly scarce about the possible effect of a late spring frost on physiological response of buds in ornamental trees. In this study, spring temperature of Changchun at Northeast China was recorded to identify the characteristics of a false spring by detecting extraordinary warming and sudden freeze in early April of 2017. Buds of six local ornamental tree species were investigated for their dynamics in biomass, non-structural carbohydrates, frost resistance on days of 7, 14, 21, and 28 April 2017. According to a comparison with spring temperature records historically from 2007 to 2016, a false spring was determined. Black pine (Pinus tabuliformis var. mukdensis) had greater bud biomass than apricot (Prunus sibirica L.). Peach (Prunus persica L. var. persica f. rubro-plena Schneid.) reserved greater non-structural carbohydrate content in post-chilling buds than black pine, and apricot and willow (Salix babylonica L.) had greater soluble sugars and starch contents in buds, respectively. Cumulative number of days with temperature below 12°C had a negative relationship with relative conductance in sorbus (Sorbus pohuashanensis [Hance] Hedl.). Chokecherry (Padus virginiana ‘Canada Red’) had greatest bud starch content on 21 April. Overall, a late spring frost imposed interruption on carbohydrate metabolism rather than direct damage on buds of ornamental trees before late April. Advanced warming induced more pronounced negative impact of a false spring than the sudden decline of minimum temperature.

Elevated CO2 Alters the Physiological and Transcriptome Responses of Pinus densiflora to Long-Term CO2 Exposure.

Physiological response and transcriptome changes were observed to investigate the effects on the growth, metabolism and genetic changes of Pinus densiflora grown for a long time in an environment with an elevated atmospheric CO2 concentration. Pine trees were grown at ambient (400 ppm) and elevated (560 ppm and 720 ppm) CO2 concentrations for 10 years in open-top chambers. The content of nonstructural carbohydrates was significantly increased in elevated CO2. It was notable that the contents of chlorophylls significantly decreased at an elevated CO2. The activities of antioxidants were significantly increased at an elevated CO2 concentration of 720 ppm. We analyzed the differences in the transcriptomes of Pinus densiflora at ambient and elevated CO2 concentrations and elucidated the functions of the differentially expressed genes (DEGs). RNA-Seq analysis identified 2415 and 4462 DEGs between an ambient and elevated CO2 concentrations of 560 ppm and 720 ppm, respectively. Genes related to glycolysis/gluconeogenesis and starch/sucrose metabolism were unchanged or decreased at an elevated CO2 concentration of 560 ppm and tended to increase at an elevated CO2 concentration of 720 ppm. It was confirmed that the expression levels of genes related to photosynthesis and antioxidants were increased at an elevated CO2 concentration of 720 ppm.

Soiltesting formula fertilization with organic fertilizer addition for target yield cannot stand long due to stem lodging of rice.

Soil testing formula fertilization using organic fertilizer (STFFOF)could increase grain yields and protect the ecological environment but the potential risks of STFFOF remains unclear. In order to assess the risk on rice stem lodging, a STFFOF field experiment is conducted continuously for 11 years. After 11 years of continuous STFFOF treatment, the stem lodging rate of rice substantially increases by 81.1%*, which completely overweigh its increase in yield. Further research found that STFFOF greatly decreases the concentration of Ca, SiO2, K, Mg, and non-structural carbohydrates in basal internodes, dramatically increases that of N, P, and weight per ear, but slightly affects the structural carbohydrates. The strong correlations imply the increasement in weight per ear, N, and P concentrations, and the significant decrease in starch in the basal internodes might directly increase the brittleness of stem internodes and further cause severe stem lodging and yield loss of rice. Results suggest that the potential risks of rice production including stem lodging must be considered when adopting the excessive exploration mode of productivity technology of paddy fields.

Dynamic changes in morphology and composition during seed development in Xanthoceras sorbifolium Bunge

The seed oil of Xanthoceras sorbifolium Bunge is widely recognized as a promising material for high-grade edible oil and biodiesel. No effort has been made to identify the accumulation dynamics of its fatty acid composition and content during seed development, nor to provide a basis for determining the optimal harvest time for each potential use. In this study, the dynamic changes in morphological traits, oil content, fatty acid composition and other components during the seed development of X. sorbifolium were investigated. Seed diameter increased rapidly within 50 days after anthesis (DAA) and then increased slowly. The seed weight peaked on 65 DAA and then decreased. It took 75–80 days for the seeds to ripen completely. Seed kernel oil accumulated rapidly from 45 DAA to 55 DAA, and the oil content peaked on 70 DAA. Twelve fatty acids were detected in seed kernel oil, including four saturated and eight unsaturated fatty acids. With the accumulation of seed oil content, the non-structural carbohydrate content of the seed kernels gradually decreased, providing raw material and energy for seed oil synthesis. The temperature during this period was also observed. The effective accumulated temperature exceeding biological zero temperature (EAT k ) and the effective accumulated temperature exceeding 10 ℃ (EAT 10 ) were calculated. During 70–75 DAA when EAT 10 and EAT k reached 1016.1 ℃ and 1567.6 ℃, respectively, the transverse and longitudinal diameters of the seeds were 16.65–17.15 mm and 19.73–19.98 mm, respectively. Based on their fatty acid composition and content, the seeds harvested during this period are recommended for the production of edible oil. For biodiesel production, the suggested harvest time is 60 DAA, when EAT 10 and EAT k were 876.6 ℃ and 1376.1 ℃, respectively, and the transverse and longitudinal diameters of seeds were approximately 16.33 mm and 19.08 mm, respectively. • The dynamic changes in morphology and composition of X. sorbifolium seeds during development are revealed. • The fatty acid composition and content can be estimated from morphological traits and temperature changes. • The study helps to determine the ideal harvest period for each use and improve seed utilization efficiency. • Some field management measures can be taken based on the results to improve seed oil quality.

Symbiotic ant traits produce differential host-plant carbon and water dynamics in a multi-species mutualism.

Cooperative interactions may frequently be reinforced by "partner fidelity feedback," in which high- or low-quality partners drive positive feedbacks with high or low benefits for the host, respectively. Benefits of plant-animal mutualisms for plants have been quantified almost universally in terms of growth or reproduction, but these are only two of many sinks to which a host-plant allocates its resources. By investigating how partners to host-plants impact two fundamental plant resources, carbon and water, we can better characterize plant-partner fidelity and understand how plant-partner mutualisms may be modulated by resource dynamics. In Laikipia, Kenya, four ant species compete for Acacia drepanolobium host-plants. These ants differ in multiple traits, from nectar consumption to host-plant protection. Using a 5-year ant removal experiment, we compared carbon fixation, leaf water status, and stem non-structural carbohydrate concentrations for adult ant-plants with and without ant partners. Removal treatments showed that the ants differentially mediate tree carbon and/or water resources. All three ant species known to be aggressive against herbivores were linked to benefits for host-plant resources, but only the two species that defend but do not prune the host, Crematogaster mimosae and Tetraponera penzigi, increased tree carbon fixation. Of these two species, only the nectivore C. mimosae increased tree simple sugars. Crematogaster nigriceps, which defends the tree but also castrates flowers and prunes meristems, was linked only to lower tree water stress approximated by pre-dawn leaf water potential. In contrast to those defensive ants, Crematogaster sjostedti, a poor defender that displaces other ants, was linked to lower tree carbon fixation. Comparing the effects of the four ant species across control trees suggests that differential ant occupancy drives substantial differences in carbon and water supply among host trees. Our results highlight that ant partners can positively or negatively impact carbon and/or water relations for their host-plant, and we discuss the likelihood that carbon- and water-related partner fidelity feedback loops occur across ant-plant mutualisms.

Uniconazole enhances lodging resistance by increasing structural carbohydrate and sclerenchyma cell wall thickness of japonica rice (Oryza sativa L.) under shading stress

Lodging is a major limiting factor for grain yield and quality, and low light enhances lodging risk by increasing stem elongation and decreasing culm thickness. This study evaluated the effect of exogenous uniconazole (UCZ) on the basal stem physiological mechanism, cell structure, carbohydrates, and lignin-related enzymes in culm tissue under shading conditions. The results showed that shading stress significantly decreased grain yield and stem mechanical strength in 2020 and 2021. Compared with normal light (CK), shading rapidly decreased the breaking strength (M) and section modulus (SM). Exogenous UCZ increased culm wall thickness and improved lodging resistance. Uniconazole application also reduced plant height, gravity height, and second basal internode length by inducing a reduction in the cell length, and caused the cells to be densely arranged under both normal light and shading conditions. Scanning electron microscopy (SEM) revealed that the thickness of the sclerenchyma tissue cell wall increased under both conditions under the UCZ treatment, which induced an increase in the cell wall content. Uniconazole application significantly increased non-structural carbohydrate, lignin, cellulose, and hemicellulose contents in culm tissue. Moreover, UCZ application regulated lignin-related enzymes, such as phenylalanine ammonia-lyase (PAL), 4-coumarate: CoA ligase (4CL), cinnamate 4-hydroxylase (C4H), laccase (LAC) and peroxidase (POD). Thus, exogenous UCZ could enlarge sclerenchyma cell wall thickness, alter cell morphology in the stem, and increase stem strength by increasing carbohydrate content, including non-structural carbohydrates, cellulose, lignin, and hemicellulose, to enhance rice (Oryza sativa L.) lodging resistance under shading conditions.

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.

Incorporating Plantain with Perennial Ryegrass-White Clover in a Dairy Grazing System: Dry Matter Yield, Botanical Composition, and Nutritive Value Response to Sowing Rate, Plantain Content and Season

Incorporating plantain with perennial ryegrass and white clover (RGWC) can improve the quality and quantity of grazing pastures; however, the sowing rate could affect the persistence of plantain, pasture yield, and nutritive value in different seasons. The objective of this study was to evaluate the effect of increasing sowing rates of plantain when established with RGWC on the dry matter (DM) yield, botanical composition, nutritive value, and bioactive compounds of the pasture over the first two years after sowing; and to determine the relationship between plantain content and nutritive characteristics in different seasons. The pasture treatments were RGWC, RGWC + low plantain rate (PLL), RGWC + medium plantain rate (PLM), and RGWC + high plantain rate (PLH). The results showed that annual DM yield was similar between treatments. The average plantain content (including leaves and reproductive stem) was 32, 44, and 48% in PLL, PLM, and PLH, respectively. The plantain composition increased in the first 15 months, then declined rapidly to about 20–30% at day 705 after sowing. Compared with RGWC, the plantain-RGWC pastures (PLL, PLM, PLH) had a higher content of organic matter digestibility (OMD), ash, starch, non-structural carbohydrates (NSC), P, S, Ca, Mg, Na, Cl, Zn, B, Co, aucubin, acteoside, and catalpol, while they contained a lower composition of DM%, acid detergent fibre (ADF), neutral detergent fibre (NDF), crude fat (CF), Fe, and Mn. These differences were linearly associated with the content of plantain leaves in the pasture and were higher in summer and autumn than in spring. In conclusion, incorporating plantain into the RGWC pasture can improve herbage nutritive quality, thus potentially increasing farm productivity and environmental benefits. However, further work is required to investigate management interventions to sustain plantain content beyond two years from sowing.

Mepiquat chloride application combined with high plant population density promotes carbon remobilization in the roots of upland cotton

Carbon reserves in cotton roots can be remobilized to support reproductive growth, thus potentially affecting cotton yield. However, the regulation of carbon remobilization in cotton roots and its relationship with cotton yield are still poorly understood. Plant population density (PPD) and mepiquat chloride (MC) have been hypothesized to affect the dynamics of nonstructural carbohydrate content and the resulting carbon remobilization in cotton roots through the regulation of carbohydrate metabolism enzyme activities. A mid-maturation cotton line 4003–6 was field-grown in 2019 and 2020. Three different levels of PPD (D1: 2.25 plants m−2, D2: 4.5 plants m−2, and D3: 6.75 plants m−2) and two levels of MC dosage (M0: 0 g hm−2, M1: 82.5 g hm−2) were combined to create six populations differing in terms of the source–sink relationship. The changes in the hexose, sucrose, and starch contents and the key carbon metabolic enzyme activities in cotton roots were examined during peak squaring (PS) to late boll opening (LB). The combination of the PPD of 6.75 plants m−2 and MC application (M1D3) exhibited the greatest cotton yield and reproductive biomass–to–leaf area ratio from peak flowering (PF) onwards. M1D3 presented the greatest total nonstructural carbohydrate (TNC) remobilization amount of 2.96 and 3.80 g m−2, the highest efficiency of 39.11% and 48.39%, and the largest gross contribution to seed cotton yield of 0.66% and 0.79% in 2019 and 2020, respectively. The three parameters were positively correlated with the seed cotton yield except for the remobilization rate in 2019. Unlike the other treatments, the greater carbohydrate content per unit ground area in M1D3 prior to the PF stage was attributed to the higher sucrose phosphate synthase (SPS) and ADP-glucose pyrophosphorylase (AGPase) activities during the PS to first flowering (FF) stages. Conversely, the greater α-amylase and β-amylase activities in M1D3 at the PF stage accounted for the lower starch content at the EB stage, and the smaller vacuolar invertase (VIN) and cell wall invertase (CWIN) activities at the EB stage could be responsible for the lower hexose concentration at that time. The TNC remobilization amount had a positive association with the AGPase and SPS activities at the FF stage and with β-amylase activity at the PF stage in cotton tap roots in 2019 and 2020. This study provides a cotton yield-improving alternative through the promotion of carbon remobilization in roots using certain agronomic practices.

Long-term water use efficiency and non-structural carbohydrates of dominant tree species in response to nitrogen and water additions in a warm temperate forest.

Nitrogen (N) deposition tends to accompany precipitation in temperate forests, and vegetation productivity is mostly controlled by water and N availability. Many studies showed that tree species response to precipitation or N deposition alone influences, while the N deposition and precipitation interactive effects on the traits of tree physiology, especially in non-structural carbohydrates (NSCs) and long-term water use efficiency (WUE), are still unclear. In this study, we measured carbon stable isotope (δ13C), total soluble sugar and starch content, total phenols, and other physiological traits (e.g., leaf C:N:P stoichiometry, lignin, and cellulose content) of two dominant tree species (Quercus variabilis Blume and Liquidambar formosana Hance) under canopy-simulated N deposition and precipitation addition to analyze the changes of long-term WUE and NSC contents and to explain the response strategies of dominant trees to abiotic environmental changes. This study showed that N deposition decreased the root NSC concentrations of L. formosana and the leaf lignin content of Q. variabilis. The increased precipitation showed a negative effect on specific leaf area (SLA) and a positive effect on leaf WUE of Q. variabilis, while it increased the leaf C and N content and decreased the leaf cellulose content of L. formosana. The nitrogen-water interaction reduced the leaf lignin and total phenol content of Q. variabilis and decreased the leaf total phenol content of L. formosana, but it increased the leaf C and N content of L. formosana. Moreover, the response of L. formosana to the nitrogen-water interaction was greater than that of Q. variabilis, highlighting the differences between the two dominant tree species. The results showed that N deposition and precipitation obviously affected the tree growth strategies by affecting the NSC contents and long-term WUE. Canopy-simulated N deposition and precipitation provide a new insight into the effect of the nitrogen-water interaction on tree growth traits in a temperate forest ecosystem, enabling a better prediction of the response of dominant tree species to global change.

Biological nitrogen fixation and nifH gene abundance in deadwood of 13 different tree species

Deadwood is an extremely nitrogen (N) poor plant litter whose decomposition may rely on external N sources. Biological N2 fixation (BNF) by free-living diazotrophs, encoded with the nifH gene, is a potential pathway of N acquisition in deadwood. Still, the control of this process by tree species specific traits is hardly known. Here, we examined (1) BNF rates and nifH gene abundances in deadwood of 13 tree species after 12 years of decomposition and (2) how BNF was related to nutrient concentrations and non-structural carbohydrates (NSC). Comparing our BNF rates with the literature revealed no difference for angiosperms but gymnosperms. Large variability prevented any significant difference in BNF and nifH gene abundance between tree species identities of deadwood. Still, higher BNF and nifH gene abundances occurred in the group of diffuse-porous angiosperms compared to ring-porous angiosperms and gymnosperms. Positive relationships between BNF rates and molybdenum, phosphor, sulfur, and N suggested co-limitation of BNF by several nutrients in deadwood. Relatively high NSC concentrations indicated good carbon availability for diazotrophs. Furthermore, structural equation modeling highlighted the importance of water content for BNF and nifH gene abundance, although the overall explanatory power was low. In conclusion, BNF is a ubiquitous microbial process in deadwood of native European tree species and the comparison with other studies suggests no down-regulation of BNF by high N deposition in Central Europe.

The combined effect of planting density and sediment fertilization on survival, growth and physiology of eelgrass Zostera marina.

We subjected shoots of eelgrass Zostera marina to different combinations of planting density [300 (control), 450, 600, 750, 900 shoots m-2] and sediment fertilization [0 (control), 35, 70, 105, 140gm-2] for 6weeks under controlled conditions. We measured eelgrass responses in terms of survivorship, growth, productivity, leaf pigmentation and carbohydrate concentrations. The ramet frequency of Z. marina reached 47.8% when exposed to the combination of 600 shoots m-2 and 70gm-2, which was 3.2 times higher than that of shoots under the control. Survival analysis combined with growth assessment suggested that the optimal ranges of planting density and sediment fertilization for the propagation of Z. marina shoots were 501 to 530 shoots m-2 and 51 to 60gm-2, respectively. The promotion of survival and propagation of Z. marina that stemmed from planting density and sediment fertilization mainly depended on the increase of chlorophyll content and accumulation of non-structural carbohydrate. The total chlorophyll content of Z. marina leaves exposed to the combination of 600 shoots m-2 and 70gm-2 was 2.1 times higher than that of shoots under the control. The results will provide data that could prove helpful in the development of efficient artificial propagation technology for Z. marina shoots.

Melatonin regulates material transport to reduce carbon emissions and increase yield under different nitrogen in rice

Carbon and nitrogen metabolism regulates yield formation and greenhouse gas emissions in rice. Melatonin can promote stress resistance under abiotic stress, but its ability to regulate carbon and nitrogen transport remains unclear. Therefore, this study explored the response mechanism of melatonin in rice under reduced nitrogen application. To further understand whether melatonin regulates carbon and nitrogen transport to increase production and reduce greenhouse gas (GHG) emissions. At the heading stage, 100 μmol L−1 melatonin was sprayed under normal fertilization, 85% nitrogen, 50% nitrogen, and 0% nitrogen treatments. Physiological detection, metabolomics analysis, and gas chromatography were used to study the response mechanism of melatonin to carbon and nitrogen metabolism accumulation and transport, and its effect on greenhouse gas emissions under different nitrogen fertilizer conditions was studied. The results revealed that melatonin could improve the genes related to sucrose transporter and nitrogen uptake under the condition of a 15% reduction of normal nitrogen application, thereby increasing the content of non-structural carbohydrates and nitrogen, promoting their transport to grains, and reducing rhizosphere transport to reduce greenhouse gas emissions. There was no significant difference in yield between the melatonin treatment and normal fertilization under 15% nitrogen fertilizer reduction, but methane and nitrous oxide emissions were significantly reduced. The results of this study provide preliminary evidence for the response mechanism of exogenous melatonin to carbon and nitrogen metabolism in rice under different nitrogen treatments.

Carbon Allocation of Quercus mongolica Fisch. ex Ledeb. across Different Life Stages Differed by Tree and Shrub Growth Forms at the Driest Site of Its Distribution

There are less than 10% of woody species that can have both tree and shrub growth forms globally. At the xeric timberline, we observed the tree-to-shrub shift of the Quercus mongolica Fisch. ex Ledeb.. Few studies have explored the underlined mechanism of this morphological transition of tree-to-shrub in arid regions. To examine whether the tree-to-shrub shift affects carbohydrate allocation and to verify the effect of life stage on non-structural carbohydrate (NSC) storage, we measured the concentration of soluble sugar and starch of Q. mongolica in the seedlings, saplings, and adult trees by selecting two sites with either tree or shrub growth forms of Q. mongolica at the driest area of its distribution. Accordingly, there was no significant difference in the radial growth with different growth forms (p > 0.05). The results showed that the effects of growth form on NSC concentrations are significant in the seedling and sapling stages, but become less pronounced as Q. mongolica grows. The results of the linear mixed model showed that life stage has a significant effect on soluble sugar concentration of tree-form (p < 0.05), starch and TNC concentration of shrub-form (p < 0.05). Compared with a shrub form without seedling stage, a tree form needs to accumulate more soluble sugar from seedling stage to adapt to arid environment. Saplings and adult shrubs store more starch, especially in thick roots, in preparation for sprout regeneration. Our study shows that the same species with tree and shrub forms embody differentiated carbohydrate allocation strategies, suggesting that shrub form can better adapt to a drier habitat, and the tree-to-shrub shift can benefit the expansion of woody species distribution in dryland.

Interactive effect between tree ageing and trunk-boring pest reduces hydraulics and carbon metabolism in Hippophae rhamnoides.

Sea-buckthorn (Hippophae rhamnoides) is widely distributed across the Eurasian continent. Recently sea-buckthorn has shown premature ageing and decline when confronted with water deficiency and Holcocerus hippophaecolus damage in northwest China and the Loess Plateau region. However, the physiological process of sea-buckthorn senescence in response to drought and pest damage is still unknown. In this study, 4-year-old (4y), 15-year-old normal growth (15yN) and 15-year-old seriously moth-damaged sea-buckthorn plants (15yH) were used as the research objects. The growth of branches and roots, branch water potential and percentage loss of conductivity (PLC), branch vulnerability to embolism (quantified by P50, xylem water potential at 50 % of PLC), branch xylem parenchyma cell viability, photosynthesis and the non-structural carbohydrate (NSC) content in branches and roots in dry and wet seasons were measured. The results showed that the length, basal diameter of 1-year-old branches and the leaf area of 4y trees were significantly larger than that of 15yN and 15yH trees, and the fine root density of 15yH trees was significantly lower than that of 15yN trees in all measured areas. The branch-specific hydraulic conductivity of 15yN and 15yH trees was only 50.2 % and 12.3 % of that of 4y trees, and the P50 of 4y, 15yH and 15yN trees was -3.69 MPa, -2.71 MPa and -1.15 MPa, respectively. The midday water potential and photosynthetic rate were highest in 4y trees, followed by 15yN and then 15yH trees in both the dry season and wet seasons, while branch PLC declined in the opposite direction (15yH trees highest, 4y trees lowest). The degree of PLC repair within a day was highest in 4y trees, followed by 15yN and then 15yH trees, and the viability of xylem cells was consistent with this pattern. The branch xylem starch and NSC content of 4y and 15yN trees were significantly higher than that of 15yH trees in the dry season, and the root starch and NSC content of 4y trees were significantly higher than that of 15yH trees in the two seasons. The above results suggest that the hydraulic properties of the normal elderly and seriously pest-damaged sea-buckthorn were significantly worse than in juvenile plants. Narrower early wood width and vessel density, high embolism vulnerability and weak embolism repair capacity led to the decline in water-conducting ability, and similarly further affected photosynthesis and the root NSC content. The decline in xylem parenchyma cell viability was the main reason for the limited embolism repair in the branches.

Reduced stem nonstructural carbohydrates caused by plant growth retardant had adverse effects on maize yield under low density.

Enhancing maize lodging resistance with plant growth retardants (PGRs) is common in maize production. However, the underlying mechanisms of yield formation as affected by PGRs are still poorly understood. A field experiment contained PGR application (a mixture of ethephon and cycocel, EC) with normal (T1) and double (T2) doses and water control (CK) was conducted at four maize plant densities (4.5, 6.0, 7.5, and 9.0 plants m-2) in 2020 and 2021. In this two-year study, the grain yield and kernel number per ear (KNE) of EC treatments were reduced by 4.8-9.0% and 3.3-12.2%, respectively, compared with CK under densities of 4.5, 6.0, and 7.5 plants m-2 without lodging. However, under the density of 9.0 plants m-2, EC treatments had no pronounced effects on grain yield and yield components. Across all densities, EC significantly decreased the leaf area index (LAI), and the lowest LAI was recorded in T2. The concentrations of nonstructural carbohydrates (NSCs; starch and soluble sugar) in the stem were significantly decreased by 9.9-10.2% in T2 averaged all densities. The sucrose and starch concentrations in grains also declined in the EC treatments. The key enzymes (cell wall acid invertase, sucrose synthase, and adenosine diphosphate pyrophosphorylase) and grain polyamine concentrations showed a slight downward trend under EC treatments compared to CK. NSCs in stems and grains, kernel enzyme activities, and polyamines in grains presented significant positive correlations with KNE. Additionally, structural carbohydrate (SC; including cellulose, hemicellulose, and lignin) concentrations in stems were improved with enhanced lodging resistance by spraying EC. Significant negative relationships were observed between SC with kernel number m-2 (KNM) and yield, suggesting that improved SC in stems might affect the availability of NSCs for kernel set. Although the lowest kernel weight and KNE were obtained at 9.0 plant m-2, relatively high LAI still ensured high KNM and high yield. Collectively, EC treatment increased SC in stems, enhanced lodging resistance of maize and reduced NSC availability for kernels, ultimately presenting adverse effects on maize kernel number and yield under relative low density.

Soil warming alters fine root lifespan, phenology, and architecture in a Cunninghamia lanceolata plantation

The mechanisms by which warming affects fine root lifespan remain unclear. In a large-scale soil warming experiment in a Chinese fir plantation, fine root dynamics were monitored for four years using minirhizotrons, and the effects of increasing temperature and co-varying factors on fine root lifespan, such as soil moisture, fine root phenology and architecture, were analysed. Fine root non-structural carbohydrate concentrations and respiration rates were measured to test if fine root lifespan is affected by carbon (C) supply. Warming shortened the overall fine root lifespan by 27.6% (warming vs. control: 197.0 ± 3.5 d vs. 272.0 ± 4.5 d). Cox regression models suggest that increased soil temperature directly and negatively affects root lifespan, whereas decreased soil moisture prolongs root lifespan. Fine roots grew thinner and deeper in warm soil and showed higher emergence in winter but lower emergence in summer; all factors affected the fine root lifespan in an integrated manner. Glucose addition stimulated fine root respiration only in warm soil, indicating a depletion of readily available carbohydrates under warming. Overall, our findings suggest that warming could accelerate the input of C by roots into soil due to shortened fine root lifespans, highlighting the important consideration of simultaneously increasing temperature and its co-varying factors to predict root lifespan under climate change.