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ABSTRACT Assessing how dominant peatland species, such as Dasiphora fruticosa, adapt to water table decline is crucial to advance understanding of their growth and survival strategies. Currently, most studies have primarily focused on their growth and biomass, with limited knowledge on the response of non‐structural carbohydrates (NSCs) and physiological adaptations of these woody plants under long‐term drainage. This study assessed the response of photosynthesis and transpiration rates, biomass, and NSC concentrations (including soluble sugars and starch) in the leaves, stems, and roots of D. fruticosa to long‐term drainage in a minerotrophic peatland. The aim was to elucidate the plant response and adaptation mechanisms to water table decline. Dasiphora fruticosa effectively regulated carbon (C) demand and supply by significantly enhancing photosynthesis, transpiration, and biomass accumulation, thereby maintaining stable C storage as the water table declined. There was a notable reduction in soluble sugar concentration in leaves with increasing water table decline, while starch concentrations in all three organs remained relatively constant. Although the concentration of soluble sugars in leaves was consistently higher than that in roots and stems, the relative proportion of soluble sugars and starch gradually decreased in leaves and increased in roots and stems with water table decline. Our findings reveal that D. fruticosa reduces NSC concentrations in leaves while increasing biomass to adapt to water table decline. This acclimation might significantly impact C dynamics in peatlands. Understanding these mechanisms is vital for predicting the dynamics of C sequestration and emission in peatland ecosystems under changing environmental conditions. [ABSTRACT FROM AUTHOR]

Xylem plasticity is important for trees to coordinate hydraulic efficiency and safety under changing soil water availability. However, the physiological and transcriptional regulations of cambium on xylem plasticity are not well understood. In this study, mulberry saplings of drought-resistant Wubu and drought-susceptible Zhongshen1 were subjected to moderate or severe drought stresses for 21 days and subsequently rewatered for 12 days. The anatomical, physiological and transcriptional responses in wood and cambium were analyzed. Most parameters were not affected significantly under moderate drought for both cultivars. Severe drought led to decreased vessel lumen diameter and increased vessel frequency, increased starch and hemicellulose in wood of both cultivars. Notably, increased soluble sugars and lignin were detected only in wood of Wubu. In cambial zone, levels of starch, glucose, fructose, mannose and cytokinin were decreased in both cultivars, whereas soluble sugars were increased in Wubu but deceased in Zhongshen1. RNA-sequencing identified 1824 and 2471 differentially expressed genes in Wubu and Zhongshen1 under severe drought, respectively. These responses were partially recovered after rewatering. Weighted gene correlation network analysis identified modules of co-expressed genes correlated with the anatomical and physiological traits of wood and cambium, with the turquoise and green modules most strongly correlated with traits under drought or rewatering. These modules were enriched in gene ontology terms related to cell division, cytoskeleton organization, cell wall modification, dark respiration, vesicle transport and protein metabolism. Detailed gene expression patterns indicate that reprogramming of cambium activity was relatively similar in both cultivars, but at different scales. These findings provide important insights into the physiological and molecular mechanisms underlying xylem plasticity based on cambium and offer valuable references for breeding drought-resistant mulberry and other woody species in light of future drier climate scenarios. [ABSTRACT FROM AUTHOR]

The article explores the impact of differential warming on primary and secondary growth in walnut trees, highlighting the lack of coordination mechanisms between primary and secondary growth at the crown scale. The study reveals that elevated temperature affects the resumption and growth rate of primary and secondary meristems differently, leading to asymmetry in canopy growth. Additionally, the response of xylem and phloem to temperature variations may differ, emphasizing the need for further research on the coordination mechanisms between primary and secondary growth in trees. [Extracted from the article]

Forecasting the effects of global change drivers on ecosystems is one of the most pressing challenges for scientists worldwide. Particularly, climate change and exotic pathogens might have a large impact on plant community dynamics and ecosystem functioning through changes in carbon uptake and sinks. Nevertheless, we still have a poor understanding of the combined effects of these two drivers on plant communities.Here, we explored the impact of rainfall reduction and exotic pathogens on the carbon balance of Mediterranean tree species. For this, we performed a 3‐year field experiment taking advantage of rainfall exclusion infrastructures (30% exclusion) installed in the southernmost European oak forests invaded by the aggressive exotic pathogen Phytophthora cinnamomi. We measured a set of 10 variables representative of tree carbon sources (photosynthetic rates) and sinks (primary production, reproduction, defence, and reserves) in adult trees of three species in two forest types: closed forests of Quercus suber and Q. canariensis, and open woodlands of Q. suber and Olea europaea.We found a large variability in the sensitivity of the different carbon sources and sinks to the effects of drought and pathogens, from variables highly sensitive to both factors (carbon fixation and reproduction, root chemistry) to variables only responsive to drought (litter production) or totally unresponsive (tree trunk, leaf chemistry). Although negative effects predominated, positive effects of rainfall exclusion were also detected in wet years, likely due to a reduction of pathogen abundance in drier soil. Trade‐offs between carbon sinks appeared in all tree species, but rainfall exclusion only modified trade‐offs in Q. suber, the species most susceptible to P. cinnamomi.Synthesis. We provide evidence on the complexity of the combined effects of abiotic (drought) and biotic (pathogens) global change drivers on carbon source and sinks of adult trees, including both negative direct effects and positive indirect effects. Our results showed that these effects varied among co‐existing species, particularly for carbon sinks directly related to tree demography (reproduction). Therefore, long‐term changes in the structure of Mediterranean mixed forests might be expected towards the dominance of species highly resistant to both drought and pathogens. [ABSTRACT FROM AUTHOR]

The carbon and nitrogen (N) metabolism of rice under different mid-stage N compensation timings is unclear. Two Japonica super rice cultivars were examined under four N compensation timings (N1-N3: N compensation at mid-tillering, panicle initiation, and spikelet differentiation. N0: no N compensation) and CK with no N application. Mid-stage N compensation increased the N concentrations of various tissues, and N2 showed the highest plant N uptake at both the heading stage, maturity, and the grain filling period. Among the treatments, N2 showed the highest N utilization efficiency. With delayed compensation timing, there was a gradual decrease in soluble sugar and starch concentrations in each tissue, accompanied by a decline in the non-structural carbohydrate (NSC) concentration. Specifically, N2 treatment exhibited the highest NSC accumulation and the remobilized NSC reserve, but NSCs per spikelet decreased with delayed compensation timing. The highest yield was also obtained with N2, exhibiting a 4.5% increase compared to the N0 treatment, primarily due to an improvement in spikelets per panicle. Conclusively, N compensation at the panicle initiation stage is a reasonable N management strategy that can coordinate the improvement of carbon and N metabolism, enhance N accumulation with efficient utilization and NSC accumulation, and ultimately increase the yield. [ABSTRACT FROM AUTHOR]

It is of great global interest how shade-tolerant and sun-tolerant species will respond to the Representative Concentration Pathways (RCP) scenarios of climate change predicted by the end of the 21st century. To elucidate this question, we used young plants of the shade- and sun-tolerant ecotypes of Paubrasilia echinata, a tree native to the Brazilian Atlantic Forest. Plants were grown in three climate scenario simulations: current Atlantic Forest for the southeast region of Brazil (CAF); average temperature of CAF + 2.0 ºC and 580 ppm CO2 (RCP 4.5); and average temperature of CAF + 3.5 °C and 936 ppm CO2 (RCP 8.5). Two substrate moisture conditions were established for each scenario: 80 (control) and 40% (water deficit). After 90 days of cultivation in these microclimatic conditions, we carried out growth analyses (survival, number of pinna and leaflets of their compound leaves and increase in stem elongation), non-structural carbohydrate content (sugars and starch) and cell wall polymer content (cellulose, hemicelluloses and lignin). The pessimistic climate scenario (RCP 8.5 + water deficit) inhibited photosynthesizing leaf area production (number of pinna/leaflets) of the shade-tolerant ecotype more, but without affecting survival. In this climate scenario, the shade-tolerant ecotype showed a greater capacity to accumulate sugars than the other ecotype. Also in the pessimistic climate scenario, the shade-tolerant ecotype accumulated more of this polysaccharide in the stem, while in the sun-tolerant ecotype this occurred in the root. This scenario increased the cellulose content of both ecotypes to the detriment of the lignin content of the sun-tolerant ecotype. We conclude that the rise in CO2, temperature and vapor pressure deficit (VPD) along with low precipitation in RCP 8.5 predicted for the southeastern region of Brazil by the end of this century may compromise more the photosynthesizing leaf area production of the shade-tolerant ecotype and the wood quality of the sun-tolerant ecotype of P. echinata. However, this does not threaten their survival.Key message: RCP 8.5 climate change scenario increased sugar content and photosynthesizing leaf area production more intensely in Paubrasilia echinata plants of the shade-tolerant ecotype. Such climatic scenario inhibited the lignification of the sun-tolerant ecotype. [ABSTRACT FROM AUTHOR]

Abstract Background As precipitation patterns are predicted to become more erratic, it’s vital to understand how abrupt climate events will affect woody seedlings that develop different hydraulic strategies. We cultivated anisohydric Robinia pseudoacacia L. and isohydric Quercus acutissima Carr. in a greenhouse, and subjected an abrupt precipitation event during a successive drought. Patterns of leaf and root gas exchange, leaf and stem hydraulics, seedlings growth, and non-structural carbohydrate (NSC) patterns were determined. Results We found that as an anisohydric species, R. pseudoacacia seedlings adopted a strategy of sacrificing leaves in response to stress, resulting in the lowered photosynthesis and ultimately leading to a decrease in NSC accumulation. In contrast, isohydric Q. acutissima maintained the integrity of leaves by reducing respiratory consumption in response to drought stress, thereby ensured the stability of NSC pool. Conclusion R. pseudoacacia exhibited an extravagant strategy with efficient water transport, photosynthetic assimilation, and growth capabilities, but its resistance to embolism was relatively weak, while Q. acutissima adopted a resource-saving strategy with higher hydraulic safety. We also found that Q. acutissima seedlings were prone to allocate carbohydrates to maintain growth, while R. pseudoacacia preferred to sacrifice growth and aboveground NSC limitation only happened when precipitation was subjected after total stomatal closure. We thus believe that hydraulic strategy could define seedlings responses to drought and recovery, and further may adversely affect their re-sprouting capacity after drought stress relief.

Abstract Botryosphaeria dothidea is the main fungal pathogen responsible for causing Chinese hickory (Carya cathayensis) dry rot disease, posing a serious threat to the Chinese hickory industry. Understanding the molecular basis of B. dothidea infection and the host’s resistance mechanisms is crucial for controlling and managing the ecological impact of Chinese hickory dry rot disease. This study utilized ultrastructural observations to reveal the process of B. dothidea infection and colonization in Chinese hickory, and investigated the impact of B. dothidea infection on Chinese hickory biochemical indicators and plant hormone levels. Through high-throughput transcriptome sequencing, the gene expression profiles associated with different stages of B. dothidea infection in Chinese hickory and their corresponding defense responses were described. Additionally, a series of key genes closely related to non-structural carbohydrate metabolism, hormone metabolism, and plant-pathogen interactions during B. dothidea infection in Chinese hickory were identified, including genes encoding DUF, Myb_DNA-binding, and ABC transporter proteins. These findings provide important insights into elucidating the pathogenic mechanisms of B. dothidea and the resistance genes in Chinese hickory.

Background: As precipitation patterns are predicted to become more erratic, it's vital to understand how abrupt climate events will affect woody seedlings that develop different hydraulic strategies. We cultivated anisohydric Robinia pseudoacacia L. and isohydric Quercus acutissima Carr. in a greenhouse, and subjected an abrupt precipitation event during a successive drought. Patterns of leaf and root gas exchange, leaf and stem hydraulics, seedlings growth, and non-structural carbohydrate (NSC) patterns were determined. Results: We found that as an anisohydric species, R. pseudoacacia seedlings adopted a strategy of sacrificing leaves in response to stress, resulting in the lowered photosynthesis and ultimately leading to a decrease in NSC accumulation. In contrast, isohydric Q. acutissima maintained the integrity of leaves by reducing respiratory consumption in response to drought stress, thereby ensured the stability of NSC pool. Conclusion: R. pseudoacacia exhibited an extravagant strategy with efficient water transport, photosynthetic assimilation, and growth capabilities, but its resistance to embolism was relatively weak, while Q. acutissima adopted a resource-saving strategy with higher hydraulic safety. We also found that Q. acutissima seedlings were prone to allocate carbohydrates to maintain growth, while R. pseudoacacia preferred to sacrifice growth and aboveground NSC limitation only happened when precipitation was subjected after total stomatal closure. We thus believe that hydraulic strategy could define seedlings responses to drought and recovery, and further may adversely affect their re-sprouting capacity after drought stress relief. [ABSTRACT FROM AUTHOR]

Pinus yunnanensis is an endemic tree species in southwest China that has high ecological and economic benefits. Nowadays, global climate change is remarkable, the frequency of drought is increasing day by day, the distribution of rainfall is unbalanced, and even the phenomenon of alternating drought and flood has appeared, which is unfavorable to the growth of P. yunnanensis. We set up four treatments, namely normal water (CK), light drought (LD), moderate drought (MD), and severe drought (SD), and water content was controlled by the weighing method. After continuous drought for 30 days, re-watering was performed for 7 days. The stoichiometric characteristics of non-structural carbohydrates (NSC), soluble sugars (SS), and starch (ST), as well as carbon (C), nitrogen (N), and phosphorus (P), in various organs of P. yunnanensis seedlings were measured. The results revealed significant effects of re-watering on NSC and its components in P. yunnanensis seedlings. The SS and NSC contents in the leaves of P. yunnanensis seedlings treated with SD were significantly higher than those of the control. The C content in the leaves and stems of P. yunnanensis seedlings recovered to the CK level after re-watering under different drought degrees. The contents of N in different organs and P in the fine roots of P. yunnanensis seedlings increased after re-watering with the LD, MD, and SD treatments, while the C/N ratio decreased. In summary, the recovery mechanism of P. yunnanensis seedlings to re-watering varied with the drought degree. The contents and ratios of NSC, C, N, and P in different organs of P. yunnanensis seedlings were significantly affected by re-watering. Combining the phenotypic plasticity index and PCA results, seedlings of P. yunnanensis adapted to drought re-watering by adjusting leaf NSC, leaf P, stem SS/ST, fine root ST, and fine root NSC. [ABSTRACT FROM AUTHOR]

(1) Tree peony (Paeonia suffruticosa Andrews) is a woody ornamental plant originating from China, and beloved by people worldwide. Non-structural carbohydrates (NSCs) play a crucial role in regulating the flowering quality of tree peonies in both field and potted conditions. However, the effects of NSCs accumulation and allocation in various organs during the vegetative growth stage on the flowering quality of tree peony under forcing culture remains unclear. (2) Two-year-old grafted seedlings of tree peony cv. 'Luoyanghong' were subjected to orthogonal treatments to investigate the role of NSCs accumulation in plants' developmental process. We measured leaf photosynthetic capacity, NSCs accumulation in the organs of seedlings, observed key ornamental characteristics of flowering quality under forcing culture conditions, and evaluated the qualities of seedlings and flowers using the seedling index (SI) and flowering index (FI), respectively. (3) There was a significant positive correlation between leaf photosynthetic capacity and NSCs accumulation in both the whole plant and roots of potted tree peony. Roots were identified as the primary organs for NSCs accumulation in potted tree peonies. Sufficient NSCs accumulation in the plant, particularly in the roots during the defoliation period, was essential not only for enhancing the seedling quality of potted tree peonies but also for improving the flowering quality under forcing culture conditions. Both the seedling index (SI) and flowering index (FI) exhibited a significant dose-response with increasing root NSCs accumulation at defoliation. The T3 group, which involved slight root pruning (by 25%), combined with a high-concentration rooting agent (750 mg·L−1) and Metarhizium anisopliae (20 million U·mL−1), resulted in the highest photosynthetic capacity, SI, FI and NSCs accumulation status (NSCAR), making it the optimal treatment combination. (4) This finding indicates that increasing NSCs accumulation in the roots of potted tree peonies is a crucial biological foundation for producing high-quality potted flowers under forcing culture conditions, which provide new insights into the importance of NSCs in tree peony flowering and may improve the production technology for high-quality potted tree peony flowers under forcing culture conditions. [ABSTRACT FROM AUTHOR]

Botryosphaeria dothidea is the main fungal pathogen responsible for causing Chinese hickory (Carya cathayensis) dry rot disease, posing a serious threat to the Chinese hickory industry. Understanding the molecular basis of B. dothidea infection and the host’s resistance mechanisms is crucial for controlling and managing the ecological impact of Chinese hickory dry rot disease. This study utilized ultrastructural observations to reveal the process of B. dothidea infection and colonization in Chinese hickory, and investigated the impact of B. dothidea infection on Chinese hickory biochemical indicators and plant hormone levels. Through high-throughput transcriptome sequencing, the gene expression profiles associated with different stages of B. dothidea infection in Chinese hickory and their corresponding defense responses were described. Additionally, a series of key genes closely related to non-structural carbohydrate metabolism, hormone metabolism, and plant-pathogen interactions during B. dothidea infection in Chinese hickory were identified, including genes encoding DUF, Myb_DNA-binding, and ABC transporter proteins. These findings provide important insights into elucidating the pathogenic mechanisms of B. dothidea and the resistance genes in Chinese hickory. [ABSTRACT FROM AUTHOR]

Ongoing climate change has a considerable influence on the seasonality, timing, and intensity of rainfall worldwide, and is also predicted to decrease snow cover in cold ecosystems. Larch is a widely distributed tree species in boreal Eurasia, calling for a comprehensive understanding of how larch adapts to changes in both rainfall and snowfall by adjusting carbon-water physiology. Here, we conducted a short-term rainfall (− 60% ambient rainfall; three-year) and snowfall (− 73% ambient snowfall; two-year) exclusions experiment in Larix gmelinii forest in northeastern China, and aimed to explore the responses of hydraulic (leaf pressure-volume traits, leaf and branch hydraulic conductivity and embolism resistance), stomatal (stomatal closure point and stomatal safety margin), and economic (photosynthetic rate, nutrient and non-structural carbohydrates contents) traits to rainfall and snowfall reductions. Despite the weak alternation of leaf and branch hydraulic traits, both rainfall and snowfall reductions significantly led to early stomatal closure and increased stomatal safety margins (the difference between stomatal closure point and xylem embolism threshold, describing drought resistance by merging both hydraulic and stomatal strategies). Reductions in rainfall and snowfall induced water or/and low-temperature stress, resulting in more conservative leaf economic traits, including a reduced photosynthetic rate, lower leaf nitrogen concentration, and higher leaf density. In addition, larch responded to reductions in rainfall and snowfall by up-regulating non-structural carbohydrates in the xylem, which helps repair embolism or lower the freezing point acting as osmolytes. Overall, our findings reveal that larch could adapt to the drought and snowpack reduction by strict stomatal regulation and investing non-structural carbohydrates in embolism repairing, at the cost of carbon assimilation. [ABSTRACT FROM AUTHOR]

Bambusa rigida was investigated to study the growth changes under different treatments, dynamic changes of non-structural carbohydrates (NSC) in the mother and new bamboos during rapid growth, and their correlation. In this study, we aimed to understand NSC supply from mother to new bamboos, optimize forest stand structure and harvesting methods, and reveal inherent rules of bamboo rapid growth. The aim of this study was to investigate the NSC supply pattern from mother bamboo to new bamboo, aiming to optimize stand structure and harvesting methods and provide insights into the rapid growth dynamics of bamboo. Two harvesting modes were implemented:retaining 1-year-old female bamboo (treatment Ⅰ) and retaining 1-and 2-year-old female bamboo (treatment Ⅱ), with non-harvested hard-headed yellow bamboo clumps serving as the control (CK) . This study analyzed bamboo shoot characteristics, bamboo formation, and biomass across different harvesting modes, comparing quantitative and qualitative changes in bamboo growth among the three treatments. The study examined dynamic changes in NSC content and water content in leaves, branches, culms, and roots of female bamboos during five critical growth stages of hard-headed yellow bamboo. This aimed to explore the supply-demand relationship of NSC between female bamboos and new bamboos at different developmental stages. Results showed that the reproduction rate of hard-headed yellow bamboo varied across treatments, with treatmentⅠ＞treatmentⅡ＞CK. Conversely, bamboo formation rate and new bamboo biomass were higher in CK＞treatmentⅡ＞treatmentⅠ, demonstrating significant differences between treatment Ⅰ and CK, and treatment Ⅱ (P＜0. 05), with no significant differences observed between CK and treatment Ⅱ. New bamboos originating from 1-year-old parent bamboos in different treatments exhibited the largest diameter at breast height, with their shoots, bamboo formation, and biomass accounting for over 90%of the total. During the rapid growth phase from shoot sprouting to growth cessation, NSC content in new bamboo generally increased initially before decreasing, peaking during rapid internode growth. NSC content in all organs of mother bamboo decreased gradually with age, with branches, leaves, culms, and roots of treatment Ⅰmother bamboo decreasing by 49. 70%, 54. 05%, 39. 85%, and 60. 86%, respectively, which were higher than those in treatmentⅡ's 1-year-old and 2-year-old female bamboos, with non-significant differences observed between the decreases of each organ in treatmentⅡ's 1-year-old and 2-year-old female bamboos. Correlation analysis indicated significant positive correlations between starch content in leaves, roots, and culms of treatmentⅠmother bamboo and NSC content, as well as between starch content in leaves, roots, and branches of 1-year-old mother bamboo and roots and culms of 2-year-old mother bamboo in treatmentⅡ (P＜0. 05) . In harvesting operations of hard-headed yellow bamboos, removing female bamboos aged 3 years and older while retaining 1-and 2-year-old female bamboos effectively enhanced bamboo forest productivity and reproductive capacity. Different harvesting treatments significantly influenced NSC transfer from parent bamboo to new bamboo. Specifically, when only 1-year-old mother bamboo was present, starch transfer to new bamboo primarily involved leaves, culms, and roots. When 1-and 2-year-old mother bamboos were present together, starch transfer involved branches, leaves, and roots of 1-year-old mother bamboo, with additional NSC transport from 2-year-old mother bamboo to new bamboo originating from 1-year-old mother bamboo. Thus, retaining 1-and 2-year-old mother bamboos during harvesting and management of hard-headed yellow bamboo forests is crucial to ensure sufficient nutrient supply during the rapid growth phase of new bamboos. [ABSTRACT FROM AUTHOR]

The injudicious use of water and fertilizer to maximize crop yield not only leads to environmental pollution, but also causes enormous economic losses. For this reason, we investigated the effect of nitrogen (N) (N0 (0), N60 (60 kg ha−1), and N120 (120 kg ha−1)) at different irrigation levels (I0 (0), I1200 (budding 600 m3 ha−1 + kernel 600 m3 ha−1), and I1800 (budding 900 m3 ha−1 + kernel 900 m3 ha−1)) on oilseed flax in the Loess Plateau of China in 2019 and 2020. The objective was to establish appropriate irrigation and fertilizer management strategies that enhance the grain yield (GY) of oilseed flax and maximize water and N productivity. The results demonstrated that irrigation and N application and their coupling effects promoted dry matter accumulation (DMA) and non-structural carbohydrate (NSC) synthesis, and increased the GY of oilseed flax. The contents of NSC in various organs of flax were closely related to grain yield and yield components. Higher NSC in stems was conducive to increased sink capacity (effective capsule number per plant (EC) and thousand kernel weight (TKW)), and the coupling of irrigation and N affected GY by promoting NSC synthesis. Higher GY was obtained by the interaction of irrigation and N fertilizer, with the increase rate ranging from 15.84% to 35.40%. Additionally, in the increased yield of oilseed flax, 39.70–78.06%, 14.49–54.11%, and −10.6–24.93% were contributed by the application of irrigation and nitrogen and the interaction of irrigation and nitrogen (I × N), respectively. Irrigation was the main factor for increasing the GY of oilseed flax. In addition, different climatic conditions changed the contribution of irrigation and N and their interaction to yield increase in oilseed flax. Drought and low temperature induced soluble sugar (SS) and starch (ST) synthesis to resist an unfavorable environment, respectively. The structural equation model showed that the key factors to increasing the GY of oilseed flax by irrigation and nitrogen fertilization were the differential increases in DMA, EC, and TKW. The increases in EC and TKW were attributed to the promotion of DMA and NSC synthesis in oilseed flax organs by irrigation, nitrogen fertilization, and their coupling effects. The I1200N60 treatment obtained higher water use efficiency (WUE) and N partial factor productivity (NPFP) due to lower actual evapotranspiration (ETa) and lower N application rate. Therefore, the strategy of 1200 m3 ha−1 irrigation and 60 kg ha−1 N application is recommended for oilseed flax in semi-arid and similar areas to achieve high grain yield and efficient use of resources. [ABSTRACT FROM AUTHOR]

The interaction between the amount and frequencies of nitrogen application has always been a hot issue in improving crop yield and reducing environmental pollution. Photosynthesis and non-structural carbohydrates (NSCs) play an important role in the formation of rice yield. However, the research on photosynthetic characteristics and NSCs under nitrogen fertilizer management on rice yield is still insufficient. This work was a two-year field trial in China's Hunan Province in 2020–2021. To analyze the photosynthetic characteristics and NSCs of the hybrid rice "Zhu Liangyou 819" (ZLY819), the experiment was set up with N application frequencies, specifically P1 (basal-tiller fertilizer at a ratio of 5:5), P2 (basal-tiller-spike fertilizer at a ratio of 4:3:3), and P3 (basal-tiller-spike-grain fertilizer at a ratio of 4:3:2:1). Additionally, three distinct amounts of N applications were utilized: N1 (90 kg ha−1), N2 (150 kg ha−1), and N3 (210 kg ha−1). The findings indicated that under the same N application amount, N2 increased the effective spike by 9.32–17.80% and the number of grains per spike by 12.21–13.28% compared with N1. Under the same N application frequency, P3 had the highest effective number of spikes and number of grains per spike, which were 320.83 × 104 ha−1 and 113.99–119.81, respectively. Under the same N application amount, the SPAD and photosynthetic rate (Pn) of N2 at the heading stage were increased by 5.61–5.68% and 11.73–13.81%, respectively, compared with that of N1; and at the maturity stage, the SPAD of N2 was increased by 14.79–17.21%. At the same N application frequency, SPAD and Pn were 5.40–6.78% and 4.70–12.85% higher in P3 compared to P1, respectively, at the heading stage. At maturity, SPAD showed 14.59–15.64% higher values in P3 compared to P1. The photosynthetically active radiations (PAR) and radiation use efficiency (RUE) of ZLY819 obtained the highest values under N2 or N3 as the differences between these both were nonsignificant. PAR and RUE tended to increase with the increase in the application frequency. NSC accumulation, output, and contribution rate to grains all exhibited a pattern of initial increase followed by a subsequent decline in response to escalating nitrogen application, i.e., it was highest under N2 treatment. A statistically significant positive correlation was observed between rice yield and effective number of spikes, number of grains per spike, SPAD, Pn RUE, output of NSCs, and contribution rate to grains. Appropriate amount and frequency of N application (P3N2) can significantly improve photosynthetic characteristics and NSCs of rice, thus increasing rice yield. [ABSTRACT FROM AUTHOR]

Despite gaining significant attention in recent years, it remains unclear whether mycorrhizal fungi distribute meaningful amounts of resources among trees in ways that increase the fitness of the receiving trees. To investigate this, we used pairs of shaded and unshaded Pinus halepensis or Quercus calliprinos saplings, growing in both inter‐ and intra‐specific combinations outdoors in forest soil. We examined the combined effects of indirect and direct below‐ground connections on tree performance and Non‐Structural Carbohydrate (NSC) pools. Although we did not observe any growth benefits, shaded recipient oaks exhibited higher levels of root and branch NSC compared to their control counterparts, which were not connected below‐ground. This finding suggests a potential benefit of establishing below‐ground connections. However, no such benefits were observed among the unshaded pairs or in the other inter‐ and intra‐specific pairs of pines and oaks. We monitored the carbon (C) flow from a 13CO2‐labelled donor pine tree to a below‐ground connected oak tree and demonstrated C transfer from pines to shaded oaks. We also identified the main fungal symbionts interacting with pines and oaks. Our findings indicate that the effects of below‐ground C transfer are context‐dependent, manifesting in nuanced alterations in plant NSC that are not readily apparent through conventional growth metrics. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

A natural low fruit set is reported in cranberry. It is hypothesised that a carbohydrate shortage limits fruit set, and thus yield potential. We aimed to evaluate the effect of carbohydrate availability induced by shade and saccharose spraying during reproductive stages of 'Stevens' cranberry to identify critical periods for yield and juice quality (soluble solids, acidity, and colour). Two independent experiments were conducted. On five separate dates, artificial shade (90% shade nets) was imposed for two weeks. On the same dates, 417 kg ha−1 of saccharose was sprayed as a 10% w/v solution. Results showed that shading from full bloom to the beginning of the fruit set reduced fruit number and juice colour. In contrast, 10% saccharose spray increased yield by 22% compared to the control without compromising juice quality. Therefore, the period between the end of full bloom and the beginning of fruit growth is the most critical stage for 'Stevens' cranberry. [ABSTRACT FROM AUTHOR]

The distribution of vegetation in coastal wetlands is significantly influenced by soil properties. However, the mechanisms of how soil characteristics impact the physiological processes of Tamarix chinensis forests remain underexplored. This study examined changes in the soil physicochemical properties and structural attributes of natural T. chinensis forests in the Yellow River Delta with increasing distance from the shoreline. T. chinensis trees were classified into healthy, intermediate, and dying categories based on growth potential, and dynamic changes in salt ions and non-structural carbohydrates (NSCs) were investigated. Results indicated that increasing distance from the shoreline corresponded to decreased soil salinity and pH, and increased soil moisture. T. chinensis mortality rate decreased, while tree height and ground diameter increased with distance. Soil salt content was positively correlated with T. chinensis mortality, but negatively correlated with tree height and ground diameter. Trees with lower growth potential had higher Na+ but lower K+ and K+/Na+ ratio. Soil salt content was positively correlated with root and stem Na+, while soil moisture was positively correlated with leaf NSCs. These findings suggest that soil salt content and moisture significantly influence T. chinensis ion absorption and NSC accumulation, with sodium toxicity being a key factor in the spatial distribution of T. chinensis forests. [ABSTRACT FROM AUTHOR]

Nonstructural carbohydrates (NSC) are important substrates for plant growth and metabolism, and their concentration reflects the plant's ability to adapt to environmental changes. Although the response of NSC to changes in water availability has been extensively studied, it is still not fully understood whether this response is modulated by tree ages and organs. This study investigates Haloxylon ammodendron (C.A. Mey.) Bunge ex Fenzl, the dominant species in the Gurbantunggut Desert in the Uyghur Autonomous Region of China. Utilizing the natural topographic conditions characterized by a gradual increase in groundwater depth from the desert edge to the hinterland, we collected samples of different age classes of H. ammodendron along a groundwater depth gradient of 3, 7, 10, and 14 m. We measured the total concentrations of non-structural carbohydrates (NSC) and its components soluble sugar (SS) and starch (ST) in the assimilative twigs and stems. The results showed that the assimilative twigs of H. ammodendron exhibited higher NSC concentrations at the site with the deepest groundwater, while the other three sites showed similar NSC concentrations. Furthermore, as groundwater depth increased, the concentrations of SS in the assimilative twigs increased, whereas ST concentrations decreased. Similarly, the concentrations of SS in the stems also increased at sites with deeper groundwater. The NSC concentrations in the assimilative twigs were significantly affected by groundwater depth, while variations in stem NSC were primarily driven by plant age. In younger trees, higher soluble sugars concentrations in the stem may enhance water transport efficiency, whereas older trees tend to store more NSC to alleviate drought stress. Overall, elevated nonstructural carbohydrate concentrations contributed to greater drought resilience in H. ammodendron. These results suggest that different age classes of H. ammodendron exhibit distinct physiological responses to decreasing groundwater depth. The varying requirements for soluble sugars and starch in H. ammodendron help to partially mitigate the adverse effects of reduced groundwater accessibility. These findings provide important insights into the physiological adaptations of H. ammodendron in arid environments and offer a scientific basis for future ecological restoration and management strategies.

Xylem plasticity is important for trees to coordinate hydraulic efficiency and safety under changing soil water availability. However, the physiological and transcriptional regulations of cambium on xylem plasticity are not well understood. In this study, mulberry saplings of drought-resistant Wubu and drought-susceptible Zhongshen1 were subjected to moderate or severe drought stresses for 21 days and subsequently rewatered for 12 days. The anatomical, physiological and transcriptional responses in wood and cambium were analyzed. Most parameters were not affected significantly under moderate drought for both cultivars. Severe drought led to decreased vessel lumen diameter and increased vessel frequency, increased starch and hemicellulose in wood of both cultivars. Notably, increased soluble sugars and lignin were detected only in wood of Wubu. In cambial zone, levels of starch, glucose, fructose, mannose and cytokinin were decreased in both cultivars, whereas soluble sugars were increased in Wubu but deceased in Zhongshen1. RNA-sequencing identified 1824 and 2471 differentially expressed genes in Wubu and Zhongshen1 under severe drought, respectively. These responses were partially recovered after rewatering. Weighted gene correlation network analysis identified modules of co-expressed genes correlated with the anatomical and physiological traits of wood and cambium, with the turquoise and green modules most strongly correlated with traits under drought or rewatering. These modules were enriched in gene ontology terms related to cell division, cytoskeleton organization, cell wall modification, dark respiration, vesicle transport and protein metabolism. Detailed gene expression patterns indicate that reprogramming of cambium activity was relatively similar in both cultivars, but at different scales. These findings provide important insights into the physiological and molecular mechanisms underlying xylem plasticity based on cambium and offer valuable references for breeding drought-resistant mulberry and other woody species in light of future drier climate scenarios.

In a tropical savanna climate like Thailand, cassava can be planted all year round and harvested at 8 to 12 months after planting (MAP). However, it is not clear how water limitation during the dry season without rain affects carbon assimilation, partitioning, and yield. In this field investigation, six cassava genotypes were planted in the rainy season (August 2021) under continuous irrigation (control) or subjected to drought for 60 days from 3MAP to 5MAP during the dry season (November 2021 to January 2022) with no irrigation and rainfall. After that, the plants were rewatered and continued growing until harvest at 12MAP. After 60 days of stress, there were significant reductions in the mean net photosynthesis rate (Pn), petiole, and root dry weight (DW), and slight reductions in leaf, stem, and tuber DW. The mean starch concentrations were reduced by 42% and 16% in leaves and tubers, respectively, but increased by 12% in stems. At 6MAP after 30 days of rewatering, Pn fully recovered, and stem starch was remobilized resulting in a dramatic increase in the DW of all the organs. Although the mean tuber DW of the drought plants at 6MAP was significantly lower than that of the control, it was significantly higher at 12MAP. Moreover, the mean tuber starch concentration at 12MAP of the drought plants (18.81%) was also significantly higher than that of the controls (16.46%). In the drought treatment, the high-yielding varieties, RY9, RY72, KU50, and CMR38-125-77 were similarly productive in terms of tuber DW and starch concentration while the breeding line CM523-7 produced the lowest tuber biomass and significantly lower starch content. Therefore, for cassava planted in the rainy season in the tropical savanna climate, the exposure to drought during the early growth stage was more beneficial than the continuous irrigation. [ABSTRACT FROM AUTHOR]

Introduction: 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. Methods: 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. Results and discussion: 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. Conclusion: 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. [ABSTRACT FROM AUTHOR]

Mineral elements and non-structural carbohydrates (NSCs) are important nutrients and energy sources for flower development in plants. However, no studies were reported on the dynamic changes of nutrient stoichiometry and NSC contents in Houpoea officinalis (H. officinalis) flower. In this study, the changes in carbon (C), nitrogen (N), phosphorus (P), and NSC contents as well as C:N:P stoichiometry in the pistil, stamen, and petal of H. officinalis flowers at four developmental stages were comparatively analyzed. The results showed that C, N, P, and NSC contents, as well as C:N:P stoichiometric ratios in the three parts of the flower exhibited large variations at four development stages. Development stages and organs had significant effects on the measured parameters in the three organs of H. officinalis flowers, but their interactions had no significant effects. During the flower development, C, N, and P contents in different floral parts ranged from 418.7 to 496.3 mg/g, 26.6 to 45.3 mg/g, and 0.396 to 0.656 mg/g. P content decreased continuously with development, C:N in stamen were significantly higher than those in other flower parts at the same developmental stage. Glucose, starch, fructose, and sucrose contents showed significant differences in three parts of H. officinalis flowers at four development stages. These differences may reflect differences in elemental storage capacity and biomass allocation patterns of H. officinalis flowers. In general, our data will help to improve our understanding of the relationship between NSCs and C:N:P stoichiometry in response to development stages and organs in H. officinalis flowers. [ABSTRACT FROM AUTHOR]

Summary: Non‐structural carbohydrates (NSCs), as the labile fraction and dominant carbon currency, are essential mediators of plant adaptation to environments. However, whether and how NSC coordinates with plant economic strategy frameworks, particularly the well‐recognized leaf economics spectrums (LES) and root economics space (RES), remains unclear.We examined the relationships between NSC and key plant economics traits in leaves and fine roots across 90 alpine coniferous populations on the Tibetan Plateau, China.We observed contrasting coordination of NSC with economics traits in leaves and roots. Leaf total NSC and soluble sugar aligned with the leaf economic spectrum, conveying a trade‐off between growth and storage in leaves. However, NSC in roots was independent of the root economic spectrum, but highly coordinated with root foraging, with more starch and less sugar in forage‐efficient, thinner roots. Further, NSC‐trait coordination in leaves and roots was, respectively, driven by local temperature and precipitation.These findings highlight distinct roles of NSC in shaping the above‐ and belowground multidimensional economics trait space, and NSC‐based carbon economics provides a mechanistic understanding of how plants adapt to heterogeneous habitats and respond to environmental changes. [ABSTRACT FROM AUTHOR]

Knowledge of the physiological mechanisms underlying species vulnerability to drought is critical for better understanding patterns of tree mortality. Investigating plant adaptive strategies to drought should thus help to fill this knowledge gap, especially in tropical rainforests exhibiting high functional diversity. In a semi-controlled drought experiment using 12 rainforest tree species, we investigated the diversity in hydraulic strategies and whether they determined the ability of saplings to use stored non-structural carbohydrates during an extreme imposed drought. We further explored the importance of water- and carbon-use strategies in relation to drought survival through a modelling approach. Hydraulic strategies varied considerably across species with a continuum between dehydration tolerance and avoidance. During dehydration leading to hydraulic failure and irrespective of hydraulic strategies, species showed strong declines in whole-plant starch concentrations and maintenance, or even increases in soluble sugar concentrations, potentially favouring osmotic adjustments. Residual water losses mediated the trade-off between time to hydraulic failure and growth, indicating that dehydration avoidance is an effective drought-survival strategy linked to the 'fast–slow' continuum of plant performance at the sapling stage. Further investigations on residual water losses may be key to understanding the response of tropical rainforest tree communities to climate change. [ABSTRACT FROM AUTHOR]

Many savannas are experiencing increased cover of trees and shrubs, resulting in reduced herbaceous productivity, shifts in savanna functional structure and potential reductions in ecotourism. Clearing woody plants has been suggested as an effective management strategy to mitigate these effects and restore these systems to an open state with higher rates of grass production and herbivory. This study investigated the effectiveness of repeated shrub clearing as a tool to mitigate bush encroachment in a semi‐arid savanna in southern Africa.We present data from a 7‐year experiment in the Mthimkhulu Game Reserve bordering Kruger National Park, South Africa. Colophospermum mopane stems and resprouting shoots were basally cut 2–3 times per year (2015–2022) in three pairs of treatment and control plots of 60 × 60 m. We monitored changes in soil moisture, grass biomass and herbivore activity via dung counts. We assessed C. mopane physiological responses to repeated cutting using non‐structural carbohydrates and stable water isotopes to infer changes to energy storage and functional rooting depth, respectively.The cleared treatment had higher soil moisture and grass biomass than the control treatment. Dung counts showed impala and buffalo visited the cleared treatment more frequently than the control treatment.Repeated cutting had limited effects on C. mopane survival in the first 2–3 years after initial clearing, but 80% of individuals were dead after 7 years. Repeatedly cut C. mopane had lower belowground starch concentrations and used water from shallower soil depths than C. mopane in control plots.Synthesis and applications. Repeated cutting increased soil moisture availability and grass biomass, and attracted charismatic grazing herbivores. While more costly than once‐off clearing methods, this practice created more employment opportunities for a neighbouring rural community. Transforming portions of the ecosystem to a grass‐dominated state may increase ecotourism potential through improved game viewing in open systems. [ABSTRACT FROM AUTHOR]

Leaves are important 'source' organs that synthesize organic matter, providing carbon sources for plant growth. Here, we used Populus talassica × Populus euphratica , the dominant species in ecological and timber forests, to simulate carbon limitation through artificial 25%, 50%, and 75% defoliation treatments and explore the effects on root, stem, and leaf morphology, biomass accumulation, and carbon allocation strategies. At the 60th d after treatment, under 25% defoliation treatment, the plant height, specific leaf weight, root surface area and volume, and concentrations of non-structural carbohydrates in stem and root were significantly increased by 9.13%, 20.00%, 16.60%, 31.95%, 5.12%, and 9.34%, respectively, relative to the control. There was no significant change in the growth indicators under 50% defoliation treatment, but the concentrations of non-structural carbohydrates in the leaf and stem significantly decreased, showing mostly a negative correlation between them. The opposite was observed in the root. Under 75% defoliation treatment, the plant height, ground diameter, leaf number, single leaf area, root, stem, and total biomass were significantly reduced by 14.15%, 10.24%, 14.86%, 11.31%, 11.56%, 21.87%, and 16.82%, respectively, relative to the control. The concentrations of non-structural carbohydrates in various organs were significantly reduced, particularly in the consumption of the starch concentrations in the stem and root. These results indicated that carbon allocation strategies can be adjusted to increase the concentration of non-structural carbohydrates in root and meet plant growth needs under 25% and 50% defoliation. However, 75% defoliation significantly limited the distribution of non-structural carbohydrates to roots and stems, reduced carbon storage, and thus inhibited plant growth. Defoliation-induced carbon limitation altered the carbon allocation pattern of P. talassica × P. euphratica , and the relationship between carbon reserves in roots and tree growth recovery after defoliation was greater. This study provides a theoretical basis for the comprehensive management of P. talassica × P. euphratica plantations, as well as a reference for the study of plantation carbon allocation strategies in the desert and semi-desert regions of Xinjiang under carbon-limitation conditions. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa) faces challenges to yield and quality due to urbanisation, deforestation and climate change, which has exacerbated high night temperature (HNT). This review explores the impacts of HNT on the physiological, molecular and agronomic aspects of rice growth. Rise in minimum temperature threatens a potential 41% reduction in rice yield by 2100. HNT disrupts rice growth stages, causing reduced seed germination, biomass, spikelet sterility and poor grain development. Recent findings indicate a 4.4% yield decline for every 1°C increase beyond 27°C, with japonica ecotypes exhibiting higher sensitivity than indica. We examine the relationships between elevated CO2, nitrogen regimes and HNT, showing that the complexity of balancing positive CO2 effects on biomass with HNT challenges. Nitrogen enrichment proves crucial during the vegetative stage but causes disruption to reproductive stages, affecting grain yield and starch synthesis. Additionally, we elucidate the impact of HNT on plant respiration, emphasising mitochondrial respiration, photorespiration and antioxidant responses. Genomic techniques, including CRISPR-Cas9, offer potential for manipulating genes for HNT tolerance. Plant hormones and carbohydrate enzymatic activities are explored, revealing their intricate roles in spikelet fertility, grain size and starch metabolism under HNT. Gaps in understanding genetic factors influencing heat tolerance and potential trade-offs associated with hormone applications remain. The importance of interdisciplinary collaboration is needed to provide a holistic approach. Research priorities include the study of regulatory mechanisms, post-anthesis effects, cumulative HNT exposure and the interaction between climate variability and HNT impact to provide a research direction to enhance rice resilience in a changing climate. We explore the impact of high night temperature (HNT) on rice phenomics, physiology and grain yield. From accelerated vegetative growth to changes in reproductive phases and enzymatic activities, we review how HNT affects rice in elevated CO2 and nitrogen environments to provide insights into photosynthesis, respiration and hormonal regulation, and their effect on grain yield and quality. This article belongs to the Collection Functional Genomics for Developing Climate Resilient Crops. [ABSTRACT FROM AUTHOR]

(1) Background: Soil salinity is one of the major abiotic stresses that limits plant growth and production. However, the response patterns of plant growth and carbon metabolism to salt stress are still unclear. (2) Methods: We measured the relative growth rate, non-structural carbohydrate (NSC) concentrations and pool size across organs, the leaf mass area (LMA), root-to-shoot ratio, midday leaf water potential (Ψmd), and photosynthetic characteristics of elm seedlings planted in the field under different salt stress intensities and durations. (3) Results: Salt stress can reduce the photosynthesis rate, stomatal conductance, and Ψmd and inhibit the growth of elm species. LMA increased with the degree and duration of salt stress, indicating an increase in leaf carbon investment to resist salt stress. The root-to-shoot ratio decreased under salt stress to reduce salt absorption by the roots. In the early stage of stress, the concentrations of starch and total NSCs in all organs increased to improve stress resistance and the survival of plants. In the late stage of stress, the concentration of NSCs in the root decreased, which could restrict root growth and water uptake. The relationships between NSC concentration and growth in different organs were contrasting. Meanwhile, the pool size of NSCs had a more significant impact on growth than their concentration. Moreover, the pool size of NSCs in below-ground organs is more closely related to growth than that of above-ground organs. (4) Conclusions: Our research elucidates the carbon allocation mechanism across organs under different salt stress intensities and durations, providing theoretical support for understanding the relationship between tree growth and carbon storage under salt stress. [ABSTRACT FROM AUTHOR]

Tree source-sink ratio has a predominant and complex impact on tree performance and can affect multiple physiological processes including vegetative and reproductive growth, water and nutrient use, photosynthesis, and productivity. In this study, we manipulated the branch level source-sink ratio by reduction of photosynthetic activity (partial branch defoliation) or thinning branch fruit load early in the growing season (after fruit set) in pistachio (Pistacia vera) trees. We then characterized the leaf photosynthetic light response curves through leaf aging. In addition, we determined changes in leaf non-structural carbohydrates (NSC) and nitrogen (N) concentrations. In leaves with high source-sink ratios, there was a gradual decrease in maximum net photosynthetic rate (ANmax) over the growing season, while in branches with low source-sink ratios, there was a sharp decline in ANmax in the first two weeks of August. Branches with high-sink showed an up-regulation (increase) in photosynthesis toward the end of July (at 1,500 growing degree days) during the period of rapid kernel growth rate and increased sink strength, with ANmax being about 7 μmol m-1 s-1 higher than in branches with low-sink. In August, low source-sink ratios precipitated leaf senescence, resulting in a drastic ANmax decline, from 25 to 8 μmol m-1 s-1 (70% drop in two weeks). This reduction was associated with the accumulation of NSC in the leaves from 20 to 30 mg g-1. The mechanisms of ANmax reduction differ between the two treatments. Lower photosynthetic rates of 8-10 μmol m-1 s-1 late in the season were associated with lower N levels in high-sink branches, suggesting N remobilization to the kernels. Lower photosynthesis late in the season was associated with lower respiration rates in low-source branches, indicating prioritization of assimilates to storage. These results can facilitate the adaptation of management practices to tree crop load changes in alternate bearing species.

[ Objective ] It is of great significance to explore the distribution of NSC ( non-structural carbohy- drate ) and their components in different organs with seasonal changes for revealing the mechanism of car- bon distribution in different age Pinus armandii . [ Methods ] The contents of NSC and their components in different organs of young and middle-aged P . armandii were determined by periodic sampling to explore the seasonal changes of P . armandii during the year. [ Results ] ( 1 ) The distribution pattern of NSC and their components in different age P . armandii was the same among all organs , where the starch content was in the order : Roots > leaves > branches > stems. The starch content in stems was significantly low- er than that in other organs , while the content of soluble sugar and NSC in leaves , roots and branches was not significantly different. The ratio of sugar to starch in stems was significantly higher than that in other organs. ( 2 ) During the growing season , NSC and their components were mainly affected by seasons , fol- lowed by the interaction between seasons and organs , and the influence of forest age was the least. ( 3 ) The correlation between NSC and their components in different P . armandii organs was the same. Except the negative correlation between the ratio of sugar to starch and starch , NSC in young-aged P . armandii and the ratio of sugar to starch and starch in middle-aged P . armandii , the other indexes were positively correlated. [ Conclusion ] NSC and their components in various organs of P . armandii had obvious season- al fluctuations. When the environment changed , the carbon supply and demand of different organs changed synergistically , which was conducive to the growth of P . armandii , and enhanced its resistance and adaptability to cope with extreme environment.

Non-structural carbohydrates (NSC) are an important "buffer" for maintaining plant physiological functions under drought conditions; however, our understanding of the dynamics of NSC at the organ level during sustained drought of varying intensities and re-watering remains poor. In this study, two-year-old Pinus yunnanensis seedlings were subjected to drought and re-watering trials. Plants were subjected to three drought intensities (light drought, moderate drought, and severe drought) as well as control conditions (suitable moisture) for 51 days, including 30 days of drought followed by 21 days of re-watering for drought-treated seedlings, to study the dynamics of NSC in the leaves, stems, coarse roots, and fine roots. Changes in the distribution of NSC concentrations in the organ of P. yunnanensis seedlings under drought stress varied; in the early drought stages, the drought resistance of P. yunnanensis seedlings was enhanced by increasing soluble sugar concentrations; in later stages of drought, the stored starch in organs, stems, and coarse roots was consumed. Drought inhibited the growth of P. yunnanensis seedlings, but the maximum limit of drought tolerance was not reached under the different drought treatments after 30 days. P. yunnanensis seedlings in all treatment groups resumed growth after re-watering, and the growth of seedlings was actually promoted during re-watering in the moderate drought treatment group, indicating that drought induced the compensatory growth of seedlings. The growth of P. yunnanensis seedlings during re-watering was inhibited in the severe drought treatment group, and NSC continued to be regulated in seedlings in this group. Given that P. yunnanensis seedlings maintain growth through the consumption of coarse root starch in the late stages of drought, seedlings with a larger root-to-shoot ratio should be selected for cultivation in actual production. Based on our findings, exposure to moderate drought stress can enhance the drought tolerance of P. yunnanensis seedlings and promote the compensatory growth of seedlings. [ABSTRACT FROM AUTHOR]

Non‐structural carbohydrates (NSC) are considered as indicators of the balance between tree carbon sources and sinks and reflect functional strategies throughout different biomes. However, little is known about the contribution of NSC to tree economics, and in particular, whether leaf, stem and coarse root traits co‐ordinate together into a whole‐tree economics spectrum.Twenty‐four functional traits (including NSC content) were measured in leaves, stem and coarse root xylem of up to 90 angiosperm tree species in temperate, Mediterranean and tropical climates. By performing principal component analysis and standardized major axis regression, we explored the relationships between NSC and other functional traits, as well as the effects of climate and phylogeny on these relationships.Our results revealed a covariation between leaf and coarse root NSC content and leaf economic traits, whereas stem NSC content was largely decoupled from the leaf economics spectrum that was mostly driven by leaf nitrogen content and leaf mass per area. Coarse root xylem traits were closely correlated with leaf traits, while most stem xylem traits were independent from the leaf economics spectrum but covaried with coarse root traits. Trade‐offs among traits in tropical species opposed those from other climates. Evolutionary history affected relationships among certain traits but did not change overall patterns.We conclude that due to leaf habit, an extended growing season and heightened defences, tropical species form distinct conservative resource acquisition strategies. Across all climates, as the stem must provide an efficient transport route between roots and leaves, while maintaining the display of branch and leaf organs, stem xylem design and NSC storage capacity lead to a stem economics spectrum that is largely independent from the leaf spectrum, but is coupled with that of coarse roots due to anatomical continuity. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Global climate change is increasing the frequency and intensity of drought and salt stress worldwide, with profound impacts on tree growth and survival. However, the response of plant hydraulic transport and carbon balance to combined drought and salt stress remains unclear. This study investigated the leaf physiological traits, stem xylem hydraulic traits, and nonstructural carbohydrate concentration of Robinia pseudoacacia seedlings under normal irrigation treatment (CK, freshwater at 80–100% FC); salt stress treatment (SS, 0.3% soil salinity with freshwater); drought stress treatment (DS, withholding irrigation); and combined drought and salt treatments (SDS, 0.3% soil salinity withholding irrigation). Our results showed that the leaf physiological traits responded differently to different treatments. DS and SDS treatment significantly decreased leaf water potential and stomatal conductance, while SS treatment did not. DS treatment increased stomatal density but decreased stomatal area to adapt to water deficit, while SS and SDS treatment decreased stomatal length or width. In terms of xylem hydraulic traits, SS, DS and SDS significantly decreased xylem specific hydraulic conductivity by 47%, 42% and 49%, while percent loss of conductivity (PLC) significantly increased by 81% and 62% in DS and SDS, but the PLC of SS was not increased significantly. Additionally, net photosynthetic rate and transpiration rate significantly decreased in SS, DS and SDS, while leaf water use efficiency significantly increased. The chlorophyll content index and maximum light quantum efficiency of photosystem II were also decreased. For nonstructural carbohydrate, the soluble sugars, starch and total non-structural carbohydrate were significantly decreased in DS in specific tissues, showing reductions of 42%, 68%, and 56% in leaves, 69%, 61%, and 62% in stem, and 30%, 59%, and 57% in root. Our findings provide evidence that salt addition alleviated drought stress by improving hydraulic traits and carbohydrate reserves, which is expected to contribute to predicting future vegetation dynamics under climate change. [ABSTRACT FROM AUTHOR]

This scientific commentary discusses a study by Hart et al. on the origin and fate of carbon and nitrogen reserves in trees. The study focused on aspen saplings and investigated the remobilization of carbon and nitrogen reserves during spring leaf flush and after an experimental defoliation event. The researchers found that the sources and sinks of carbon and nitrogen differed between these two events, with stems being the main source of carbon during spring and roots playing a significant role in nitrogen transfer. The study also highlighted the existence of sink hierarchy in woody plants, where carbon is prioritized in certain sinks based on their proximity to the source. The findings suggest that factors other than carbon and nitrogen reserves may limit leaf mass recovery after defoliation. The study provides valuable insights into the complex dynamics of carbon and nitrogen in trees and has implications for understanding tree mortality and dieback. [Extracted from the article]

Increasing the application of nitrogen fertilizer is the main approach to increase rice production, but it also brings problems of environmental pollution and increases agricultural production costs. Cultivating high‐yielding and high nitrogen use efficiency (NUE) rice varieties is an important approach to solving this problem. The rice varieties carrying dep1 (dense and erect panicle 1) have both high grain yield and high NUE. However, their plant traits have not been fully explored. In this study, two rice near‐isogenic lines carrying dep1 (NIL‐DEP1 and NIL‐dep1) were grown in paddy fields under 0, 120 and 270 kg N ha−1. We analyzed agronomic traits of panicle type, plant type, leaves and roots, and physiological traits of vascular bundles, photosynthetic rate and carbon and nitrogen transport. The results showed that the NIL‐dep1 exhibited higher grain yield and NUE than NIL‐DEP1, mainly due to the higher spikelet number per panicle, grain filling percentage and dry matter production. Compared with NIL‐DEP1, NIL‐dep1 had improved flag leaf morpho–physiological traits, including erect flag leaves, greater leaf thickness and specific leaf weight, higher root dry weight, root length, root volume and root surface area, and a better canopy structure, as reflected by a lower light interception percent and canopy extinction coefficient, leading to better photosynthetic performance and dry matter production. In addition, NIL‐dep1 exhibited better vascular bundle traits of peduncle and enhanced dry matter, stem carbon and nitrogen translocation during grain filling. In conclusion, NIL‐dep1 had high grain yield and NUE by improved agronomic and physiological traits and increasing carbon and nitrogen translocation during grain filling. These traits mentioned above could be used to select and breed high grain yield with high NUE rice varieties. [ABSTRACT FROM AUTHOR]

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Zanthoxylum armatum (Z. armatum) is an economic crop widely planted for both spice and medicinal purposes in Southwest China. Soil is a key environmental condition that affects seedling growth and development, and screening suitable soil types is of great significance for the large-scale cultivation of crops. This study designed growth experiments of Z. armatum seedlings in red soil (RS), yellow soil (YS), acidic purple soil (ACPS), alkaline purple soil (ALPS), and alluvial soil (AS) to screen for more suitable soil types. The growth traits of Z. armatum seedlings and the carbon (C), nitrogen (N), phosphorus (P), C:N:P stoichiometry, and non-structural carbohydrate (NSC) content of different organs were comparatively analyzed. The results showed that the morphological indexes of Z. armatum seedlings cultured in AS were better than those in the other four soils.AS and RS may be beneficial for the culture of Z. armatum seedlings due to higher nutrient levels in three organs. Two-factor ANOVA and PCA analysis showed that C, N, and P and their proportions would affect the uptake and distribution of NSC in various organs of Z. armatum seedlings. These results showed that soil types and plant organs significantly affected the accumulation and distribution of N, P, and NSC in Z. armatum seedlings. These results are conducive to screening soil types suitable for the growth and development of Z. armatum and provide data support for further large-scale cultivation of Z. armatum in suitable areas. [ABSTRACT FROM AUTHOR]

This study investigated the allocation strategies of non-structural carbohydrates and functional traits in Quercus mongolica seedlings of different ages under different light conditions. The study took place at the Urban Forestry Demonstration Base in Harbin City, Heilongjiang Province, China. Seedlings of three age classes were collected in two light environments, the forest edge and the forest understory. By measuring specific leaf area, biomass, soluble sugar concentration and starch concentration, we revealed the growth adaptation strategies and responses to different light conditions in Q. mongolica seedlings of different age classes. Our results show that the adaptation strategies of seedlings of different age classes are very different. First, our study showed a strong coordination of soluble sugars between roots, stems, and leaves of 1−2 year old Q. mongolica seedlings, indicating an efficient partitioning of carbon between organs at this age. In 3−4 year old Q. mongolica seedlings, a significant negative correlation was observed between starch in the roots and soluble sugars in the leaves, indicating the transformation of various non-structural carbohydrates. In addition, 5−6 year old seedlings start to increase their investment in the above-ground part to achieve a height advantage. In conclusion, this study improves our understanding of the light adaptation strategies of Q. mongolica seedlings and provides valuable insights for the natural regeneration and management of Q. mongolica forest vegetation.

The carbon and nitrogen (N) metabolism of rice under different mid-stage N compensation timings is unclear. Two Japonica super rice cultivars were examined under four N compensation timings (N1-N3: N compensation at mid-tillering, panicle initiation, and spikelet differentiation. N0: no N compensation) and CK with no N application. Mid-stage N compensation increased the N concentrations of various tissues, and N2 showed the highest plant N uptake at both the heading stage, maturity, and the grain filling period. Among the treatments, N2 showed the highest N utilization efficiency. With delayed compensation timing, there was a gradual decrease in soluble sugar and starch concentrations in each tissue, accompanied by a decline in the non-structural carbohydrate (NSC) concentration. Specifically, N2 treatment exhibited the highest NSC accumulation and the remobilized NSC reserve, but NSCs per spikelet decreased with delayed compensation timing. The highest yield was also obtained with N2, exhibiting a 4.5% increase compared to the N0 treatment, primarily due to an improvement in spikelets per panicle. Conclusively, N compensation at the panicle initiation stage is a reasonable N management strategy that can coordinate the improvement of carbon and N metabolism, enhance N accumulation with efficient utilization and NSC accumulation, and ultimately increase the yield.