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As the single link between leaves and the rest of the plant, petioles must develop conductive tissues according to the water influx and sugar outflow of the leaf lamina. A scaling relationship between leaf area and anatomical traits of xylem and phloem is expected to improve the efficiency of these tissues. However, the different constraints compromising the functionality of both tissues (e.g., risk of cavitation) must not be disregarded. Additionally, deciduous and evergreen plants may have different strategies to produce and package their petiole conduits to cope with environmental restrictions. We explored in 33 oak species the relationships between petiole anatomical traits, leaf area, stomatal conductance, and photosynthesis rate. Results showed allometric scaling between anatomical structure of xylem and phloem with leaf area. We also found correlations between photosynthesis rate, stomatal conductance, and anatomical traits in the petiole. The main novelty is how oaks present a different strategy depending on the leaf habit. Deciduous species tend to increase their diameters to achieve greater leaf‐specific conductivity. By contrast, evergreen oaks develop larger xylem conductive areas for a given leaf area than deciduous ones. This trade‐off between safety‐efficiency in petioles has never been attributed to the leaf habit of the species. Summary statement: We explored the scaling relationships between conductive tissues in the petiole and leaf lamina in a wide group of Quercus species. We found how deciduous and evergreen oaks follow different strategies producing and packaging their conduits, even after removing the scaling effect of leaf area. [ABSTRACT FROM AUTHOR]

Key message: Austropuccinia psidii infection and increase in diseased leaf area resulted in a reduction of photosynthesis, an upregulation of stomatal conductance, and an increase in leaf starch and sucrose content. Austropuccinia psidii is a biotrophic rust pathogen that causes myrtle rust, affecting over 480 species in the Myrtaceae family. The development of chlorotic and necrotic leaf areas following A. psidii infection has been shown to affect leaf gas exchange. In this study, we quantified photosynthesis, stomatal conductance, and non-structural carbohydrates in seedlings of a long-lived tree, Metrosideros excelsa (pōhutukawa), following A. psidii infection in a glasshouse experiment (infected and control seedlings) conducted over 20 weeks. The diseased leaf area rose from 8% in week 2 to 95% in week 20 after A. psidii inoculation. The photosynthetic rate declined by over 90% within 6 weeks after inoculation and was associated with biochemical damage in CO2 fixation. Stomatal conductance decreased over the first 4 weeks after inoculation and then increased. An increase in lesions and necrotic cells may inhibit stomatal regulation. Starch content was threefold higher in infected than control leaves 20 weeks after inoculation. Increased starch accumulation in the infected leaf area could be due to reduced export of newly fixed carbon from the infected leaves. Meanwhile, glucose + fructose content was 31% lower in infected leaves at the experiment’s end, likely because of leaf necrosis. If the pathogen-induced damage and loss of leaves, reduction in photosynthesis and changes in non-structural carbohydrates shown in this study also occur in wild M. excelsa seedlings and reduces their biomass, this may in turn reduce their competitive ability in the primary successions that they currently often dominate. [ABSTRACT FROM AUTHOR]

This research investigates the interactive effects of elevated ozone (eO3) and carbon dioxide (eCO2) on stomatal morphology and leaf anatomical characteristics in two wheat cultivars with varying O3 sensitivities. Elevated O3 increased stomatal density and conductance, causing oxidative stress and cellular damage, particularly in the O3-sensitive cultivar PBW-550 (PW), compared to HUW-55 (HW). Conversely, eCO2 reduced stomatal density and pore size, mitigating O3-induced damage by limiting O3 influx. Ultrastructural analysis showed that eO3 increased plastoglobule density and damaged chloroplast structure, while eCO2 preserved chloroplast integrity and enhanced photosynthetic efficiency. Additionally, eCO2 increased leaf thickness and improved mesophyll conductance, counteracting the negative effects of O3 on leaf anatomy. The CO2-induced modifications in stomatal and leaf anatomy significantly impacted plant physiology by altering stomatal conductance and O3 uptake. The protective effect of eCO2 was more pronounced in the O3-sensitive cultivar PW than in the O3-tolerant HW. These findings provide insights into the stomatal and leaf anatomical responses of plants under future climate conditions, aiding in the developing strategies to improve crop resilience and productivity under O3 stress. [ABSTRACT FROM AUTHOR]

Global changes and growing demands have led to the development of new molecular approaches to improve crop physiological performances. Carbonic anhydrase (CA) enzymes, ubiquitous across various life kingdoms, stand out for their critical roles in plant photosynthesis and water relations. We hypothesize that the modulators of human CAs could affect plant physiology. Our research demonstrated that foliar treatments with a synthetic selenium-containing CA activator (Se-AMA) influenced the physiological performances of Arabidopsis thaliana. Se-AMA increased net photosynthesis (A + 31.7%) and stomatal conductance (gs + 48.2%) at 100 µM, with the most notable effects after 10 days of treatment. Se-AMA at 300 µM proved to be even more effective, boosting A and gs by 19.9% and 55.3%, respectively, already after 3 days of application. Morning treatment with Se-AMA at 300 µM enhanced photosynthetic performances throughout the day, suggesting that the positive effect of Se-AMA lasted for several hours. Additionally, Se-AMA increased water content in plants by 17.1%, suggesting that Se-AMA treatment may have improved plant water absorption and resource management. This effect might be linked to Se-AMA's role in modulating specific CA isoforms working with aquaporins. Although preliminary, these findings suggest that Se-AMA could enhance plant physiological performances under the conditions of non-limiting water availability. [ABSTRACT FROM AUTHOR]

Measuring ecophysiological responses of Eucalyptus clones grown under reduced water availability could assist in clonal selection for climate resilience. We hypothesized that clonal variation in chlorophyll a fluorescence was more readily detected than variations in leaf-level gas exchanges when 2-year-old Eucalyptus grandis W.Hill ex Maiden  × Eucalyptus urophylla S.T. Blake hybrid clones (C1, C2, C3 and C4) grown under rainfed (RF) and water-restricted (WR) conditions were evaluated during dry and rainy seasons, in the morning and midday diurnal periods. The C2 clone was the most drought tolerant as it had a similar net CO2 assimilation rate (A) considering the RF and WR conditions at midday during the dry season, while C1, C3 and C4 CO2 assimilation rates (A) decreased by 29.1%, 28.3% and 13%, respectively. This response was associated with a reduction to a lesser extent in leaf water potential, stomatal conductance (g s) and transpiration rates (E) (ca 10%, 30% and 13% under WR, respectively), when compared with the other clones during the dry season at midday. The lower leaf to air vapor pressure deficit of C2 contributed to its greater water-use efficiency (WUE), resulting in greater total dry mass gain. C1, C3 and C4 were less drought tolerant, decreasing g s, E and especially A under WR, resulting in lower WUE and total dry mass gain. Chlorophyll a fluorescence indexes were better indicators of drought tolerance compared with gas exchange parameters in definition of drought tolerance of clonal Eucalyptus. Three drought-sensitive clones showed low photochemical efficiency under WR, with the electron transport rate being impaired between photosystems II and I, indicated by the greater changes in photosynthetic performance index (PIabs). Under WR conditions, F v/ F m, Ψ0, ΦE0 and PIabs decreased in all clones while ΦD0 and DI0/CS0 increased, with C2 showing the most stable responses suggesting that the photochemical apparatus was the less damaged by drought. Thus, C2 was the best clone for regions with water scarcity. Statements In situ ecophysiological responses of ~15 m tall Eucalyptus hybrid clones were investigated. Soil water restriction levels segregated clones by their drought tolerance. Drought tolerance was expressed as fluorescence index stability and low reduction of leaf gas exchanges. The most suitable indexes for water restriction tolerance were F v/ F m, Ψ0, ΦE0, ΦD0, DI0/CS0 and PIabs. [ABSTRACT FROM AUTHOR]

Scenarios for future climate predict an increase in precipitation amounts and frequency of rain events, resulting in higher air humidity and soil moisture at high latitudes, including in northern Europe. We analysed the effects of artificially elevated environmental humidity (air relative humidity and soil moisture) on leaf gas exchange, water relations, growth and phenology of silver birch (Betula pendula) trees growing at the free air humidity manipulation experimental site situated in the hemiboreal vegetation zone, in eastern Estonia, with no occurring water deficit to the trees. The environmental humidity manipulation did not significantly affect the water relations traits but did affect some leaf gas exchange parameters, growth and phenology of the trees. Elevated air humidity (H) did not influence photosynthetic capacity and stomatal conductance, while the trees exhibited higher stomatal sensitivity to leaf-to-air vapour pressure difference compared with the trees at ambient conditions (C) or at elevated soil moisture (I). H trees demonstrated reduced height growth and foliage biomass, increased allocation to stem radial growth and prolonged leaf retention in autumn compared with the C trees. Increased air humidity supports longer leaf retention and growth period, but this does not translate into increased growth parameters at the tree level. The changes in tree growth in response to increasing atmospheric humidity could plausibly be explained by (i) retardation of foliage development and (ii) changes in resource allocation, causing a shift in the ratio of photosynthetic to non-photosynthetic tissues in favour of the latter. Under high atmospheric evaporative demand, higher stomatal sensitivity in H trees induces faster stomatal closure, which may result in carbon starvation. A future rise in atmospheric humidity at high latitudes may lead to reduced tree growth and forest productivity, in contrast to the predicted future of forests. [ABSTRACT FROM AUTHOR]

Tree water status is mainly determined by the amount of water taken up from roots and lost through leaves by transpiration. Variations in transpiration and stomatal conductance are often related to atmospheric conditions and leaf water potential. Yet, few experimental datasets exist that enable to relate leaf water potential, transpiration dynamics and temporal variation of root water uptake from different depths during soil drying. Here we explored the soil–plant hydraulic system using field measurements of water potentials and fluxes in soils, roots, stems and leaves of beech (Fagus sylvatica) and spruce (Picea abies) trees. Spruce maintained less negative water potentials than beech during soil drying, reflecting a more stringent stomatal control. While root water uptake depths were similar between species, water potentials in plant tissues of spruce were rather constant and less correlated across roots and the stem, possibly because of large water storage and hydraulic capacitance in these tissues. Root water uptake from deep soil layers increased during dry periods, particularly for beech. Our data suggest that species-specific root hydraulic conductance, capacitance and water uptake strategy are linked and affect transpiration dynamics. Thus, it is important to include such species-specific hydraulics when predicting transpiration rates based on plant water status. [ABSTRACT FROM AUTHOR]

Background and Aims Abiotic and biotic components of the environment both limit plant reproduction, but how they interact with one another in combination is less understood. Understanding these interactions is especially relevant because abiotic and biotic environmental components respond differently to various drivers of global change. Here, we aim to understand whether the effects of pollination (biotic component) on plant reproduction depend on soil moisture (abiotic component), two factors known to affect plant reproduction and that are changing with global change. Methods We conducted pollen supplementation experiments for two plant species, Delphinium nuttallianum and Hydrophyllum fendleri , in subalpine meadows in the Western USA across 4 years that varied in soil moisture. In a separate 1-year field experiment, we crossed water addition with pollen supplementation factorially. We measured the proportion of fruit set, seeds per fruit and seeds per plant, in addition to stomatal conductance, to determine whether plant physiology responded to watering. Key Results In the 4-year study, only H. fendleri reproduction was pollen limited, and this occurred independently of soil moisture. Experimental water addition significantly increased soil moisture and stomatal conductance for both species. The effect of pollen addition on reproduction depended on the watering treatment only for H. fendleri fruit production. Reproduction in D. nuttallianum was not significantly affected by pollen addition or water addition, but it did respond to interannual variation in soil moisture. Conclusions Although we found some evidence for the effect of a biotic interaction depending on abiotic conditions, it was only for one aspect of reproduction in one species, and it was in an unexpected direction. Our work highlights interactions between the abiotic and biotic components of the environment as an area of further research for improving our understanding of how plant reproduction responds to global change. [ABSTRACT FROM AUTHOR]

Cultivated oil palm is commonly found in several ecosystems with different topographies, including riparian areas. This ecosystem is expected to affect the morphology and physiology of oil palms. In addition, oil palm habitats in riparian or flooded ecosystems will experience anaerobic respiration. Indonesia has the potential to access quality palm oil that can be used for cultivation. This study aimed to determine which oil palm accessions could adapt physiologically to the duration of waterlogging. The accession of oil palm seedlings from Jambi tested were Merangin, Tebo, Muara Jambi, Tanjung Jabung, and Simalungun. The research design was to treat waterlogging in a greenhouse and then analyze the plant growth and physiology. Waterlogging was given for two, four, and six weeks. The results showed that the accession of oil palm seedlings and the duration of waterlogging affected photosynthesis rate, transpiration rate, and stomatal conductance. Growth parameters, i.e., fresh weight, dry weight, and root/shoot ratio, were significantly different in accession and waterlogging duration. In conclusion, accessions from Tebo and Merangin can adapt to waterlogging. [ABSTRACT FROM AUTHOR]

The relative impacts of biochemical and stomatal limitations on photosynthesis during photosynthetic induction have been well studied for diverse plants under ambient CO2 concentration (Ca). However, a knowledge gap remains regarding how the various photosynthetic components limit duction efficiency under elevated CO2. In this study, we experimentally investigated the influence of elevated CO2 (from 400 to 800 μmol mol–1) on photosynthetic induction dynamics and its associated limitation components in two broadleaved tree species, Populus tomentosa and Eucalyptus robusta. The results show that elevated CO2 increased the steady-state photosynthesis rate (A) and decreased stomatal conductance (gs) and the maximum carboxylation rate (Vcmax) in both species. While E. robusta exhibited a decrease in the linear electron transport rate (J) and the fraction of open reaction centers in photosynthesis II (qL), P. tomentosa showed a significant increase in non-photochemical quenching (NPQ). With respect to non-steady-state photosynthesis, elevated CO2 significantly reduced the induction time of A following a shift from low to high light intensity in both species. Time-integrated limitation analysis during induction revealed that elevated CO2 reduces the relative impacts of stomatal limitations in both species, consequently shifting the predominant limitation on induction efficiency from stomatal to biochemical components. Additionally, species-specific changes in qL and NPQ suggest that elevated CO2 may increase biochemical limitation by affecting energy allocation between carbon fixation and photoprotection. These findings suggest that, in a future CO2-rich atmosphere, plants productivity under fluctuating light may be primarily constrained by photochemical and non-photochemical quenching. [ABSTRACT FROM AUTHOR]

Dioecious species show a division of labor expressed through the differentiated manifestation of resource acquisition. We hypothesized that the expression of secondary sexual dimorphism (SSD) in the leaf gas exchange of yerba mate would be more intensive in females than in males to permit females the carbon investments necessary to finish the reproductive cycle. This species can present two growth units annually (GU1-fall and GU2-spring) intercalated with two rest periods (R1-summer and R2-winter). The leaf area index (LAI) and the diurnal courses of leaf photosynthesis (Anet), stomatal conductance (gs), leaf transpiration (E), intercellular CO2 concentration (Ci), water use efficiency (WUE), and instantaneous carboxylation efficiency (Anet/Ci) were estimated in female and male plants of yerba mate during four periods of annual rhythmic growth in monoculture (MO) and agroforestry (AFS). Leaf gas exchanges varied over the annual rhythmic growth and were more intensive under MO than under AFS. Anet, Anet/Ci ratios, and WUE were higher in females than in males during the summer (R1) and spring (GU2). Also, gs and E were more intensive in females than males during the summer. Oppositely, higher WUE in males than in females was observed during the fall (GU1) and winter (R2), with males also showing a higher Anet/Ci ratio during the winter and higher E during the spring (GU2). Despite the strong effect of the cultivation system on LAI and leaf gas exchange traits over the diurnal course, SSD expression was rarely modified by the cultivation system, being expressed only in MO for E during the spring (GU2) and WUE during the winter (R2). High WUE in males during the winter would benefit plants during cold and dry periods, improving the balance between carbon acquisition and water loss through transpiration. On the other hand, high Anet during the summer and spring could be considered as a general fitness strategy of female plants to improve photoassimilate supply and support their additional reproduction costs. [ABSTRACT FROM AUTHOR]

This study investigates the impact of leaf temperatures (Tleaf) and irradiance on photosynthesis rates of maize (Zea mays) leaves. The research focuses on how maize plants respond to abiotic stress factors, which are crucial for determining crop growth and yield in a way to develop maize lines that are optimized for arid environments. This is crucial for improving crop productivity in areas facing high temperature and light stress, contributing to food security in challenging climates. The photosynthesis rate and stomatal conductance decreased at high irradiance while transpiration rate remained unaffected. Conversely, the photosynthesis rate declined at elevated leaf temperatures, specifically around 41℃ but stomatal conductance and transpiration rates increased. These findings indicate that high Tleaf and irradiance significantly affect the photosynthetic performance of maize, potentially impacting plant growth and yield. [ABSTRACT FROM AUTHOR]

Potassium (K) is an essential mineral element that supports numerous plant processes, including photosynthesis, enzyme activation, osmoregulation, and nutrient balance. This study investigated how K deficiency impacts growth, physiological performance, and carbohydrate metabolism in 'Granny Smith' apple trees grafted onto M9 rootstock. The experimental material was cultivated hydroponically in a greenhouse under four K regimes, including 0.00, 0.75, 1.50, and 3.00 mM K, over 159 days. Deficiency symptoms such as chlorosis and necrosis were observed primarily in basal leaves. A reduced net photosynthetic rate in top and basal leaves was linked to a decreased stomatal conductance, thus limiting CO2 uptake (stomatal limitations of photosynthesis). Photosynthetic pigments, including chlorophyll a, chlorophyll b, and carotenoids, were also significantly reduced in K-limited leaves. Furthermore, photochemical performance of PSII also declined under K deficiency, with lower electron transport rates, PSII efficiency, and photochemical quenching (non-stomatal limitations of photosynthesis). While the photosynthetic rate declined under K deficiency conditions, the carbohydrate metabolism remained relatively stable without significant variation in total, translocating, or non-translocating sugars. Notably, an increase in sucrose-to-hexose ratio under low K suggests changes in sugar partitioning and utilization. Biomass allocation was also affected, with a notable decrease in the shoot-to-root ratio, mainly due to increased dry weight of roots, likely reflecting an adaptive response to enhance K uptake. Our study provides valuable insights into sustainable K fertilization practices aiming to maximize photosynthetic capacity, pigment content, and biomass production. These findings emphasize the importance of considering rootstock/scion interactions in future research to enhance apple tree vigor and productivity. [ABSTRACT FROM AUTHOR]

Summary: Carbon isotope discrimination (∆) in leaf biomass (∆BL) and tree rings (∆TR) provides important proxies for plant responses to climate change, specifically in terms of intrinsic water‐use efficiency (iWUE). However, the nonphotosynthetic 12C/13C fractionation in plant tissues has rarely been quantified and its influence on iWUE estimation remains uncertain.We derived a comprehensive, ∆ based iWUE model (iWUEcom) which includes nonphotosynthetic fractionations (d) and characterized tissue‐specific d‐values based on global compilations of data of ∆BL, ∆TR and real‐time ∆ in leaf photosynthesis (∆online). iWUEcom was further validated with independent datasets.∆BL was larger than ∆online by 2.53‰, while ∆BL and ∆TR showed a mean offset of 2.76‰, indicating that ∆TR is quantitatively very similar to ∆online. Applying the tissue‐specific d‐values (dBL = 2.5‰, dTR = 0‰), iWUE estimated from ∆BL aligned well with those estimated from ∆TR or gas exchange. ∆BL and ∆TR showed a consistent iWUE trend with an average CO2 sensitivity of 0.15 ppm ppm−1 during 1975–2015.Accounting for nonphotosynthetic fractionations improves the estimation of iWUE based on isotope records in leaf biomass and tree rings, which is ultimate for inferring changes in carbon and water cycles under historical and future climate. [ABSTRACT FROM AUTHOR]

Summary: A long‐standing debate looks at whether air or soil dryness is more limiting to vegetation water use and productivity. The answer has large implications for future ecosystem functioning, as atmospheric dryness is predicted to increase globally while changes in soil moisture are predicted to be far more variable. Here, I review the complexities that contribute to this debate, including the strong coupling between atmospheric and soil dryness, and the widespread heterogeneity in vegetation hydraulic traits, acclimations, and adaptations to water stress. I discuss solutions to improve understanding and modeling of vegetation sensitivity to dryness, including how different types of observational data can be used together to gain insight into vegetation response to water stress across spatial and temporal scales. [ABSTRACT FROM AUTHOR]

Oregon white oak (Quercus garryana) woodlands are threatened by conifer encroachment established during decades of fire exclusion. Widespread restoration efforts are underway to remove conifers from many oak woodlands in California, Oregon, and Washington. Using water potential, stomatal conductance, stable isotopes, and three metrics of biodiversity, we investigated the effects of Douglas‐fir (Pseudotsuga menziesii) encroachment and removal at the ecosystem scale across 3 years in a northern California woodland. We found that heavily encroached stands had the highest water potential and often the lowest stomatal conductance, compared to moderately encroached and open stands. Xylem water stable isotopes indicated that oaks and Douglas‐firs were likely not directly competing for water, as oaks appeared to use a relatively deeper water source. Under certain climatic conditions, heavily encroached oaks were more vulnerable to water stress than oaks in open or moderately encroached stands. Following low‐intensity conifer removal, thinned stands had slightly lower predawn water potential and higher gas exchange compared to unthinned stands, particularly under dry conditions. For ecosystem biodiversity, understory plant and bird diversity did not meaningfully vary with encroachment or thinning, but mammal diversity was greater in encroached stands compared to open stands. Findings from this work demonstrate that negative impacts of conifer encroachment on oaks are not due to increased competition for water, conifer removal is physiologically beneficial for shaded oaks, and that heavier thinning treatments are likely needed to yield long‐term responses and influence biodiversity. [ABSTRACT FROM AUTHOR]

Maize (Zea mays L.) is an important cereal crop grown in arid and semiarid regions of the world. During the reproductive phase, it is more frequently exposed to drought stress, resulting in lower grain yield due to oxidative damage. Selenium and zinc oxide nanoparticles possess inherent antioxidant properties that can alleviate drought-induced oxidative stress by the catalytic scavenging of reactive oxygen species, thereby protecting maize photosynthesis and grain yield. However, the effect of zinc selenide quantum dots (ZnSe QDs) under drought stress was not been quantified. Hence, the aim of this study was to quantify the (i) toxicity potential of ZnSe QDs and (ii) drought mitigation potential of ZnSe QDs by assessing the transpiration rate, photosynthetic rate, oxidant production, antioxidant enzyme activity and seed yield of maize under limited soil moisture levels. Toxicity experiments were carried out with 0 mg L−1 to 500 mg L−1 of ZnSe QDs on earthworms and azolla. The results showed that up to 20 mg L−1, the growth rates of earthworms and azolla were not affected. The dry-down experiment was conducted with three treatments: foliar spray of (i) water, (ii) ZnSe QDs (20 mg L−1), and (iii) combined zinc sulfate (10 mg L−1) and sodium selenate (10 mg L−1). ZnSe or Se applications under drying soil reduced the transpiration rate compared to water spray by partially closing the stomata. ZnSe application at 20 mg L−1 at the tasselling stage significantly increased the photosynthetic rate (25%) by increasing catalase (98%) and peroxidase (85%) enzyme activity and decreased the hydrogen peroxide (23%) content compared to water spray, indicating that premature leaf senescence was delayed under rainfed conditions. ZnSe spray increased seed yield (26%) over water spray by increasing the number of seeds cob-1 (42%). The study concluded that foliar application of ZnSe (20 mg L−1) could decrease drought-induced effects in maize. [ABSTRACT FROM AUTHOR]

Summary During periods of stomatal closure, such as drought, plant leaves continue to lose water at a rate determined by the minimum leaf conductance, gmin. Although gmin varies with temperature, less is known about what drives this variation, including how the pathways of water loss (cuticle or stomata) vary with temperature. We used gas exchange and bench drying methods to measure gmin and cuticular conductance, gcw, across a wide temperature range (20–50°C) in 11 broadleaf species. Vapour pressure deficit (VPD) covaried with temperature from 0.83 to 10.7 kPa. The dominant pathway of water loss for gmin shifted from stomatal transpiration towards cuticular transpiration as temperature increased. Leaf traits had variable, temperature‐dependent relationships with gmin and gcw, with trait–conductance relationships being generally stronger at higher temperatures. Cuticular thickness varied inversely with high‐temperature gcw. Simulation results showed that gcw may impact photosynthetic capacity estimates, particularly in species with low stomatal conductance. The pathways of water loss in leaves during times of stomatal closure depend strongly on temperature. This effect may have large implications for landscape‐scale water balance modelling and improving gas exchange measurements. We propose variation in VPD as a potential contributing factor in gmin and gcw variation among studies. [ABSTRACT FROM AUTHOR]

The article discusses the relationship between sun-induced fluorescence (SIF) and gross primary production (GPP) under heatwave conditions, challenging the notion that nonphotochemical quenching (NPQ) alters this relationship. The study suggests that environmental stresses, such as heatwaves, can disrupt the correlation between SIF and GPP due to factors like water availability and stomatal conductance. The data presented in the article highlight the complexities of energy partitioning in plants under stress conditions, emphasizing the need for further research in this area. [Extracted from the article]

Accounting for the dynamic responses of photosynthesis and photoprotection to naturally fluctuating irradiance can improve predictions of plant performance in the field, but the variation of these dynamics within crop canopies is poorly understood. We conducted a detailed study of dynamic and steady-state photosynthesis, photoprotection, leaf pigmentation, and stomatal anatomy in four leaf layers (100, 150, 200, and 250 cm from the floor) of a fully grown tomato (Solanum lycopersicum cv. Foundation) canopy in a greenhouse. We found that leaves at the top of the canopy exhibited higher photosynthetic capacity and slightly faster photosynthetic induction compared with lower-canopy leaves, accompanied by higher stomatal conductance and a faster activation of carboxylation and linear electron transport capacities. In upper-canopy leaves, non-photochemical quenching showed faster induction and relaxation after increases and decreases in irradiance, allowing for more effective photoprotection in these leaves. Despite these observed differences in transient responses between leaf layers, steady-state rather than dynamic photosynthesis traits were more influential for predicting photosynthesis under fluctuating irradiance. Also, a model analysis revealed that time-averaged photosynthesis under fluctuating irradiance could be accurately predicted by one set of Rubisco activation/deactivation parameters across all four leaf layers, thereby greatly simplifying future modelling efforts of whole-canopy photosynthesis. [ABSTRACT FROM AUTHOR]

Water shortage leads researchers and farmers to find new water resources. Water production from air vapor is a new idea. A field experiment was designed to determine the effect of dew-irrigation on chickpea seed yield and physiological traits. The field experiment included three treatments (dew-irrigation, conventional irrigation, and dryland farming). Irrigation treatments had no significant effect on chlorophyll a, chlorophyll b, total chlorophyll, chlorophyll a/b, relative water content, seed yield and yield attributing traits, and morphological traits. The mean comparison showed that dew-irrigation had higher stomatal conductance, chlorophyll fluorescence parameter (FV/FM), and photosynthesis performance index compared to dryland farming (62, 16, and 245% increase, respectively). Conventional irrigation had a higher photosynthesis performance index compared to dryland farming. Some plant physiological traits such as stomatal conductance clearly showed the positive effect of dew-irrigation on plant growth. The study of different levels of energy for water production can be informative in the next experiments. [ABSTRACT FROM AUTHOR]

Increases in shrub height, biomass and canopy cover are key whole‐plant features of warming‐induced vegetation change in tundra. We investigated leaf functional traits underlying photosynthetic capacity of Arctic shrub species, particularly its main limiting processes such as mesophyll conductance. In this nutrient‐limited ecosystem, we expect leaf nitrogen concentration to be the main limiting factor for photosynthesis. We measured the net photosynthetic rate at saturated light (Asat) in three Salix species throughout a glacial valley in High‐Arctic tundra and used a causal approach to test relationships between leaf stomatal and mesophyll conductances (gsc, gm), carboxylation capacity (Vcmax), nitrogen and phosphorus concentration (Narea, Parea) and leaf mass ratio (LMA). Arctic Salix species showed no difference in Asat compared to a global data set, while being characterized by higher Narea, Parea and LMA. Vcmax, gsc and gm independently increased Asat, with Vcmax as its main limitation. We highlighted a nitrogen‐influenced pathway for increasing photosynthesis in the two prostrate mesic habitat species. In contrast, the erect wetland habitat Salix richardsonii mainly increased Asat with increasing gsc. Overall, our study revealed high photosynthetic capacities of Arctic Salix species but contrasting regulatory pathways that may influence shrub ability to respond to environmental changes in High Arctic tundra. Summary statement: The photosynthetic capacity and limitations in Arctic shrubs revealing contrasting adaptations among Salix species that may influence their ability to provide negative carbon feedback to the atmosphere in high‐Arctic tundra, despite their similar photosynthetic rate compared to a global data set. [ABSTRACT FROM AUTHOR]

Soils are highly sensitive to the type of tillage practices used, as these practices influence soil properties and affect crops, the environment, and society. However, research on cassava production under different tillage systems during drought conditions in the Peruvian Amazon has not been reported. The objective of this study was to compare soil properties, cassava physiology, and yield under conservation agriculture (CA) and traditional agriculture (TA) practices, with and without mulch, in a water-scarce environment. Soil moisture, earthworm population (Ew), stomatal conductance, leaf area index, and commercial yield under CA were 5.26% (~105.2 m3 ha−1), 83%, 1.2 times, 1.14 times, and 7.3 t ha−1, respectively, higher than under TA. Hydraulic conductivity (Ks) in TA was 2.1 times higher than that in CA. However, Ks, bulk density, and Ew over time showed a gradual recovery under CA. The mulch factor only affected Ew, which was higher without mulch than with mulch. The results indicate that CA practices were superior to TA practices, improving soil properties, cassava physiology, and yield, and, therefore, offer significant benefits in resource conservation and higher production and profitability in a drought-prone environment. [ABSTRACT FROM AUTHOR]

Strawberry (Fragraria x ananassa) is a crop affected by various soil-borne fungal pathogens with mostly non-specific foliar symptoms and often requiring laboratory isolation for correct diagnosis. Moreover, these nonspecific foliar symptoms, appreciated by the human eye, appear after some time following infection by the pathogen. Early detection of plant diseases is one of the primary objectives in agriculture because it may contribute to identifying more tolerant cultivars in breeding programs and optimise pesticide use in agricultural production with earlier applications in emerging disease foci. New technologies, such as remote sensing and machine learning (ML) algorithms, have arisen as potential tools to improve the ability to detect and classify different crop diseases. The combined use of hyperspectral imagery and ML algorithms were investigated to detect and classify the physiological stress caused by early infections of Fusarium wilt in strawberry plants. Six ML models, namely artificial neural network, decision tree, K-nearest neighbour, support vector machine, multinomial logistic regression and Naïve Bayes were developed to estimate physiological stress associated with Fusarium wilt disease. The results showed that stomatal conductance (gs) and photosynthesis (A) declined even without visual symptoms of the disease. Among the six ML models evaluated, the artificial neural network model showed the highest classification performance with an overall accuracy of 81%, regardless of the physiological parameter utilized for model training. Moreover, the artificial neural network accurately predicted the absolute values of both physiological parameters (gs and A) based on the complete spectral signature from visually healthy foliar tissue, achieving coefficients of determination of 84% and 81%, respectively. Consequently, ML models utilizing physiological response data and hyperspectral imaging exhibited remarkable robustness, facilitating the estimation of Fusarium wilt severity in strawberry plants even without visual symptoms. [ABSTRACT FROM AUTHOR]

In agroforestry systems, higher-positioned crops frequently tend to impose shade stress on lower-positioned ones, with consequent negative repercussions on the agronomic characteristics of the latter. The present study was conducted under field conditions over two cropping seasons 2020-2021 and 2021-2022, to evaluate the mechanisms of physiological (e.g., stomatal conductance and water relative content) and biochemical (e.g., proline and chlorophyll content) variations, as well as grain yield and its components of different Faba bean varieties subjected to shade stress. Six varieties of Vicia faba L. (Aguadulce, Hiba, Zina, Alfia17, Defes, and Extra hative) were subjected to three levels of artificial shade stress S1 (0%), S2 (50%), and S3 (90%) during the flowering stage. The results showed that variety, shade treatment, and year significantly affected above-ground biomass and yield attributes. Substantial reductions in grain yield of 31.17% and 53.34% were observed under S2 and S3, respectively, compared with S1, demonstrating the adverse impact of shading on this parameter. Significant differences between the studied varieties were noticed. Among the varieties tested, Hiba and Zina showed the highest grain yield under shade stress conditions. Shading decreased stomatal conductance for all varieties tested, influencing proline synthesis in response to this abiotic stress. The results suggest that incorporating high-performance varieties Hiba and Zina into agroforestry systems can provide significant added value to local farmers since they are the most tolerant to shade stress, which can improve the performance of the tree-plant association in terms of yield and productivity. [ABSTRACT FROM AUTHOR]

This study assesses how zinc oxide nanoparticles (ZnO-NPs) and calcium chloride (CaCl2), affect the physiology and growth of tomato (Solanum lycopersicum L.) under salt (NaCl) stress. Before sowing, tomato seeds were soaked in 100 mM of ZnO-NPs and 2 mM of CaCl2 for 12 h alone and in combination with 100 mM of NaCl. The findings showed that salinity stress had an adverse effect on tomato plant growth and physiology by reducing photosynthesis, fresh and dry weight, and the SPAD value of chlorophyll, carbonic anhydrase (CA), nitrate reductase (NR) while increasing the activity of antioxidant enzymes, hydrogen peroxide (H2O2), malondialdehyde (MDA), proline, and other chemicals that are directly linked to increased oxidative stress. Pre-treatment of ZnO-NPs and CaCl2 alleviated the negative effects of salinity on tomato plants, as indicated by improving these attributes. Seed soaking treatments of ZnO-NPs and CaCl2 was found efficient in improving the length, fresh and dry weight, photosynthesis, transpiration rate, total carbohydrate and reducing sugar in tomato plants under salinity stress. Beside, ZnO-NPs and CaCl2 decreased the NaCl-induced oxidative stress by declining proline, Na+, and Na+/K+ contents. Thus, our research showed that ZnO-NPs are more efficient and advantageous than CaCl2 in encouraging tomato plant growth and mitigating the negative impacts of NaCl stress. [ABSTRACT FROM AUTHOR]

Climate change is leading to increased heavy rainfall, making plant submergence in flood-prone pastures more common. Forage legumes play a vital role in boosting herbage production and quality, especially when grown with grasses in low nitrogen input areas. However, their tolerance to complete submergence and subsequent recovery remains poorly understood. This study evaluated eight forage legumes after 5 or 10 days of complete submergence: (1) Lotus tenuis ; (2) Lotus corniculatus ; (3) Lotus japonicus ; (4) Trifolium repens ; (5) Trifolium fragiferum ; (6) Trifolium pratense ; (7) Trifolium michelianum ; and (8) Melilotus albus. We assessed physiological and growth traits related to tolerance and recovery. All species survived except M. albus and T. michelianum. For the six surviving species, growth parameters linked to recovery were more prominent in Lotus species than in Trifolium species. Lotus species maintained higher biomass, improved stomatal conductance, and increased chlorophyll concentration in young leaves, along with a quicker recovery of PSII efficiency. In contrast, T. pratense showed the least tolerance and recovery, indicating its unsuitability for waterlogged areas. L. tenuis emerged as the most promising species for submergence tolerance, with L. corniculatus also showing potential, particularly in areas prone to short-term flooding. Variable adaptability to complete submergence was observed among Lotus and Trifolium species, while Melilotus albus and Trifolium michelianum did not survive. Lotus species demonstrated superior recovery growth from submergence compared to Trifolium species, particularly Lotus tenuis , making it suitable for flood-prone areas. The better performance of Lotus species after submergence was due to their ability to maintain higher stomatal conductance, increased chlorophyll concentration in young leaves, and quicker recovery of PSII efficiency. [ABSTRACT FROM AUTHOR]