Plant Water Relations Research Articles

The impact of elevated CO2 concentration on photosynthesis, growth and hydraulics of evergreen and deciduous tree seedlings from a subtropical forest in Southwest China

Elevated CO2 concentration (eCO2) in the atmosphere is expected to impact plant water relations and growth in several ecosystems across the globe. However, we still know little about such impact on tree species in subtropical regions. The present study investigated the impact of eCO2 on leaf gas exchange, nitrogen and phosphorus concentrations, leaf and stem hydraulic conductivity, and growth of seedlings of four evergreen and four deciduous tree species from a subtropical forest in Southwest China. We found that both evergreen and deciduous tree species at eCO2 had higher leaf area-based photosynthetic rates and lower leaf stomatal conductance. Further, leaf mass-based photosynthetic rate was more enhanced in evergreen than in deciduous trees at eCO2. Biomass of evergreen and deciduous species was significantly higher at eCO2, with large species-specific variation among the evergreen species. Leaf-specific hydraulic conductivity was more enhanced in deciduous tree species than that of evergreen tree species with eCO2, which was mainly driven by the increase of biomass at eCO2. Interestingly, eCO2 significantly strengthened the coordination of stem hydraulic conductivity with leaf-gas exchange, leaf phosphorus concentration, and plant biomass across evergreen and deciduous species. These results highlighted greater enhancement of photosynthesis and greater species-specific variation in biomass at eCO2 for evergreen species compared to deciduous species, and stronger hydraulic-photosynthesis correlations at eCO2 than at aCO2 for tree species from subtropical forests. The present study provides important insights on the potential impacts of eCO2 on plant eco-physiology, growth and forest succession in a subtropical forest under global climate change.

Water status dynamics and drought tolerance of juvenile European beech, Douglas fir and Norway spruce trees as dependent on neighborhood and nitrogen supply.

To increase the resilience of forests to drought and other hazards, foresters are increasingly planting mixed stands. This requires knowledge about the drought response of tree species in pure and mixed-culture neighborhoods. In addition, drought frequently interacts with continued atmospheric nitrogen (N) deposition. To disentangle these factors for European beech, Norway spruce and Douglas fir, we conducted a replicated 3-factorial sapling growth experiment with three moisture levels, (high, medium, and low), two N levels (high and ambient), and pure and mixed-culture neighborhoods. We measured biomass, stomatal conductance (GS), shoot water potential (at predawn: ΨPD, midday, and turgor loss point: ΨTLP), branch xylem embolism resistance (Ψ50) and minimum epidermal conductance (Gmin). The three species differed most with respect to Gmin (10-fold higher in beech than in the conifers), hydroscape area (larger in beech), and the time elapsed to reach stomatal closure (TΨGS90) and ΨTLP (TTLP; shorter in beech), while Ψ50 and ΨTLP were remarkably similar. Neighborhood (pure vs mixed-culture) influenced biomass production, water status and hydraulic traits, notably GS (higher in Douglas fir, but lower in spruce and beech, in mixtures than pure culture), hydraulic safety margin (smaller for beech in mixtures), and TΨGS90 and TTLP (shorter for spruce in mixture). High N generally increased GS, but no consistent N effects on leaf water status and hydraulic traits were detected, suggesting that neighbor identity had a larger effect on plant water relations than N availability. We conclude that both tree neighborhood and N availability modulate the drought response of beech, spruce, and Douglas fir. Species mixing can alleviate the drought stress of some species, but often by disadvantaging other species. Thus, our study suggests that stabilizing and building resilience of production forests against a drier and warmer climate may depend primarily on the right species choice; species mixing can support the agenda.

Nocturnal stomatal behaviour and its impact on water use strategies of desert herbs in the Gurbantunggut Desert, Northwest China

Nocturnal stomatal behaviour has the potential to exert a profound influence on plant-water relations, especially water use efficiency. However, we know very less about plant functional type differences in nocturnal stomatal conductance and their roles in plant stress adaptation, especially drought adaptation. To address this critical knowledge gap, we assessed diel leaf gas exchanges in eight ephemeral and perennial herbs growing on the southern edge of the Gurbantunggut Desert, Northwest China. For both ephemeral and perennial herbs, the nocturnal stomatal conductance (gs) exceeded 30 % of daytime gs, except for an ephemeral herb (Malcolmia scorpioides). The nocturnal gs in the studied perennial herbs were significantly higher than it in the ephemeral herbs. The results suggest that circadian-driven stomatal priming plays a pivotal role in accelerating the attainment of steady-state gs during the morning for perennial herbs, thereby enhancing their capacity for carbon capture. Moreover, the nocturnal stomatal behaviour of the ephemeral herbs favored water retention in the morning, consequently enhanced intrinsic water use efficiency and long-term water use efficiency. In summary, plant functional type differences in the magnitude of nocturnal stomatal opening were related to differences in water acquisition and utilization and highlighted diverse water use strategies in the desert plants.

Host Plant Modulated Physio-Biochemical Process Enhances Adaptive Response of Sandalwood (Santalum album L.) under Salinity Stress.

Salinity is one of the most significant abiotic stress that affects the growth and development of high-value tree species, including sandalwood, which can also be managed effectively on saline soils with the help of suitable host species. Therefore, the current investigation was conducted to understand the physiological processes and antioxidant mechanisms in sandalwood along the different salinity gradients to explore the host species that could support sandalwood growth in salt-affected agro-ecosystems. Sandalwood seedlings were grown with ten diverse host species with saline water irrigation gradients (ECiw~3, 6, and 9 dS m-1) and control (ECiw~0.82 dS m-1). Experimental findings indicate a decline in the chlorophyll content (13-33%), relative water content (3-23%), photosynthetic (27-61%) and transpiration rate (23-66%), water and osmotic potential (up to 137%), and ion dynamics (up to 61%) with increasing salinity levels. Conversely, the carotenoid content (23-43%), antioxidant activity (up to 285%), and membrane injury (82-205%) were enhanced with increasing salinity stress. Specifically, among the hosts, Dalbergia sissoo and Melia dubia showed a minimum reduction in chlorophyll content, relative water content, and plant water relation and gas exchange parameters of sandalwood plants. Surprisingly, most of the host tree species maintained K+/Na+ of sandalwood up to moderate water salinity of ECiw~6 dS m-1; however, a further increase in water salinity decreased the K+/Na+ ratio of sandalwood by many-fold. Salinity stress also enhanced the antioxidative enzyme activity, although the maximum increase was noted with host plants M. dubia, followed by D. sissoo and Azadirachta indica. Overall, the investigation concluded that sandalwood with the host D. sissoo can be successfully grown in nurseries using saline irrigation water and, with the host M. dubia, it can be grown using good quality irrigation water.

Coupled hydraulics and carbon economy underlie age-related growth decline and revitalisation of sand-fixing shrubs after crown removal.

Crown removal revitalises sand-fixing shrubs that show declining vigour with age in drought-prone environments; however, the underlying mechanisms are poorly understood. Here, we addressed this knowledge gap by comparing the growth performance, xylem hydraulics and plant carbon economy across different plant ages (10, 21 and 33 years) and treatments (control and crown removal) using a representative sand-fixing shrub (Caragana microphylla Lam.) in northern China. We found that growth decline with plant age was accompanied by simultaneous decreases in soil moisture, plant hydraulic efficiency and photosynthetic capacity, suggesting that these interconnected changes in plant water relations and carbon economy were responsible for this decline. Following crown removal, quick resprouting, involving remobilisation of root nonstructural carbohydrate reserves, contributed to the reconstruction of an efficient hydraulic system and improved plant carbon status, but this became less effective in older shrubs. These age-dependent effects of carbon economy and hydraulics on plant growth vigour provide a mechanistic explanation for the age-related decline and revitalisation of sand-fixing shrubs. This understanding is crucial for the development of suitable management strategies for shrub plantations constructed with species having the resprouting ability and contributes to the sustainability of ecological restoration projects in water-limited sandy lands.

Contrasting Regulation of Phaseolus vulgaris Root Hydraulic Properties Under Drought and Saline Conditions by Three Arbuscular Mycorrhizal Fungal Species From Soils with Divergent Moisture Regime

PurposeArbuscular mycorrhizal fungi (AMF) may help plants to overcome abiotic stresses, in part by improving their water uptake capacity. However how different AMF isolated from different climatic regions regulate plant abiotic stress tolerance and water uptake capacity is barely studied. The aim of this study was to reveal how three AMF isolated from two Mediterranean climate locations contrasting in annual precipitation, modify bean (Phaseolus vulgaris L.) root hydraulic properties facing drought and salinity.MethodsRhizophagus intraradices (Ri) and Funneliformis mosseae (Fm) were isolated from a humid area, whereas Claroideoglomus etunicatum (Ce) was isolated from a dry location. All plants (inoculated or not) were subjected to four days of withholding water or salt treatment. Root hydraulic properties including root hydraulic conductivity and aquaporin expression and abundance were determined.ResultsAll three AMF isolate induced significant differences in plant physiology regardless their different mycorrhizal colonization extent. Drought treatment diminished root hydraulic conductivity and only Fm inoculated plants featured measurable amount of sap exudate. After salt irrigation, AMF inoculation counterbalanced the drop of root hydraulic conductivity. In such situation two AMF, Fm and Ce, presented lowered phosphorylated (Ser-283) PIP2 AQP amount. AQP gene expression highlighted the importance of PvPIP1;2 and PvPIP2;3 plasticity in plants facing osmotic stress. After drought treatment AMF species from the humid location, Ri and Fm, improved plant water status and Fm enhanced root hydraulic conductivity, whereas all AMF performed similarly after salt irrigation, enhancing stomatal conductance and root hydraulic conductivity.ConclusionUnder drought conditions, the AMF isolates from humid regions were the ones that most effectively improved plant water relations. However, under salt stress, all three AMF isolates exhibited similar behavior. Therefore, to some extent, the climatic origin of the AMF could have influenced the response of host plants to drought stress, suggesting that those originating from dry areas may not necessarily be the most efficient.

Spectral ecophysiology: hyperspectral pressure-volume curves to estimate leaf turgor loss.

Turgor loss point (TLP) is an important proxy for plant drought tolerance, species habitat suitability, and drought-induced plant mortality risk. Thus, TLP serves as a critical tool for evaluating climate change impacts on plants, making it imperative to develop high-throughput and in situ methods to measure TLP. We developed hyperspectral pressure-volume curves (PV curves) to estimate TLP using leaf spectral reflectance. We used partial least square regression models to estimate water potential (Ψ) and relative water content (RWC) for two species, Frangula caroliniana and Magnolia grandiflora. RWC and Ψ's model for each species had R2 ≥ 0.7 and %RMSE = 7-10. We constructed PV curves with model estimates and compared the accuracy of directly measured and spectra-predicted TLP. Our findings indicate that leaf spectral measurements are an alternative method for estimating TLP. F. caroliniana TLP's values were -1.62 ± 0.15 (means ± SD) and -1.62 ± 0.34 MPa for observed and reflectance predicted, respectively (P > 0.05), while M. grandiflora were -1.78 ± 0.34 and -1.66 ± 0.41 MPa (P > 0.05). The estimation of TLP through leaf reflectance-based PV curves opens a broad range of possibilities for future research aimed at understanding and monitoring plant water relations on a large scale with spectral ecophysiology.

Water exchange between the Chlorenchyma and the Hydrenchyma and its physiological role in leaves with Crassulacean acid metabolism.

Direct and non-destructive measurements of plant-water relations of plants exhibiting the Crassulacean acid metabolism (CAM) photosynthetic pathway are seldom addressed, with most findings inferred from gas exchange measurements. The main focus of this paper was to study how the water exchange between the chlorenchyma and the hydrenchyma depends on and follows the CAM photosynthetic diel pattern using non-invasive and continuous methods. Gas exchange and leaf patch clamp pressure probe (LPCP) measurements were performed on Aloe vera (L.) Burm f., a CAM species, and compared to measurements on banana (Musa acuminata Colla), a C3 species. The LPCP output pressure, Pp , of Aloe vera plants follows its diel CAM photosynthetic cycle, reversed to that observed in banana and other C3 species. The four phases of CAM photosynthesis can also be identified in the diel LPCP output pressure, Pp , cycle. The Pp values in Aloe vera are determined by the hydrenchyma turgor pressure, with both parameters being reversely related. A non-invasive and continuous assessment of the water exchange between the chlorenchyma and the hydrenchyma in CAM plants, namely, by following the changes in the hydrenchyma turgor pressure, is presented. However, showing once more how the LPCP output pressure, Pp , depends on the leaf structure, such an approach can be used to study plant-water relations in other CAM species with a leaf structure similar to Aloe vera, with the hydrenchyma composing most of the leaf volume.

Differences in plant water use between check-dam land and slope land on the Loess Plateau: Significance for vegetation restoration

Check dam lands (DLs) and hillslope lands (SLs) are two typical landscape units in the semi-arid Loess Plateau of China (CLP). Knowledge of the water resource distribution and water use characteristics of plant species used for revegetation in SL and DL has profound implications for understanding plant–water relations and guiding revegetation strategies in water-limited ecosystems. To assess the spatiotemporal characteristics of water resource and investigate water use strategies of two widely used species for revegetation (i.e., Medicago sativa and Caragana korshinskii) in the SL and DL, numerous types of water samples (including rain-, soil-, plant-, and groundwater) were collected from a watershed in the semi-arid CLP for analysis. The oxygen and hydrogen stable isotopic ratios (δ18O and δD) of the water samples were estimated for three consecutive hydrological years (2018−2020). The soil water storage in the unsaturated zone of 0–600cm in the DL (mean 1008mm) was estimated to be 64% higher than that in the SL (mean 613mm). Below 600cm, soil was saturated with water (i.e. groundwater) in the DL and remained unsaturated in the SL. The Bayesian mixing model was applied to the stable isotopic ratios of H and O, which revealed significant differences (p < 0.05) in the proportional contributions of water resources between the two revegetated species. Although M. sativa (mean 76% for SL and 61% for DL) and C. korshinskii (mean 72% for SL and 47% for DL) relied on water from the upper 100-cm soil layer during the observation period, C. korshinskii generally utilised more water from the deep soil layer (>100cm) than M. sativa. Furthermore, the mean water uptake fractions of C. korshinskii in both the SL and DL for the deep soil layers and groundwater significantly increased with decreasing annual rainfall, whereas this was not observed for M. sativa, suggesting that the environmental adaptability of C. korshinskii may be more ecologically plastic than that of M. sativa. Additionally, the contribution of groundwater (>600cm) to root water uptake in M. sativa (mean, 21%) and C. korshinskii (mean, 28%) was comparable in the DL, indicating the importance of groundwater in combating possible water stress for revegetated plants. These results indicate that natural and engineering measure-induced water resource distributions result in different plant water-use characteristics and responses to variations in precipitation. Therefore, engineering measures and species are essential factors in ecological restoration management for enhancing the effectiveness of vegetation restoration strategies.

Photosynthetic gas exchange, plant water relations and osmotic adjustment of three tropical perennials during drought stress and re-watering.

Planting vegetation on slopes is an effective way of improving slope stability while enhancing the aesthetic appearance of the landscape. However, plants growing on slopes are susceptible to natural drought stress (DS) conditions which commonly lead to water deficit in plant tissues that affect plant health and growth. This study investigated the photosynthetic gas exchange, plant water status and proline accumulation of three tropical perennials namely Clerodendrum paniculatum, Ipomoea pes-caprae and Melastoma malabathricum after being subjected to DS and re-watering (RW). During DS, there was a significant decrease in light-saturated photosynthetic CO2 assimilation rate (Asat), stomatal conductance (gs sat), and transpiration rate (Tr) for all three plant species. Leaf relative water content, shoot water potential, and leaf, stem and root water content also declined during DS. Proline concentration increased for all three species during DS, reaching especially high levels for C. paniculatum, suggesting that it heavily relies on the accumulation of proline to cope with DS. Most of the parameters recovered almost completely to levels similar to well-watered plants after RW, apart from M. malabathricum. Strong linear correlations were found between Asat and gs sat and between gs sat and Tr. Ultimately, C. paniculatum and I. pes-caprae had better drought tolerance than M. malabathricum.

Water Uptake Characteristics of Stipa bungeana Trin: Affected by Subsidence in the Coal Mining Areas of Northwest China

Revealing the water use pattern of plants influenced by coal-mining-caused land subsidence is crucial to understand plant–water interactions and guide ecological restoration. However, available information on herbaceous plants, the dominant species in most arid and semi-arid regions with abundant coal resources, remains inadequate. We investigated the water use patterns of Stipa bungeana Trin. by measuring soil water content, root distribution, and stable isotopes of hydrogen (δ2H) and oxygen (δ18O) of soil water and plant stem water both before and after a rainfall event. The results revealed that prior to rainfall, both areas exhibited a low soil water content with no discernible difference in soil drought. However, the soil waters δ2H and δ18O were found to be more enriched at varying depths within the subsidence area, indicating a heightened level of soil evaporation. Both soil water content and soil water isotopic composition responded sensitively to rainfall, with rainfall primarily replenishing the shallow layer (0–20 cm), thereby reflecting an infiltration mode dominated by piston flow. More water seeped into deeper soil layers in the subsidence area compared to the non-subsidence area, with more preferential flow. Before rainfall, the sources of plant water uptake were consistent both at shallow and deep soil layers, implying that the proportion of water uptake gradually decreased with increasing depth. After rainfall, the sources of plant water uptake differed slightly between the two soil layers. The plants in non-subsidence and subsidence areas dominantly extracted soil water at depths greater than 10 cm and 20 cm, respectively. The root system in the subsidence area was more developed than that in the non-subsidence area. Plant water uptake was primarily influenced by the spatial distribution of roots, as well as the post-rainfall water distribution, regardless of whether they were in the subsidence area or not. Although land subsidence affected soil water transport, the water uptake pattern of Stipa bungeana Trin. was similar before and after rainfall, indicating the adaptive growth of plants through their roots in the subsidence area. The high adaptability of herbs such as Stipa bungeana Trin. makes them a viable option for vegetation restoration in subsidence areas. This study has significant implications for evaluating plant–water relationships in subsidence areas due to coal mining, thereby providing a fundamental basis and valuable reference for ecological restoration and management strategies within such affected regions.

Foliar Application of Biostimulant Mitigates Water Stress Effects on Soybean

Climate change has emerged as a challenge for soybean cultivation around the world, stimulating the development of technological alternatives that aim to mitigate the damage caused by water deficit. From this perspective, algae extract-based biostimulants have been tested to reduce water stress in several crops, but little is known about their effects on soybean. Thus, we hypothesize that a commercial biostimulant based on Ascophyllum nodosum can improve the physiological performance and water relations of Glycine max plants subjected to water deficit. To test this hypothesis, we set up an experiment in controlled conditions in a greenhouse, considering five treatments (control; application of biostimulant; water deficit (WD); WD + application of biostimulant; and WD + split application of biostimulant). The experiment was designed in completely randomized blocks with four replications per treatment and conducted in polyethylene pots containing 10 L of soil and three plants per pot. The irrigation was carried out daily; the water deficit was 50% soil moisture at field capacity, starting at the R1 stage (beginning of flowering, where there is at least one flower open at any node on the plant) and maintained for ten days. The biostimulant was applied concurrently with the onset of water deficit. We confirmed the hypothesis that foliar application of 1.0 L ha−1 of the biostimulant reduces the deleterious effects of the common water deficit at the beginning of the reproductive stage of soybean through the reduction of damage from oxidative stress (reduction of malondialdehyde synthesis by 31.2% in relation to the WD plants), maintenance of water potential and cellular homeostasis (10.2% increase in relative water content when compared with WD plants), and conservation of the contents of chlorophyll in leaves and stimulation of photosynthesis and carboxylation (68% increase in net photosynthetic rate and 49.3% increase in carboxylation efficiency in relation to WD plants). However, when applied in installments, the biostimulant was not efficient in reducing soybean water stress. Therefore, we conclude that the application of a biostimulant based on A. nodosum can help reduce the harmful effects of water deficit on soybean plants, opening up perspectives for the mass use of this extract in agricultural crops produced on a large scale.

Biofilm producing plant growth promoting bacteria in combination with glycine betaine uplift drought stress tolerance of maize plant.

The escalating threat of drought poses a significant challenge to sustainable food production and human health, as water scarcity adversely impacts various aspects of plant physiology. Maize, a cornerstone in staple cereal crops, faces the formidable challenge of drought stress that triggers a series of transformative responses in the plant. The present study was carried out in two sets of experiments. In first experiment, drought stress was applied after maintaining growth for 45 days and then irrigation was skipped, and plant samples were collected at 1st, 3rd and 6th day of drought interval for evaluation of changes in plant growth, water relation (relative water content) and antioxidants activity by inoculating indigenously isolated drought tolerant biofilm producing rhizobacterial isolates (Bacillus subtilis SRJ4, Curtobacterium citreum MJ1). In the second experiment, glycine betaine was applied as osmoregulator in addition to drought tolerant PGPR to perceive modulation in photosynthetic pigments (Chlorophyll a and b) and plant growth under varying moisture stress levels (100, 75 and 50% FC). Results of the study revealed upsurge in root and shoot length, fresh and dry biomass of root and shoot besides increasing chlorophyll contents in water stressed inoculated plants compared to uninoculated plants. Glycine betaine application resulted in an additional boost to plant growth and photosynthetic pigments, when applied in combination with bacterial inoculants. However, both bacterial inoculants behaved differently under drought stress as evident from their biochemical and physiological attributes. Isolate SRJ4 proved to be superior for its potential to express antioxidant activity, leaf water potential and relative water contents and drought responsive gene expression while isolate MJ1 showed exclusive increase in root dry biomass and plant P contents. Though it is quite difficult to isolate the bacterial isolates having both plant growth promoting traits and drought tolerance together yet, such biological resources could be an exceptional option to be applied for improving crop productivity and sustainable agriculture under abiotic stresses. By exploring the combined application of PGPR and glycine betaine, the study seeks to provide insights into potential strategies for developing sustainable agricultural practices aimed at improving crop resilience under challenging environmental conditions.

High-quality production of red plum apricot in semiarid Loess Hilly region of China

Red plum apricot is a deciduous fruit tree and the best cash forest in semi-arid Loess hilly regions of China. Since 1995, the distribution area of the apricot has spread in most of the water-limited regions, in China, and the yield and benefits of red plum apricot increase dramatically. Since 2017, China put forward high-quality development, and red plum apricot must carry out high-quality production. But, as the red plum apricot tree grows, low temperatures and frost, hazards of heart-eating insects and soil drying will appear, which seriously influence the yield, quality, and benefits of red plum apricot in turn. However, there are few reports on the method for High-quality production of red plum apricot. In this study, the effectiveness of different methods of controlling low temperature and frost and hazards of heart-eating insects and soil drying was estimated. The results show that the greenhouse method is the better method for controlling Low temperature and frost, spraying Beta-cypermethrin still is the better method for controlling Hazards of heart-eating insects. When the soil water resource in the maximal infiltration depth is lower than the soil water resource use limitation by red plum apricot, the plant water relationship enters the key period of plant water relationship regulation. The ending time of the critical period of plant water relation regulation is the failure time of plant water relation regulation. When the current plant density is more than the soil water vegetation carrying capacity, the plant-water relation should be regulated, and then the vegetative growth and reproductive growth on the appropriate leaf quantity when the current plant density is equal to the soil water vegetation carrying capacity and the leaf fruit relation.

Spatiotemporal variation in ecophysiological traits align with high resolution niche modelling in the short-range banded ironstone endemic Aluta quadrata.

Defining plant ecophysiological responses across natural distributions enables a greater understanding of the niche that plants occupy. Much of the foundational knowledge of species' ecology and responses to environmental change across their distribution is often lacking, particularly for rare and threatened species, exacerbating management and conservation challenges. Combining high-resolution species distribution models (SDMs) with ecophysiological monitoring characterized the spatiotemporal variation in both plant traits and their interactions with their surrounding environment for the range-restricted Aluta quadrata Rye & Trudgen, and a common, co-occurring generalist, Eremophila latrobei subsp. glabra (L.S.Sm.) Chinnock., from the semi-arid Pilbara and Gascoyne region in northwest Western Australia. The plants reflected differences in gas exchange, plant health and plant water relations at sites with contrasting suitability from the SDM, with higher performance measured in the SDM-predicted high-suitability site. Seasonal differences demonstrated the highest variation across ecophysiological traits in both species, with higher performance in the austral wet season across all levels of habitat suitability. The results of this study allow us to effectively describe how plant performance in A. quadrata is distributed across the landscape in contrast to a common, widespread co-occurring species and demonstrate a level of confidence in the habitat suitability modelling derived from the SDM in predicting plant function determined through intensive ecophysiology monitoring programmes. In addition, the findings also provide a baseline approach for future conservation actions, as well as to explore the mechanisms underpinning the short-range endemism arid zone systems.

Trehalose Induced regulations in Physio-biochemical attributes of Helianthus annuus under Lead stress

Heavy metal is a substantially severe abiotic environmental stress that is rising in many regions of the world. Current climate change circumstances and rapid industrialization increased heavy metal accumulation in soil and water. Overall, worldwide agricultural production decreased. Trehalose, a well-known plant growth regulator, is crucial in plants' responses to a variety of abiotic conditions. The Morpho-physiological and biochemical parameters were analyzed in hydroponic research to identify the possible role of trehalose in alleviating heavy metal lead acetate stress in sunflower (Helianthus annuus L.) crops. In the sole and mixed form, two Pb(C2H3O2)2 (Control and 30 micron) and one trehalose (50 M L-1) levels were used, and a half-strength Hoagland solution was used as a nutritional medium. The current study found that heavy metal stress had a significant negative impact on plant growth (root and shoot length), fresh and dry biomass, and plant water relations, as well as poor plant water relations, membrane stability, chlorophyll content, and antioxidant enzyme activities such as superoxide dismutase (SOD), peroxide (POD), ascorbate peroxide (APX), and catalase (CAT). MDA and H2O2 are the stress markers reduced by the application of trehalose. Exogenous treatment of trehalose, on the other hand, significantly mitigates the detrimental effects of metal toxicity by altering plant physiology, enhancing water relations, and providing robust antioxidant defense against heavy metal lead acetate stress. The findings of this study provide a new dimension to scientists' understanding of the beneficial usage of trehalose in plant science and offer up new research opportunities.

Plant hydraulics at the heart of plant, crops and ecosystem functions in the face of climate change.

Plant hydraulics is crucial for assessing the plants' capacity to extract and transport water from the soil up to their aerial organs. Along with their capacity to exchange water between plant compartments and regulate evaporation, hydraulic properties determine plant water relations, water status and susceptibility to pathogen attacks. Consequently, any variation in the hydraulic characteristics of plants is likely to significantly impact various mechanisms and processes related to plant growth, survival and production, as well as the risk of biotic attacks and forest fire behaviour. However, the integration of hydraulic traits into disciplines such as plant pathology, entomology, fire ecology or agriculture can be significantly improved. This review examines how plant hydraulics can provide new insights into our understanding of these processes, including modelling processes of vegetation dynamics, illuminating numerous perspectives for assessing the consequences of climate change on forest and agronomic systems, and addressing unanswered questions across multiple areas of knowledge.

Biochar a promising amendment to mitigate the drought stress in plants: review and future prospective

Drought stress (DS) is one of the most destructive abiotic stresses that negatively affects plant growth, and yield. The intensity of DS is continuously increasing due rapid of water sources, less rainfall, and an increase in global warming. The world’s population is increasing at an alarming rate which needs a substantial increase in crop production to meet global food needs. Therefore, in this context, we must have to increase crop production in the scenarios of rapid climate change and increasing intensity of abiotic stresses. Globally, different measures are used to mitigate the adverse impacts of DS, recently biochar (BC) has emerged as an excellent soil amendment to mitigate the toxic effects of DS and improve crop production. The application maintains membrane integrity, plant water relations, nutrient homeostasis, photosynthetic performance, hormonal balance and osmolytes accumulation, and gene expression thereby improving plant performance under DS. Moreover, BC application under DS also improves soil organic matter, water holding capacity, soil structure stability, and activity of beneficial microbes which can improve the plant performance under DS. In the present review different mechanisms through which BC mitigates the adverse impacts of DS on plants are discussed. This review provides new suggestions on the role of BC in mitigating the adverse impacts of DS.

Inoculation with a microbial consortium increases soil microbial diversity and improves agronomic traits of tomato under water and nitrogen deficiency.

Microbial-based biostimulants, functioning as biotic and abiotic stress protectants and growth enhancers, are becoming increasingly important in agriculture also in the context of climate change. The search for new products that can help reduce chemical inputs under a variety of field conditions is the new challenge. In this study, we tested whether the combination of two microbial growth enhancers with complementary modes of action, Azotobacter chroococcum 76A and Trichoderma afroharzianum T22, could facilitate tomato adaptation to a 30% reduction of optimal water and nitrogen requirements. The microbial inoculum increased tomato yield (+48.5%) under optimal water and nutrient conditions. In addition, the microbial application improved leaf water potential under stress conditions (+9.5%), decreased the overall leaf temperature (-4.6%), and increased shoot fresh weight (+15%), indicating that this consortium could act as a positive regulator of plant water relations under limited water and nitrogen availability. A significant increase in microbial populations in the rhizosphere with applications of A. chroococcum 76A and T. afroharzianum T22 under stress conditions, suggested that these inoculants could enhance soil microbial abundance, including the abundance of native beneficial microorganisms. Sampling time, limited water and nitrogen regimes and microbial inoculations all affected bacterial and fungal populations in the rhizospheric soil. Overall, these results indicated that the selected microbial consortium could function as plant growth enhancer and stress protectant, possibly by triggering adaptation mechanisms via functional changes in the soil microbial diversity and relative abundance.

The Effect of Bacterial Treatment in Combination with Humic Substances on Growth, Indicators of Oxidative Stress and Water Relations of Wheat Plants under Soil Water Shortage

The Effect of Bacterial Treatment in Combination with Humic Substances on Growth, Indicators of Oxidative Stress and Water Relations of Wheat Plants under Soil Water Shortage