Mitigate Heat Stress Research Articles

Contrasting moist heat across local climate zones in heat and non-heat waves: Insights from 29 Chinese metropolises

A thorough comprehension of moist heat (MH) variations across Local Climate Zones (LCZ) during both heat wave (HW) and non-heat waves (NHW) is crucial for mitigating heat stress in residents and urban climate. However, the LCZ-based MH differences between HW and NHW, and their climatic disparities, remain unclear. Here we investigated the heat index difference between HW and NHW (ΔHI) of LCZs across six climate zones (29 Chinese cities), based on three-year (2017–2019) hourly air temperature and relative humidity data collected from 675 stations. The results showed that (1) the ΔHI in high-rise LCZs (LCZ 1 and 4) exceeded that of mid- and low-rise LCZs (LCZ 2, 3, 5, 6, and 8) across cities, indicating that high-rise LCZs in non-shaded area face greater heat risks during HWs and therefore require special attention. Nevertheless, LCZ 9, a low-rise LCZ type, still exhibited a higher daytime ΔHI (8.2 °C) due to its high coverage of vegetation. This implies that the addition of vegetation in urban planning requires caution, and a re-evaluation of its combined effects on MH from evaporative cooling and increased humidification is quite necessary. (2) The ΔHI of LCZs peaked in the north subtropical (NS) climate zone, followed by mid subtropical and warm temperate, mid temperate, plateau temperate and south subtropical. This suggests that NS cities require greater mitigation of heat stress during HWs. We believe that these results are helpful for better understanding the MH responses of LCZs to HWs and the design of urban heat mitigation strategies.

Cool Facades and Pavements: Mitigating Heat Stress and Improving Urban Thermal Conditions in Affordable Housing Project – a Case Study in Thailand

Cool Facades and Pavements: Mitigating Heat Stress and Improving Urban Thermal Conditions in Affordable Housing Project – a Case Study in Thailand

Prevalent underestimation of tree cooling efficiency attributed to urban intrinsic heterogeneity

As cities worldwide grapple with the escalating challenges of extreme heat events, afforestation can serve as an effective adaptation measure to mitigate heat stress. This study presents a comprehensive nationwide assessment of urban tree-induced cooling effects and provides a more accurate and robust methodology that accounts for the influence of spatial heterogeneity within the complex urban environment. Results reveal that the conventional method for assessing cooling efficiency (TCE) is substantially influenced by urban heterogeneity, in terms of both horizontal and vertical structures. The revised tree cooling efficiency (RTCE), designed to minimize the impacts of other land cover types on surface temperature variations, was proved to be a more accurate estimation. In 362 out of 379 cities across China, TCE tended to underestimate the cooling effects as a result of spatial heterogeneity. The nationwide average disparity between RTCE and TCE was approximately 0.047±0.0145 ℃ per percent (95 % confidence interval). The largest differences were observed among high-rise environments, highlighting the undervalued heat mitigation potential of urban trees in compact and densely populated urban settings. This study emphasizes the considerable potential of urban tree-cooling effects in mitigating heat stress in the face of a warming planet.

Effect of three different insect larvae on growth performance and antioxidant activity of thigh, breast, and liver tissues of chickens reared under mild heat stress

This study investigated the potential of insect-based diets to mitigate heat stress impact on broiler chickens, focusing on growth performance and antioxidant stability. Four dietary groups were examined, including a control and three treated groups with Tenebrio molitor (TM), Hermetia illucens (HI), and Zophobas morio (ZM) larvae, respectively, at a 5% replacement ratio. Temperature and relative humidity of the poultry house were monitored. Under heat stress conditions, the HI-fed group consistently exhibited the highest body weight, demonstrating their remarkable growth-promoting potential. TM-fed broilers also displayed commendable growth compared to the control. Insect larvae inclusion in the diet improved feed intake during early growth stages, indicating their positive influence on nutrient utilization. Regarding antioxidant stability, malondialdehyde (MDA) levels in the liver, an oxidative stress and lipid peroxidation marker, were significantly lower in the TM-fed group, suggesting reduced oxidative stress. While the specific insect-based diet did not significantly affect MDA levels in thigh and breast tissues, variations in the total phenolic content (TPC) were observed across tissues, with HI larvae significantly increasing it in the breast. However, the total antioxidant capacity (TAC) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) levels did not differ significantly among dietary groups in the examined tissues. Results suggest that insect-based diets enhance broiler growth and potentially reduce oxidative stress, particularly in the liver. Dietary presence of bioactive compounds may contribute to these benefits. Further research is required to fully elucidate the mechanisms underlying these findings. Insect-based diets seem to offer promise as feed additives in addressing the multifaceted challenges of oxidative stress and enhancing broiler health and resilience under heat stress conditions.

Effect of Street Asymmetry, Albedo, and Shading on Pedestrian Outdoor Thermal Comfort in Hot Desert Climates

Improving urban walkability in the face of climate change is a critical challenge for urban designers. Street design strategies can mitigate heat stress and enhance pedestrian livability. Most previous studies conducted in hot climates recommend adopting deep canyons to improve summer conditions, overlooking the potential improvement of wide streets as essential structural elements of the urban fabric. This study was conducted in Biskra city, southern Algeria, where several mitigation strategies were applied to ‘Emir Abdelkader Boulevard’, as the main structural street inside the city, to create an optimal street model for arid climates. Five scenarios were developed based on three criteria: (Sc1) asymmetric profile northeast side (NES) > southwest side (SWS); (Sc2) asymmetric profile SWS > NES; (Sc3) cool paving; (Sc4) horizontal shading; and(Sc5) shading with a linear tree arrangement. ENVI-met software version 5.1.1 and the RayMan model were used to estimate the local climate conditions and outdoor thermal comfort levels based on the physiological equivalent temperature (PET). All scenarios reduced PET values across the street, with optimal reductions of −2.0 °C, −3.1 °C, −1.3 °C, −1.7 °C, and −1.2 °C in Sc1, Sc2, Sc3, Sc4, and Sc5, respectively. Concerning pedestrian areas, the optimal results durations were at the southwest side below the arcades’ sidewalks during peak hours: Sc2, Sc3, Sc4, Sc5 (2.2 °C–3 H, 2.3 °C–3 H, 2.4 °C–3 H, 2.5 °C–2 H). Sc1 performed best during daytime hours on the northeast side. The utilizing of these results can strongly help urban planners and landscape architects in creating climate-responsive streets that enhance citizens’ quality of life.

Insight into carbohydrate metabolism, protein quantification and mineral regulation in wheat (Triticum aestivum L.) by the action of green synthesized silver nanoparticles (AgNPs) against heat stress

In the present investigation, the role of GS-AgNPs treatment in wheat plants was carried out in reducing heat stress with the aim of facilitating scientists on this topic. The effect of GS-AgNPs against heat stress has rarely been deliberated in wheat plants, and only a few studies have been established earlier in this scenario. This work illustrated the effect of GS-AgNPs on the regulation of carbohydrates metabolism, SOD, proteins, crude fibers, and minerals changes in wheat plants. Data were analysed using PCA analysis, correlation parameters, and normal probability distribution in PAST 3 software. The results indicated that heat stress alone caused severe changes in carbohydrates metabolism, SOD, proteins, crude fibers, and minerals immediately so that plants could not recover without foreign stabilizers such as GS-AgNPs. The application of GS-AgNPs increases the flux of carbohydrates metabolism, SOD, and proteins, including HSPs, crude fibers, and minerals, in wheat plants to reduce the effect of heat stress. The 50 mg/l concentration of GS-AgNPs has shown an increase in carbohydrates metabolism and SOD activity, while crude fibres have shown a significant enhancement at 100 mg/l of GS-AgNPs. The crude and true proteins were also shown pronounced increase in treatment to a concentration of 50 mg/l of GS-AgNPs. GS-AgNPs stimulated HSP production; most importantly, smHSP production was observed in the present results with other HSPs in wheat plants treated with a 50 mg/l concentration of GS-AgNPs. The mineral distribution was also regulated by the respective treatment of GS-AgNPs, and the highest amounts of Ca, P and Fe were found to be highest in wheat under heat stress. In general, we computed the expected model based on GS-AgNPs on the genes/factors that respond to heat stress and their potential role in mitigating heat stress in wheat. In addition, we discussed the prospective signalling pathway triggered by GS-AgNPs in wheat against heat stress. In the future, this work might be helpful in distinguishing the genetic variation due to GS-AgNPs in promoting tolerance in wheat against heat stress. Communicated by Ramaswamy H. Sarma

Pre-hatch thermal manipulation of embryos and post-hatch baicalein supplementation mitigated heat stress in broiler chickens

BackgroundHigh environmental temperatures induce heat stress in broiler chickens, affecting their health and production performance. Several dietary, managerial, and genetics strategies have been tested with some success in mitigating heat stress (HS) in broilers. Developing novel HS mitigation strategies for sustaining broiler production is critically needed. This study investigated the effects of pre-hatch thermal manipulation (TM) and post-hatch baicalein supplementation on growth performance and health parameters in heat-stressed broilers.ResultsSix hundred fertile Cobb 500 eggs were incubated for 21 d. After candling on embryonic day (ED) 10, 238 eggs were thermally manipulated at 38.5 °C with 55% relative humidity (RH) from ED 12 to 18, then transferred to the hatcher (ED 19 to 21, standard temperature) and 236 eggs were incubated at a controlled temperature (37.5 °C) till hatch. After hatch, 180-day-old chicks from both groups were raised in 36 pens (n = 10 birds/pen, 6 replicates per treatment). The treatments were: 1) Control, 2) TM, 3) control heat stress (CHS), 4) thermal manipulation heat stress (TMHS), 5) control heat stress supplement (CHSS), and 6) thermal manipulation heat stress supplement (TMHSS). All birds were raised under the standard environment for 21 d, followed by chronic heat stress from d 22 to 35 (32–33 °C for 8 h) in the CHS, TMHS, CHSS, and TMHSS groups. A thermoneutral (22–24 °C) environment was maintained in the Control and TM groups. RH was constant (50% ± 5%) throughout the trial. All the data were analyzed using one-way ANOVA in R and GraphPad software at P < 0.05 and are presented as mean ± SEM. Heat stress significantly decreased (P < 0.05) the final body weight and ADG in CHS and TMHS groups compared to the other groups. Embryonic TM significantly increased (P < 0.05) the expression of heat shock protein-related genes (HSP70, HSP90, and HSPH1) and antioxidant-related genes (GPX1 and TXN). TMHS birds showed a significant increment (P < 0.05) in total cecal volatile fatty acid (VFA) concentration compared to the CHS birds. The cecal microbial analysis showed significant enrichment (P < 0.05) in alpha and beta diversity and Coprococcus in the TMHSS group.ConclusionsPre-hatch TM and post-hatch baicalein supplementation in heat-stressed birds mitigate the detrimental effects of heat stress on chickens' growth performance, upregulate favorable gene expression, increase VFA production, and promote gut health by increasing beneficial microbial communities.

Exploring the evolving landscape: Urban horticulture cropping systems–trends and challenges

Urban horticulture cropping systems offer a promising solution for food security and sustainable agriculture in rapidly urbanizing areas. This paper explores their evolving landscape, emphasizing trends and challenges shaping their development and impact on urban environments. Vertical farming, rooftop gardens, hydroponics, aeroponics, Internet of Things (IoT), integration of optimized space, resources, and year-round cultivation are considered as key trends in urban horticulture. These innovations reflect the growing interest in sustainable urban agriculture and technology's role in boosting productivity and resilience. However, urban horticulture faces challenges that demand attention. Limited space requires creative land-use solutions, while soil quality and contamination concerns necessitate remediation strategies for crop safety. Similarly, access to water is crucial, driving the adoption of water-saving technologies. The urban heat island effect poses another challenge, urging heat stress mitigation for crop health. Zoning and regulations play a vital role, requiring supportive policies and secure land tenure. High costs must be managed with innovative financial approaches to ensure urban farming's viability. Finally, public perception and awareness play a critical role. Advocacy, education, and community engagement are vital to dispel misconceptions, garner support, and encourage involvement in urban horticulture. Even with challenges, urban horticulture helps to provide food for the growing population, creates business opportunities, and contributes to a greener environment for sustainable development.

The effect of heat mitigation strategies on thermoregulation and productivity during simulated occupational work in the heat in physically active young men.

To investigate heat stress mitigation strategies on productivity and thermoregulatory responses during simulated occupational work in the heat. Thirteen physically active men (age, 25 ± 4 years; body mass,77.8 ± 14.7 kg; VO2peak, 44.5 ± 9.2 ml·kg-1·min-1) completed five randomized-controlled trials in a hot environment (40°C, 40% relative humidity). Each trial was 4.5 h in duration to simulate an outdoor occupational shift. Thermoregulatory responses (heart rate, HR; rectal temperature, Trec; mean skin temperature, Tsk), perceptual responses (rating of perceived exertion, RPE; thermal sensation; thermal comfort; fatigue) and productivity outcomes (box lifting repetitions, time to exhaustion) were examined in the following heat mitigation strategy interventions: (1) simulated solar radiation with limited fluid intake [SUN]; (2) simulated solar radiation with no fluid restrictions [SUN + H2O]; (3) shade (no simulated solar radiation during trial) with no fluid restrictions [SHADE + H2O]; (4) shade and cooling towels during rest breaks with no fluid restrictions [COOL + H2O]; and (5) shade with cooling towels, cooling vest during activity with no fluid restrictions [COOL + VEST + H2O]. [COOL + VEST + H2O] had lower Trec compared to [SUN] [p = 0.004, effect size(ES) = 1.48], [SUN + H2O] (p < 0.001, ES = -1.87), and [SHADE + H2O] (p = 0.001, ES = 1.62). Average Tsk was lower during the treadmill and box lifting activities in the [COOL + VEST + H2O] compared to [SUN] (p < 0.001, ES = 7.92), [SUN + H2O] (p < 0.001,7.96), [SHADE + H2O] (p < 0.001), and [COOL + H2O] (p < 0.001, ES = 3.01). There were performance differences during the [COOL + VEST + H2O] (p = 0.033) and [COOL + H2O] (p = 0.023) conditions compared to [SUN] during phases of the experimental trial, however, there were no differences in total box lifting repetitions between trials (p > 0.05). Our results suggest that during a simulated occupational shift in a laboratory setting, additional heat mitigation strategies ([COOL + VEST + H2O] and [COOL + H2O]) reduced physiological strain and improved box lifting performance to a greater degree than [SUN]. These differences may have been attributed to a larger core to skin temperature gradient or reduction in fatigue, thermal sensation, and RPE during [COOL + H2O] and [COOL + VEST + H2O]. These data suggest that body cooling, hydration, and "shade" (removal of simulated radiant heat) as heat stress mitigation strategies should be considered as it reduces physiological strain while producing no additional harm.

Exploring climate-adaptive green-space designs for hot and humid climates: Lessons from Japanese dry gardens

The number of studies on green spaces’ cooling effects has significantly increased in recent years, driven by the rising occurrence and severity of heat waves. Nevertheless, our current understanding of optimal green space designs for mitigating heat stress remains limited. This study delves into the historic Japanese dry gardens to examine the design strategies employed by ancient Japanese people in addressing hot and humid climates while crafting a thermally comfortable environment for garden visitors. We selectively investigated the thermal condition and spatial design of four compact dry gardens (<1500 m2) in Kyoto, Japan as we aimed to propose design strategies for small urban green spaces which are the major urban green spaces in Japan. The results indicated that the thermal condition in all the resting areas of the gardens was dramatically ameliorated to a “warm” condition when nearby open areas were “extremely hot.” This enhancement was achieved through the provision of extensive shade, primarily in the form of roofs, covering approximately 80% and 70% of the areas within 5 and 10 m radii around the resting areas, respectively. Nonetheless, we observed spatial heterogeneity in thermal conditions among the resting areas, which were influenced by the varying degrees of greenery cover within a 20 m radius. This study demonstrates that Japanese dry gardens were designed climate accordingly and can effectively reduce summer heat stress. It highlights the value of historic gardens as urban green spaces providing regulating ecosystem services and as a strategic design reference for guiding climate-adaptive green space designs.

Impact of anthropological activities on land-use and land-cover changes in the lower Okavango Delta, Botswana

Anthropogenic land alterations in Maun village have transformed natural vegetation into urban infrastructure, including pavements, and residential and commercial areas, leading to elevated Land Surface Temperature (LST). This urban expansion resulted from economic growth driven by population increase and tourism-related development. This study aims to evaluate the relationship between Land Use and Land Cover Changes (LULCCs) and LST. Utilising Landsat 5-TM and Landsat-8 data from 1990, 2000, and 2020, we employed a random forest algorithm for supervised classification, generating Land Use and Land Cover (LULC) maps. The mono-window algorithm was used to extract LST data from Landsat 5 and 8 images, alongside Normalised Difference Vegetation Index (NDVI) maps. s regression analysis assessed the LST-NDVI correlation. Results indicate that urban LULCCs significantly contribute to rising LST. Minimum and maximum LST values for 1990, 2000, and 2020 were 18.6°C, 22.8°C, 22.6°C, and 26.7°C, 34.5°C, and 42.1°C, respectively. NDVI values ranged from −0.2 to 0.56 in 1990, −0.17 to 0.58 in 2000, and 0.07 to 0.46 in 2020. Roads, pavements, barren land, and built-up areas displayed the highest LST (44.6°C), while water bodies and healthy vegetation exhibited the lowest (16.1°C). Additionally, NDVI exhibited a negative correlation with LST. Our findings emphasise the role of human activities in exacerbating LST. They highlight the need for regulated urban growth patterns to ensure sustainable development. Moreover, quantifying spatiotemporal variations in LULC, LST, and NDVI holds importance for conserving land resources and enhancing land use planning policies. Policymakers and city planners can utilise this research to mitigate heat stress effects and promote sustainable urban environments by evaluating distribution maps of LULC, NDVI, and LST.

Tensile Membranes and Public Spaces Thermal Comfort: An Analytical Review

Urbanization altered urban microclimates intensifying the Urban Heat Island (UHI) effect and thereby increasing outdoor thermal discomfort. Tensile membrane structures (TMS), due to their shading and cooling properties, present a viable solution for enhancing thermal comfort in urban public spaces. This paper synthesizes numerical outcomes from several studies integrating empirical data, computational models, and subjective assessments to evaluate the impact of TMS on thermal comfort. Results indicate that TMS can reduce ambient temperatures by 2-3°C and Physiological Equivalent Temperature (PET) by approximately 2.3-2.4°C or up to 5.4ºC on Mean Radiant Temperature (MRT) values, therefore enhancing user thermal comfort. The study underscores the critical role of design factors such as form, aperture, location, and strategic placement in optimizing TMS effectiveness. It also highlights the importance of considering local climatic conditions and user behaviours in the design and implementation of shading solutions. Subjective assessments reveal higher comfort levels in shaded areas, emphasizing the psychological benefits of TMS. Overall, TMS not only mitigate heat stress but also enhances the aesthetic and functional quality of urban environments, contributing to sustainable and liveable urban development. This comprehensive review provides valuable insights for urban planners, designers, and policymakers in creating more comfortable and resilient public spaces.

Regulatory effects of tea polysaccharides on hepatic inflammation, gut microbiota dysbiosis, and serum metabolomic signatures in beef cattle under heat stress.

Long-term heat stress (HS) severely restricts the growth performance of beef cattle and causes various health problems. The gut microbiota plays a crucial role in HS-associated inflammation and immune stress involving lymphocyte function. This study investigated the effects of dietary tea polysaccharide (TPS), a natural acidic glycoprotein, on HS-induced anorexia, inflammation, and gut microbiota dysbiosis in Simmental beef cattle. The cattle were divided into two groups, receiving either normal chow or normal chow plus TPS (8g/kg, 0.8%). Transcriptome sequencing analysis was used to analysis the differential signaling pathway of liver tissue. 16S rDNA sequencing was performed to analysis gut microbiota of beef cattle. Serum metabolite components were detected by untargeted metabolomics analysis. Hepatic transcriptomics analysis revealed that differentially expressed genes in TPS-fed cattle were primarily enriched in immune processes and lymphocyte activation. TPS administration significantly reduced the expression of the TLR4/NF-κB inflammatory signaling pathway, alleviating HS-induced hepatic inflammation. Gut microbiota analysis revealed that TPS improved intestinal homeostasis in HS-affected cattle by increasing bacterial diversity and increasing the relative abundances of Akkermansia and Alistipes while decreasing the Firmicutes-to-Bacteroidetes ratio and the abundance of Agathobacter. Liquid chromatography-tandem mass spectrometry (LC‒MS/MS) analysis indicated that TPS significantly increased the levels of long-chain fatty acids, including stearic acid, linolenic acid, arachidonic acid, and adrenic acid, in the serum of cattle. These findings suggest that long-term consumption of tea polysaccharides can ameliorate heat stress-induced hepatic inflammation and gut microbiota dysbiosis in beef cattle, suggesting a possible liver-gut axis mechanism to mitigate heat stress.

Potentials of Phyllanthus amarus, Viscum album and Moringa oleifera supplements to mitigate heat stress in female rabbits in humid tropics.

Global warming is a key challenge subjecting animals to heat stress conditions resulting in multiple physiological alterations in tropical climate. Dietary approach seems to be the more friendly approach to curb the adverse effects of heat stress in rabbits. Some herbs have been categorized to have high potential for promotion of immune responses for amelioration of heat stress. Thus, this research aims to evaluate the potential of Mistletoe (Viscum album), Moringa (Moringa oleifera) and Phyllanthus (Phyllanthus amarus) leaf meal as herbal supplements for the alleviation of heat stress in female rabbits by measuring improvement in sex and stress hormonal responses in serum biochemistry. 80 Rabbit does were exposed to 4 dietary groups supplemented with each of Mistletoe, Moringa, Phyllanthus and a control in an 84-day trial at the summit of thermal stress in South west Nigeria. Growth indices were monitored throughout the study, blood samples were compiled at the end of the trial to assess serum biochemistry, stress and sex hormonal responses of the Does using standard protocols. The results revealed that final weight and weight gain of Does fed on Phyllanthus were significantly (p < 0.05) higher (11.46% and 14.25%, respectively) than Does on control. The herbal supplements enhance glucose, protein, albumin and globulin, reduced cholesterol, and creatinine of Does under heat stress conditions. Among the herbal treatment groups, mistletoe, moringa and phyllanthus had 12.42%, 18.39% and 16.90%, respectively, lower corticosterone than control groups which had 39.76ng/ml. Triiodothyronine of Does fed control were significantly (p < 0.05) lower than Does on Moringa oleifera and Phyllanthus amarus supplements. Estradiol and Follicle stimulating hormone of rabbit Does fed on moringa supplement were significantly (p < 0.05) higher than other treatments. In conclusion, the herbal supplements tend to mitigate the detrimental outcome of thermal stress on Does by suppressing stress hormones. Moringa oleifera and Phyllanthus amarus enhanced sex hormones while Phyllanthus amarus confered growth promoting effects on the Does.

Community Adaptation to Heat stress − Social Network Analysis

Rising climate disasters underscore the overlooked impact of heat stress on health and productivity in densely populated Southeast Asia, particularly vulnerable coastal areas like India's. This study in the Indian Sundarbans employs surveys and social network analysis to explore heat stress effects, community adaptation, and support networks. Recognizing community significance, it views resilience as a blend of agency, wisdom, and networks. The research unveils rural adaptive behaviours, co-occurring stress responses, and network use for health solutions. These insights aim to enhance health advisories and crisis responses, fostering resilience in communities facing escalating climate challenges. The research covered 747 households from nine village segments, examining heat stress adaptation and social support networks. Social Network Analysis revealed internal and external sources of support for heat stress-induced health issues. The study employed matrices and network analysis tools to represent co-occurrence patterns of adaptation strategies and support networks. Findings highlighted collective adaptive behaviour and the role of social connections in combating climatic stress. The study outlines dual interventions to mitigate heat stress impacts: enhancing endogenous community adaptability and optimizing social-institutional networks for external support. Occupational profiling, socio-economic context, and health access can identify vulnerable groups. Perceived impacts can serve as early health crisis indicators, though not always linked to adaptive actions. Diverse adaptive activities co-occur, reflecting collective behaviour, but less central actions require attention. Medical care usage for heat stress remains minimal. Social networks lack local health providers needing community-level provisions. A comprehensive mitigation plan for identified vulnerable communities aims to bridge knowledge gaps, promote equitable healthcare access, and strengthen adaptive capacity through informed interventions.

Radicle Stage Heat Stress Mitigation through Spermidine Seed Priming in Rice

High temperature has adverse effects on rice seed seedling establishment. Priming is one of the easiest methods to alleviate heat stress. Spermidine is a polyamine that effectively reduces several abiotic stresses, including heat stress. A study was conducted for the spermidine seed priming to alleviate heat stress during the radicle stage of rice. The seeds were primed with three different concentrations of spermidine (0.5 mM, 1 mM and 1.5 mM), using three different methods of imbibition (direct soaking, blotter method, polyethylene glycol (PEG) method) before subjecting them to heat stress at the radicle stage. Results showed enhanced survival percentage with 1 mM spermidine priming in all the three methods of imbibition. In conclusion, seed priming with 1 mM spermidine concentration can effectively alleviate the adverse consequences of high temperature at the radicle stage and help in the development of normal seedlings.

Assessment of the temperature and humidity index (THI) to facilitate the establishment of a ruminant rearing system in Bangladesh

The objective of this study was to assess the temperature-humidity index (THI) values in the selected regions of Bangladesh for the suitability of ruminant rearing. Data on monthly temperatures and relative humidity were collected from the Bangladesh Meteorological Department (BMD) for a 27-year time period (1995–2022). The study region’s data indicated that the hottest area was west central region and hottest month was June. In comparison, the coolest area was northwest region and coolest month was January. The northwest region had no heat stress from November to February, mild heat stress from March to May and October, as well as moderate heat stress from June to September. In the northeast region, mild heat stress occurred from March to May, October, and November, and moderate heat stress from June to September. December to February were comfortable, March, October, and November were mild heat stress, and April through September were moderate heat stress in the west central region. In the east central region, mild heat stress occurred in March to April, October, and November, and severe heat stress in May to September. In contrast to the west central region, which showed moderate heat stress during the rainy season, most other seasons showed mild heat stress. Thus, heat stress periods might vary depending on regional meteorological scenarios. Animals faced heat stress (THI &gt; 72) or a warning signal due to a progressive increase in temperature and humidity indices over months and years of investigation. When THI levels are high, especially in July and August, livestock farmers must emphasize various herd management techniques to limit the risk of milk production and quality concerns, disease prevalence, and reproductive performance. The findings of the present investigation suggest heat stress mitigation measures for Bangladeshi ruminant farmers. Ann. Bangladesh Agric. 27 (2): 161-174

Heat-shock proteins, oxidative stress, and antioxidants in one-humped camels.

One-humped camels (Camelus dromedarius) exhibit remarkable adaptability to harsh desert environments through various physiological adaptations. This study aimed to assess variations and reference values of Heat-shock proteins (HSPs), physiological parameters, mineral concentrations, total antioxidant capacity (TAC), and malondialdehyde (MDA) in 90 healthy female one-humped camels from Zabol's outskirts in Iran. The objective was to understand how these camels adapt to heat stress. Blood samples were collected from camels located at five geographical regions and analyzed using standard kits and methods. Reference intervals for heat-shock protein 30 (HSP30), heat-shock protein 40 (HSP40), heat-shock protein 70 (HSP70), and heat-shock protein 90 (HSP90) were determined using the reference value advisor (RVA). The study found significant differences among different regions for HSPs (P < 0.05), MDA (P = 0.021), and TAC (P = 0.042) levels, indicating variations in adaptation mechanisms. However, no notable differences were observed for other measured parameters between these regions. There were no significant differences observed in the evaluated parameters between the age categories of > 36 months and < 36 months. The positive correlation between HSPs and MDA levels (ranging from 0.754 to 0.884) suggests that the synthesis of HSPs is triggered as a response to oxidative stress caused by an imbalance between the production of reactive oxygen species (ROS) and the body's antioxidant defenses. This oxidative stress, in turn, is a consequence of thermal stress. Additionally, the study reveals a negative association between TAC and HSP levels (ranging from - 0.660 to - 0.820), emphasizing the role of antioxidants in mitigating heat stress. The findings of this research offer compelling support for the critical role that HSPs play in protecting cells from heat-induced damage. Additionally, the presence of higher levels of HSPs in regions with more severe climate conditions serves as evidence of camels' adaptation to heat stress. These findings emphasize the substantial impact of environmental factors on HSP production and further reinforce the crucial role of HSPs in bolstering the resilience of camels. Further research is needed to explore HSP expression and mechanisms to effectively manage and enhance camel resilience in extreme temperatures.

Hiding from heat: The transcriptomic response of two clam species is modulated by behaviour and habitat

Rising occurrence of extreme warming events are profoundly impacting ecosystems, altering their functioning and services with significant socio-economic consequences. Particularly susceptible to heatwaves are intertidal shellfish beds, located in estuarine areas already stressed by factors such as rainfall events, red tides, eutrophication, and pollution. In Galicia, Northwestern Spain, these beds support vital shellfisheries, featuring the native clam Ruditapes decussatus and the non-indigenous R. philippinarum. Over recent decades, these populations have experienced notable abundance shifts due to various anthropogenic impacts, including climate change. In this habitat, patches of the seagrass Zostera noltei that coexist with bare sand can act as thermal refuges for benthic organisms such as clams. To assess the impact of heatwaves on these ecosystems, a mesocosm experiment was conducted. Juveniles of both clam species in two habitat types—bare sand and sand with Z. noltei—were exposed to simulated atmospheric heatwaves during diurnal low tide for four consecutive days. Subsequent transcriptomic analysis revealed that high temperatures had a more pronounced impact on the transcriptome of R. philippinarum compared to R. decussatus. The habitat type played a crucial role in mitigating heat stress in R. philippinarum, with the presence of Z. noltei notably ameliorating the transcriptomic response. These findings have direct applications in shellfishery management, emphasizing the importance of preserving undisturbed patches of Z. noltei as thermal refuges, contributing to the mitigation of heatwave effects on shellfish populations.

Efficacy evaluation of apple sunburn mitigation techniques in WA 38 cultivar using crop physiology sensing system

This study evaluated the efficacy of two heat stress mitigation techniques, i.e., modified evaporative cooling (EC), and drape/shade net (SN) against untreated control (UC) in terms of fruit surface temperature (FST) suppression and internal fruit quality for cv. WA 38. The EC treatment used foggers (flow rate: 4.1 L s−1 ha−1) spaced at 3.3 m along the row to create mist within the canopy. The experiment was conducted in a 0.2 acre block planted on two randomly distributed rootstocks [Geneva 41 (G41) and Malling 9-Nic 29 (M9)], trained in a bi-axis vertical wall architecture. Treatments were divided into three sub-blocks. Alternate wet and dry zones were observed in the sub-block treated with fogger-based EC and was therefore subdivided into EC-Wet and EC-Dry treatments. The proximal thermal-RGB imaging and in-field weather sensing integrated crop physiology sensing system (CPS2.0) was upgraded with edge computing capability to monitor real-time apple FST, an indicator of heat stress. Deployed nodes monitored imagery and weather data based FST in each treatment at an interval of 5-min throughout the growing season (i.e., during fruit maturation). Aerial imagery-based canopy temperature mapping with ground sampling distance of 4 cm/pixel was also utilized to monitor the canopy heat stress at key growth stages. CPS2.0 imagery derived apple FST was effectively reduced by EC-Wet (G41: 27.1 ± 0.4 and M9: 28.8 ± 0.4 °C) (mean ± std. error) and SN (G41: 29.8 ± 0.2 and M9: 30.5 ± 0.1 °C) treatments compared to the UC (G41: 33.1 ± 0.2 and M9: 31.4 ± 0.4 °C) throughout the production season. However, convective cooling from EC-Dry (G41: 33.1 ± 0.2 and M9: 32.5 ± 0.2 °C) treatment failed to mitigate heat stress. Results suggest that fogger spacing, and orientation need adjustments along tree-rows for effective sunburn management. Overall, canopy temperature quantified by aerial imagery was significantly lower under modified EC (30.3 ± 1.3 °C) than UC (34.2 ± 1.3 °C) treatment. Compared to UC, EC-Wet and SN protection enhanced fruit quality with higher or similar crop load, fruit firmness, and quality.