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• This work assessed the physiological properties of dark-colored caladium (dark green, pinkish-dark green, dark maroon, maroon, and green lime) and light-colored caladium (yellow, white, young pinkish green, pink, and red). • A higher rate of photosynthesis was positively correlated to the higher stomatal conductance and lower RGB in the dark-colored caladium group rather than the light-colored ones. • The main characteristics of the group of light-colored leaves were a high RGB, LUE, and leaf temperature. This work aims to analyze the physiological characteristics of caladium ornamental plants with different leaf colors. Ten leaf colors, i.e., dark maroon, maroon, red, pink, white, pinkish young green, yellow, lime green, pinkish dark green, and dark green, were arranged in a completely randomized design and subjected to colorimetric red–green–blue (RGB) and portable photosynthesis measurement. Caladium leaf color, defined by the colorimetric RGB value, significantly impacted leaf physiological properties. Heatmap analysis apparently clustered caladiums into dark-colored group and light-colored ones. Dark-colored caladiums, as indicated by lower RGB values, exhibited higher photosynthesis rate, stomatal conductance, and water use efficiency (WUE). In contrast, light-colored caladium show a higher RGB, leaf temperature and light use efficiency (LUE) than the dark ones. By considering their leaf color-based physiological adaptability, this work recommends moderate sunlight and adequate water conditions for growing light-colored caladiums, while dark caladiums potentially tolerate excess light and water scarcity. Further research, including quantitative pigment analysis, is necessary to verify this hypothesis. [ABSTRACT FROM AUTHOR]

Main conclusion: PATOL1 contributes to increasing biomass not only by effective stomatal movement but also by root meristematic activity. PATROL1 (PROTON ATPase TRANSLOCATION CONTROL 1), a protein with a MUN domain, is involved in the intercellular trafficking of AHA1 H+-ATPase to the plasma membrane in guard cells. This allows for larger stomatal opening and more efficient photosynthesis, leading to increased biomass. Although PATROL1 is expressed not only in stomata but also in other tissues of the shoot and root, the role in other tissues than stomata has not been determined yet. Here, we investigated PATROL1 functions in roots using a loss-of-function mutant and an overexpressor. Cytological observations revealed that root meristematic size was significantly smaller in the mutant resulting in the short primary root. Grafting experiments showed that the shoot biomass of the mutant scion was increased when it grafted onto wild-type or overexpressor rootstocks. Conversely, grafting of the overexpressor scion shoot enhanced the growth of the mutant rootstock. The leaf temperatures of the grafted plants were consistent with those of their respective genotypes, indicating cell-autonomous behavior of stomatal movement and independent roles of PATROL1 in plant growth. Moreover, plasma membrane localization of AHA1 was not altered in root epidermal cells in the patrol1 mutant implying existence of a different mode of PATROL1 action in roots. Thus PATROL1 plays a role in root meristem and contributes to increase shoot biomass. [ABSTRACT FROM AUTHOR]

Drought stress severely impedes plant growth, development, and yield. Therefore, it is critical to uncover the genetic mechanisms underlying drought resistance to ensure future food security. To identify the genetic controls of these responses in Sorghum, an agriculturally and economically important grain crop, an interspecific recombinant inbred line (RIL) population was established by crossing a domesticated inbred line of Sorghum bicolor (TX7000) with its wild relative, Sorghum propinquum. This RIL population was evaluated under drought conditions, allowing for the identification of quantitative trait loci (QTL) that contribute to drought resistance. We detected eight QTL in the drought population that explain a significant portion of the observed variation for four traits (height, aboveground biomass, relative water content, and leaf temperature/transpiration). The allelic effects of, and the candidate genes within, these QTL emphasize: (1) the influence of domestication on drought‐responsive phenotypes, such as height and aboveground biomass, and (2) how control of water uptake and/or loss can be driven by species‐specific plant architecture. Our findings shed light on the interconnected roles of shoot and root responses in drought resistance as it relates to regulation of water uptake and/or loss, while the detected allelic effects demonstrate how maintenance of grain production and yield under drought is a likely result of domestication‐derived drought tolerance. [ABSTRACT FROM AUTHOR]

ABSTRACT Pollen, a pivotal stage in the plant reproductive cycle, is highly sensitive to temperature fluctuations, impacting seed quality and quantity. While the importance of understanding pollen temperature limits (Tmin, Topt, Tmax – collectively PTLs) is recognized, a comprehensive synthesis of underlying drivers is lacking. Here, we examined PTLs, correlating them with vegetative tissue thermotolerance and assessing variability at the intra‐ and interspecific levels across 191 species with contrasting phylogeny, cultivation history, growth form and ecology. At the species level, the PTLs range from 9.0 to 42.4°C, with considerable differences among individual species. Vegetative tissue showed greater tolerance to both low and high temperatures than pollen. A significant, though weak, correlation was observed between PTLs and leaf temperature tolerance. Pollen heat tolerance was independent of that in leaves and stems. The greatest intraspecific variability was observed in pollen cold tolerance (Tmin), followed by Topt and Tmax. Phylogenetic analysis revealed family‐level conservation in all three pollen temperature tolerance measures. Climate emerged as a significant PTL driver of pollen cold tolerance, with species from colder and stable climates exhibiting enhanced cold tolerance. Cultivated and wild species did not differ in their pollen temperature tolerances. Herbaceous plants showed higher tolerance to high temperatures compared to shrubs and trees, potentially reflecting divergent thermal conditions during anthesis. This study provides the first formal analysis of complex relationships between pollen temperature limits, plant characteristics and environmental factors, providing crucial insights into climate change impacts on plant reproduction. [ABSTRACT FROM AUTHOR]

Increasing heatwaves are threatening forest ecosystems globally. Leaf thermal regulation and tolerance are important for plant survival during heatwaves, though the interaction between these processes and water availability is unclear. Genotypes of the widely distributed foundation tree species Populus fremontii were studied in a controlled common garden during a record summer heatwave—where air temperature exceeded 48 °C. When water was not limiting, all genotypes cooled leaves 2 to 5 °C below air temperatures. Homeothermic cooling was disrupted for weeks following a 72-h reduction in soil water, resulting in leaf temperatures rising 3 °C above air temperature and 1.3 °C above leaf thresholds for physiological damage, despite the water stress having little effect on leaf water potentials. Tradeoffs between leaf thermal safety and hydraulic safety emerged but, regardless of water use strategy, all genotypes experienced significant leaf mortality following water stress. Genotypes from warmer climates showed greater leaf cooling and less leaf mortality after water stress in comparison with genotypes from cooler climates. These results illustrate how brief soil water limitation disrupts leaf thermal regulation and potentially compromises plant survival during extreme heatwaves, thus providing insight into future scenarios in which ecosystems will be challenged with extreme heat and unreliable soil water access. [ABSTRACT FROM AUTHOR]

ABSTRACT In ecophysiology leaves are frequently stored for hours after sampling before measuring their leaf water potential (Ψleaf). Here, we address a previously unidentified source of error, that metabolic heat generation can cause continuous water loss from leaves stored in impermeable bags, leading to a Ψleaf drop over time. We tested Ψleaf drop rates under various conditions: two bag materials, two species, initial Ψleaf above or below the turgor loss point (Ψtlp), and storage at 25°C versus 4°C. We partitioned leaf water loss due to condensation on the inner bag surface or permeation through the bag. We found that Ψleaf dropped by up to 0.39 MPa per hour, with 41%–89% of the water leaving the leaf condensed on the inner bag surface. Plastic bags showed higher Ψleaf drop rates than aluminium bags, and leaves above Ψtlp experienced greater drops. Storing leaves at 4°C reduced the Ψleaf drop rate by 60% compared to 25°C. Leaves were 0.2–0.3°C warmer than the bags, likely due to metabolic heating. Our energy balance model suggests that water loss is lower when storing leaves at cooler temperatures, using leaves with low stomatal conductance, deflated bags, and leaves with low Ψleaf. [ABSTRACT FROM AUTHOR]

Increased temperatures are altering rates of organic matter (OM) breakdown in stream ecosystems with implications for carbon (C) cycling in the face of global change. The metabolic theory of ecology (MTE) provides a framework for predicting temperature effects on OM breakdown, but differences in the temperature dependence of breakdown driven by different organismal groups (i.e., microorganisms vs. invertebrate detritivores) and litter species remain unresolved. Over two years, we conducted 12 60‐day leaf litterbag incubations in 20 headwater streams in the southern Appalachian Mountains (USA). We compared temperature dependence (as activation energy, Ea) between microbial and detritivore‐mediated breakdown, and between a highly recalcitrant (Rhododendron maximum) and a relatively labile (Acer rubrum) leaf species. Detritivore‐mediated breakdown had a higher Ea than microbial breakdown for both leaf species (Rhododendron: 1.48 > 0.56 eV; Acer: 0.97 > 0.29 eV), and Rhododendron breakdown had a higher Ea than Acer breakdown for both organismal groups. Similarly, the Ea of total (coarse‐mesh) Rhododendron breakdown was higher than the Ea of total Acer breakdown (0.89 > 0.52 eV). These effects for total breakdown were large, implying that the number of days to 95% mass loss would decline by 40% for Rhododendron and 26% for Acer between 12°C (our mean temperature value) and 16°C (+4°C, reflecting projected increases in global surface temperature due to climate change). Despite patterns in Ea, overall breakdown rates were higher for microbes than detritivores, and for Acer than Rhododendron over most of our temperature gradient. Additionally, the Ea for a subset of the microbial breakdown data declined from 0.40 to 0.22 eV when fungal biomass was included as a model predictor, highlighting the key role of fungi in determining the temperature dependence of litter breakdown. Our results imply that, as streams warm, routing of leaf litter C to detritivore‐mediated fates will increase faster than predicted by previous studies and MTE, especially for labile litter. As temperatures rise, earlier depletion of autumn‐shed, labile leaf litter combined with rapid breakdown rates of recalcitrant litter could exacerbate seasonal resource limitation and alter carbon storage and transport dynamics in temperate headwater stream networks. [ABSTRACT FROM AUTHOR]

High‐temperature limits early season vegetative growth of cotton, and the physiological response of cotton (Gossypium hirsutum L.) to high daytime or nighttime temperature needs to be explored. The objectives of the current study were to determine (1) plant growth response, (2) physiological contributors to variation in biomass production and (3) mechanisms driving variation in net photosynthetic rate (AN) in response to different combinations of high daytime and nighttime temperatures. Beginning at planting, cotton was exposed to four different growth temperature regimes: (1) optimum (30/20°C day/night), (2) high nighttime (30/30°C), (3) high daytime (40/20°C) and combined high daytime and nighttime (40/30°C) for 4 weeks. Relative to the 30/20°C treatment, plant growth was positively affected by high nighttime temperature and negatively affected by high daytime temperature and combined high day and night temperature. Increased leaf area mainly contributed to increased biomass production in high nighttime temperature; higher nighttime respiration (RN) drove reductions in biomass in combined high daytime and nighttime temperature; and decreased leaf area and AN and increased RN drove reductions in biomass under high daytime temperature alone. AN was not impacted by high nighttime temperature, while decreased under high daytime temperature and increased with combined high daytime and nighttime temperature. Adjustments in leaf traits contributed to increases in AN in combined high daytime and nighttime temperature, and increased photorespiration and respiration contributed to reductions in AN under high daytime temperature. Overall, early season vegetative growth of cotton exhibited differential responses to high daytime and nighttime temperatures. [ABSTRACT FROM AUTHOR]

Estimating foliar dust (FD) is essential in understanding the complex interaction between FD, vegetation, and the environment. The elevated FD has a significant impacts on vegetation physiological processes. The present study aims to explore the potential of multi‐sensor optical satellite data sets (e.g., Landsat‐8, 9; Sentinel‐2B, and PlanetScope) in conjunction with in situ data sets for FD estimation over the Jharsuguda coal mining region in Eastern India. The efficacy of different spectral bands and various radiometric indices (RIs) was tested using linear regression models for FD estimation. Furthermore, the study attempts to quantify the impacts of FD on vegetation's physiological processes (e.g., carbon uptake, transpiration, water use efficiency, leaf temperature) through proxy data sets. The key findings of the study uncovered sensor‐specific and common trends in vegetation spectral profiles under varying FD concentrations. A saturation threshold was observed around 50 g/m2 of FD concentration, beyond which additional FD concentration exhibited limited impact on spectral reflectance. On the other hand, the assessment of FD estimation models revealed distinct performances and shared trends across various satellite sensors. Notably, near‐infrared and shortwave infrared‐1 bands, along with certain RIs, such as the Global Environmental Monitoring Index and the Non‐Linear Index, emerged as pivotal for accurate FD estimation. Besides, the study results revealed that vegetation‐associated carbon uptake experienced a ∼2 to 3 gC reduction for every additional gram of FD per square meter. Moreover, the vegetation transpiration reduction per unit of FD ranged from approximately 0.0005 to 0.0006 mm/m2/day, highlighting a moderate impact on transpiration levels. These findings aid a significant evidence base to our understanding of FD's impact on vegetation physiological processes. Plain Language Summary: Estimating foliar dust (FD) cover is essential to understand its impact on vegetation and the environment. Elevated FD levels can reduce photosynthesis, hinder carbon sequestration, and affect transpiration, thereby altering plant health and ecosystem functions. Accurate FD estimation helps in assessing these ecological impacts and developing strategies to mitigate adverse effects. Furthermore, FD can affect remote sensing‐based analysis by altering the spectral reflectance properties of vegetation, potentially leading to inaccuracies in vegetation‐related studies (e.g., health assessment, productivity estimation, species identification, etc.). By understanding these effects, the study shall aid in refining remote sensing models for more precise vegetation analysis. So, the present study utilizes multi‐sensor optical satellite data sets (Landsat‐8, Landsat‐9, Sentinel‐2B, and PlanetScope) along with in situ data to estimate FD in the Jharsuguda coal mining region in Eastern India. Vegetation's spectral profiles under dusty and non‐dusty conditions are also studied. This study also quantifies the impacts of FD on vegetation physiological processes, providing critical insights into the ecological consequences of dust accumulation on plant surfaces. Key Points: Demonstrated an approach to predict foliar dust concentration from satellite dataEvaluated the efficacy of spectral bands of 4 satellite sensors and 26 radiometric indicesQuantified the effect of foliar dust on vegetation physiological processes [ABSTRACT FROM AUTHOR]

Urban green infrastructure (UGI) plays a vital role in mitigating climate change risks, including urban development-induced warming. The effective maintenance and monitoring of UGI are essential for detecting early signs of water stress and preventing potential fire hazards. Recent research shows that plants close their stomata under limited soil moisture availability, leading to an increase in leaf temperature. Multi-spectral cameras can detect thermal differentiation during periods of water stress and well-watered conditions. This paper examines the thermography of five characteristic green wall and green roof plant types (Pachysandra terminalis, Lonicera nit. Hohenheimer, Rubus tricolor, Liriope muscari Big Blue, and Hedera algeriensis Bellecour) under different levels of water stress compared to a well-watered reference group measured by thermal cameras. The experiment consists of a (1) pre-test experiment identifying the suitable number of days to create three different levels of water stress, and (2) the main experiment tested the suitability of thermal imaging with a drone to detect water stress in plants across three different dehydration stages. The thermal images were captured analyzed from three different types of green infrastructure. The method was suitable to detect temperature differences between plant types, between levels of water stress, and between GI types. The results show that leaf temperatures were approximately 1–3 °C warmer for water-stressed plants on the green walls, and around 3–6 °C warmer on the green roof compared to reference plants with differences among plant types. These insights are particularly relevant for UGI maintenance strategies and regulations, offering valuable information for sustainable urban planning. [ABSTRACT FROM AUTHOR]

ABSTRACT To avoid reaching lethal temperatures during periods of heat stress, plants may acclimate either their biochemical thermal tolerance or leaf morphological and physiological characteristics to reduce leaf temperature (Tleaf). While plants from warmer environments may have a greater capacity to regulate Tleaf, the extent of intraspecific variation and contribution of provenance is relatively unexplored. We tested whether upland and lowland provenances of four tropical tree species grown in a common garden differed in their thermal safety margins by measuring leaf thermal traits, midday leaf‐to‐air temperature differences (∆Tleaf) and critical leaf temperatures defined by chlorophyll fluorescence (Tcrit). Provenance variation was species‐ and trait‐specific. Higher ∆Tleaf and Tcrit were observed in the lowland provenance for Terminalia microcarpa, and in the upland provenance for Castanospermum australe, with no provenance effects in the other two species. Within‐species covariation of Tcrit and ∆Tleaf led to a convergence of thermal safety margins across provenances. While future studies should expand the number of provenances and species investigated, our findings suggest that lowland and upland provenances may not differ substantially in their vulnerability to heat stress, as determined by thermal safety margins, despite differences in operating temperatures and Tcrit. [ABSTRACT FROM AUTHOR]

Extreme heat events are becoming increasingly common, and the short‐term acclimation of photosynthesis will have a large impact on plant performance. Trees in lowland tropical forests, which are hypothesized to have limited abilities to tolerate rising temperatures, may need to rely on short‐term acclimation of their more plastic traits, like photosynthetic thermal tolerance, to persist in the face of increasingly variable climates. Here, we investigated seasonal acclimation of thermal tolerances in plant species of the moist Amazon. Specifically, we measured the photosynthetic thermal tolerances of six common woody Amazonian species at the beginning and at the end of the dry season to determine the species' abilities to acclimate to intra‐annual changes to climate. In addition, we used the natural thermal gradient present at our research site to test the acclimation of individual plants to maximum air temperatures not currently observed elsewhere in the moist lowland Amazon (up to ~43°C). Between seasons, there were significant overall increases in the thermal tolerances of three species (i.e. higher thermal tolerances in the hotter dry season), suggesting that leaf megathermy is prominent in these species. Also, three species acclimated their thermal tolerances to microsite‐level differences in seasonal temperature maxima, suggesting closer fidelity between leaf and air temperatures (i.e. limited homeothermy) for these species. Our results show that some woody species from the moist Amazon can acclimate their thermal tolerances over short time‐scales, although acclimation is likely insufficient to overcome thermal stress during extreme temperature events. Some species may therefore be more sensitive to heatwaves than others, which could impact survival and composition of tropical lowland forests into the future. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

An outdoor reduced-scale canyon street was set-up in Angers, France, to study the impact of well-watered trees on urban microclimate and human comfort, with an integrated approach of the soil-plant-atmosphere continuum. Data were acquired during 26 days in summer 2020. The street is oriented north-south, with an aspect ratio of 1. It is organized in three zones: two zones with a central alignment of 5 ornamental apple trees, and one zone without trees. The water inputs are controlled through a drip-irrigation system. Each zone is instrumented to characterise the local microclimate and energy fluxes, the soil water status, and tree leaf temperature. To allow a better understanding of the physical mechanisms at stake in tree services, tree transpiration as well as crown light interception are also quantified, and the trees are characterised in terms of leaf area and crown dimensions. The data can benefit to researchers in urban meteorology and environmental physics. It can also provide reference data to run and evaluate microclimate models, especially regarding plant-atmosphere interactions. [ABSTRACT FROM AUTHOR]

Summary: Current estimates of temperature effects on plants mostly rely on air temperature, although it can significantly deviate from leaf temperature (Tleaf). To address this, some studies have used canopy temperature (Tcan). However, Tcan fails to capture the fine‐scale variation in Tleaf among leaves and species in diverse canopies.We used infrared radiometers to study Tleaf and Tcan and how they deviate from air temperature (ΔTleaf and ΔTcan) in multispecies tropical tree plantations at three sites along an elevation and temperature gradient in Rwanda.Our results showed high Tleaf (up to c. 50°C) and ΔTleaf (on average 8–10°C and up to c. 20°C) of sun‐exposed leaves during 10:00 h–15:00 h, being close to or exceeding photosynthetic heat tolerance thresholds. These values greatly exceeded simultaneously measured values of Tcan and ΔTcan, respectively, leading to strongly overestimated leaf thermal safety margins if basing those on Tcan data. Stomatal conductance and leaf size affected Tleaf and Tcan in line with their expected influences on leaf energy balance.Our findings highlight the importance of leaf traits for leaf thermoregulation and show that monitoring Tcan is not enough to capture the peak temperatures and heat stress experienced by individual leaves of different species in tropical forest canopies. [ABSTRACT FROM AUTHOR]

ABSTRACT Traditional leaf gas exchange experiments have focused on net CO2 exchange (Anet). Here, using California poplar (Populus trichocarpa), we coupled measurements of net oxygen production (NOP), isoprene emissions and δ18O in O2 to traditional CO2/H2O gas exchange with chlorophyll fluorescence, and measured light, CO2 and temperature response curves. This allowed us to obtain a comprehensive picture of the photosynthetic redox budget including electron transport rate (ETR) and estimates of the mean assimilatory quotient (AQ = Anet/NOP). We found that Anet and NOP were linearly correlated across environmental gradients with similar observed AQ values during light (1.25 ± 0.05) and CO2 responses (1.23 ± 0.07). In contrast, AQ was suppressed during leaf temperature responses in the light (0.87 ± 0.28), potentially due to the acceleration of alternative ETR sinks like lipid synthesis. Anet and NOP had an optimum temperature (Topt) of 31°C, while ETR and δ18O in O2 (35°C) and isoprene emissions (39°C) had distinctly higher Topt. The results confirm a tight connection between water oxidation and ETR and support a view of light‐dependent lipid synthesis primarily driven by photosynthetic ATP/NADPH not consumed by the Calvin–Benson cycle, as an important thermotolerance mechanism linked with high rates of (photo)respiration and CO2/O2 recycling. [ABSTRACT FROM AUTHOR]

Monitoring of Phyllosticta citricarpa (causal agent of citrus black spot [CBS]) inoculum in orchards has previously been performed using volumetric spore traps. However, volumetric traps are nonspecific, and only capture ascospores (not pycnidiospores) of different Phyllosticta species. This research aimed to monitor and quantify the DNA of P. citricarpa using young citrus plants as a spore trap combined with quantitative PCR (qPCR), as well as quantify the number of ascospores and pycnidiospores, and to correlate results with weather variables. Citrus nursery plants were placed as traps under and outside tree canopies during fruit developmental stages (from October to July) in two seasons in commercial ‘Valencia’ sweet orange orchards. DNA was extracted from trap leaves to quantify P. citricarpa inoculum by qPCR of the ribosomal internal transcribed spacer 1 (ITS1 rRNA) region of P. citricarpa (Pc‐ITS). Correlations of Pc‐ITS to rainy days, leaf wetness and temperature were performed. Overall, the highest numbers of 400 Pc‐ITS/cm2 of leaf tissue, which represented up to 12 ascospores or pycnidiospores per cm2, were detected on leaves sampled from October to March, regardless of the trap position, season and orchard. Trap plants placed under canopies had up to 20‐fold more Pc‐ITS than those placed outside. Rainy days and leaf wetness were the variables most positively correlated with Pc‐ITS. Both results in the fluctuation of P. citricarpa inoculum in orchards and the most favourable weather variables associated with inoculum production contribute to better understanding of the critical periods for CBS management in citrus‐growing areas. [ABSTRACT FROM AUTHOR]

In this study, the effects of repeated cycles of drying and rehydration on some physiological traits were assessed in long shelf-life tomatoes cultivated in a typical semi-arid area of Southern Italy. Three Sicilian landraces ('Custonaci', 'Salina', and 'Vulcano') from the germplasm collection at CNR-IBE (Catania, Italy) and a commercial tomato mini-plum ('Faino Hy., control) were investigated under three water regimes: DRY (no irrigation), IRR (long-season full irrigation) and REW (post-drought rewaterings). Net photosynthetic assimilation rate (Pn), leaf transpiration (E), stomatal conductance (gs), instantaneous water use efficiency (WUEi), leaf intercellular CO2 (Ci, ppm), and leaf temperature (°C), were measured during the growing season. At harvest (late July), fruit production per plant was measured and ripened fruits were analysed for total solids (TS), soluble solids (SS), reducing sugars (RS), vitamin C (AscA), and total phenols (TP). Pn promptly responded to rewatering (REW), quickly increasing immediately after irrigation, and declined with soil drying up. All genotypes had similar physiological pathways in DRY, but in IRR, 'Faino' had higher Pn (up to 31 μmol CO2 m−2s−1) and E (up to 18 mmol H2O m−2s−1). Stomatal conductance (gs) after rewatering steeply increased and quickly declined after that. All local landraces had the same gs in IRR and REW. Variations in RWC were less pronounced than those in other physiological parameters. WUEi in REW and DRY proceeded similarly (up to 3 μmol CO2 mmol H2O). Irrigation in REW significantly promoted plant productivity over the DRY control (up to +150% in 'Vulcano'). TS and SS in REW were lower than those in DRY, but higher (+19 and +7%, respectively) than in IRR. Vitamin C was greater in DRY and REW (26 and 18% higher than in IRR, respectively). TP in all local tomatoes were significantly higher (up to +29% in 'Vulcano') than those in the commercial control. Water regime had a minor effect on TP in 'Custonaci' and 'Salina'. Principal Component Analysis (PCA) provided information on the changes in physiological and fruit quality traits in tomatoes in relation to cultivars and water regimes. The results of this study also revealed that a water-saving irrigation strategy where few irrigations are applied after prolonged periods of drought might be profitable in terms of fruit production enhancement in long shelf-life tomatoes and that limited rewaterings in most cases, help retaining high levels of fruit quality traits. [ABSTRACT FROM AUTHOR]

The Ficus genus, having radiated from the tropics and subtropics to the temperate zone worldwide, is the largest genus among woody plants, comprising over 800 species. Evolution of the Ficus species results in genetic diversity, global radiation and geographical differentiations, suggesting adaption to diverse environments and coping with stresses. Apart from familiar physiological changes, such as stomatal closure and alteration in plant hormone levels, the Ficus species exhibit a unique mechanism in response to abiotic stress, such as regulation of leaf temperature and retention of drought memory. The stress-resistance genes harbored by Ficus result in effective responses to abiotic stress. Understanding the stress-resistance mechanisms in Ficus provides insights into the genetic breeding toward stress-tolerant crop cultivars. Following upon these issues, we comprehensively reviewed recent progress concerning the Ficus genes and relevant mechanisms that play important roles in the abiotic stress responses. These highlight prospectively important application potentials of the stress-resistance genes in Ficus. [ABSTRACT FROM AUTHOR]

During the actual operation of the power plant, the steam turbine will appear to operate under low load conditions. This paper proposes a novel water spray arrangement for the exhaust channel. Spraying ports are evenly arranged on the cone wall so that the direction of water spraying is opposite to that of the exhaust steam flow (reverse spraying). The feasibility of the nozzle was verified by simulation calculations of existing wind tunnel experiments. The results show that evaporation increases with decreasing load. And the evaporation volume is greater in the reverse spraying than in the down spraying (the direction of water spraying is the same as the direction of steam flow), with a maximum difference of 0.42 kg/s. The deterioration of the aerodynamic performance in the exhaust passage after water spraying can be attributed to the combined effect of the evaporation of water droplets and droplet interference with the flow field. The maximum reduction of 8.17% in the static pressure recovery coefficient in the reverse spray mode increased the total pressure drop by 377.4 Pa. After the water spraying, the temperature dropped significantly compared to before the water spraying. In reverse spraying, the vortex scale in the exhaust passage becomes larger, the return vortex flow increases, the volume absorption ability is stronger, the water droplets and steam contact time is long, good temperature reduction is achieved, and the temperature of the leaf root high-temperature zone is reduced. The maximum difference in temperature drop between the two spraying methods is 56.87 K. The results of this paper provide a reference for the cooling of the exhaust passage when the turbine is operated under low flow conditions for a long time. [ABSTRACT FROM AUTHOR]

C2 photosynthesis is a photosynthetic pathway in which photorespiratory CO2 release and refixation are enhanced in leaf bundle sheath (BS) tissues. The evolution of C2 photosynthesis has been hypothesized to be a major step in the origin of C4 photosynthesis, highlighting the importance of studying C2 evolution. In this study, physiological, anatomical, ultrastructural, and immunohistochemical properties of leaf photosynthetic tissues were investigated in six non‐C4Tribulus species and four C4Tribulus species. At 42°C, T. cristatus exhibited a photosynthetic CO2 compensation point in the absence of respiration (C*) of 21 µmol mol−1, below the C3 mean C* of 73 µmol mol−1. Tribulus astrocarpus had a C* value at 42°C of 55 µmol mol−1, intermediate between the C3 species and the C2T. cristatus. Glycine decarboxylase (GDC) allocation to BS tissues was associated with lower C*. Tribulus cristatus and T. astrocarpus allocated 86% and 30% of their GDC to the BS tissues, respectively, well above the C3 mean of 11%. Tribulus astrocarpus thus exhibits a weaker C2 (termed sub‐C2) phenotype. Increased allocation of mitochondria to the BS and decreased length‐to‐width ratios of BS cells, were present in non‐C4 species, indicating a potential role in C2 and C4 evolution. Summary statement: Physiological, structural, and immunohistochemical analyses of leaf tissues indicate sub‐C2 and C2 character states occurring in Tribulus (Zygophyllaceae). These data reveal novel insights into the mechanisms by which photorespiratory CO2 refixation facilitates the evolution of C4 photosynthesis. [ABSTRACT FROM AUTHOR]

Changes in leaf temperature are known to drive stomatal responses, because the leaf‐to‐air water vapour gradient (Δw) increases with temperature if ambient vapour pressure is held constant, and stomata respond to changes in Δw. However, the direct response of stomata to temperature (DRST; the response when Δw is held constant by adjusting ambient humidity) has been examined far less extensively. Though the meagre available data suggest the response is usually positive, results differ widely and defy broad generalisation. As a result, little is known about the DRST. This review discusses the current state of knowledge about the DRST, including numerous hypothesised biophysical mechanisms, potential implications of the response for plant adaptation, and possible impacts of the DRST on plant‐atmosphere carbon and water exchange in a changing climate. Summary statement: The direct response of stomata to temperature (the response when evaporative demand is held constant by adjusting ambient humidity) is very poorly known. This review summarises the current state of knowledge about the response, a range of potential biophysical mechanisms, and its possible implications for plant‐atmosphere gas exchange and evolution. [ABSTRACT FROM AUTHOR]

Water and nitrogen are widely used agricultural inputs in potato production areas. However, the excessive and inappropriate use of these significant inputs may lead to the rapid depletion of water resources and inappropriate nitrogen leakage. In potato production, insight into the effects of water and nitrogen on the physiological properties will help to overcome these difficulties. This study was therefore conducted to determine the effects of different nitrogen and irrigation levels on the physiological (photosynthesis rate, leaf area index, leaf chlorophyll content, and leaf temperature) characteristics of potato. Field experiments were conducted during the 2021–2022 and 2022–2023 primary potato cropping seasons to select the suitable combination of irrigation and fertilization levels for potato production in the Nigde Province of the Central Anatolia Region of Turkey. Employing a factorial design, the study encompassed six nitrogen fertilization rates and three irrigation levels. Measurements were systematically recorded at five distinct intervals (40, 50, 60, 70, and 80 days) post-emergence. The outcomes underscored that nitrogen treatments augmented physiological traits, manifesting in heightened photosynthetic rates, chlorophyll content, and leaf area indices, barring leaf temperature, in comparison to the control group (devoid of nitrogen treatments). Full irrigation (I1) yielded the utmost values for both photosynthesis and leaf area index, with I1N3 (full irrigation and intermediate nitrogen supply) was identified as the most efficacious treatment for these parameters. This study identifies the most appropriate nitrogen and irrigation application for optimum physiological yield of the potato for crop producers. However, it is important to note that the study focused solely on one commercial potato cultivar (Agria), and further research on various potato cultivars is recommended for more conclusive results. [ABSTRACT FROM AUTHOR]

Stem water potential (Ψstem) is a key indicator for assessing plant water status, which is crucial in understanding plant health and productivity. However, existing measurement methods for Ψstem, characterized by destructiveness and intermittency, limit its applicability. Microtensiometers, an emerging plant-based sensor, offer continuous monitoring capabilities and have shown success in certain vine and tree species. In this study, we investigate the efficacy of microtensiometers ability to monitor the Ψstem of cotton (Gossypium hirsutum L.) under three distinct irrigation treatments in Maricopa, Arizona, an extremely hot, arid environment. We analyze the diurnal dynamics of Ψstem across the irrigation regimes and compare these measurements with midday leaf water potentials (Ψleaf) obtained using a dewpoint potentiometer. Our results demonstrate that the microtensiometer-derived Ψstem closely follows known diurnal patterns of Ψleaf, tracking with vapor pressure deficit (VPD) and responding to variations in irrigation levels and soil moisture content. Time cross-correlation analysis reveals an 80-minute lag in Ψstem response to changing VPD under non-water limiting conditions, which shortens under water-limiting conditions. Additionally, we establish a robust linear relationship (R2adj = 0.82) between Ψstem and Ψleaf, with this relationship strengthening as water availability decreases. Notably, we observe mean gradients of 1.2 and 0.06 MPa between soil vs. stem and stem vs. leaf water potentials, respectively. Moreover, Ψstem data proves to be more sensitive in distinguishing between irrigation treatments earlier in the growing season compared to Ψleaf, leaf temperature and leaf gas exchange parameters. These findings highlight the utility of microtensiometers as valuable tools for monitoring water status in smaller-stemmed row crops such as cotton. [ABSTRACT FROM AUTHOR]

The summer of 2022 has been the so far hottest summer on record in Central Europe. High temperatures negatively affect the physiology of plants and cause considerable thermal stress in particular on the leaf level. The assessment of the temperature-dependent decline of the quantum use efficiency of the photosystem II (Fv/Fm) has gained much popularity to quantify the leaf-level sensitivity to thermal stress. An open question is whether leaves heat to those in vitro estimated threshold temperatures on hot days or if plants can avoid heat stress through transpirational cooling. Therefore, leaf temperatures were monitored on a non-native Austrian oak (Quercus cerris) during a heatwave in July 2022 and compared to observed air temperature and leaf thermal traits assessed with a chlorophyll fluorometer. The highest air temperature recorded during the heatwave was 42.5 °C and surpassed the breaking point temperature (temperature at 5% decline of Fv/Fm; T5) by 0.3 °C, but was 6.1 °C lower than T50 (temperature at 50% decline of Fv/Fm). However, during the hottest day, the maximum leaf temperature was significantly below the air temperature. Even the directly illuminated leaf facing south reached a maximum temperature of only 38.7 °C but reached 39.8 °C on the second hottest day when the air temperature went up to 39.6 °C. All leaves showed a certain degree of homeothermy as the slope between leaf temperature and air temperature was 0.83 (P < 0.05). In conclusion, Austrian oak can buffer thermal stress during heatwaves to a certain degree, however, leaf temperatures are only marginally below critical threshold temperatures. [ABSTRACT FROM AUTHOR]

Productivity in strawberry is dependent on carbon assimilation in the leaves. The main scenarios for climate change include an increase in the concentration of CO2 in the atmosphere and an increase in temperature. This review examined the relationship between leaf growth and temperature in strawberry. Leaf growth follows a linear, sigmoid or Gaussian pattern over the season or is variable depending on the weather. There was a linear increase in leaf growth with temperatures below 26°C, and a linear decrease in growth with temperatures above 26°C. In other studies, the mean lower optimum for 90% of maximum growth was 18.3° ± 3.9°C, the median was 19.6°C, and the range was from 7.2° to 22.0°C (N = 11). The mean higher optimum was 27.3° ± 3.6°C, the median was 27.4°C, and the range was from 21.1° to 33.5°C (N = 12). Leaf growth was higher under 30°C and lower above 30°C. Limited studies suggest that elevated CO2 will not counteract the impact of high temperatures on growth. Climate change will increase leaf growth in cool areas and decrease growth in warm areas. The decrease in leaf growth in locations with temperatures above 30°C will contribute to lower yields under global warming. [ABSTRACT FROM AUTHOR]

Model representation of carbon uptake and storage is essential for accurate projection of the response of the arctic‐boreal zone to a rapidly changing climate. Land model estimates of LAI and aboveground biomass that can have a marked influence on model projections of carbon uptake and storage vary substantially in the arctic and boreal zone, making it challenging to correctly evaluate model estimates of Gross Primary Productivity (GPP). To understand and correct bias of LAI and aboveground biomass in the Community Land Model (CLM), we assimilated the 8‐day Moderate Resolution Imaging Spectroradiometer (MODIS) LAI observation and a machine learning product of annual aboveground biomass into CLM using an Ensemble Adjustment Kalman Filter (EAKF) in an experimental region including Alaska and Western Canada. Assimilating LAI and aboveground biomass reduced these model estimates by 58% and 72%, respectively. The change of aboveground biomass was consistent with independent estimates of canopy top height at both regional and site levels. The International Land Model Benchmarking system assessment showed that data assimilation significantly improved CLM's performance in simulating the carbon and hydrological cycles, as well as in representing the functional relationships between LAI and other variables. To further reduce the remaining bias in GPP after LAI bias correction, we re‐parameterized CLM to account for low temperature suppression of photosynthesis. The LAI bias corrected model that included the new parameterization showed the best agreement with model benchmarks. Combining data assimilation with model parameterization provides a useful framework to assess photosynthetic processes in LSMs. Plain Language Summary: The arctic‐boreal zone is warming rapidly, impacting regional and global carbon cycles. The Community Land Model (CLM) can be used to project future carbon uptake and storage in this region. However, CLM is biased in estimating leave area index (LAI) and aboveground biomass that can significantly affect model projections of carbon uptake and storage. We forced the model estimates of LAI and the aboveground biomass to be consistent with satellite‐derived LAI observations and a high‐quality machine learning product of aboveground biomass in Alaska and Western Canada using data assimilation. The change of aboveground biomass resulted in model estimates of vegetation height consistent with independent estimates at regional and site levels. The assessment using the International Land Model Benchmarking System showed that CLM's performance in simulating carbon and hydrologic cycles was improved. Fixing the model bias in LAI only removed partial bias in carbon uptake, and a new parameterization allowing two key parameters in photosynthesis to vary with leaf temperature was introduced into CLM, to further remove the remaining bias in carbon uptake. Combining data assimilation with this new parameterization yielded more accurate model estimates of carbon uptake. Key Points: Assimilating leaf area index and aboveground biomass observations into CLM reduced model bias in estimating themData assimilation significantly improved CLM's performance in carbon and hydrologic cycles, as well as the functional relationshipsImplementation of a new parameterization of photosynthesis in CLM further reduced model bias in estimating the gross primary productivity [ABSTRACT FROM AUTHOR]

Purpose: Environmental stresses are a main disturbing factor influencing horticultural productivity around the world. It will affect all plants including resistant or non-resistant cultivars. So, it is important to find the better cultivars and to check the response to adverse environmental conditions. Research method: Thus, the present research was conducted to evaluate responses of different bearing status of pistachio cultivars including Kalleh-Ghochi (K), Ohadi (O) and Ahmad-Aghaii (A), grafted on Badami-Rize-Zarand as rootstock, for six consecutive years to soil salinity. Findings: ONbearing trees of 'Ahmad-Aghaii' showed the highest yield, followed by 'Ohadi' and 'Kalleh-Ghochi'. In addition, the lowest leaf temperature was observed with this cultivar. Although the highest nitrogen, sodium, carbohydrate, peroxidase and leaf temperature was obtained in ON-bearing trees, however, the lowest potassium and total phenol content indicated in OFF-bearing status. It was found a negative correlation between leaf potassium content and ABI, between leaf peroxidase activity and ABI and between leaf temperature and ABI. On the other hand, leaf temperature increased as leaf sodium content increased. Research limitations: There was no limitation. Originality/Value: From data presented here, it is concluded that salinity and Na accumulation might be effective in changing the response of the pistachio cultivar under harsh environmental conditions which affects yield component and alternate bearing index. [ABSTRACT FROM AUTHOR]

Abstract Drought affects crops directly, and indirectly by affecting the activity of insect pests and the transmitted pathogens. Here, we established an experiment with well-watered or water-stressed melon plants, later single infected with either cucumber mosaic virus (CMV: non-persistent), or cucurbit aphid-borne yellow virus (CABYV: persistent), or both CMV and CABYV, and mock-inoculated control. We tested whether i) the relation between CMV and CABYV is additive, and ii) the relationship between water stress and virus infection is antagonistic, i.e., water stress primes plants for enhanced tolerance to virus infection. Water stress increased leaf greenness and temperature, and reduced leaf water potential, shoot biomass, stem dimensions, rate of flowering, CABYV symptom severity, and marketable fruit yield. Virus infection reduced leaf water potential transiently in single infected plants and persistently until harvest in double-infected plants. Double-virus infection caused the largest and synergistic reduction of marketable fruit yield. The relationship between water regime and virus treatment was additive in 12 out of 15 traits at harvest, with interactions for leaf water content, leaf:stem ratio, and fruit set. We conclude that both virus-virus relations in double infection and virus-drought relations cannot be generalized because they vary with virus, trait, and plant ontogeny.

Climate change has become a concern, emphasizing the need for the development of crops tolerant to drought. Therefore, this study is designed to explore the physiological characteristics of quinoa that enable it to thrive under drought and other extreme stress conditions by investigating the combined effects of irrigation water levels (100%, 75%, and 50% of quinoa's water requirements, WR as I1, I2 and I3) and different planting methods (basin, on-ridge, and in-furrow as P1, P2 and P3) on quinoa's physiological traits and gas exchange. Results showed that quinoa's yield is lowest with on-ridge planting and highest in the in-furrow planting method. Notably, the seed protein concentrations in I2 and I3 did not significantly differ but they were 25% higher than those obtained in I1, which highlighted the possibility of using a more effective irrigation method without compromising the seed quality. On the other hand, protein yield (PY) was lowest in P2 (mean of I1 and I2 as 257 kg ha−1) and highest in P3 (mean of I1 and I2 as 394 kg ha−1, 53% higher). Interestingly, PY values were not significantly different in I1 and I2, but they were lower significantly in I3 by 28%, 27% and 20% in P1, P2, and P3, respectively. Essential plant characteristics including plant height, stem diameter, and panicle number were 6.1–16.7%, 6.4–24.5%, and 18.4–36.5% lower, respectively, in I2 and I3 than those in I1. The highest Leaf Area Index (LAI) value (5.34) was recorded in the in-furrow planting and I1, while the lowest value was observed in the on-ridge planting method and I3 (3.47). In I3, leaf temperature increased by an average of 2.5–3 oC, particularly during the anthesis stage. The results also showed that at a similar leaf water potential (LWP) higher yield and dry matter were obtained in the in-furrow planting compared to those obtained in the basin and on-ridge planting methods. The highest stomatal conductance (gs) value was observed within the in-furrow planting method and full irrigation (I1P3), while the lowest values were obtained in the on-ridge and 50%WR (I3P2). Finally, photosynthesis rate (An) reduction with diminishing LWP was mild, providing insights into quinoa's adaptability to drought. In conclusion, considering the thorough evaluation of all the measured parameters, the study suggests using the in-furrow planting method with a 75%WR as the best approach for growing quinoa in arid and semi-arid regions to enhance production and resource efficiency. [ABSTRACT FROM AUTHOR]

Summary: Plant leaf temperatures can differ from ambient air temperatures. A temperature gradient in a gas mixture gives rise to a phenomenon known as thermodiffusion, which operates in addition to ordinary diffusion. Whilst transpiration is generally understood to be driven solely by the ordinary diffusion of water vapour along a concentration gradient, we consider the implications of thermodiffusion for transpiration.We develop a new modelling framework that introduces the effects of thermodiffusion on the transpiration rate, E.By applying this framework, we quantify the proportion of E attributable to thermodiffusion for a set of physiological and environmental conditions, varied over a wide range.Thermodiffusion is found to be most significant (in some cases > 30% of E) when a leaf‐to‐air temperature difference coincides with a relatively small water vapour concentration difference across the boundary layer; a boundary layer conductance that is large as compared to the stomatal conductance; or a relatively low transpiration rate. Thermodiffusion also alters the conditions required for the onset of reverse transpiration, and the rate at which this water vapour uptake occurs. See also the Commentary on this article by Vesala, 243: 1281–1283. [ABSTRACT FROM AUTHOR]

Water stress on crops can severely disrupt crop growth and reduce yields, requiring the accurate and prompt diagnosis of crop water stress, especially in semiarid regions. Infrared thermal imaging cameras are effective tools to monitor the spatial distribution of canopy temperature (Tc), which is the basis of the daily water stress index (DWSI) calculation. This research aimed to evaluate the variability of plant water stress under different soil cover conditions through geostatistical techniques, using detailed thermographic images of Neem canopies in the Brazilian northeastern semiarid region. Two experimental plots were established with Neem cropped under mulch and bare soil conditions. Thermal images of the leaves were taken with a portable thermographic camera and processed using Python language and the OpenCV database. The application of the geostatistical technique enabled stress indicator mapping at the leaf scale, with the spherical and exponential models providing the best fit for both soil cover conditions. The results showed that the highest levels of water stress were observed during the months with the highest air temperatures and no rainfall, especially at the apex of the leaf and close to the central veins, due to a negative water balance. Even under extreme drought conditions, mulching reduced Neem physiological water stress, leading to lower plant water stress, associated with a higher soil moisture content and a negative skewness of temperature distribution. Regarding the mapping of the stress index, the sequential Gaussian simulation method reduced the temperature uncertainty and the variation on the leaf surface. Our findings highlight that mapping the Water Stress Index offers a robust framework to precisely detect stress for agricultural management, as well as soil cover management in semiarid regions. These findings underscore the impact of meteorological and planting conditions on leaf temperature and baseline water stress, which can be valuable for regional water resource managers in diagnosing crop water status more accurately. [ABSTRACT FROM AUTHOR]

Background and aims: A better understanding of plant carbon assimilation, water status and photosystem performance responses to combined heat and drought stress would help to optimize grapevine management under such limiting conditions. Methods: Gas exchange and chlorophyll fluorescence parameters were measured in potted grapevines, cv Sauvignon Blanc, before, during and after simulated six-day heat (Tmax = 40 °C) wave using heated well-watered (HW), heated drought-stressed (HD), non-heated well-watered (CW) and non-heated dry (CD) vines. Results: Photosynthesis and stomatal conductance in HW vines increased during the morning and dropped in the afternoon with respect to CW vines. Daily plant transpiration in HW almost doubled that of CW vines. When grapevines were already exposed to drought, the effects of the heat wave were negligible, with HD plants showing similar leaf photosynthesis and transpiration to their CD counterparts. Heat, but not drought stress, decreased the maximum (Fv/Fm) and effective photochemical quantum yield of PSII (φPSII), and also affected the use of absorbed energy. HW plants dissipated more radiative energy as heat, a protective mechanism of the photosystem, while HD vines increased the energy dissipated by non-regulated non-photochemical pathways, which might lead to photoinhibition damages. The different behavior could be due to the enhanced transpiration rate and consequent decrease in leaf temperature in HW as compared to HD vines. After the heat wave, only HW vines recovered the afternoon values of photosynthesis, stomatal conductance and φPSII to similar levels as those in CW vines. Conclusion: Drought had a more significant effect than heat stress on photosynthesis, stomatal conductance and transpiration. The combined heat and drought stress, however, increased the proportion of energy lost by the leaves through harmful non-regulated dissipative pathways. With adequate soil water availability, grapevines withstood the heat wave period through an increase in leaf transpiration, which decreased leaf temperature and protected the PSII from heat damage. Highlights: Drought had a stronger impact on gas exchange parameters than elevated temperature during a simulated heatwave, while heat stress was the main driver of PSII functionality and absorbed energy partitioning. Well-watered grapevines were able to recover their physiological function after a six-day heatwave (Tmax 40 °C), while plants under heat and drought stress were unable to resume PSII performance after one day of recovery. [ABSTRACT FROM AUTHOR]

Sugarbeets are largely produced without irrigation, making drought stress inevitable when rainfall is insufficient. Whether drought stress impacts root storage, however, is currently unknown. Research was conducted to determine the effect of preharvest water stress on postharvest sugarbeet root respiration rate and susceptibility to storage rots as these traits are the primary determinants for sucrose loss and quality deterioration. Greenhouse‐grown plants were subjected to four levels of water deficit by discontinuing watering for 0, 7, 14 or 21 days prior to harvest. Plants receiving water‐restrictive treatments displayed physiological stress by leaf epinasty, reductions in net photosynthetic rate and leaf relative water content and increases in leaf temperature, whereas the water content of roots harvested from these plants progressively decreased with the severity of the preharvest water‐deficit treatment. Harvested roots from all watering treatments were stored at 10°C and 95% relative humidity for up to 12 weeks and evaluated for respiration rate and susceptibility to storage rot. Root respiration rate during storage was inversely related to root water content at harvest by second‐order equations, such that respiration was not significantly affected by minor reductions in root water content but increased exponentially for roots obtained from severely drought‐stressed plants with water contents at harvest of ≤75%. Similarly, roots with water contents ≤75% had elevated levels of electrolyte leakage, a measure of cellular membrane damage, and were more susceptible to dehydration and fungal infection during storage. In separate experiments, roots harvested from water‐stressed plants were inoculated with Botrytis cinerea or Penicillium vulpinum, two causal agents for storage rots. In these experiments, preharvest water stress quantitatively increased root rot and qualitatively altered symptoms of their infection. Overall, these results demonstrate that severe preharvest drought stress is likely to significantly increase sugarbeet root storage losses caused by root respiration and storage rots and that storage losses are likely to accelerate with time in storage. However, mild‐to‐moderate drought conditions prior to harvest are expected to have no or minimal effect on storage losses from root respiration or storage rots. [ABSTRACT FROM AUTHOR]

Heatwaves and soil droughts are increasing in frequency and intensity, leading many tree species to exceed their thermal thresholds, and driving wide‐scale forest mortality. Therefore, investigating heat tolerance and canopy temperature regulation mechanisms is essential to understanding and predicting tree vulnerability to hot droughts. We measured the diurnal and seasonal variation in leaf water potential (Ψ), gas exchange (photosynthesis Anet and stomatal conductance gs), canopy temperature (Tcan), and heat tolerance (leaf critical temperature Tcrit and thermal safety margins TSM, i.e., the difference between maximum Tcan and Tcrit) in three oak species in forests along a latitudinal gradient (Quercus petraea in Switzerland, Quercus ilex in France, and Quercus coccifera in Spain) throughout the growing season. Gas exchange and Ψ of all species were strongly reduced by increased air temperature (Tair) and soil drying, resulting in stomatal closure and inhibition of photosynthesis in Q. ilex and Q. coccifera when Tair surpassed 30°C and soil moisture dropped below 14%. Across all seasons, Tcan was mainly above Tair but increased strongly (up to 10°C > Tair) when Anet was null or negative. Although trees endured extreme Tair (up to 42°C), positive TSM were maintained during the growing season due to high Tcrit in all species (average Tcrit of 54.7°C) and possibly stomatal decoupling (i.e., Anet ≤0 while gs >0). Indeed, Q. ilex and Q. coccifera trees maintained low but positive gs (despite null Anet), decreasing Ψ passed embolism thresholds. This may have prevented Tcan from rising above Tcrit during extreme heat. Overall, our work highlighted that the mechanisms behind heat tolerance and leaf temperature regulation in oak trees include a combination of high evaporative cooling, large heat tolerance limits, and stomatal decoupling. These processes must be considered to accurately predict plant damages, survival, and mortality during extreme heatwaves. [ABSTRACT FROM AUTHOR]

Background: Drought is a significant abiotic stress that adversely affects plant growth, development, and metabolic processes, thereby reducing plant yield, quality, and production, and threatening global food security. In recent years, nanotechnology has emerged as a promising strategy to overcome the existing environmental challenges and has been tested on some plant species. But it is still awaiting investigation for grapevines. The aim of this study was to investigate the potential of selenium nanoparticles (Se-NPs) to modulate some morphological, physiological, and biochemical parameters in grapevine saplings (5 BB/Crimson Seedless, 41 B/Crimson Seedless, and 1103 P/Crimson Seedless) under drought stress conditions. Results: In the study, Se-NP solutions at different concentrations (0 (control), 1, 10, and 100 ppm) were applied by the spray method to wet the entire green surface of grapevine saplings grown under well-irrigated (90–100% field capacity) and drought stress (40–50% field capacity) conditions. Our results showed that 10 ppm Se-NP concentration had the most positive effect, 1 ppm concentration showed limited effects, and 100 ppm concentration led to toxic effects, especially when combined with drought conditions. Se-NP applications at 10 ppm concentration improved the growth parameters (leaf number, leaf area, root fresh and dry weight, shoot fresh and dry weight, etc.) and increased the SPAD index of grapevine saplings under both normal and drought conditions. Additionally, 10 ppm Se-NP applications improved the relative water content (RWC) and stomatal conductance values, proportional to the increases in protein content. On the other hand, under drought conditions, the drought index, leaf temperature, membrane damage index, hydrogen peroxide (H2O2) content, and malondialdehyde (MDA) levels significantly decreased as a result of 10 ppm Se-NP applications, showing an opposite trend. Furthermore, the levels of proline, total phenolics, and antioxidant enzymes (CAT, SOD, and APX) that rose significantly due to drought stress were reduced by 10 ppm Se-NP applications, which also helped to lessen the oxidative stress caused by the drought. Conclusion: The study concluded that foliar application of Se-NPs at 10 ppm significantly enhances drought tolerance in grapevine saplings by improving antioxidant defense, proline and protein accumulation, and overall growth, while lower concentrations are less effective and higher concentrations can cause phytotoxicity. These findings indicate that Se-NPs applications may hold promise not only for grapevines but also for mitigating drought stress effects and improving productivity in other economically important fruit species, warranting further exploration across diverse crop systems. [ABSTRACT FROM AUTHOR]

Impatiens walleriana is of great ornamental value, but it may suffer growth inhibition when it is exposed to sub-low temperatures for a long time. Although there are many studies on the positive effect of arbuscular mycorrhizal fungi (AMF) on cold tolerance, whether AMF could alleviate the sub-low temperature injury of Impatiens walleriana is unknown. In this experiment, two kinds of Impatiens walleriana were inoculated with AMF and treated with sub-low temperature to evaluate the physiological and biochemical characteristics of Impatiens walleriana seedlings. The results showed that the plant height of 'Super Elf (Rose red)' under stress and inoculated with 50 g and 100 g AMF compared to sub-low temperature treatment increased by 4.94% and 19.01%, and the plant height of 'Super Elf (red)' under stress and inoculated with 50 g and 100 g AMF increased by 3.11% and 17.03%, respectively. Compared to sub-low temperature treatment, the stem diameter of 'Super Elf (Rose red)' under stress and inoculated with 50 g and 100g AMF increased by 47.17% and 50.94%, respectively. The same mitigation effect was observed in 'Super Elf (red)'. Compared with sub-low temperature treatment, Fv'/Fm', Y(II) and qP of 'Super Elf (Rose red)' inoculated with 50 g AMF significantly increased by 75.76%, 52.17%, and 43.48%, while NPQ significantly decreased by 2.96 times, whereas the corresponding values for 'Super Elf (Rose red)' inoculated with 100 g AMF increased by 87.88%, 82.61%, and 65.22%, while NPQ significantly increased by 1.47 times. Compared with sub-low temperature treatment, Fv'/Fm', Y(II) and qP of 'Super Elf (red)' inoculated with 50 g AMF significantly increased by 53.49%, 28.95%, and 29.31%, while NPQ significantly decreased by 0.84 times, whereas the corresponding values for 'Super Elf (red)' inoculated with 100 g AMF increased by 53.49%, 23.68%, and 22.41%, while NPQ significantly increased by 3.48 times. Meanwhile, 'Super Elf (Rose red)' and 'Super Elf (red)' vaccination with AMF reduced the levels of O2− and H2O2 accumulation in leaves at sub-low temperatures and mitigated the extent of damage to cell membrane lipid peroxidation. Therefore, AMF inoculation can improve the tolerance of plants to sub-low temperatures. [ABSTRACT FROM AUTHOR]

Heat stress represents a significant environmental challenge that adversely impacts the growth, physiology, and productivity of wheat. In order to determine the response to high temperatures of the wheat varieties developed mostly in the Pannonian environmental zone, as well as varietal differences, we subjected seven varieties from Serbia, one from Australia, and one from the UK to thermal stress during anthesis and mid-grain filling and combined stress during both of these periods. The changes in chlorophyll fluorescence and index, leaf temperature, and main agronomic traits of nine winter wheat varieties were investigated under high temperatures. Heat stress negatively affected leaf temperature, chlorophyll fluorescence, and the chlorophyll index during different growth stages. Compared to the control, stress at anthesis, mid-grain filling, and combined stress resulted in yield reductions of 32%, 46%, and 59%, respectively. Single treatment at anthesis had a more severe effect on the number of grains per plant, causing a 38% reduction compared to the control. Moreover, single treatment during mid-grain filling resulted in the greatest decline in grain weight, with a 29% reduction compared to the control. There was a significant varietal variation in heat tolerance, highlighting Avangarda and NS 40s as the most tolerant varieties that should be included in regular breeding programs as valuable sources of heat tolerance. Understanding the genetic and physiological mechanisms of heat tolerance in these promising varieties should be the primary focus of future research and help develop targeted breeding strategies and agronomic practices to mitigate the adverse effects of heat stress on wheat production. [ABSTRACT FROM AUTHOR]

Background & Objective: The aim of this research was to evaluate the effect of nano-superabsorbent treatments and bio-fertilizers on some morpho-physiological characteristics, yield and yield components of Spring Canola seed under different levels of irrigation. Materials & Methods: The field experiment was conducted during 2017 and 2018 as a factorial split plot based on a randomized complete block design in 3 replications. The treatments included irrigation at three levels (irrigation after evaporation of 70, 120 and 170 mm of evaporation from the Class A pan in the main plots) and nano-superabsorbent treatments at two levels (0 and 45 kg/ha) and fertilizer treatments at four levels: control, Chitosan, growth-stimulating bacteria and chitosan + growth-stimulating bacteria were factorially placed in sub-plots. Results: Nitrogen and phosphorus content, leaf water percentage, green cover percentage, chlorophyll content, plant height, number of branches and leaves per plant, number of seeds per plant, number of seeds per plant, biological yield and consequently grain yield decreased, but the temperature Canola leaves increased. The application of fertilizer treatments, especially the combined treatment of bio-fertilizers + nano-superabsorbent under all irrigation levels, led to the improvement of these traits and rape seed yield, especially under severe stress. The application of nano-superabsorbent alone only under moderate and severe stress led to the improvement of these characteristics compared to its non-use. Conclusion: Improvement of morpho-physiological traits and product components ultimately increased seed yield. Therefore, it can be concluded that the combined application of nano-superabsorbent with bio-fertilizers can be an effective method to improve grain yield under drought stress conditions. [ABSTRACT FROM AUTHOR]

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The use of pesticides is an efficient approach for pest management. However, their increasing application in recent decades has come under the spotlight of world policies. In this context, this study addresses the usefulness of a forecasting model (TOMCAST) combined with aerobiological information and a plant development model (physiological days, PDays) for the control of early blight in potatoes in Northwest Spain. Control plots were compared to treated plots, according to the original TOMCAST model and the daily Alternaria spp. concentration, meteorological factors, and phenological and epidemiological observations were monitored for better adjustment of the TOMCAST model to the weather conditions of the geographical area during three crop seasons. The results of the linear regression analysis showed a strong relationship between the parameters included in TOMCAST (leaf wetness and temperature) and the Alternaria spp. conidia concentration. In addition, an unbalanced pattern of trapped conidia was detected throughout the growing season, with an increase near the flowering stage. The epidemiological parameters (infection period, r-AUDPC, maximum severity value, and total and commercial yields) showed significant differences between the cultivars in the control and the TOMCAST plots in terms of r-AUDPC and the maximum severity value. Given the study's results, the original TOMCAST model was improved with aerobiological and phenological information. The improved model recommends a first spray on a day when the following three requirements are met: Ten accumulated disease severity values (DSVs) according to the TOMCAST model, two days with an aerobiological level greater than 10 conidia/m3, and a PDays value greater than 200. This will reduce the number of fungicide treatments used to control early blight in potato crops, promoting the principles of sustainable agriculture. [ABSTRACT FROM AUTHOR]

Summary: Elevated air temperature (Tair) and vapour pressure deficit (VPDair) significantly influence plant functioning, yet their relative impacts are difficult to disentangle.We examined the effects of elevated Tair (+6°C) and VPDair (+0.7 kPa) on the growth and physiology of six tropical tree species. Saplings were grown under well‐watered conditions in climate‐controlled glasshouses for 6 months under three treatments: (1) low Tair and low VPDair, (2) high Tair and low VPDair, and (3) high Tair and high VPDair. To assess acclimation, physiological parameters were measured at a set temperature.Warm‐grown plants grown under elevated VPDair had significantly reduced stomatal conductance and increased instantaneous water use efficiency compared to plants grown under low VPDair. Photosynthetic biochemistry and thermal tolerance (Tcrit) were unaffected by VPDair, but elevated Tair caused Jmax25 to decrease and Tcrit to increase. Sapling biomass accumulation for all species responded positively to an increase in Tair, but elevated VPDair limited growth.This study shows that stomatal limitation caused by even moderate increases in VPDair can decrease productivity and growth rates in tropical species independently from Tair and has important implications for modelling the impacts of climate change on tropical forests. [ABSTRACT FROM AUTHOR]

Increasing exposure to unfavorable temperatures and water deficit imposes major constraints on most crops worldwide. Despite several studies regarding coffee responses to abiotic stresses, transcriptome modulation due to simultaneous stresses remains poorly understood. This study unravels transcriptomic responses under the combined action of drought and temperature in leaves from the two most traded species: Coffea canephora cv. Conilon Clone 153 (CL153) and C. arabica cv. Icatu. Substantial transcriptomic changes were found, especially in response to the combination of stresses that cannot be explained by an additive effect. A large number of genes were involved in stress responses, with photosynthesis and other physiologically related genes usually being negatively affected. In both genotypes, genes encoding for protective proteins, such as dehydrins and heat shock proteins, were positively regulated. Transcription factors (TFs), including MADS-box genes, were down-regulated, although responses were genotype-dependent. In contrast to Icatu, only a few drought- and heat-responsive DEGs were recorded in CL153, which also reacted more significantly in terms of the number of DEGs and enriched GO terms, suggesting a high ability to cope with stresses. This research provides novel insights into the molecular mechanisms underlying leaf Coffea responses to drought and heat, revealing their influence on gene expression. [ABSTRACT FROM AUTHOR]

High solar radiation, combined with high temperature, causes losses in plant production. The application of foliar protector in plants is associated with improvements in photosynthesis, reduction in leaf temperature and, consequently, improved productivity. Two experiments were conducted. The first aimed to assess the efficacy of foliar protector versus artificial shading in mitigating the negative impacts of excessive radiation and temperature on the physiology, growth, and yield of common bean plants. The second experiment focused on comparing the timing in cycle plants (phenological phases) of foliar protector application in two different bean cultivars (BRS Fc 104 and BRS MG Realce) under field conditions. Artificial shading provided better results for photosynthesis, transpiration, growth and production compared to the application of foliar protector. In the field conditions experiment, the application timing of the foliar protector at different phenological phases did not increase productivity in the cultivars. The application of foliar protector under the conditions studied was not effective in mitigating the negative impacts of high solar radiation and temperature on common bean cultivation. However, it is opportune to evaluate the application of foliar protector in bean plants grown under conditions with water deficit, high solar radiation and high temperature. [ABSTRACT FROM AUTHOR]

Global warming and waterlogging stress due to climate change are expected to continue influencing agricultural production worldwide. In the field, two or more environmental stresses usually happen simultaneously, inducing more complex responses in plants compared with individual stresses. Our aim was to clarify how the two key factors (temperature and water) interacted and influenced physiological response and plant growth in tomatoes under ambient temperature, moderately elevated temperature, waterlogging stress, and moderately elevated temperature and waterlogging stress. The results showed that leaf photosynthesis was inhibited by waterlogging stress but enhanced by elevated temperature, as shown by both the light- and temperature-response curves. The elevated temperature decreased leaf water-use efficiency, but enhanced plant growth and fresh and dry weights of plants under both normal water supply and waterlogging stress conditions. Elevated temperature generally decreased the anthocyanin and flavonol index in tomato leaves compared with the control temperature, regardless of water status. The increase in the optimal temperature was more pronounced in plants under normal irrigation than under waterlogging stress. Waterlogging stress significantly inhibited the root length, and leaf number and area, while the moderately elevated temperature significantly enhanced the leaf number and area. Overall, the moderately elevated temperature offset the effects of waterlogging stress on tomato plants, as shown by leaf gas exchange, plant size, and dry matter accumulation. Our study will improve the understanding of how tomatoes respond to increasing temperature and excess water. [ABSTRACT FROM AUTHOR]

Centella asiatica (Indian pennywort) is a green leafy vegetable containing centelloside' (triterpenoid), a key phytochemical component in traditional medicine. Being a glycophytic species, they exhibit decline in growth performance and yield traits when subjected to water-deficit (WD) conditions. Glycine betaine (GB) is a low molecular-weight organic metabolite that plays a crucial role in abiotic stress conditions in higher plants. The objective of this study was to investigate the potential of GB in alleviating water-deficit stress (in terms of morphological and physiological responses) in two different genotypes of Indian pennywort, "Nakhon Pathom" (NP; high centelloside-yielding genotype) and "Pathum Thani" (PT; low centelloside-yielding genotype). The genotypes of Indian pennywort were propagated by stolon cutting and transplanted into plastic bags containing 2 kg of garden soil. At the flower-initiation stage (30 days after transplantation), uniform plant material was treated exogenously with 0 (control), 25, and 50 mM GB at 100 mL per plant (one-time foliar spray) and then divided into two groups, 1) well watered (WW; irrigated daily with 400 mL fresh water; 98% field capacity) and 2) water deficit (WD; withheld water for 14 days; 72% field capacity). Foliar application of GB (25 mM) significantly improved leaf osmotic potential in NP under WD conditions via osmotic adjustment by free proline and fructose. Differences in leaf temperature (Tleaf) between WD and WW in NP were maximized (+ 1.93 °C) and the gap of Tleaf was reduced in the case of 25–50 mM GB application. Similarly, crop water stress index (CWSI) in NP and PT plants under WD condition was significantly increased by 1.95- and 1.86-fold over the control, respectively; however, it was significantly decreased by exogenous GB application. Increasing Tleaf and CWSI in drought-stressed plants was closely related to stomatal closure, leading to reduced gas exchange parameters, i.e., stomatal conductance (gs), transpiration rate (E), net photosynthetic rate (Pn), and intercellular CO2 concentration (Ci), and consequently decreased plant biomass and total centelloside yield. Overall physiological, morphological, and secondary metabolite traits were enhanced in NP under WD conditions using 25 mM GB exogenous application compared with the control. The study highlights the significance of GB in Indian pennywort production under limited water irrigation (water deficit) with higher vegetable yield and phytochemical stabilization. [ABSTRACT FROM AUTHOR]

Drought stress adversely affects growth, development, productivity, and fiber quality of cotton (Gossypium hirsutum L). Breeding strategies to enhance drought tolerance require an improved knowledge of plant drought responses necessitating proper identification of drought-tolerant genotypes of crops, including cotton. The objective of this study was to classify the selected cotton genotypes for their drought tolerance ability based on morpho-physio-biochemical traits using Hierarchical Ward's cluster analysis. Five genotypes of cotton (Takfa 3, Takfa 6, Takfa 7, Takfa 84–4, and Takfa 86–5) were selected as plant materials, and were grown under well-watered (WW; 98 ± 2% field capacity) and water-deficit (WD; 50 ± 2% field capacity) conditions for 16 days during the flower initiation stage. Data on morpho-physio-biochemical parameters and gene expression levels for these parameters were collected, and subsequently genotypes were classified either as a drought tolerant or drought susceptible one. Upregulation of GhPRP (proline-rich protein), GhP5CS (Δ1-pyrroline-5-carboxylate synthetase), and GhP5CR (Δ1-pyrroline-5-carboxylate reductase) in relation to free proline enrichment was observed in Takfa 3 genotype under WD condition. An accumulation of free proline, total soluble sugar, and potassium in plants under WD conditions was detected, which played a key role as major osmolytes controlling cellular osmotic potential. Magnesium and calcium concentrations were also enriched in leaves under WD conditions, functioning as essential elements and regulating photosynthetic abilities. Leaf greenness, net photosynthetic rate, stomatal conductance, and transpiration rate were also declined under WD conditions, leading to growth retardation, especially aboveground traits of Takfa 6, Takfa 7, Takfa 84–4, and Takfa 86–5 genotypes. An increase in leaf temperature (1.1 − 4.0 °C) and crop water stress index (CWSI > 0.75) in relation to stomatal closure and reduced transpiration rate was recorded in cotton genotypes under WD conditions compared with WW conditions. Based on the increase of free proline, soluble sugar, leaf temperature, and CWSI, as well as the decrease of aboveground growth traits and physiological attributes, five genotypes were categorized into two cluster groups: drought tolerant (Takfa 3) and drought susceptible (Takfa 6, Takfa 7, Takfa 84–4, and Takfa 86–5). The identified drought-tolerant cotton genotype, namely, Takfa 3, may be grown in areas experiencing drought conditions. It is recommended to further validate the yield traits of Takfa 3 under rainfed field conditions in drought-prone environments. [ABSTRACT FROM AUTHOR]

In this study, the physiological performance and fruit quality responses of the highbush blueberry (Vaccinium corymbosum) cultivar Legacy to high temperatures (HTs) were evaluated in a field experiment. Three-year-old V. corymbosum plants were exposed to two temperature treatments between fruit load set and harvest during the 2022/2023 season: (i) ambient temperature (AT) and (ii) high temperature (HT) (5 °C ± 1 °C above ambient temperature). A chamber covered with transparent polyethylene (100 µm thick) was used to apply the HT treatment. In our study, the diurnal temperature was maintained with a difference of 5.03 °C ± 0.12 °C between the AT and HT treatments. Our findings indicated that HT significantly decreased CO2 assimilation (Pn) by 45% and stomatal conductance (gs) by 35.2% compared to the AT treatment. By contrast, the intercellular CO2 concentration (Ci) showed higher levels (about 6%) in HT plants than in AT plants. Fruit quality analyses revealed that the fruit weight and equatorial diameter decreased by 39% and 13%, respectively, in the HT treatment compared to the AT treatment. By contrast, the firmness and total soluble solids (TSS) were higher in the HT treatment than in the AT treatment. Meanwhile, the titratable acidity showed no changes between temperature treatments. In our study, Pn reduction could be associated with stomatal and non-stomatal limitations under HT treatment. Although these findings improve our understanding of the impact of HTs on fruit growth and quality in V. corymbosum, further biochemical and molecular studies are need. [ABSTRACT FROM AUTHOR]

Introduction: One of the most important problems threatening agriculture is water deficit stress in many regions of the world. Water deficit stress could result in a decrease in yielding or death of a wide range of crops. In Iran, like other arid and semi-arid regions, forage quality and production have decreased due to the occurrence of frequent water stress. Restriction of water resources, especially in arid and semi-arid regions where agricultural systems depend on supplementary irrigation, has become the most important problem of fodder production. Persian clover (Trifolium resupinatum L.) is a forage legume cultivated in the temperate region of world; it is of great value for livestock feed, soil improvement, and reclaiming disturbed land because of its nitrogen-fixing capability. The purpose of this research, was evaluate the effect of water deficit stress on the physiological and qualitative traits of fodder of Persian clover. Materials and methods: An experiment was carried out during the 2016 and 2017 cropping seasons as a randomized complete block design at the Research Farm of Tarbiat Modares University. Experimental treatments included water deficit stress at four levels. The tested treatments included water deficit stress at four levels (irrigation after reaching the levels of 80, 60, 40 and 20% available moisture). Irrigation of all treatments was carried out at the level of 70% of available water until the start of stress in the final stages of vegetative growth of the second cut. To measure the effects of water deficit stress on physiological traits physiological indexes were recorded during the first 10 days of stress treatment, every day. The clovers were harvested at about 20-25% flowering stage. After drying, they were transferred to the laboratory to determine the quantitative and qualitative feed yield. Based on Bartlett's test results, the experiment's dependent variables had the same trend. Results and discussion: The results show that the irrigation regime had a significant effect on all traits. Irrigation treatments at 80 and 60% of available water had the highest dry matter yield, and delaying irrigation until 40 and 20% caused a 19% and 36% significant decrease in this trait. Also, stress at the level of 20% caused a 27% decrease in fodder protein, a 10% increase in acid detergent fiber and neutral detergent fiber, and finally, an 16% reducing relative feed value. Evaluation of physiological traits in the first ten days of the beginning of water stress showed a continuous increase in leaf temperature from 30.5 to 34 °C, and 49, 50, and 15% decrease in photosynthesis rate, stomatal conductance, and SPAD index, respectively. It Also reduces the concentration of chlorophyll a and b 25 and 40 percent. The return of increased leaf temperature and reduced stomatal conductance due to the discharge of 80% moisture was fast to the initial level, but other traits slowly approached the value before the stress. It seems that returning to initial values at levels of 80 and 60 is easily possible for the plant, but with the increase in the intensity of stress, the damage of dehydration is slowly compensated. Conclusion The experiment results showed that the photosynthesis rate and other physiological traits of Persian clover significantly react to the soil's decreased available water. In most physiological traits, irrigation after the available soil moisture reached 60% caused a relatively quick return to the initial value. There was no significant difference in fodder yield in the 80% and 60% irrigation treatments. When the available soil moisture reached 40%, the physiological traits showed a greater decrease than before. It seems that some damages to physiological traits are irreparable to such an extent that they eventually lead to a drop in yield or a decrease in the quality of Persian clover fodder. Finally, it is not necessary for clover irrigation at levels of more than 60% of available water, taking into account the more quality of forage in the level of 60% (about 1.5% of insoluble fiber, and 11% feed value), considering the water conditions of the country. [ABSTRACT FROM AUTHOR]

Canopy temperature (CT) is often interpreted as representing leaf activity traits such as photosynthetic rates, gas exchange rates, or stomatal conductance. This interpretation is based on the observation that leaf activity traits correlate with transpiration which affects leaf temperature. Accordingly, CT measurements may provide a basis for high throughput assessments of the productivity of wheat canopies during early grain filling, which would allow distinguishing functional from dysfunctional stay-green. However, whereas the usefulness of CT as a fast surrogate measure of sustained vigor under soil drying is well established, its potential to quantify leaf activity traits under high-yielding conditions is less clear. To better understand sensitivity limits of CT measurements under high yielding conditions, we generated within-genotype variability in stay-green functionality by means of differential short-term pre-anthesis canopy shading that modified the sink:source balance. We quantified the effects of these modifications on staygreen properties through a combination of gold standard physiological measurements of leaf activity and newly developed methods for organ-level senescence monitoring based on timeseries of high-resolution imagery and deep-learning-based semantic image segmentation. In parallel, we monitored CT by means of a pole-mounted thermal camera that delivered continuous, ultra-high temporal resolution CT data. Our results show that differences in staygreen functionality translate into measurable differences in CT in the absence of major confounding factors. Differences amounted to approximately 0.8°C and 1.5°C for a very high-yielding source-limited genotype, and a medium-yielding sink-limited genotype, respectively. The gradual nature of the effects of shading on CT during the stay-green phase underscore the importance of a high measurement frequency and a time-integrated analysis of CT, whilst modest effect sizes confirm the importance of restricting screenings to a limited range of morphological and phenological diversity. [ABSTRACT FROM AUTHOR]