Assimilative Capacity Research Articles

Cambuci Festival as an Attraction for Cultural Tourism From the Perspective of the Sustainable Supply Chain

Objective: To characterize the use of cambuci, a native Brazilian fruit, during the Festival in the village of Paranapiacaba, Santo André-SP, as a circular chain supply. Theoretical Framework: Supply chains are configured in linear or circular. Linear chain is an open system that ignores the extraction environment, resource yield, waste, assimilative capacity, and recycling. A circular chain is a closed system where the environment is part of the system, as it considers extraction, resource yield, waste, assimilative capacity and recycling. Gastronomic tourism was considered as a segment of cultural tourism. Method: A qualitative study was carried out through testimonies as a methodological approach proposed by Meksenas (2002). For analysis, testimonies from 2023-2013 were selected, from electronic addresses. The categorization of testimonies transcribed from the corpus allowed the thematic analysis according to Jovchelovitch and Bauer, (2002). Results and Discussion: The community works in the extraction of cambuci, in the elaboration of derivatives, in the organization of the event, in the commercialization, but there are no testimonies about the destination of waste. Thus, cambuci is an open-system linear chain supply with no mention of waste. Gastronomic tourism requires proper planning to mitigate impacts on the destination. Research Implications: Interviews coincided with the pandemic period. Originality/Value: Gastronomy fosters cultural tourism. The participation of the community in the collection, elaboration, and organization of the event made it possible to describe the trajectory of cambuci as a supply of an open system production chain due to the disposal of waste. The methodological approach of testimonies optimized the study during the pandemic.

Optimal algae species inoculation strategy for algal-bacterial granular sludge: Sludge characteristics, performance and microbial community

The algal-bacterial granular sludge (ABGS) system is emerging as a promising technology for future wastewater treatment. This study assessed the impact of different algae species inoculation on granulation, performance, and microbial communities within ABGS systems. The experimental setup included single-species inoculations (Chlorella sp. (R1), Scenedesmus sp. (R2), and Desmodesmus sp. (R3)) and a mixed-species inoculation strategy (R4). Results revealed that R4 achieved the fastest completed granulation process (15 days) with the largest average granule diameter (772.93 μm) and highest physical strength (2.24 ± 0.26%) in the end of the experiment. The relative abundance of extracellular polymeric substances secreting bacteria of R4 maintained high level in whole operation time. Algae assimilation capacity and the abundance of functional bacteria can also influence removal performance. In mature stage, only the average effluent total nitrogen (3.15 ± 2.87 mg/L), total phosphorus (0.37 ± 0.27 mg/L), chemical oxygen demand (25.25 ± 2.98 mg/L) concentration in R4 was lower than that of Grade I discharge standard of municipal wastewater treatment plants in China. The best inorganic carbon utilization and lipid production ability were observed in R4 and R3, respectively. The choice of inoculated algae species was identified as a key factor for bacterial community dynamics. Overall, above results demonstrated that mixed algae species inoculation can be selected as the optimal algae inoculation strategy due to its excellent granulation, performance, and acceptable carbon utilization and lipid production.

Integrative physiological and transcriptome analysis unravels the mechanism of low nitrogen use efficiency in burley tobacco.

Burley tobacco, a chlorophyll-deficient mutant with impaired nitrogen use efficiency (NUE), generally requires three to five times more nitrogen fertilization than flue-cured tobacco to achieve a comparable yield, which generates serious environmental pollution and negatively affects human health. Therefore, exploring the mechanisms underlying NUE is an effective measure to reduce environmental pollution and an essential direction for burley tobacco plant improvement. Physiological and genetic factors affecting tobacco NUE were identified using two tobacco genotypes with contrasting NUE in hydroponic experiments. Nitrogen use inefficient genotype (TN90) had lower nitrogen uptake and transport efficiencies, reduced leaf and root biomass, lower nitrogen assimilation and photosynthesis capacity, and lower nitrogen remobilization ability than the nitrogen use efficient genotype (K326). Transcriptomic analysis revealed that genes associated with photosynthesis, carbon fixation, and nitrogen metabolism are implicated in NUE. Three nitrate transporter genes in the leaves (NPF2.11, NPF2.13, and NPF3.1) and three nitrate transporter genes (NPF6.3, NRT2.1, and NRT2.4) in roots were down-regulated by nitrogen starvation, all of which showed lower expression in TN90 than in K326. In addition, the protein-protein interaction (PPI) network diagram identified eight key genes (TPIP1, GAPB, HEMB, PGK3, PSBO, PSBP2, PSAG, and GLN2) that may affect NUE. Less advantageous changes in nitrogen uptake, nitrogen assimilation in combination with nitrogen remobilization, and maintenance of photosynthesis in response to nitrogen deficiency led to a lower NUE in TN90. The key genes (TPIP1, GAPB, PGK3, PSBO, PSBP2, PSAG, and GLN2) were associated with improving photosynthesis and nitrogen metabolism in tobacco plants grown under N-deficient conditions.

Analisis Beban Pencemar dan Kapasitas Asimilasi Sungai Klinter Nganjuk

Klinter River in Nganjuk is subjected to pollution loads from various pollution sources, including domestic and industrial waste. Water quality can affect the condition of Klinter River, which is still used by the local community to support daily activities. The parameters analyzed include TSS, COD, BOD, NO3-, NO2-, NH3, PO4, and oil and grease, taken from data provided by the Nganjuk Environmental Agency. The study aims to assess the carrying capacity of Klinter River by analyzing pollutant loads and the river's assimilative capacity. Regression analysis is conducted to obtain equations and graphs illustrating the relationship between pollutant concentration and assimilation capacity for each parameter. The analysis results indicate that COD, BOD, and NH3 parameters are no longer able to undergo self-purification.

River quality management: Integrating uncertainty, failure probability, and assimilation capacity

Managing river water quality is challenging due to uncertainties in hydraulic and hydrologic parameters. This study integrates the symmetric exponential function (SEF) approach for solving the advection-dispersion equation with the Monte Carlo method in MATLAB. This combination allows us to explore the river's assimilation capacity and the failure probability (Pf) of maintaining desired water quality standards. Here, Pf represents the likelihood of pollutant concentrations exceeding acceptable limits under varying river conditions. A key contribution of this study is the introduction of a novel equation, developed using the Genetic Programming (GP) soft computing tool, to calculate assimilation capacity considering the failure probability of water quality provision. This equation provides a valuable tool for risk assessment in water resource management by quantifying pollutant assimilation dynamics. Its robustness is validated through high Coefficient of Determination (R2) and Overall Index (OI) values near 1, along with low Root Mean Square Error (RMSE) and Mean Absolute Error (MAE). The study identifies critical river characteristics, such as flow velocity and pollutant load, significantly influencing the reliability index (β). By outlining how adjustments in these parameters can achieve a target reliability index (β=4.526), our study offers a practical approach to safeguarding river ecosystems. For example, increasing flow velocity by 76 % can shift the river from a safe state (Pf=3×10−5) to a hazardous state (Pf=1), while a 44 % decrease in velocity allows for 57 % more pollutant assimilation. These findings highlight the importance of flow control as a cost-effective strategy for mitigating high pollutant concentrations and ensuring sustainable water quality management. By integrating numerical approaches with reliability sampling methods and soft computing techniques, this study enhances understanding of river system dynamics and supports informed decision-making for protecting water resources.

Exploring the Molecular Landscape of Nitrogen Use Efficiency in Potato (Solanum tuberosum L.) under Low Nitrogen Stress: A Transcriptomic and Metabolomic Approach

Enhancing crop nitrogen use efficiency (NUE) in agricultural sciences is a pivotal challenge, particularly for high-demand crops like potatoes (Solanum tuberosum L.), the world’s third most significant food crop. This study delves into the molecular responses of potatoes to low nitrogen (LN) stress, employing an integrative approach that combines transcriptomics and metabolomics to compare two cultivars with divergent NUE traits: XS6, known for its high NUE, and NS7, characterized by lower NUE. Our research unveils that XS6 exhibits higher chlorophyll and N content, increased tuber yield, and elevated N assimilation capacity under LN stress conditions compared to NS7. Through transcriptome analysis, we identified critical genes involved in C and N metabolism that had higher expression in XS6. A significant discovery was the high-affinity nitrate transporter 2.7 gene, which showed elevated expression in XS6, suggesting its key role in enhancing NUE. Metabolomics analysis further complemented these findings, revealing a sophisticated alteration of 1252 metabolites under LN stress, highlighting the dynamic interplay between carbon and N metabolism in coping with N scarcity. The integration of transcriptomic and metabolomic data underscored the crucial role of trehalose in mitigating N deficiency and enhancing NUE. This study provides novel insights into the molecular mechanisms governing NUE in potatoes, offering valuable perspectives for molecular breeding to enhance NUE in potatoes and potentially other crops.

Reduced diffusional limitations in carnation stems facilitate higher photosynthetic rates and reduced photorespiratory losses compared with leaves.

Green stem photosynthesis has been shown to be relatively inefficient but can occasionally contribute significantly to the carbon budget of desert plants. Although the possession of green photosynthetic stems is a common trait, little is known about their photosynthetic characteristics in non-desert species. Dianthus caryophyllus is a semi-woody species with prominent green stems, which show similar photosynthetic anatomy with leaves. In the present study, we used a combination of gas exchange and chlorophyll fluorescence measurements, some of which were taken under varying O2 and CO2 partial pressures, to investigate whether the apparent anatomical similarities between the species' leaves and stems translate into similar photosynthetic physiology and capacity for CO2 assimilation. Both organs displayed high photosynthetic electron transport rates (ETR) and similar values of steady-state non-photochemical quenching (NPQ), albeit leaves could attain them faster. The analysis of OJIP transients showed that the quantum efficiencies and energy fluxes along the photosynthetic electron transport chain are largely similar between leaves and stems. Stems displayed higher total conductance to CO2 diffusion, similar biochemical properties, significantly higher photosynthetic rates and lower water use efficiency than leaves. Leaf ETR was more sensitive to sub-ambient O2 and super-ambient CO2 partial pressures, while leaves also displayed a higher relative rate of Rubisco oxygenation. We conclude that the highly responsive NPQ and the enhanced photorespiration and WUE in leaves represent photoprotective and water-conserving adaptations to the high incident light intensities they experience naturally, at the expense of higher CO2 assimilation rates, which the vertically orientated stems can readily attain.

Nitrogen Supply Mitigates Heat Stress on Photosynthesis of Maize (Zea mays L.) During Early Grain Filling by Improving Nitrogen Assimilation

ABSTRACTHigh temperature during early grain‐filling stage is one of the serious abiotic stresses limiting maize yield in the North China Plain. Nitrogen (N) fertiliser has an important role in promoting crop growth, especially under abiotic stresses. However, its contribution to alleviating heat stress (HS) inhibition on maize photosynthesis during early grain‐filling stage is still unclear. Experiments with three N rates (LN, low nitrogen; MN, medium nitrogen; HN, high nitrogen) and two temperature (HS, heat stress; CK, ambient temperature as control) regimes were conducted to examine the effects of increasing N supply on photosynthesis, N assimilation, antioxidant system, and hormones homeostasis of maize during early grain‐filling stage using two maize hybrids Xianyu335 (XY335, heat‐sensitive) and Zhengdan (ZD958, heat‐tolerant). HS negatively affected photosynthesis of both two hybrids, exhibited lower net photosynthetic rate, chlorophyll content and activities of Rubisco and phosphoenolpyruvate carboxylase (PEPC) compared with CK, and then decreased dry matter accumulation of maize, with a lesser extent for ZD958 than XY335. However, increasing N supply alleviated the adverse effects of HS on maize photosynthesis due to improved N assimilation capacity. Under HS condition, greater N content and higher activities of glutamine synthetase and glutamate synthase in maize ear leaf were found in treatment of HN compared with LN and MN. HN with higher N assimilation capacity directly increased the net photosynthetic rate due to improved chlorophyll content, activities of Rubisco and PEPC and antioxidant capacity. HS‐induced abscisic acid (ABA) accumulation was also repressed by HN, and then enhanced the stomatal conductance and transpiration rate to maintain higher photosynthetic capacity compared with LN and MN. Moreover, the positive effects of increasing N supply on maize photosynthesis under HS condition exhibited a larger extent for XY335 than ZD958. As a result of improved photosynthesis and N assimilation capacity by adequate N supply, maize accumulated more biomass under HS, especially for heat‐sensitive hybrid.

Knowledge capital and innovation management: Impact of transboundary investment and assimilative capacity

Background: In today’s volatile and highly competitive business environment, the importance of knowledge capital and innovation management for multinational manufacturing firms has been widely recognised by both academia and industry.Aim: This article aims to explore the impact of transboundary investment and assimilative capacity on the association between knowledge capital and innovation management in this specific context.Setting: A total of 217 managers and employees were selected from 19 multinational manufacturing firms listed on the Ghana stock exchange to participate in the survey.Method: Using a theoretical-based association existing research model, data were collected through an online electronic questionnaire survey. The collected data were then analysed using path analysis, utilising SPSS 22.0 and AMOS 24.0 software to test the formulated hypotheses.Results: The study found that an organisation-wide unified system, technological, organisational resource and knowledge capital-enabling structures strongly influence multinational manufacturing firms. Besides, knowledge capital and innovation management have a positive mediating role and a significant impact on multinational manufacturing firms. However, there was no significant impact between knowledge of empirical capital and innovation management.Conclusion: The findings of this study highlight the importance of knowledge capital in enhancing innovation management and emphasise the role of transboundary investment and assimilative capacity in mediating this relationship.Contribution: This research contributes to the theoretical understanding of how knowledge capital and innovation management are interconnected, as well as the relationship between transboundary investment and assimilative capacity, and their respective roles in mediating this relationship.

Determining Water Quality Status and Assimilation Capacity of Pollutant Loads in West Lombok Regency

Babak watershed is one of the essential watersheds in Lombok Island providing water supply for irrigation, fish pool, drinking water supply, and micro-hydro power plant. Excessive human activities degrade the water quality of Babak watershed, and more pollutants are present in the water column. Thus, this study aims to determine Babak watershed's water quality status and assimilating capacity to plan effective and holistic mitigation measures properly. The study calculates the pollution index (PI) using a formula based on the Minister of Environment No.115/2003 Decree and assimilating capacity (AC) based on the Minister of Environment No.110/2003 Decree. The results found that Babak watershed is lightly polluted, defined by exceeding chemical parameters such as DO, total phosphate, nitrite, and dissolved iron (Fe). Similarly, these parameters (total phosphate, nitrite, and Dissolved iron (Fe) also reached the maximum assimilation capacity of Babak watershed to contain and self-purify these pollutants from the water column. Thus, planning mitigation and adaptation measures are required to prevent further contaminations in this watershed.

Integrative analysis of transcriptome and phytohormones reveals new genes network involved in shoot apical meristem development in maize under blue and red light

Blue and red light play a significant role in regulating transcriptional expression, phytohormone levels, and gene signal network reconstruction in the shoot apical meristem. To further elucidate the effects of red and blue light on transcriptional characteristics and phytohormone expression, and to explore signaling pathways and novel genes, we conducted comparative experiments under different light quality treatments. The results are as follows: a total of 22,327 genes were found to be effectively expressed, with a considerable number of alternative splicing events occurring concurrently. Furthermore, 1063 differentially expressed genes were identified, primarily associated with transcriptional variations resulting from the transition from blue light to red light. These differentially expressed genes are predominantly involved in KEGG annotations related to photosynthesis, DNA replication and carbon metabolism. The findings from targeted metabolism analysis reveal significant variations in 45 phytohormones, including ABA, auxin, CK, ETH, GA, JA, and SA. Correlation analysis between transcription and metabolism further indicates that IAA.Glc, IAA.Glu, TRP, mT9G, and GA53 show the strongest correlation with differentially expressed genes, with genes ssu1, ssu2, pep1, me3, and hsp90 displaying a significant relationship. Additionally, in the protein–protein interaction network, three novel genes (LOC100286132, LOC100510780, and LOC103653934) were identified as significant responding to the regulation of blue and red light. Following protein function analysis, the proteins were provisionally identified as ubiquitin conjugating enzyme-like, OXIDATIVE STRESS 3LIKE 2-like, and Ribosomal L 18p/L5e, respectively. Conclusively, it is depicted that the most significant impact of transitions between red light, blue light, and two light qualities lies in the transcriptional process of shot apical meristem of the C4 plant maize. This process is intricately linked to nitrogen availability, carbon dioxide assimilation capacity, and the stimulatory effects of auxin, cytokinin, and gibberellin. The expression of the putative L 18/L5e in blue and BTR light conditions may enhance transcript and synthesis capabilities of ribosome.

Clinical evaluation on the use of a new accessory device for Fox plane.

Evaluate the assimilation capacity and ease of handling of the Fox plane accessory by dentistry students, through a questionnaire about the experience in using this device compared to the conventional one. Its intention is to minimize possible interpretation errors and challenges that the traditional method determines. After approval by the Research Ethics Committee, registration at Sistema Nacional de Informações sobre Ética em Pesquisa/National Information System on Research Ethics (SISNEP) and signing of the free and informed consent form, 51 undergraduate students treating patients in need of complete dentures at Instituto de Ciência e Tecnologia/Institute of Science and Technology (ICT) Unesp in São José dos Campos completed a questionnaire to evaluate the technical ease of use and provider acceptance. The obtained data were submitted to statistical analysis, evaluating technical ease and acceptance by operators. The results were analyzed using descriptive and inferential statistics using the Jamovi 2.2.5 software. From the responses, the frequency was obtained for each question in the questionnaire, then the weighted mean was calculated, average rating and percentage. With the results of these analyses it was possible to measure the level of satisfaction of the participants in relation to the use of the device. It was concluded that most students have difficulty using the conventional Fox plane and that the accessory facilitated the process of determining the superior orientation plane, and its ease of use.

SlPGR5/SlPGRL1 pathway-dependent cyclic electron transport regulates photoprotection and chloroplast quality in tomato plants

The essential photoprotective role of proton gradient regulation 5 (PGR5)-dependent cyclic electron flow (CEF) has been reported in Arabidopsis, rice, and algae. However, its functional assessment has not been performed in tomato yet. In this study, we focused on elucidate the function of SlPGR5 and SlPGR5-like photosynthetic phenotype 1 (PGRL1) in tomato. We performed RNA interference and found that SlPGR5/SlPGRL1-suppressed transformants exhibited extremely low CO2 assimilation capacity, their photosystem I (PSI) and PSII were severely photoinhibited and chloroplasts were obviously damaged. The SlPGR5/SlPGRL1-suppressed plants almost completely inhibited CEF and Y(ND), and PSII photoinhibition may be directly related to the inability to produce sufficient proton motive force to induce NPQ. The transgenic plants overexpressing SlPGR5 and SlPGRL1 driven by 35S promoter capable alleviate photoinhibition of plants under low night temperature. The transcriptomic and proteomic analyses suggested that the nuclear gene transcription and turnover of chloroplast proteins, including the plastoglobule-related proteins, were closely related to SlPGR5/SlPGRL1 pathway dependent CEF. The bridge relationship between CEF and chloroplast quality maintenance was a novel report to our knowledge. In conclusion, these results revealed the regulatory mechanism of the SlPGR5/SlPGRL1 pathway in photoprotection and maintenance of chloroplast function in tomato, which is crucial for reduce yield loss, especially under adverse environmental conditions.

High-throughput screening carbon and nitrogen sources to promote growth and sporulation in Rhizopus arrhizus

Rhizopus arrhizus is a saprotrophic, sometimes clinically- and industrially-relevant mold (Mucorales) and distributed worldwide, suggesting it can assimilate a broad spectrum of substrates. Here, 69 strains of R. arrhizus were investigated by using the Biolog FF MicroPlate for the profiles of utilizing 95 carbon and nitrogen substrates. The study showed that most R. arrhizus strains were similar in average well color development (AWCD) and substrate richness (SR). Nevertheless, 13 strains were unique in principal component analyses, heatmap, AWCD, and SR analyses, which may imply a niche differentiation within R. arrhizus. The species R. arrhizus was able to utilize all the 95 carbon and nitrogen substrates, consistent with the hypothesis of a great metabolic diversity. It possessed a substrate preference of alcohols, and seven substrates were most frequently utilized, with N-acetyl-d-galactosamine and l-phenylalanine ranking at the top of the list. Eight substrates, especially l-arabinose and xylitol, were capable of promoting sporulation and being applied for rejuvenating degenerated strains. By phenotyping R. arrhizus strains in carbon and nitrogen assimilation capacity, this study revealed the extent of intra-specific variability and laid a foundation for estimating optimum substrates that may be useful for industrial applications.

Nitrogen and potassium limit fine root growth in a humid Afrotropical forest

Nutrient limitations play a key regulatory role in plant growth, thereby affecting ecosystem productivity and carbon uptake. Experimental observations identifying the most limiting nutrients are lacking, particularly in Afrotropical forests. We conducted an ecosystem-scale, full factorial nitrogen (N)-phosphorus (P)-potassium (K) addition experiment consisting 32 40 × 40 m plots (eight treatments × four replicates) in Uganda to investigate which (if any) nutrient limits fine root growth. After two years of observations, added N rapidly decreased fine root biomass by up to 36% in the first and second years of the experiment. Added K decreased fine root biomass by 27% and fine root production by 30% in the second year. These rapid reductions in fine root growth highlight a scaled-back carbon investment in the costly maintenance of large fine root network as N and K limitations become alleviated. No fine root growth response to P addition was observed. Fine root turnover rate was not significantly affected by nutrient additions but tended to be higher in N added than non-N added treatments. These results suggest that N and K availability may restrict the ecosystem’s capacity for CO2 assimilation, with implications for ecosystem productivity and resilience to climate change.

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.

Response of the functional traits of Schoenoplectus tabernaemontani to simulated warming in the Napahai wetland of northwestern Yunnan, China

The impact of climate warming on wetland ecosystems is a current focal point in ecological research. In this study, the Napahai wetland, a typical plateau wetland in northwest Yunnan Province, was selected as the study site to understand the growth and survival strategies of emergent plants in a plateau wetland under climate warming conditions. Open-top chambers (OTCs) were used to simulate warming in three treatments (i.e., control group, 2.0 ± 0.5°C, and 4.0 ± 0.5°C) in order to study the responses of the functional traits of the dominant emergent plant Schoenoplectus tabernaemontani to simulated warming. The results showed that simulated warming significantly reduced the photosynthetic carbon assimilation capacity and biomass accumulation of S. tabernaemontani, as well as its nitrogen content and vascular bundle density, while it significantly increased the vascular bundle size. The growing season accumulated temperature (AT) and the mean temperature of the hottest month (WT) were the main temperature factors influencing the functional traits of S. tabernaemontani. In summary, simulated warming significantly affected the functional traits of S. tabernaemontani, which demonstrated effective adaptation to warming conditions. As the temperature rises and the light and productivity decrease, S. tabernaemontani prioritizes the supply of limited resources to the underground part to ensure the biomass supply of the reproductive structure. This study provides a case for revealing the response patterns and ecological adaptation strategies of plateau wetland plants to climate warming.

Continuous warming drives the colonization dynamics of periphytic ciliate fauna in marine environments.

In order to evaluate the influence of global warming on the ecosystem processes in marine environments, the changes in colonization dynamics of periphytic microbiota were studied using the periphytic ciliate communities as the test organism fauna under a continuous warming gradient of 22℃ (control), 25℃, 28℃, 31℃, and 34 ℃. The results demonstrated that (1) the test ciliate communities generally showed a similar temporal pattern in within the colonization process under the water temperatures from 22 up to 28℃; however, (2) the colonization dynamics were significantly changed, and the fitness of colonization curves to the MacArthur-Wilson model equation was failed under the temperature increased by 6 ℃, and (3) the loading or assimilative capacity of the test aquatic ecosystem was decreased with the increase of water temperature. Therefore, this study suggests that continuous warming may significantly drive the colonization dynamics of periphytic ciliates in marine ecosystems.

The tetraploid wheat (Triticum dicoccum (Schrank) Schuebl.) improves nitrogen uptake and assimilation adaptation to nitrogen-deficit stress.

The genetic diversity in tetraploid wheat provides a genetic pool for improving wheat productivity and environmental resilience. The tetraploid wheat had strong N uptake, translocation, and assimilation capacity under N deficit stress, thus alleviating growth inhibition and plant N loss to maintain healthy development and adapt to environments with low N inputs. Tetraploid wheat with a rich genetic variability provides an indispensable genetic pool for improving wheat yield. Mining the physiological mechanisms of tetraploid wheat in response to nitrogen (N) deficit stress is important for low-N-tolerant wheat breeding. In this study, we selected emmer wheat (Kronos, tetraploid), Yangmai 25 (YM25, hexaploid), and Chinese spring (CS, hexaploid) as materials. We investigated the differences in the response of root morphology, leaf and root N accumulation, N uptake, translocation, and assimilation-related enzymes and gene expression in wheat seedlings of different ploidy under N deficit stress through hydroponic experiments. The tetraploid wheat (Kronos) had stronger adaptability to N deficit stress than the hexaploid wheats (YM25, CS). Kronos had better root growth under low N stress, expanding the N uptake area and enhancing N uptake to maintain higher NO3- and soluble protein contents. Kronos exhibited high TaNRT1.1, TaNRT2.1, and TaNRT2.2 expression in roots, which promoted NO3- uptake, and high TaNRT1.5 and TaNRT1.8 expression in roots and leaves enhanced NO3- translocation to the aboveground. NR and GS activity in roots and leaves of Kronos was higher by increasing the expression of TANIA2, TAGS1, and TAGS2, which enhanced the reduction and assimilation of NO3- as well as the re-assimilation of photorespiratory-released NH4+. Overall, Kronos had strong N uptake, translocation, and assimilation capacity under N deficit stress, alleviating growth inhibition and plant N loss and thus maintaining a healthy development. This study reveals the physiological mechanisms of tetraploid wheat that improve nitrogen uptake and assimilation adaptation under low N stress, which will provide indispensable germplasm resources for elite low-N-tolerant wheat improvement and breeding.

Different nitrogen concentrations affect strawberry seedlings nitrogen form preferences through nitrogen assimilation and metabolic pathways

The preference for different forms of nitrogen (N) is an essential means to improve plant nitrogen utilization efficiency (NUE). Currently, little information is known about the N uptake preferences of strawberries and their interaction with N concentration. In this study, the preference and distribution of nitrate nitrogen (NO3−-N) and ammonium nitrogen (NH4+-N) in strawberry seedlings were investigated in response to different N concentrations. This study used two labeled N sources (15NH4NO3 and NH415NO3) for tracer labeling. Three levels of NH4NO3 were set: low N 5 mM (N1), medium N 15 mM (N2), and high N 25 mM (N3). Each N level included two 15N labeling treatments, totaling six treatments. The results showed that under low N, medium N, and high N conditions, strawberry seedlings exhibited preferences for NH4+-N, NO3−-N, and NH4+-N, respectively. Compared with N1 and N3 treatments, N2 treatment significantly increased the activity of NR, NiR, GS, and GOGAT in strawberry seedlings roots and leaves, and the relative expression levels of FaNRT1.1, FaNRT2.1, and FaAMT1.1 in roots were significantly upregulated; When the N supply concentration increases, the distribution center of NO3−-N in strawberry seedlings shifts from stem to leaf, and under high N conditions, NH4+-N accumulates significantly in the strawberry roots. According our research, the N assimilation and metabolic capacity of strawberries themselves are important factors affecting N form preferences.