Respiration Rate Research Articles

Thinning-induced decrease in fine root biomass, but not other fine root traits in global forests

In forest ecosystems, changes in the expression of tree absorptive root traits following management interventions are expected to influence post-thinning forest structure and function. Fine root traits are expected to be especially responsive to forest thinning—one of the most common forest management interventions and the focus of our research here—influencing tree-level responses to environmental change, and thereby contributing to post-thinning stand-level dynamics and ecosystem processes. However, there remains limited understanding surrounding whether or not forest thinning influences the expression of root morphological, chemical, and physiological traits associated with belowground resource acquisition. We conducted a global meta-analysis to evaluate the response of 13 fine root traits to forest thinning. Our study included analysis of 769 paired observations of root traits values pre- and post-thinning, derived from 89 peer-reviewed publications. Our meta-analysis found that forest thinning leads to a decrease in fine root biomass by 11.7% on average, while other root traits including fine root length, root C and N concentrations, root lifespan, and root respiration rates, are largely unresponsive to thinning treatments. Thinning tended to reduce fine root biomass at early stand recovery stages, with increases in fine root biomass being detected at later seral stages, especially in heavy thinning experiments. The effect of thinning on fine root biomass was most pronounced in deeper soil horizons. The influence of thinning on fine root trait expression was not affected by ecosystem or stand type, with the exception of biomass which decreased in temperate and coniferous forests. Our results demonstrate variations of fine root traits to forest management, as well as the importance of stand recovery time and thinning intensity in regulating fine root trait expression in retention trees. These patterns may have strong implications for governing soil carbon stocks in managed forests associated with decreased root inputs into deeper soils. Overall, our findings can enhance our comprehension of how forest management affects fine root trait expression, and relationship between managed forests and belowground ecosystem structure and function.

Dispersal of microbes from grassland fire smoke to soils.

Wildland fire is increasingly recognized as a driver of bioaerosol emissions, but the effects that smoke-emitted microbes have on the diversity and community assembly patterns of the habitats where they are deposited remain unknown. In this study, we examined whether microbes aerosolized by biomass burning smoke detectably impact the composition and function of soil sinks using lab-based mesocosm experiments. Soils either containing the native microbial community or presterilized by γ-irradiation were inundated with various doses of smoke from native tallgrass prairie grasses. Smoke-inundated, γ-irradiated soils exhibited significantly higher respiration rates than both smoke-inundated, native soils and γ-irradiated soils exposed to ambient air only. Microbial communities in γ-irradiated soils were significantly different between smoke-treated and control soils, which supports the hypothesis that wildland fire smoke can act as a dispersal agent. Community compositions differed based on smoke dose, incubation time, and soil type. Concentrations of phosphate and microbial biomass carbon and nitrogen together with pH were significant predictors of community composition. Source tracking analysis attributed smoke as contributing nearly 30% of the taxa found in smoke-inundated, γ-irradiated soils, suggesting smoke may play a role in the recovery of microbial communities in similar damaged soils. Our findings demonstrate that short-distance microbial dispersal by biomass burning smoke can influence the assembly processes of microbial communities in soils and has implications for a broad range of fields including agriculture, restoration, plant disease, and biodiversity.

Hydrogen Sulfide Modulates Astrocytic Toxicity in Mouse Spinal Cord Cultures: Implications for Amyotrophic Lateral Sclerosis.

Hydrogen sulfide (H2S), a known inhibitor of the electron transport chain, is endogenously produced in the periphery as well as in the central nervous system, where is mainly generated by glial cells. It affects, as a cellular signaling molecule, many different biochemical processes. In the central nervous system, depending on its concentration, it can be protective or damaging to neurons. In the study, we have demonstrated, in a primary mouse spinal cord cultures, that it is particularly harmful to motor neurons, is produced by glial cells, and is stimulated by inflammation. However, its role on glial cells, especially astrocytes, is still under-investigated. The present study was designed to evaluate the impact of H2S on astrocytes and their phenotypic heterogeneity, together with the functionality and homeostasis of mitochondria in primary spinal cord cultures. We found that H2S modulates astrocytes' morphological changes and their phenotypic transformation, exerts toxic properties by decreasing ATP production and the mitochondrial respiration rate, disturbs mitochondrial depolarization, and alters the energetic metabolism. These results further support the hypothesis that H2S is a toxic mediator, mainly released by astrocytes, possibly acting as an autocrine factor toward astrocytes, and probably involved in the non-cell autonomous mechanisms leading to motor neuron death.

Effects of Temperature and Packaging Atmosphere on Shelf Life, Biochemical, and Sensory Attributes of Glasswort (Salicornia europaea L.) Grown Hydroponically at Different Salinity Levels.

Halophytes, such as Salicornia species, are promising new foods and are consumed for their pleasant salty taste and nutritional value. Since Salicornia is perishable, modified atmospheric packaging (MAP) can be a useful tool, in combination with proper temperature, to halt further quality degradation in this type of product. The purpose of this study was to investigate the effect of MAP, with or without refrigeration, to extend the shelf life of glasswort (Salicornia europaea L.) grown hydroponically (floating raft system) in a greenhouse with a nutrient solution containing 0 g/L (C) or 12.5 g/L of NaCl (T). The dry matter content, weight loss, respiration rate, biochemical composition, color, antioxidant capacity, and sensorial attributes were determined in shoots after harvest and during storage in plastic bags filled with technical air or with MAP at 4 or 20 °C for 120 h. At harvest, plants supplied with salt-enriched solution (T) showed a significant improvement in nutritional value and sensory profile. Storage in air at room temperature (20 °C) accelerated weight loss and diminished color stability, particularly in non-salinity samples (C), while MAP extended the shelf life of all the samples regardless of the storage temperature adopted. Optimal storage conditions were observed when MAP was combined with refrigeration, which allowed to effectively preserve shoots sensory acceptability for a period of about seven days. Future research could further explore the long-term effects on the nutritional value and sensory quality of S. europaea under various combinations of MAP and different storage temperatures ranging between 4 °C and 20 °C.

Extending Raspberry Shelf Life and Maintaining Postharvest Quality with CO2 Atmospheres

Raspberry (Rubus idaeus L.) fruit are known for their extremely short shelf life. Decay, leakiness, and loss of firmness are the most common limiting factors contributing to their short storage life. However, storage in elevated CO2 and reduced O2 atmospheres can delay senescence in fruit by reducing softening, respiration and ethylene production rates, and pathogen growth. In this study, raspberries were exposed to four different CO2 atmospheres—15 kPa CO2 and 6 kPa O2 (15 kPa); 8 kPa CO2 and 13 kPa O2 (8 kPa); 5 kPa CO2 and 16 kPa O2 (5 kPa); or 0.03 kPa CO2 and 21 kPa O2 (0.03 kPa)—and were evaluated for their postharvest quality periodically during two weeks of storage in 2020 and 2021. Raspberry fruits kept in a 15 kPa CO2 atmosphere followed by 8 kPa CO2 had higher firmness, brighter red color, and the least fungal decay or leakiness. In all atmospheres, the total anthocyanin content increased over time, although the rate of increase was slowed by high CO2. The raspberries’ visual attributes deteriorated over time in all atmospheres, but high CO2 atmospheres slowed the rate of deterioration. After five days, the quality of air-stored raspberries was significantly degraded, while the raspberries stored in elevated CO2 maintained good quality for up to ten days.

Soil Respiration in Anthropogenic Disturbed Ecosystems Compared to Deciduous Forests in the Urban Industrial Area

In urban industrial area, mining activity directly affects the dynamic of carbon, and consequently, the release of carbon dioxide (CO2) into the atmosphere. The main objective of this research is to study the impact of most important abiotic environmental factors on soil respiration in post-coalmine ecosystems. The moisture and temperature of the soil, along with CO2 outflow from the soil, were measured over three consecutive seasons, using 92 samples from coalmine heaps and 10 samples from deciduous forests in the same urban industrial region. Based on a survey of 396 species, a cluster analysis distinguished all deciduous and 22 forest plots grown on coalmine heaps from herbaceous plots from same coalmine heaps. The lowest soil respiration rate (0.62 mg CO2 per hour per square meter) was recorded in the herbaceous vegetation class on coalmine heaps, compared to (0.76 mg and 0.96 mg) from coalmine-heap forests and deciduous forests, respectively. Species richness and diversity positively affected soil respiration in heap herbaceous plots, though this effect was less pronounced in forests grown on coalmine heaps and in deciduous mixed forests. Unlike soil water content, soil temperature negatively correlated with soil respiration on coalmine heaps, diverging from the well-studied positive impact of soil temperature and respiration in deciduous mixed forests. Our spatial and temporal analyses emphasize that the water content of the substrate is the most significant abiotic element that affects the soil respiration on coalmine heaps positively during early vegetation succession.

Personalized Intervention Strategy Based on a Risk Score Generated From Subcutaneous Insertable Cardiac Monitor: Results From Phase 1 of ALLEVIATE-HF.

Diagnostic variables from insertable cardiac monitors may be useful in identifying patients at increased risk of heart failure (HF) events. High-risk alerts must be coupled with interventions to improve outcomes. We aim to assess the safety of a predefined protocolized intervention pathway activated by insertable cardiac monitor high-risk alerts. ALLEVIATE-HF (Algorithm Using LINQ Sensors for Evaluation and Treatment of Heart Failure) Phase 1 was a randomized interventional study enrolling patients with New York Heart Association class II/III and a recent HF event. A HF risk score based on insertable cardiac monitor diagnostics, including impedance, respiration rate, atrial fibrillation burden, heart rate during atrial fibrillation, heart rate variability, and activity duration, was calculated. A protocolized intervention pathway was activated when high-risk scores were detected that involved physician-prescribed nurse-implemented uptitration of diuretic for 4 days, unless safety rule-out conditions were met. Interventions could be repeated if high-risk scores persisted and did not require worsening symptoms. In total, 59 patients were randomized (mean age 68.2±11.8 years; 59.3% male); 67.8% with ejection fraction ≥50%. The mean follow-up was 11.8±8.1 months. Overall, 146 high-risk scores were recorded in 33 patients and 118 interventions occurred in 75 (51.4%) high-risk alerts that did not meet safety rule-out criteria. There were no serious adverse events and 13 adverse events related to interventions. In patients with symptoms at intervention initiation, symptoms resolved in 37 interventions (80%) and worsened in 8 (17%). In asymptomatic patients, symptoms developed in 3 interventions (7%). A personalized medication intervention based on insertable cardiac monitor risk score can be safely instituted in patients with HF, irrespective of symptoms. URL: https://www.clinicaltrials.gov; Unique Identifier: NCT04452149.

Assessing the ecological functioning and biodiversity of remnant native flat oyster (Ostrea angasi) reefs in temperate southeast Australia

Oyster reefs are critically endangered coastal habitats which provide valuable ecosystems services. Despite their importance, there remains a significant knowledge gap in our understanding of how oyster and sediment characteristics influence the ecological functioning and biodiversity of remnant Australian flat oyster (Ostrea angasi) reefs. To inform restoration efforts, we assessed relationships between community respiration rates (CR), inorganic nitrogen fluxes, filtration rates, biodiversity, and oyster morphometrics as well as sediment conditions for three remanent flat oyster reefs (Oyster Cove, Ralphs Bay, and Quarantine Bay) in southeast Tasmania. Additionally, we explored relationships between net denitrification, and flat oyster morphometrics and sediment conditions at one of the sites (Ralphs Bay) in southeast Tasmania. We observed positive relationships between CR, inorganic nitrogen fluxes, filtration rates, and live flat oyster biomass, as well as between the richness and biomass of associated taxa and total flat oyster biomass (both tissue and shell including dead shell), across all three locations. We also found an increase in net denitrification associated with live oyster biomass at one of the oyster reefs (Ralphs Bay). The CR, inorganic nitrogen fluxes, filtration rates, diversity of taxa and biomass of bivalves and flat oyster biomass was higher at Ralphs Bay, which has the most intact reef, compared to the other two locations. In contrast to other studies, the organic and silt content of the sediment showed limited influence on CR, inorganic nitrogen fluxes, filtration rates and net denitrification. CR, and inorganic nitrogen fluxes in these flat oyster reefs were like other restored and natural oyster reefs globally, but net denitrification, filtration rate and taxonomic richness exceeded those previously observed globally. These results highlight the important role of oyster biomass in enhancing water quality and biodiversity. Burgeoning flat oyster reef restoration initiatives should prioritise the enhancement of both live oyster populations and dead shells to recover their associated ecological functions and biological diversity.

Global perspective of ecological risk of plastic pollution on soil microbial communities.

The impacts of plastic pollution on soil ecosystems have emerged as a significant global environmental concern. The progress in understanding how plastic pollution affects soil microbial communities and ecological functions is essential for addressing this issue effectively. A bibliometric analysis was conducted on the literature from the Web of Science Core Collection database to offer valuable insights into the dynamics and trends in this field. To date, the effects of plastic residues on soil enzymatic activities, microbial biomass, respiration rate, community diversity and functions have been examined, whereas the effects of plastic pollution on soil microbes are still controversial. To include a comprehensive examination of the combined effects of plastic residue properties (Type, element composition, size and age), soil properties (soil texture, pH) at environmentally relevant concentrations with various exposure durations under field conditions in future studies is crucial for a holistic understanding of the impact of plastic pollution on soil ecosystems. Risk assessment of plastic pollution, particularly for nanoplasctics, from the perspective of soil food web and ecosystem multifunctioning is also needed. By addressing critical knowledge gaps, scholars can play a pivotal role in developing strategies to mitigate the ecological risks posed by plastic pollution on soil microorganisms.

Application of different phosphatic fertilizers influences the different phosphorus fractions and morphophysiological traits of wheat in saline sodic soil

Nutrient constraints in salt-affected soils are one of the limiting factors for crop production. We investigated phosphorus (P) availability to wheat crop and its correlations with different fractions of P in salt-affected soils in response to various phosphatic fertilizer’s application. Three different types of soils having electrical conductivity of soil extract (ECe) < 4 dS m−1 and sodium adsorption ratio (SAR) < 13.2 (mmol L−1)1/2, ECe 8 dS m−1 SAR 20 (mmol L−1)1/2 and ECe 12 dS m−1 and SAR 30 (mmol L−1)1/2 were used for this experiment. Different P fertilizers viz. control, diammonium phosphate (DAP), single super phosphate (SSP) and nitrophos (NP) were applied on these soils. The doses of nitrogen, phosphorus and potassium were remained same for all the treatments. The P fractions, agronomic parameters and P-availability to plants were determined. Results indicated increase in shoot dry weight (61%) and photosynthetic rate (9%) in SSP treated soil at EC 8 dS m−1 and SAR 20 (mmol L)1/2. The total P (7.6%) in soil and respiration rate (1.9%) in plant was recorded maximum in DAP treated soil at EC 8 dS m−1 and SAR 20 (mmol L)1/2, and membrane stability index (44%) in plant shoot, extractable P (23%) in soil and P concentration (22%) in shoot were recorded maximum in SSP treated soil at EC 12 dS m−1 and SAR 30 (mmol L)1/2. It was concluded that SSP fertilizer perform better in salt-affected soil for growth and yield of wheat compared to other phosphatic fertilizers.

Role of Squalene Epoxidase Gene (SQE1) in the Response of the Lichen Lobaria pulmonaria to Temperature Stress.

Currently, due to the increasing impact of anthropogenic factors and changes in solar activity, the temperature on Earth is rising, posing a threat to biodiversity. Lichens are among the most sensitive organisms to climate change. Elevated ambient temperatures can have a significant impact on lichens, resulting in more frequent and intense drying events that can impede metabolic activity. It has been suggested that the possession of a diverse sterol composition may contribute to the tolerance of lichens to adverse temperatures and other biotic and abiotic stresses. The major sterol found in lichens is ergosterol (ERG); however, the regulation of the ERG biosynthetic pathway, specifically the step of epoxidation of squalene to 2,3-oxidosqualene catalyzed by squalene epoxidase during stress, has not been extensively studied. In this study, we used lichen Lobaria pulmonaria as a model species that is well known to be sensitive to air pollution and habitat loss. Using in silico analysis, we identified cDNAs encoding squalene epoxidase from L. pulmonaria, designating them as LpSQE1 for the mycobiont and SrSQE1 for the photobiont Symbiochloris reticulata. Our results showed that compared with a control kept at room temperature (+20 °C), mild temperatures (+4 °C and +30 °C) did not affect the physiology of L. pulmonaria, assessed by changes in membrane integrity, respiration rates, and PSII activity. An extreme negative temperature (-20 °C) noticeably inhibited respiration but did not affect membrane stability. In contrast, treating lichen with a high positive temperature (+40 °C) significantly reduced all physiological parameters. Quantitative PCR analysis revealed that exposing thalli to -20 °C, +4 °C, +30 °C, and +40 °C stimulated the expression levels of LpSQE1 and SrSQE1 and led to a significant upregulation of Hsps. These data provide new information regarding the roles of sterols and Hsps in the response of lichens to climate change.

Toxicodynamics of cadmium in the green mussel Perna viridis (Linnaeus, 1758) using bioenergetic and physiological biomarkers.

This study evaluated the toxicity of cadmium (Cd) on the green mussel Perna viridis, aiming to identify toxicological endpoints and investigate its responses across physiological, bioenergetic, and biochemical parameters. The 96-hour LC50 value for Cd in P. viridis was 3.03 ± 0.12 mg L-1, with a 95% confidence interval of 2.35-3.91 mg L-1. Chronic toxicity tests revealed a No Observable Effect Concentration (NOEC), Lowest Observable Effect Concentration (LOEC), and chronic toxicity values of 0.20, 0.37, and 0.29 mg L-1, respectively. Cadmium accumulation in treated mussels increased 46- to 215-fold compared to the control group. Superoxide dismutase, catalase, glutathione S-transferase, and glutathione peroxidase levels in exposed mussels exhibited a significant increase compared to the control group. The redox index ratio, acetylcholinesterase activity, and lysosomal membrane stability decreased with increasing exposure concentrations. Levels of reduced and oxidized glutathione, glutathione reductase, lipid peroxidation, and metallothionein-like proteins increased in exposed mussels. Clearance rate, respiration rate, and excretion rate decreased in a dose-dependent manner. Protein, carbohydrate, and lipid levels decreased with increasing exposure concentration (p < 0.001). Mitochondrial electron transport system activity increased, while cellular energy allocation (p < 0.001) and scope for growth decreased in a dose-dependent manner (p < 0.01). The significant increase in antioxidants suggests heightened oxidative stress in mussels under Cd exposure. The physiological activities of the mussels were severely affected, ultimately leading to a reduced scope for growth. The toxicological data generated in this study contribute to the development of seawater quality criteria for the metal Cd.

Using a virtual reality game to train biofeedback-based regulation under stress conditions.

Physiological regulation strategies can be effective in reducing anxiety. However, while these strategies are often learned and practised under low-stress conditions, they are more likely to be required under conditions of high stress. We created virtual reality (VR) biofeedback games to both teach participants a breathing technique and then practise that technique under stress. We present two studies: the first provides a proof of concept, demonstrating that participants can apply the breathing technique during stress, with a significant lowering of both respiration rate and increase in heart rate variability (HRV) under stress (p < .001). The second study explicitly evaluated the effectiveness of training by comparing trained and untrained groups. Training was associated with a significantly greater HRV (p = .008) under stress. In within-group comparisons of HRV during stress compared to a baseline stressor presented before training, the trained group showed a significantly greater increase compared to untrained controls (p = .025). Our results show the feasibility and potential effectiveness of VR-based games for biofeedback training under experimentally applied stress. This may offer the opportunity for clinical techniques to more closely reflect the circumstances under which those techniques will be required.

Varying photosynthetic quotients strongly influence net kelp primary production and seasonal differences increase under warming

Reliable net primary production (NPP) estimations of kelp forests are important to evaluate their C-fixation potential. Photosynthetic oxygen measurements can be converted to C-fixation using photosynthetic quotients (PQs). Although there is a known high variability in PQs, the extent and the consequences for NPP is understudied in kelp species. Thus, the present study aimed (i) to quantify the variability of PQs, (ii) to model NPP and (iii) to assess the impact of warming on both. The kelp, Laminaria hyperborea, was studied near the island of Helgoland (North Sea, Germany) along a depth gradient (2, 4, 6 m below mean low water spring tide) across all four seasons. Blade discs were cultivated during at least 6 days per season under simulated ambient photosynthetic photon flux density (PPFD) and temperature conditions and, in parallel, in a warming scenario (+ 4°C). PQs were calculated from parallel oxygen production and 14C-fixation measurements at saturating PPFD at the end of the incubation period. Seasonal PQs varied between 1.7 and 4.4, with highest values in summer due to increased oxygen production. The warming scenario stimulated C-fixation in most seasons, lowering the PQ in comparison to ambient temperature conditions, while collection depth had no significant effect on PQs. The seasonal PQs were used to model daily NPP rates for kelp standing stock at 4 m depth. These daily NPP rates were compared between temperature treatments and with daily NPP rates based on fixed PQs. The warming scenario had a stimulating effect on daily NPP rates in the high-light season spring. In the low-light season autumn, warming resulted in negative daily NPP rates, as the high respiration rates could not be compensated by gross photosynthesis. Overall, annual NPP rate under warming conditions (347 g C m–2 yr–1) was 14% higher than the annual NPP rate under ambient conditions (303 g C m–2 yr–1). Modelling daily NPP with fixed PQs, which neglects the seasonal variation of the PQs, led to a high overestimation of up to 255%. We, therefore, recommend modelling NPP rates not with a fixed PQ, but with seasonal PQs determined under different temperature scenarios in order to obtain reliable future predictions.

Longitudinal single-subject neuroimaging study reveals effects of daily environmental, physiological, and lifestyle factors on functional brain connectivity.

Our behavior and mental states are constantly shaped by our environment and experiences. However, little is known about the response of brain functional connectivity to environmental, physiological, and behavioral changes on different timescales, from days to months. This gives rise to an urgent need for longitudinal studies that collect high-frequency data. To this end, for a single subject, we collected 133 days of behavioral data with smartphones and wearables and performed 30 functional magnetic resonance imaging (fMRI) scans measuring attention, memory, resting state, and the effects of naturalistic stimuli. We find traces of past behavior and physiology in brain connectivity that extend up as far as 15 days. While sleep and physical activity relate to brain connectivity during cognitively demanding tasks, heart rate variability and respiration rate are more relevant for resting-state connectivity and movie-watching. This unique data set is openly accessible, offering an exceptional opportunity for further discoveries. Our results demonstrate that we should not study brain connectivity in isolation, but rather acknowledge its interdependence with the dynamics of the environment, changes in lifestyle, and short-term fluctuations such as transient illnesses or restless sleep. These results reflect a prolonged and sustained relationship between external factors and neural processes. Overall, precision mapping designs such as the one employed here can help to better understand intraindividual variability, which may explain some of the observed heterogeneity in fMRI findings. The integration of brain connectivity, physiology data and environmental cues will propel future environmental neuroscience research and support precision healthcare.

Characteristics of Soil Respiration and Organic Carbon Mineralization in Dryland Potato Fields Under Different Ridge-furrow Mulching Patterns

Exploring the response mechanism of soil respiration rate to hydrothermal factors and organic carbon mineralization under different ridge-furrow mulching modes is of high importance for the development of the regional carbon cycle and assessment of its ecological benefits. An experimental study was carried out in 2020 in a dry-crop potato field in the mountainous area of southern Ningxia by setting three furrow-ridge ratios [60 cm∶30 cm （R1）, 60 cm∶45 cm （R2）, and 60 cm∶60 cm （R3）] combined with three mulching modes [ridge covered with ordinary plastic film, furrow covered with straw （DJ）, degradable water-permeable plastic film （DS）, and no mulching （DB） in furrows, respectively]. The soil hydrothermal factors, respiration rate, organic carbon content, and mineralization characteristics of potatoes during the reproductive period under different mulching modes were investigated with plain mulching without mulching （CK） as the control. The results showed that different furrow-ridge ratios combined with the mulching mode could significantly increase the soil water storage capacity in the 0-60 cm layer, and the R3DJ treatment had a better effect, with a significant increase of 24.99% compared with that in CK. The R2 treatment had the best effect of increasing temperature during the whole life cycle of the potato. The DS treatment had the effect of increasing temperature, and the DJ treatment had the effect of decreasing temperature under different mulching materials. Different furrow and ridge cover patterns could significantly increase the average soil respiration rate during the reproductive period, and the R3DS treatment was the most significant among the different furrow and ridge cover patterns, with a significant increase of 24.71% compared with that in the CK treatment. The soil organic carbon content in the 0-20 cm and 20-40 cm layers at harvest time was higher in the R2 and R1 ridges, respectively, and higher in the DB and DS treatments for different mulching materials. The soil organic carbon mineralization rate declined rapidly in the early stage of cultivation and then slowly declined and leveled off in the middle and late stages, which was highest in the R3 treatment for the three types of ridge ratios and highest in the DS treatment for different mulching materials. The fitting equations of soil respiration rate with soil hydrothermal factors during the reproductive period revealed that the synergistic effect of soil hydrothermal dual factors on soil respiration was higher than that of a soil hydrothermal single factor and that the quadratic hydrothermal dual factors could well explain 86.4% to 99.9% of the soil respiration. Correlation analysis showed that the average soil respiration rate during the whole life span of the potato was highly significantly and positively correlated with the average soil temperature in the 0-25 cm layer and the average soil organic carbon mineralization rate in the 0-40 cm layer, and the soil temperature was highly significantly and positively correlated with the organic carbon mineralization rate. The furrow-ridge ratio combined with the mulching mode was shown to improve the soil hydrothermal environment and increase the rate of organic carbon mineralization, thus affecting the soil respiration rate, with a furrow-ridge ratio of 60 cm∶45 cm or 60 cm∶60 cm under the ridge mulching mulch ditch covering biodegradable seepage mulch mode being more effective.

Energy costs of the sponge pump

Sponges pump large volumes of water to obtain nutrition from a dilute suspension of food particles and dissolved organic matter. Our review of the literature shows pumping power ranging from 0.85% up to 28% of the total metabolic respiration rate Rtot, where the pumping power (Pp = pumping rate × pump pressure) is the energy per unit time transferred to the water flow. Some published values of pumping costs are high while others are low due to incorrect estimates of some pressure losses in the aquiferous system of sponges. However, as improved descriptions of detailed structures and function, especially of the filter apparatus of the choanocytes, have become available, our corrected values for pressure losses show the respiration-specific pumping costs of Pp/Rtot = 1.3 to 22%. The stated pumping cost is based on the minimal (theoretical) pump power delivered to the water, which excludes a mechanical efficiency of pump action and a metabolic efficiency that expresses the fraction of total metabolism that is devoted to driving the pump action, considerations that should be included in future studies.

Preserving refrigeration and shelf life quality of hardy kiwifruit (Actinidia arguta) with alginate oligosaccharides preharvest application.

Alginate oligosaccharide (AOS) is a bioactive carbohydrate known for its preservation properties. However, the efficacy of preharvest AOS treatment in maintaining the postharvest quality of hardy kiwifruit (Actinidia arguta) has not been previously reported. This study explores the effects of preharvest AOS treatment (80mg L-1) on A. arguta fruit, assessing visual quality, physiological attributes, aroma, and antioxidant capacity during refrigeration and shelf life. Results showed that AOS treatment maintained higher lightness, chroma, firmness, and antioxidant levels (total phenolics, flavonoids, ascorbic acid, and glutathione), along with antioxidant enzyme activities (peroxidase, catalase, and ascorbate peroxidase). Specifically, AOS-treated fruit had 9% higher chroma and double the firmness after 60 days of refrigeration. AOS treatment reduced ripening and senescence, with 25% lower soluble solids content, 22% lower respiration rate, 30% lower ethylene production, and 35% lower malondialdehyde content. Electronic nose analysis indicated that AOS treatment suppressed changes in fruit aroma and off-odor development, maintaining significantly higher quality during the shelf life period. These findings demonstrate the effectiveness of AOS as a sustainable method to extend shelf life and preserve the quality of A. arguta fruit, enhancing its market value and consumer appeal. PRACTICAL APPLICATION: The research on using alginate oligosaccharides (AOS) for preharvest treatment of hardy kiwifruit (Actinidia arguta) has practical applications in the food industry. By extending the shelf life and preserving the quality of the fruit during storage, this method can help reduce postharvest losses and improve the market value and consumer appeal of A. arguta fruit. This sustainable preservation technique offers an eco-friendly alternative to traditional methods, enhancing the freshness and nutritional quality of the fruit available to consumers.

Growth, Morphology and Respiratory Cost Responses to Salinity in the Mangrove Plant Rhizophora Stylosa Depend on Growth Temperature.

Mangrove plants, which have evolved to inhabit tidal flats, may adjust their physiological and morphological traits to optimize their growth in saline habitats. Furthermore, the confined distribution of mangroves within warm regions suggests that warm temperature is advantageous to their growth in saline environments. We analyzed growth, morphology and respiratory responses to moderate salinity and temperature in a mangrove species, Rhizophora stylosa. The growth of R. stylosa was accelerated in moderate salinity compared with its growth in fresh water. Under warm conditions, the increased growth is accompanied by increased specific leaf area (SLA) and specific root length. Low temperature resulted in a low relative growth rate due to a low leaf area ratio and small SLA, regardless of salinity. Salinity lowered the ratio of the amounts of alternative oxidase to cytochrome c oxidase in the mitochondrial respiratory chain in leaves. Salinity enhanced the leaf respiration rate for maintenance, but under warm conditions this enhancement was compensated by a low leaf respiration rate for growth. In contrast, salinity enhanced overall leaf respiration rates at low temperature. Our results indicate that under moderate saline conditions R. stylosa leaves require warm temperatures to grow with a high rate of resource acquisition without enhancing respiratory cost.

Physiological and behavioral indicators of water buffaloes with access to heat mitigation resources in a grazing system during the hot season in the subtropics

Water buffaloes are increasingly being raised in similar way to dairy cows, in grazing systems frequently deprived of shade and water for immersion. This study aimed to evaluate the effects of different heat mitigation resources, 1) only shade and 2) shade plus water for immersion, on the behavioral repertoire and physiological characteristics of female grazing buffaloes in the subtropics during the hot season. Twenty buffaloes (Bubalus bubalis), including calves, heifers and non-lactating cows were allocated throughout the hot season (from December 2021 to April 2022) in a grazing system with two different heat mitigation resources (treatments): only shade (SH) and shade plus water for immersion (SHW). Diurnal behavioral repertoire was recorded every 15 days, individually and focally, at every 5 minutes for 12 hours per day. Heart rate (HR; beats/min), respiration rate (RR; breaths/min), rectal temperature (RT; °C) and panting score were also measured. Buffaloes reduced grazing time especially with THI above 75. Buffaloes at SHW spent more time grazing and lying than SH buffaloes (P < 0.05). Cows and heifers had higher ruminating (P < 0.05) and standing time (P < 0.05) compared with calves. Physiological variables did not differ (P > 0.05) between treatments (SH vs. SHW) and were positively correlated with air temperature and THI (P < 0.05). HR was higher for heifers (59.6) and calves (63.5) than for cows (53.3; P < 0.05). RT tended to be higher for heifers (38.4) and calves (38.3) than for cows (38.1; 0.05 < P < 0.10). However, respiration rate did not differ across buffalo categories (P > 0.05). Panting behavior was not reported throughout the observation days (panting score = 0). When both heat mitigation resources, shade and water for immersion were available, buffaloes preferred water for immersion to mitigate the effects of heat stress. Regardless animal category, buffaloes were able to maintain physiological variables within the normal range, indicating that providing shade and/or water for immersion, as environmental enrichment resources for thermoregulation, is suitable for heat stress mitigation in water buffaloes throughout the hot season in the subtropics.