Non-structural Carbohydrates Research Articles

Responses of Physiological Traits and Soil Properties in Pinus thunbergia and Euonymus japonicus Saplings under Drought and Cadmium (Cd) Stress

Pinus thunbergii and Euonymus japonicus are two species commonly found in arid and semi-arid areas; however, their responses in terms of physiological traits and soil properties under drought and cadmium (Cd) stress are not clear. In this study, we carried out single and combined stress treatments consisting of drought and Cd on saplings of P. thunbergii and E. japonicus and investigated the responses in terms of the physiological traits and soil properties of both species. For both species, under single Cd stress, Cd was observed in both the xylem and phloem, while the root Cd2+ flow rate fluctuated at different levels of Cd stress. Under both single and combined stress, as the stress level increased, the abscisic acid (ABA) content of the leaves and roots increased significantly, while the indole-3-acetic acid (IAA) content of the leaves and roots decreased significantly. Moreover, the non-structural carbohydrate (NSC) content of the leaves, stems, and roots, as well as the leaf chlorophyll content, decreased significantly. Under drought stress, the xylem water potential and hydraulic conductivity significantly decreased, which was exacerbated by Cd stress; this led to a more significant decrease in water potential and hydraulic conductivity under the combined stresses. Meanwhile, no significant changes in the conduit lumen diameter and double-wall thickness were observed, except for the double cell wall thickness of the P. thunbergii tracheid, which increased. In addition, both the single stresses and the combined stress of drought and Cd induced significant changes in the soil properties of the two species, i.e., the ammonium nitrogen, nitrate nitrogen, and effective phosphorus of the soil increased significantly, and the increase in content was more significant under combined stress. The diversity of the soil microbial community of P. thunbergii saplings significantly increased, while no change was found in its microbial community abundance under the single stresses and combined stress; however, the diversity and abundance of the soil microbial community in E. japonicus saplings showed the opposite pattern, which indicates that the effect of Cd on soil microorganisms is more significant than the effect of drought. The activity of sucrase and catalase in P. thunbergii soil fluctuated under the single stress and combined stress when compared, and the activity of sucrase in the soil of the E. japonicus species decreased. However, its catalase activity increased significantly under the single drought and Cd stress and combined stress when compared. We found that the combined stresses exacerbated the effects of the single stress in both species. Our study provides more detailed information on the responses in terms of the physiological traits and soil properties of the two species under single and combined stress consisting of drought and Cd.

Seasonal coordination of aboveground vegetative and reproductive growth and storage in apple trees subjected to defoliation, flower and fruit thinning

Key messageThe growth rates of current-year shoots, fruits and trunks in apple trees peak sequentially during the growing season. The period of most intense growth coincided with the lowest NSC reserves.Vegetative and reproductive growth and storage are major carbon sinks in fruit trees; however, little is known about their mutual seasonal coordination. In this study, we monitored growth dynamics of trunks, fruits and current-year shoots together with the concentration of non-structural carbohydrates (NSC) in trees subjected to defoliation, early season flower thinning, mid-season fruit thinning and their respective combinations across the season. We found that defoliation had a negative effect on both trunk radial growth and annual fruit yield. Flower and fruit thinning caused lower fruit number per tree, but the individual fruits were larger resulting in a similar annual fruit yield among the treatments. Shoot extension growth was not significantly affected by the defoliation and flower and fruit thinning treatments. The concentration of non-structural carbohydrates was also similar across treatments. Modelled daily growth rates of shoots, fruits and trunks peaked sequentially one after another throughout the growing season with a delay of 15 and 18 days, respectively. The period of most intense growth of tree’s organs corresponded well with the lowest NSC reserves and a temporary depletion of starch in 1-year-old branches. Taken together, our study illustrates a tight temporal coordination of major carbon sinks and improves our understanding of sink/source relations of commercially important apple trees.

Spaceborne imaging spectroscopy enables carbon trait estimation in cover crop and cash crop residues

PurposeCover crops and reduced tillage are two key climate smart agricultural practices that can provide agroecosystem services including improved soil health, increased soil carbon sequestration, and reduced fertilizer needs. Crop residue carbon traits (i.e., lignin, holocellulose, non-structural carbohydrates) and nitrogen concentrations largely mediate decomposition rates and amount of plant-available nitrogen accessible to cash crops and determine soil carbon residence time. Non-destructive approaches to quantify these important traits are possible using spectroscopy.MethodsThe objective of this study was to evaluate the efficacy of spectroscopy instruments to quantify crop residue biochemical traits in cover crop agriculture systems using partial least squares regression models and a combination of (1) the band equivalent reflectance (BER) of the PRecursore IperSpettrale della Missione Applicativa (PRISMA) imaging spectroscopy sensor derived from laboratory collected Analytical Spectral Devices (ASD) spectra (n = 296) of 11 cover crop species and three cash crop species, and (2) spaceborne PRISMA imagery that coincided with destructive crop residue collections in the spring of 2022 (n = 65). Spectral range was constrained to 1200 to 2400 nm to reduce the likelihood of confounding relationships in wavelengths sensitive to plant pigments or those related to canopy structure for both analytical approaches.ResultsModels using laboratory BER of PRISMA all demonstrated high accuracies and low errors for estimation of nitrogen and carbon traits (adj. R2 = 0.86 − 0.98; RMSE = 0.24 − 4.25%) and results indicate that a single model may be used for a given trait across all species. Models using spaceborne imaging spectroscopy demonstrated that crop residue carbon traits can be successfully estimated using PRISMA imagery (adj. R2 = 0.65 − 0.75; RMSE = 2.71 − 4.16%). We found moderate relationships between nitrogen concentration and PRISMA imagery (adj. R2 = 0.52; RMSE = 0.25%), which is partly related to the range of nitrogen in these senesced crop residues (0.38–1.85%). PRISMA imagery models were also influenced by atmospheric absorption, variability in surface moisture content, and some presence of green vegetation.ConclusionAs spaceborne imaging spectroscopy data become more widely available from upcoming missions, crop residue trait estimates could be regularly generated and integrated into decision support tools to calculate decomposition rates and associated nitrogen credits to inform precision field management, as well as to enable measurement, monitoring, reporting, and verification of net carbon benefits from climate smart agricultural practice adoption in an emerging carbon marketplace.

Allium Cepa L. Var. Aggregatum Don – A Treasure Of Micronutrients and Non-structural Carbohydrates

The study was conducted with four aggregatum onion viz., Co (On) 5, Co (On) 6, Local Perambalur (LP) and Local Manachanalur (LM), varieties of Tamil Nadu. Selected micronutrients were analyzed in which, the LP variety was reported to be higher in Na, K, Ca, Zn, Mn, Mg and Se. Similarly, the highest folic acid (48.23 ± 0. 47 mg/Kg) and pyruvic acid (3.02 ± 0. 02µmole g-1) was observed in the same variety. Non-structural carbohydrates, fructose and sucrose were found higher (463.8 ± 0.26 and 257.37 ± 3. 49 mg/kg) in LP variety. However, LM variety is higher in glucose (1169.57 ± 33.73 mg/kg), galactose (234.4 ± 0.62 mg/kg) and maltose (227.2 ± 1.44 mg/kg). This study therefore, provides preliminary information on micronutrients and non-structural carbohydrates of selected aggregatum onion varieties of Tamil Nadu. Bangladesh J. Bot. 53(2): 243-247, 2024 (June)

Influence of Replacing Soybean Meal with Nigella sativa Seed Meal on Feed Intake, Digestibility, Growth Performance, Blood Metabolites, and Antioxidant Activity of Growing Lambs.

The present experiment aimed to evaluate the partial or complete substitution of soybean meal (SBM) with Nigella sativa seed meal (NSM) on chemical composition, in vitro ruminal fermentation, and the growth performance and economic efficiency of growing lambs. Thirty-two male Ossimi lambs weighing 41 ± 0.4 kg at 195 ± 5 d were divided randomly into four experimental groups of eight lambs each. Lambs were fed four diets containing 40% berseem clover and 60% concentrate feed mixture. Soybean meal was replaced with NSM at 0% (NSM0; control), 50% (NSM50), 75% (NSM75), or 100% (NSM100). The experiment lasted for 105 d, consisting of 15 d for adaptation and 90 days for measurements. Higher concentrations of crude protein (CP) and nonstructural carbohydrates were observed with SBM; however, NSM contained more fibers and gross energy. Moreover, SBM contained higher concentrations of individual amino acids and lower concentrations of polyphenols. The replacement did not affect in vitro gas production and decreased (p < 0.05) methane production and CP degradability. Treatments did not affect feed intake, nutrient digestibility, and diet's nutritive value measured as starch value, total digestible nutrient, digestible energy, and apparent digestible crude protein. The NSM50 and NSM75 treatments increased (p < 0.001) total weight gain and daily gain compared to the control treatment, with lower feed conversion values associated with the NSM75 treatment. Treatments decreased cholesterol (p = 0.028) and high-density lipoprotein (p = 0.029) and increased antioxidant activity. Higher economic efficiencies were observed with the NSM75 followed by NSM50 and then NSM100 treatments. It is concluded that replacing 75% of SBM with NSM enhanced feed conversion and economic efficiency.

Radial Growth of Dahurian Larch (Larix gmelinii) Responses to Climate and Competition

The phenomenon of divergent responses in tree ring radial growth to climate change has been observed in the mid- and high-latitude regions of the Northern Hemisphere amidst global warming. However, the stability of the responses of the primary conifer species to climate factors in the mountainous regions of northeastern China remains unclear. Additionally, it is uncertain whether the radial growth in this area consistently responds to different competition indices. In our study, we developed tree ring width chronologies for Dahurian larch (Larix gmelinii) and analysed the radial growth responses to the regional climate from 1980 to 2012. This analysis was conducted by correlating meteorological data from different physiological stages of trees. We also evaluated the reliability of competition indices in predicting tree growth by constructing multiple linear regression models. Furthermore, we explored the relationship between the Basal Area Increment (BAI) of each tree and the competition indices in the sample plot over the previous five years. Our results showed that the temperature during the Non-Structural Carbohydrate (NSC) accumulation period and the NSC consumption period was significantly negatively correlated with the Ring Width Index (RWI) of Dahurian larch. Conversely, the RWI was significantly positively correlated with precipitation during these periods. The Standardised Precipitation Evapotranspiration Index (SPEI) at any period had a significantly positive correlation with the RWI. These findings suggest that future radial growth is likely to continue to be constrained by rising temperatures and water scarcity. Our findings also demonstrated that radial growth was less negatively impacted by competition from nearby trees and more influenced by the initial size of the tree. Compared to models that included other indices, models that included the BAL index as a single explanatory variable demonstrated superior statistical effectiveness. Our research suggests that before evaluating the competitive effects of the neighbourhood on radial growth, it is necessary to consider the stand diversity of tree species and the parameters related to spatial structure when selecting an appropriate competition index.

Post-heading accumulation of nonstructural carbohydrates and nitrogen in rice (Oryza sativa L.) roots

ContextRoots are plant organs that absorb nutrients and water. While roots serve as sink organs for nutrients in perennial and woody plant species, the dynamics of nutrient accumulation in roots for annual plant species, particularly in crop species like Oryza sativa L. (rice), are not well understood. Japanese rice cultivars bred for whole-crop silage exhibit large aboveground biomass and a notably small number of spikelets. This sink-source imbalance leads to the accumulation of non-structural carbohydrates (NSC) in stems after heading. Research questionIt is hypothesized that rice cultivars with substantial aboveground biomass might also develop significant belowground biomass. Consequently, the sink-source imbalance may result in NSC accumulation in roots. This study aims to test two hypotheses: firstly, that newly developed small-panicle rice cultivars accumulate NSC in roots post-heading, and secondly, that this post-heading NSC accumulation in roots can be influenced by cultural practices affecting spikelet number per panicle. MethodsTwo small-panicle cultivars, Tachisuzuka and Tachiayaka, and two large-panicle cultivars, Kusanohoshi and Hoshiaoba, were grown using different methods of three cultural practices: nitrogen application, transplanting season, and planting density. Measurements of dry matter, NSC (starch and sugars), and nitrogen in each plant part (panicle, leaf, stem, and roots) were taken over time after heading. The spikelet number per panicle was also counted. ResultsPost-heading, the small-panicle cultivars exhibited NSC accumulation in roots, a phenomenon not observed in the large-panicle cultivars. Although the three cultural practices altered the spikelet number per panicle and thus the sink capacity of the small-panicle cultivars, root NSC accumulation remained unaffected. Additionally, nitrogen weight per unit field area increased with increases in root weight in the small-panicle cultivars. ConclusionsThe imbalance in the sink-source relationship is likely responsible for the post-heading NSC accumulation in roots observed in small-panicle cultivars. However, the lack of root response in NSC accumulation to changes in panicle sink capacity suggests other mechanisms might be involved in root NSC accumulation. Notably, significant amounts of NSC and nitrogen remain in the roots of small-panicle cultivars after harvest. ImplicationsThe accumulation of NSC and nitrogen in roots post-heading could potentially enhance crop growth in subsequent years.

Water-Saving Irrigation and N Reduction Increased the Rice Harvest Index, Enhanced Yield and Resource Use Efficiency in Northeast China

For agricultural production, improving the rice harvest index (HI) through agricultural management practices is a major means to enhance water and N utilization efficiency and yield. Both irrigation regimes and nitrogen (N) rates are important aspects of agricultural management practices. However, it is unclear how the rice HI is affected by water and N. This study aimed to clarify the mechanism underlying the response of the rice HI to water and N, and to explore the most suitable water-saving and N reduction management practices to ensure yield. A two-year (2021~2022) field experiment was conducted on Mollisols in Northeast China. In this experiment, nine treatments were performed, involving three irrigation regimes (flooded irrigation, controlled irrigation, and “thin-shallow-wet-dry” irrigation) and three N rates (110, 99, and 88 kg/ha). The rice agronomic traits and transfer of photoassimilates under different water and N management practices were observed and studied; rice HI, WUE, and the NUE of rice was calculated and analyzed. The highest HI was achieved under controlled irrigation with a 99 kg/ha N rate, at values of 0.622 and 0.621 in 2021 and 2022, respectively. Controlled irrigation (CI) with an appropriate reduction in the N rate increased the proportion of productive tillers, the transfer rate of dry matter and non-structural carbohydrates (NSCs), the sugar–spikelet ratio, the grain–leaf ratio, and the leaf area index (LAI) during the heading–flowering stage. A subsequent analysis indicated that the main reason for the increase in the HI was the increase in the sugar–spikelet ratio during the heading–flowering stage. A high HI increased the rice yield by increasing the thousand-grain weight. The present study suggested that water-saving irrigation regimes and appropriate N reduction not only led to water and fertilizer resource savings but also improved agronomic characteristics during rice growth and enhanced transport capacity. Thus, these practices improved the rice HI and have enormous potential for increasing yield. Therefore, regulating the rice HI through water and N management methods should be considered an important strategy for improving rice yield.

New Intrinsic Ecological Mechanisms of Leaf Nutrient Resorption in Temperate Deciduous Trees.

Leaf nutrient resorption is a critical process in plant nutrient conservation during leaf senescence. However, the ecological mechanisms underlying the large variability in nitrogen (NRE) and phosphorous (PRE) resorption efficiencies among trees remain poorly understood. We conducted a comprehensive study on NRE and PRE variability using 61 tree individuals of 10 temperate broad-leaved tree species. Three potentially interrelated intrinsic ecological mechanisms (i.e., leaf senescence phenology, leaf pigments, and energy residual) were verified. We found that a delayed leaf senescence date, increased degradation of chlorophylls and carotenoids, biosynthesis of anthocyanins, and reduced nonstructural carbohydrates were all positively correlated with NRE and PRE at the individual tree level. The intrinsic factors affecting resorption efficiency were ranked in decreasing order of importance: leaf pigments > energy residual > senescence phenology. These factors explained more variability in NRE than in PRE. Our findings highlight the significance of these three ecological mechanisms in leaf nutrient resorption and have important implications for understanding how nutrient resorption responds to climate change.

Auxins differentially affect growth in Scots pine and Norway spruce in spring and autumn

Trees adapt to changing environmental conditions largely by regulating growth processes, and ongoing climate aridization puts pressure on growth processes during spring and summer. However, trees can be limited in their ability to utilize favourable early-season and late-season conditions for growth, and many of these limitations can be due to shortages in auxin transport and/or signalling. We studied whether leaf spraying with auxins in spring and autumn can aid in the growth of Pinus sylvestris and Picea abies saplings. In spring, spruce demonstrated prominent positive effects of auxin supplementation on the growth of current-year shoot and xylem growth, with increased xylem cell formation, whereas a limited effect was observed in pine. Autumnal auxin treatment had prominent positive effects on the growth of the root system and xylem area in pine, activating xylem cell enlargement and increasing carbon deposition in cell walls. In spruce, the effects of auxin spraying on xylem growth were less prominent, and the effects on root growth were absent compared to those in pine. The metabolome analysis of pine organs demonstrated that the activation of growth processes in the xylem and roots was accompanied by a decrease in nonstructural carbohydrates in the cambial zone but an increase in roots, indicating that auxin influenced the link between growth and carbon balance in an organ-specific manner. The major amino acid content was not influenced by auxin treatment. The observed results indicate that changes in the auxin balance during the autumnal period can activate growth processes to increase plant adaptation to changing climate conditions.

Modeling cassava root system architecture and the underlying dynamics in shoot–root carbon allocation during the early storage root bulking stage

Abstract Background and aims Plants store carbohydrates for later use during, e.g., night, drought, and recovery after stress. Carbon allocation presents the plant with tradeoffs, notably between growth and storage. We asked how this tradeoff works for cassava (Manihot esculenta) pre- and post-storage root (SR) formation and if manipulation of the number of storage organs and leaf growth rate might increase yield. Methods We developed a functional-structural plant model, called MeOSR, to simulate carbon partitioning underlying cassava growth and SR formation in conjunction with the root system's three-dimensional (3D) architecture (RSA). We compared the model results to experimental data and simulated phenotypes varying in the number of SR and leaf growth rate. Results The simulated 3D RSA and the root mass closely represented those of field-grown plants. The model simulated root growth and associated carbon allocation across developmental stages. Substantial accumulation of non-structural carbohydrates (NSC) preceded SR formation, suggesting sink-limited growth. SR mass and canopy photosynthesis might be increased by both increasing the number of SR and the leaf growth rate. Conclusion MeOSR offers a valuable tool for simulating plant growth, its associated carbon economy, and 3D RSA over time. In the first month, the specific root length increased due to root branching, but in the third month, it decreased due to secondary root growth. The accumulation of NSC might initiate SR development in cassava. Cassava growth is relatively slow during the first 3 months, and a faster crop establishment combined with a greater SR growth might increase yield.

Effects of warming on the seedling adaptation and growth of Machilus gamblei in a subtropical forest

Accurate predictions of community stability feedback to climate warming depend on an advanced understanding of responses of the key species. The transition from seed germination to seedling establishment is the most vulnerable stage of plants, which determines the maintenance of plant diversity and community resistance to climate change. To elucidate how the establishment and physiological characteristics of Machilus gamblei seedlings will respond to future global warming, artificial warming experiments (infrared warming, +0.75 ℃, +1.5 ℃, +3 ℃, +4 ℃) were conducted at the Ailao Mountain National Nature Reserve in Yunnan Province, China. The responses of seedling establishment and their physiological adaptation to different warming conditions were studied, and the contents of nutrients, chlorophyll, and nonstructural carbohydrate (NSC) in the leaves were measured. The results showed that: (1) increasing the temperature by 0.75 ℃ did not affect the survival rate or physiological characteristics of the seedlings, but increasing the temperature by 4 ℃ reduced the survival rate of the seedlings; (2) As the temperature increased from 1.5 ℃ to 3 ℃, the chlorophyll production in the seedling leaves improved, thus particularly promoting the accumulation of NSC by increasing the starch content. In summary, our work suggests that the temperature increase in 1.5 ℃ and 3 ℃ might be conducive to the establishment and growth of Machilus gamblei seedlings in the two-year experimental period, but increasing the temperature by 4 ℃ would threaten their survival and development.

Perturbation of tonoplast sucrose transport alters carbohydrate utilization for seasonal growth and defense metabolism in coppiced poplar.

Nonstructural carbohydrate reserves of stems and roots underpin overall tree fitness and productivity under short-rotation management practices such as coppicing for bioenergy. While sucrose and starch comprise the predominant stem carbohydrate reserves of Populus, utilization for fitness and agricultural productivity is understood primarily in terms of starch turnover. The tonoplast sucrose transport protein SUT4 modulates sucrose export from source leaves to distant sinks during photoautotrophic growth, but the possibility of its involvement in remobilizing carbohydrates from storage organs during heterotrophic growth has not been explored. Here, we used PtaSUT4-knockout mutants of Populus tremula × P. alba (INRA 717-1B4) in winter (cool) and summer (warm) glasshouse coppicing experiments to assess SUT4 involvement in reserve utilization. Conditions preceding and supporting summer sprouting were considered favorable for growth, while those preceding and supporting cool temperature sprouting were suboptimal akin to conditions associated with coppicing as generally practiced. Epicormic bud emergence was delayed in sut4 mutants following lower temperature 'winter' but not summer coppicing. Winter xylem hexose increases were observed in control but not in sut4 stumps after coppicing. The magnitude of starch and sucrose reserve depletion was similar in control and sut4 stumps during the winter and did not explain the sprouting and xylem hexose differences. However, winter maintenance costs appeared higher in sut4 based partly on Krebs cycle intermediate levels. In control plants, bark accrual of abundant defense metabolites, including salicinoids and condensed tannins, was higher in summer than in winter, but this increase of summer defense allocations was attenuated in sut4 mutants. Temperature-sensitive trade-offs between growth and other priorities may therefore depend on SUT4 in Populus.

Seasonal dynamics and punctuated carbon sink reduction suggest photosynthetic capacity of boreal silver birch is reduced by the accumulation of hexose.

The 'assimilates inhibition hypothesis' posits that accumulation of nonstructural carbohydrates (NSCs) in leaves reduces leaf net photosynthetic rate, thus internally regulating photosynthesis. Experimental work provides equivocal support mostly under controlled conditions without identifying a particular NSC as involved in the regulation. We combined 3-yr in situ leaf gas exchange observations (natural dynamics) in the upper crown of mature Betula pendula simultaneously with measurements of concentrations of sucrose, hexoses (glucose and fructose), and starch, and similar measurements during several one-day shoot girdling (perturbation dynamics). Leaf water potential and water and nitrogen content were measured to account for their possible contribution to photosynthesis regulation. Leaf photosynthetic capacity (A/Ci) was temporally negatively correlated with NSC accumulation under both natural and perturbation states. For developed leaves, leaf hexose concentration explained A/Ci variation better than environmental variables (temperature history and daylength); the opposite was observed for developing leaves. The weaker correlations between NSCs and A/Ci in developing leaves may reflect their strong internal sink strength for carbohydrates. By contrast, the strong decline in photosynthetic capacity with NSCs accumulation in mature leaves, observed most clearly with hexose, and even more tightly with its constituents, provides support for the role of assimilates in regulating photosynthesis under natural conditions.

The Growth and Non-Structural Carbohydrate Response Patterns of Siberian Elm (Ulmus pumila) under Salt Stress with Different Intensities and Durations

The Growth and Non-Structural Carbohydrate Response Patterns of Siberian Elm (Ulmus pumila) under Salt Stress with Different Intensities and Durations

Divergent effects of single and combined stress of drought and salinity on the physiological traits and soil properties of Platycladus orientalis saplings.

Drought and salinity are two abiotic stresses that affect plant productivity. We exposed 2-year-old Platycladus orientalis saplings to single and combined stress of drought and salinity. Subsequently, the responses of physiological traits and soil properties were investigated. Biochemical traits such as leaf and root phytohormone content significantly increased under most stress conditions. Single drought stress resulted in significantly decreased nonstructural carbohydrate (NSC) content in stems and roots, while single salt stress and combined stress resulted in diverse response of NSC content. Xylem water potential of P. orientalis decreased significantly under both single drought and single salt stress, as well as the combined stress. Under the combined stress of drought and severe salt, xylem hydraulic conductivity significantly decreased while NSC content was unaffected, demonstrating that the risk of xylem hydraulic failure may be greater than carbon starvation. The tracheid lumen diameter and the tracheid double wall thickness of root and stem xylem was hardly affected by any stress, except for the stem tracheid lumen diameter, which was significantly increased under the combined stress. Soil ammonium nitrogen, nitrate nitrogen and available potassium content was only significantly affected by single salt stress, while soil available phosphorus content was not affected by any stress. Single drought stress had a stronger effect on the alpha diversity of rhizobacteria communities, and single salt stress had a stronger effect on soil nutrient availability, while combined stress showed relatively limited effect on these soil properties. Regarding physiological traits, responses of P. orientalis saplings under single and combined stress of drought and salt were diverse, and effects of combined stress could not be directly extrapolated from any single stress. Compared to single stress, the effect of combined stress on phytohormone content and hydraulic traits was negative to P. orientalis saplings, while the combined stress offset the negative effects of single drought stress on NSC content. Our study provided more comprehensive information on the response of the physiological traits and soil properties of P. orientalis saplings under single and combined stress of drought and salt, which would be helpful to understand the adapting mechanism of woody plants to abiotic stress.

Variability in soybean yield responses to elevated atmospheric CO2: Insights from non-structural carbohydrate remobilisation during seed filling

The increasing atmospheric CO2 concentration (e[CO2]) has mixed effects on soybean most varieties’ yield. This study elucidated the effect of e[CO2] on soybean yield and the underlying mechanisms related to photosynthetic capacity, non-structural carbohydrate (NSC) accumulation, and remobilisation. Four soybean cultivars were cultivated in open-top chambers at two CO2 levels. Photosynthesis rates were determined from R2 to R6. Plants were sampled at R5 and R8 to determine carbohydrate concentrations. There were significant variations in yield responses among the soybean cultivars under e[CO2], from no change in DS1 to a 22% increase in SN14. DS1 and SN14 had the smallest and largest increase, respectively, in daily carbon assimilation capacity. Under e[CO2], DS1, MF5, and XHJ had an increase in Ci, at which point the transition from Rubisco-limited to ribulose-1,5-bisphosphate regeneration-limited photosynthesis occurred, in contrast with SN14. Thus, the cultivars might have distinct mechanisms that enhance photosynthesis under e[CO2] conditions. A positive correlation was between daily carbon assimilation response to e[CO2] and soybean yield, emphasising the importance of enhanced photosynthate accumulation before the R5 stage in determining yield response to e[CO2]. E[CO2] significantly influenced NSC accumulation in vegetative organs at R5, with variation among cultivars. There was enhanced NSC remobilisation during seed filling, indicating cultivar-specific responses to the remobilisation of sucrose and soluble sugars, excluding sucrose and starch. A positive correlation was between leaf and stem NSC remobilisation and yield response to e[CO2], emphasising the role of genetic differences in carbohydrate remobilisation mechanisms in determining soybean yield variation under elevated CO2 levels.

Effect of nonstructural carbohydrates on production performance, rumen metabolism and rumen health in lambs fed with isocaloric and isonitrogenous complete diets.

Nonstructural carbohydrates (NSC) are readily fermentable in the rumen and, are a critical factor while preparing protracted feed for higher animal performance. Four isocaloric and isonitrogenous complete feeds were prepared for this investigation to contain varying levels of nonstructural carbohydrates viz., 40.13 (NSC1), 45.21 (NSC2), 50.00 (NSC3) and 55.85 (NSC4) per cent, respectively. The four isocaloric and isonitrogenous complete feeds were tested in 32 Mecheri ram lambs (around three months of age) in a completely randomised block design (n = 8), and the lambs were fed their respective feed for six months. The study revealed that the increased NSC level in the complete diet increased the body weight and weight gain linearly (P < 0.05). The dietary NSC level affected the dry matter consumption in a quadratic manner (P < 0.05) and the lambs of the NSC4 group consumed significantly (P < 0.05) less DM compared to other dietary groups. The overall average feed conversion efficiency differed significantly (P < 0.05) among dietary groups. The correlation between dietary NSC level and faecal score was quadratic (r2 = 62.7, P < 0.05). The rumen pH, total nitrogen and NH3-N concentration were linearly decreased (P < 0.05) and the molar proportion of total short-chain fatty acids and propionic acid were increased (P < 0.05). The energy loss expressed as methane production was significantly (P < 0.01) lower for the high NSC diet-fed lambs. The lambs fed on a low NSC diet had significantly (P < 0.05) lower carcass weights, dressing percentage and loin eye area. The per cent share of rumen weight in the total fore stomach and the rumen papillae measurements length, width and surface area were significantly (P < 0.05) higher in high NSC diet-fed lambs. Increased levels of NSC in the diet increased (P < 0.05) fat deposition in the internal organs. The saturated fatty acids content in the meat was significantly (P < 0.05) lowered, whereas, the oleic acid and linoleic acid were increased (P < 0.05) as the NSC level increased in the diet. The study revealed that as the level of NSC increased in the complete diet there was a concomitant improvement in the final body weight, ADG and feed efficiency of post-weaned Mecheri lambs. It can therefore be recommended that the complete feed with 50 per cent NSC levels would be optimum to reap maximum returns from fattening Mecheri lambs.

The Application Timing of a Cytokinin B-Mo-based Product Affects the Characteristics of Rooted Cuttings and Nonstructural Carbohydrates of Coleus (Plectranthus scutellarioides cv. Wild Lime) during Adventitious Root Development

A large group of horticulture species are propagated vegetatively through shoot-tip cuttings harvested from stock plants and planted to form adventitious roots. Adventitious rooting leads to establishing a carbohydrate sink in the region of root regeneration that is highly dependent on energy and carbon skeletons. We hypothesized that the timing of exogenous applications of cytokinin (CK) and boron (B)–molybdenum (Mo)-based products during adventitious root development can affect the flow of sugars from leaves to sinks, carbon allocation to the adventitious roots, and the quality of rooted cuttings. During this project, we aimed to determine if the application time of a CK/B-Mo-based product during the adventitious root development of unrooted cuttings would impact the source-to-sink relationship and, hence, affect plug growth and quality. A sink-strengthening commercial product based on cytokinin, B, and Mo was applied at four plug development stages plus a negative control as follows: T1, plants without product (control); T2, sticking stage (starting 24 hours after the sticking); T3, callus formation stage; T4, root development stage; and T5, toning stage. The root and shoot lengths and dry matter, number of leaves, leaf chlorophyll content, root-to-shoot ratio (based on dry matter), and nonstructural carbohydrate contents were measured. The timing of the application of the product impacted the root development, quality of the cuttings, and nonstructural carbohydrate content. Product application during the adventitious root dedifferentiation and induction phases (T2) resulted in the shortest root and shoot lengths, lowest dry matter accumulation, lowest nonstructural carbohydrate contents, and some phytotoxicity. Application during the initiation phase (T3) resulted in greater root length, total dry matter, and total soluble sugar contents compared with the control. Application during the expression phase (T4) resulted in the largest root length and mass and the highest sucrose contents. Applying the product when the roots had grown and reached all the edges of the growing media (T5) did not have any benefits compared with the control. This study provides new insights into the application timing of exogenous CKs, B, and Mo to generate a well-toned rooted coleus cutting and potential explanations in relation to nonstructural carbohydrate metabolism.

Windthrow causes declines in carbohydrate and phenolic concentrations and increased monoterpene emission in Norway spruce.

With the increasing frequencies of extreme weather events caused by climate change, the risk of forest damage from insect attacks grows. Storms and droughts can damage and weaken trees, reduce tree vigour and defence capacity and thus provide host trees that can be successfully attacked by damaging insects, as often observed in Norway spruce stands attacked by the Eurasian spruce bark beetle Ips typographus. Following storms, partially uprooted trees with grounded crowns suffer reduced water uptake and carbon assimilation, which may lower their vigour and decrease their ability to defend against insect attack. We conducted in situ measurements on windthrown and standing control trees to determine the concentrations of non-structural carbohydrates (NSCs), of phenolic defences and volatile monoterpene emissions. These are the main storage and defence compounds responsible for beetle´s pioneer success and host tree selection. Our results show that while sugar and phenolic concentrations of standing trees remained rather constant over a 4-month period, windthrown trees experienced a decrease of 78% and 37% of sugar and phenolic concentrations, respectively. This strong decline was especially pronounced for fructose (-83%) and glucose (-85%) and for taxifolin (-50.1%). Windthrown trees emitted 25 times greater monoterpene concentrations than standing trees, in particular alpha-pinene (23 times greater), beta-pinene (27 times greater) and 3-carene (90 times greater). We conclude that windthrown trees exhibited reduced resources of anti-herbivore and anti-pathogen defence compounds needed for the response to herbivore attack. The enhanced emission rates of volatile terpenes from windthrown trees may provide olfactory cues during bark beetle early swarming related to altered tree defences. Our results contribute to the knowledge of fallen trees vigour and their defence capacity during the first months after the wind-throw disturbance. Yet, the influence of different emission rates and profiles on bark beetle behaviour and host selection requires further investigation.