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Summary: 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. [ABSTRACT FROM AUTHOR]

Summary: The water status of the living tissue in leaves is critical in determining plant function and global exchange of water and CO2. Despite significant advances in the past two decades, persistent questions remain about the tissue‐specific origins of leaf hydraulic properties and their dependence on water status.We use a fluorescent nanoparticle reporter that provides water potential in the mesophyll apoplast adjacent to the epidermis of intact leaves to complement existing methods based on the Scholander Pressure Chamber (SPC). Working in tomato leaves, this approach provides access to the hydraulic conductance of the whole leaf, xylem, and outside‐xylem tissues.These measurements show that, as stem water potential decreases, the water potential in the mesophyll apoplast can drop below that assessed with the SPC and can fall significantly below the turgor loss point of the leaf. We find that this drop in potential, dominated by the large loss (10‐fold) of hydraulic conductance of the outside‐xylem tissue, is not however strong enough to significantly limit transpiration.These observations highlight the need to reassess models of water transfer through the outside‐xylem tissues, the potential importance of this tissue in regulating transpiration, and the power of new approaches for probing leaf hydraulics. [ABSTRACT FROM AUTHOR]

Rising temperatures and increases in drought negatively impact the efficiency and sustainability of both agricultural and forest ecosystems. Although hydraulic limitations on photosynthesis have been extensively studied, a solid understanding of the links between whole plant hydraulics and photosynthetic processes at the cellular level under changing environmental conditions is still missing, hampering our predictive power for plant mortality. Here, we examined plant hydraulic traits and CO2 assimilation rate under progressive water limitation by implementing Photosystem II (PSII) dynamics with a whole plant process model (TREES). The photosynthetic responses to plant water status were parameterized based on measurements of chlorophyll a fluorescence, gas exchange and water potential for Brassica rapa (R500) grown in a greenhouse under fully watered to lethal drought conditions. The updated model significantly improved predictions of photosynthesis, stomatal conductance and leaf water potential. TREES with PSII knowledge predicted a larger hydraulic safety margin and a decrease in percent loss of conductivity. TREES predicted a slower decrease in leaf water potential, which agreed with measurements. Our results highlight the pressing need for incorporating PSII drought photochemistry into current process models to capture cross‐scale plant water dynamics from cell to whole plant level. Summary statement: Implementation of Photosystem II dynamics improved predictions of photosynthesis, stomatal conductance and leaf water potential. This approach indicated a larger hydraulic safety margin and a decrease in percent loss of conductivity to reduce the risk of premature embolism during drought. [ABSTRACT FROM AUTHOR]

Objective: to evaluate the effect of the drip-tape irrigation depth on the efficiency of water use, yield, nutritional quality and profitability of forage maize, a study was established by installing drip-tape at a depths 0.05, 0.15 and 0.30 meters. Design/Methodology/Approach: a randomized block experimental design was used. Treatments evaluated consisted of the installation of drip-tape at three depths 0.05, 0.15 and 0.30 m; each treatment in three replicates. The experimental unit was a 15 m² surface (comprising four 5m-long furrows, with a 0.76 m separation between furrows). Results: results showed that with the drip-tape installed at a depth of 0.15 m, the highest biomass production and water use efficiency were obtained, without modifying the bromatological quality of the forage. However, the best benefit-cost ratio corresponded to the drip-tape installed at 0.3 m, recovering $1.27 for each MXN peso invested in crop production. Limitations/Implications of the study: water scarcity in arid and semi-arid regions is a global problem, so it is necessary to use irrigation methods that make water use more efficient without reducing crop yield. Findings/conclusions: the installation of the drip-tape at a depth of 0.15 m is recommended, due to the improvement in yield and water use efficiency without affecting nutritional quality of the forage or profitability of maize crop. [ABSTRACT FROM AUTHOR]

Temperature and water potential are critical factors influencing the germination of Sporisorium scitamineum teliospores and subsequent crop infection. This paper reports on the effect of temperature, water potential and incubation time on S. scitamineum teliospore germination. A field trial was conducted to determine the influence of temperature and length of exposure to teliospores on smut incidence. A 200 μL aliquot of teliospore (1.5 × 106 teliospores/mL) was cultured on water agar (WA) amended by potassium chloride (KCl) or sucrose. The plates were incubated across a range of temperatures and incubation times. For the field trial, sugarcane setts were inoculated and incubated at different temperatures and for varying incubation periods. The results demonstrated that germination decreased with declining water potential with either KCl or sucrose. The greatest germination (95.8%) occurred on unamended WA incubated at 30°C for 6 h. Even at the lowest water potential of −45 bars and 30°C, 50% teliospores were still able to germinate. These results indicate that 30°C is the optimum temperature for teliospore germination and that S. scitamineum may still germinate in fairly dry conditions. However, high temperatures (40°C), greatly reduce S. scitamineum germination. These results are consistent with field trial outcomes, which showed that the highest disease incidence (40.4%) occurred when temperature of inoculation was maintained at 30°C. On the other hand, the incidence was significantly reduced to 5.7% at 35°C. The results suggested consistent conditions for teliospore germination and sugarcane bud infection, with a temperature of 30°C being optimal for both. [ABSTRACT FROM AUTHOR]

Global warming is increasing the frequency and intensity of heat waves and droughts. One important phase in the life cycle of plants is seed germination. To date, the association of the temperature and water potential thresholds of germination with seed traits has not been explored in much detail. Therefore, we set up different temperature gradients (5–35 °C), water potential gradients (−1.2–0 MPa), and temperature × water potential combinations for nine native plants in the Loess Plateau region to clarify the temperature and water combinations suitable for their germination. Meanwhile, we elucidated the temperature and water potential thresholds of the plants and their correlations with the mean seed mass and flatness index by using the thermal time and hydrotime models. According to our findings, the germination rate was positively correlated with the germination percentage and water potential, with the former rising and the latter decreasing as the temperature increased. Using the thermal time and hydrotime models, the seed germination thresholds could be predicted accurately, and the germination thresholds of the studied species varied with an increase in germination percentage. Moreover, temperature altered the impact of water potential on the germination rate. Overall, the base water potential for germination, but not the temperature threshold, was negatively correlated with mean seed mass and was lower for rounder seeds than for longer seeds. This study contributes to improving our understanding of the seed germination characteristics of typical plants and has important implications for the management and vegetation restoration of degraded grasslands. [ABSTRACT FROM AUTHOR]

Climate change-induced prolonged water stress (WS) affects crassulacean acid metabolism photosynthesis in pitaya (Hylocereus), limiting crop productivity through insufficient photosynthate. To document how WS/rehydration affects diel photosynthesis, red-fleshed pitaya (H. polyrhizus) micropropagules were studied for 5 weeks in a mannitol-induced water potential gradient replaced with moderate (MWS; −1.0 MPa in week 2; −0.5 MPa for the rest) or intensified (IWS; −1.0 and −1.5 MPa in weeks 2 and 3; −0.5 MPa for the rest) WS in vitro. Net photosynthetic rate (Pn) and integrated net CO2 uptake (INCU) were measured using an Arduino-based photosynthesis system. Micropropagules under MWS had similar Pn in weeks 5 and 1, whereas the control (−0.5 MPa) increased. Pn recovery did not occur after IWS. The average relative INCU was similar in the control and MWS, but lower in IWS. The Pn difference increased with WS, becoming more evident at dawn (Phase II), evening (Phase IV), and predawn the next day (Phase I), and occurred earlier in Phases IV and I under IWS. MWS did not reduce photosynthesis, demonstrating that the photosynthetic regulation could respond to short-term WS in pitaya and indicating the potential of watering for Pn recovery at evening and predawn under IWS. [ABSTRACT FROM AUTHOR]

Background and Aims Plant water status is important for fruit development, because many fleshy fruits contain large amounts of water. However, there is no information on vascular flows of Persea americana 'Hass' avocado. The aims of this research were to explore the impact of drought stress on the water relationships of the 'Hass' avocado plant and its fruit growth. Methods Well-watered and water-stressed 'Hass' avocado plants were compared. Over 4 weeks, water flows through the shoot and fruit pedicel were monitored using external sap flow gauges. Fruit diameter was monitored using linear transducers, and stomatal conductance (g s), photosynthesis (A) and leaf and stem water potentials (Ѱleaf and Ѱstem) were measured to assess the response of the plants to water supply. Key Results In well-watered conditions, the average water inflow to the shoot was 72 g day−1. Fruit water inflow was 2.72 g day−1, but there was water loss of 0.37 g day−1 caused by the outflow (loss back into the tree) through the vascular tissues and 1.06 g day−1 from the fruit skin. Overall, fruit volume increased by 1.4 cm3 day−1. In contrast, water flow into fruit of water-stressed plants decreased to 1.88 g day−1, with the outflow increasing to 0.61 g day−1. As a result, increases in fruit volume were reduced to 0.4 cm3 day−1. The values of A , g s and sap flow to shoots were also reduced during drought conditions. Changes in the hourly time-courses of pedicel sap flow, fruit volume and stem water potential during drought suggest that the stomatal response prevented larger increases in outflow from the fruit. Following re-watering, a substantial recovery in growth rate was observed. Conclusions In summary, a reduction in growth of avocado fruit was observed with induced water deficit, but the isohydric stomatal behaviour of the leaves helped to minimize negative changes in water balance. Also, there was substantial recovery after re-watering, hence the short-term water stress did not decrease avocado fruit size. Negative impacts might appear if the drought treatment were prolonged. [ABSTRACT FROM AUTHOR]

The wet (rain, snow, fog, sleet, dew) and dry (transport of aerosol, particles and gases) deposition of acidic substance in environment results due to human, automobile, fossil fuel burning and industrial activities. Acid deposition is worldwide environmental degradation problems and in recent years these acidic materials are increasing at alarming scale in the environment both in developed and developing countries, including Pakistan. Some scientific literature survey reports suggest that plant growth and agriculture yield decrease due to consequence of acid rain. In addition, acid rain is found responsible for producing toxic effects on the morphological parameters of agricultural crop. The evidence collected from last more than fifty years showed the common significant effects of acid rain on seed germination percentage, seedling height, root hair and structure, alteration in leaf anatomy, size and area, stomatal structure, size, pollen germination, photosynthetic pigments and physiological changes in herbs, shrubs and trees. Still, little is known on the impact of acid rain on plant growth. This study was aimed to review the effects of acid mist on growth performances of some selected plant species. This review is contributed with the help of literature survey, research work published on the impact of acid rain on the plant growth.

There is currently a need for inexpensive, continuous, non-destructive water potential measurements at high temporal resolution (<1 min). We describe here the development and testing of an entirely open-source dendrometer that, when combined with periodic Scholander pressure chamber measurements, provides sub-minute resolution estimates of water potential when placed on tissues exhibiting little or no secondary growth (petioles, monocotyledon stems). The dendrometer can also be used to measure radial growth of stems and branches when placed on dicotyledon and gymnosperm species. The dendrometer can be interfaced directly with a computer in real time in the lab or greenhouse, or connected to a datalogger for long periods of use in the field on batteries. We tested this device on a herbaceous dicotyledon (Helianthus annuus) (petioles and stems) and a monocotyledon (Zea mays) species (stems) for 1 week during dehydration and re-watering treatments under laboratory conditions. We also demonstrated the ability of the device to record branch and trunk diameter variation of a woody dicotyledon (Rhus typhina) in the field. Under laboratory conditions, we compared our device (hereafter 'contact' dendrometer) with modified versions of another open-source dendrometer (the 'optical' dendrometer). Overall, contact and optical dendrometers were well aligned with one another, with Pearson correlation coefficients ranging from 0.77 to 0.97. Both dendrometer devices were well aligned with direct measurements of xylem water potential, with calibration curves exhibiting significant non-linearity, especially at water potentials near the point of incipient plasmolysis, with pseudo R 2 values (Efron) ranging from 0.89 to 0.99. Overall, both dendrometers were comparable and provided sufficient resolution to detect subtle differences in stem water potential (ca. 50 kPa) resulting from light-induced changes in transpiration, vapour pressure deficit and drying/wetting soils. All hardware designs, alternative configurations, software and build instructions for the contact dendrometers are provided. [ABSTRACT FROM AUTHOR]

Seed germination is among the most crucial and vulnerable stages in plant life cycles. Quercus marlipoensis is a critically endangered sclerophyllous oak. Only one population has ever been found worldwide in the tropical montane cloud forests of southeastern Yunnan, China, and it has shown difficulties with regeneration. However, its seed biological traits and key restrictive germination factors remain unknown. We investigate the impacts of scarification, temperature, and water potential on the seed germination of Q. marlipoensis. Results show that the seeds show typical epicotyl dormancy. The seed germination increased when removing part or all of the pericarp and part of the cotyledon (one-third and two-thirds). The seeds can germinate at 5 to 30 °C, but the highest T50 was achieved at 25 °C. When the water potential decreased from 0 to −1.0 MPa, the germination rate decreased but the germination time increased. Q. marlipoensis seeds are typically recalcitrant and highly sensitive to moisture loss, but the species can tolerate animal predation and low germination temperatures. The more frequent climatic extremes and droughts in the Indo-China region will severely degrade its natural habitats. Therefore, ex situ conservation to preserve its germplasm and introduce seedlings into a suitable habitat are essential for its conservation management. [ABSTRACT FROM AUTHOR]

Xylem transport is essential for the growth, development and survival of vascular plants. Bark wounding may increase the risk of xylem transport failure by tension-driven embolism. However, the consequences of bark wounding for xylem transport are poorly understood. Here, we examined the impacts of the bark wounding on embolism formation, leaf water potential and gas exchange in the terminal branches of two diffuse-porous tree species (Acer platanoides L. and Prunus avium L.). The effects of bark removal were examined on field-grown mature trees exposed to increased evaporative demands on a short-term and longer-term basis (6 h vs 6 days after bark wounding). Bark removal of 30% of branch circumference had a limited effect on the xylem hydraulic conductivity when embolized vessels were typically restricted to the last annual ring near the bark wound. Over the 6-day exposure, the non-conductive xylem area had significantly increased in the xylem tissue underneath the bark wound (from 22–29% to 51–52% of the last annual ring area in the bark wound zone), pointing to gradual yet relatively limited embolism spreading to deeper xylem layers over time. In both species, the bark removal tended to result in a small but non-significant increase in the percent loss of hydraulic conductivity compared with control intact branches 6 days after bark wounding (from 6 to 8–10% in both species). The bark wounding had no significant effects on midday leaf water potential, CO2 assimilation rates, stomatal conductance and water-use efficiency of the leaves of the current-year shoot, possibly due to limited impacts on xylem transport. The results of this study demonstrate that bark wounding induces limited but gradual embolism spreading. However, the impacts of bark wounding may not significantly limit water delivery to distal organs and leaf gas exchange at the scale of several days. [ABSTRACT FROM AUTHOR]

Objective / Background. The objective was to assess the biocontrol capacity of Bacillus sp. A8a in avocado (Persea americana) plants infected by Phytophthora cinnamomi. Materials and Methods. A greenhouse experiment was implemented with four treatments: 1) control plants; 2) plants infected with P. cinnamomi; 3) plants inoculated with Bacillus sp. A8a; 4) plants infected with P. cinnamomi and inoculated with Bacillus sp. A8a. We evaluated several morpho-physiological variables during the experiment, which lasted 25 days after infection (dai). Moreover, we analyzed tannin density in stems at 25 dai to determine the plant defense response against the disease. Results. Inoculation with strain A8a reduced wilting symptoms by 49 % at 25 dai, compared with non-inoculated plants. No differences were detected in morphophysiological variables between treatments. However, a greater tannin accumulation was registered in the xylem of infected plants, whilst plants inoculated with strain A8a displayed a larger tannin density in the cortex. Conclusion. Our results confirm the biocontrol activity of Bacillus sp. A8a in avocado plants and suggest that tannin differential accumulation in the cortex of plants inoculated with the bacteria may contribute to the enhanced tolerance of avocado plants against Phytophthora root rot. [ABSTRACT FROM AUTHOR]

Viscum schimperi is an evergreen hemiparasitic plant that can grow on stems and branches of several tree species. It penetrates the host tissues and forms a vascular bridge (haustorium) to withdraw the nutritive resources. Its relationships with hosts remain unknown. This study aimed to investigate the physiological and biochemical attributes of the host-hemiparasite association Acacia gerrardii-Viscum schimperi. The hemiparasite exhibited 2.4- and 3.0-fold lower photosynthetic activity and water use efficiency, and 1.2- and 4.1-fold higher transpiration rate and stomatal conductance. Equally, it displayed 4.9- and 2.6-fold greater water potential and osmotic potential, and in least 3.0 times more accumulated 39K, 85Rb and 51V, compared to the host. Nevertheless, it had no detrimental effect on photosynthetic activity, water status and multi-element accumulations in the host. Based on metabolome profiling, V. schimperi could use xanthurenic acid and propylparaben to acquire potassium from the host, and N-1-naphthylacetamide and N-Boc-hydroxylamine to weaken or kill the distal part of the infected branch and to receive the total xylem contents. In contrast, A. gerrardii could used N-acetylserotonin, arecoline, acetophenone and 6-methoxymellein to defend against V. schimperi infection. [ABSTRACT FROM AUTHOR]

Stomata are the key nodes linking photosynthesis and transpiration. By regulating the opening degree of stomata, plants successively achieve the balance between water loss and carbon dioxide acquisition. The dynamic behaviour of stomata is an important cornerstone of plant adaptability. Though there have been miscellaneous experimental results on stomata and their constituent cells, the guard cells and the subsidiary cells, current theory of stomata regulation is far from clear and unified. In this work, we develop an integrated model to describe the stomatal dynamics of seed plants based on existing experimental results. The model includes three parts: (1) a passive mechanical model of the stomatal aperture as a bivariate function of the guard‐cell turgor and the subsidiary‐cell turgor; (2) an active regulation model with a target ion‐content in guard cells as a function of their water potential; and (3) a dynamical model for the movement of potassium ions and water content. Our model has been used to reproduce abundant experimental phenomena semi‐quantitatively. With accurately measured parameters, our model can also be used to predict stomatal responses to changes of environmental conditions. Summary statement: A stomata model is developed based on existing experiments and reproduces important stomatal behaviour. The model takes into account passive mechanical interaction between guard cells and subsidiary cells, active movement of potassium ions, and water transport driven by water potential. [ABSTRACT FROM AUTHOR]

Plants develop a series of mechanisms under drought stress, involving changes in chemical, physiological, and electrical signals. Measurement of these signal changes could reflect the growth status of plants under adversity stress. Aim of this study was to investigate the changes in water potential, photosynthetic parameters (i.e., net photosynthesis rate, transpiration rate, stomatal conductance, and the concentration of inter-cellular CO 2), and electrical signals (peak-to-peak value, mean value, gravity frequency, power spectral entropy) of Rosa chinensis under drought stress. Analysing these parameters fills in the research need to have a comprehensive understanding of plants' responses to drought stress. The results show all parameters present an overall decreasing trend, except the concentration of inter-cellular CO 2 and peak-to-peak value. There is a slight recovery at the end of the drought treatment, indicating that plants are adapted to the new level of drought status. Besides, most of the electrical signals (mean value, gravity frequency, power spectrum entropy) and water potential first showed significant differences (P < 0.05) from the control, followed by photosynthetic parameters, and transpiration. This result, combined with the results on the correlation between these parameters, indicates that changes in electrical signals can reflect physiological processes in plants. Therefore, this study reveals that electrical signals could serve as an early and accurate indicator to reflect the growth status of plants under drought stress, which provides a theoretical basis for the water management of Rosa chinensis. • Electrical spectrum is studied to reveal the dynamic status of plants under drought. • Electrical signals can reflect photosynthetic parameters response to drought. • Electrical signals can serve as early indicators of plant drought stress. [ABSTRACT FROM AUTHOR]

Climate change is often associated with increasing vapour pressure deficit (VPD) and changes in soil moisture (SM). While atmospheric and soil drying often co‐occur, their differential effects on plant functioning and productivity remain uncertain. We investigated the divergent effects and underlying mechanisms of soil and atmospheric drought based on continuous, in situ measurements of branch gas exchange with automated chambers in a mature semiarid Aleppo pine forest. We investigated the response of control trees exposed to combined soil‒atmospheric drought (low SM, high VPD) during the rainless Mediterranean summer and that of trees experimentally unconstrained by soil dryness (high SM; using supplementary dry season water supply) but subjected to atmospheric drought (high VPD). During the seasonal dry period, branch conductance (gbr), transpiration rate (E) and net photosynthesis (Anet) decreased in low‐SM trees but greatly increased in high‐SM trees. The response of E and gbr to the massive rise in VPD (to 7 kPa) was negative in low‐SM trees and positive in high‐SM trees. These observations were consistent with predictions based on a simple plant hydraulic model showing the importance of plant water potential in the gbr and E response to VPD. These results demonstrate that avoiding drought on the supply side (SM) and relying on plant hydraulic regulation constrains the effects of atmospheric drought (VPD) as a stressor on canopy gas exchange in mature pine trees under field conditions. Summary statement: Under high evaporative demand conditions, mature Aleppo pine trees demonstrated increased transpiration and photosynthesis in response to supplementary irrigation. Stomatal conductance exhibited hypo‐sensitivity to increasing water demand (high vapour pressure deficit) but was sensitive to a decrease in water supply, expressed as soil water content or plant water potential. Our findings highlight that water supply, rather than water demand, is the primary limiting factor for transpiration in Aleppo pine trees. [ABSTRACT FROM AUTHOR]

Climate change has become one of the most complex challenges actually because of its impact on agrosystems (aggravated drought, salinity, etc.) and its subsequent risks on the global food security. Salinity stress (both soil salinity or saline irrigation water) is a significant threat to food security and agrosystems resilience. Selenium (Se) has been reported to mitigate abiotic stress effects, such as salinity, on various plant species. The purpose of the current study was to investigate the impact of an exogenous supply of Se on the alleviation of salinity stress in tomato plants cultivated in the field. For this purpose, a field experiment was conducted on the Firenze cultivar cultivated in the agricultural plot of the Regional Centre for Agricultural Research (CRRA), Sidi Bouzid, Tunisia (9°430′ E, 35°010′ N). Plant irrigation was made using underground water with adjusted salinity for moderate stress (MS, 50 mM NaCl) and severe stress (SS, 100 mM NaCl). Two levels of Se were applied to sprayed plants (0.5 mM, Se0.5 and 1 mM, Se1 in the form of Na2SO4), in addition to the non-sprayed plants (Se0). Plant growth, photosynthetic pigments, photosynthesis and gas exchange, osmotic and water potentials, relative osmolyte content (ROC) and ionic compartmentation were deeply analysed, and their interrelationships were established. Obtained results demonstrated the beneficial effect of exogenous Se application on alleviating salinity stress in tomato plants. Spraying plants with Se significantly increased photosynthetic pigment (particularly chlorophyll a and carotenoids), potassium (K+), and relative osmolyte content in shoots, improved photosynthesis (Pn), and increased osmotic potential (Ѱo, negatively), allowing the maintenance of adequate shoot hydration. The increased K+/Na+ ratio in shoots following Se application plays a key role in the overall plant metabolism under salinity by promoting K-dependent functions (stomates opening, etc.) and decreasing Na-dependent toxicity. The established correlations demonstrated the interdependence of plant growth and photosynthesis on shoot K+, Na+, ROC, K+/Na+ ratio, and Chl a. [ABSTRACT FROM AUTHOR]

Grapevine leaves contain abundant CaOx crystals located either within the mesophyll in the form of raphides, or in the bundle sheaths as druses. CaOx crystals function as internal carbon pools providing CO2 for a baseline level of photosynthesis, named "alarm photosynthesis", despite closed stomata; thus, preventing the photoinhibition and the oxidative risk due to carbon starvation under adverse conditions. Structural and functional leaf traits of acclimated grapevine plants (Vitis vinifera L. cv. Assyrtiko) were investigated in response to water availability, in order to evaluate the dynamic functionality of CaOx. Leaf water potential, leaf area, leaf mass per area, stomatal properties, gas exchange parameters and performance index (PI) were decreased in leaves of vines acclimated to water deficit in comparison to the leaves of well-irrigated vines, although the chlorophyll fluorescence parameters showed that the operational efficiency of the photosystem II (PSII) photochemistry (Fv/Fm) did not change, indicating that the photosynthetic apparatus was not subjected to water stress. During the afternoon, more than half of the morning's existing druses disappeared in the drought-acclimated leaves. Also, the raphides' area of the drought-acclimated leaves was reduced more than that of the well-watered leaves. The substantial decomposition of druses under water deficit conditions compared to that of the raphides may have important implications for the maintenance of their different though overlapping roles. According to the results, it seems likely that, under water deficit conditions, a mechanism of "alarm photosynthesis" provides an additional tolerance trait in the leaves of Vitis vinifera cv. Assyrtiko; hence, leaf structure relates to function. [ABSTRACT FROM AUTHOR]

Two formerly broadly distributed woody Atriplex species now occur as fragmented populations across a range of microhabitats in the San Joaquin Valley Desert, southern California. We hypothesized that A. lentiformis and A. polycarpa exhibit inter- and intra-specific differences in their leaf and stem structural and functional traits corresponding with differences in soil salinity and aridity. Water potential, xylem structure and function and leaf traits were compared between three populations of A. lentiformis and four populations of A. polycarpa. The two species significantly differed in their xylem traits, with A. lentiformis displaying lower xylem density, wider mean and maximum vessel diameters and higher hydraulic conductivity (K s). They also differed in their leaf traits, such that A. lentiformis had larger leaves with higher specific leaf area (SLA) than A. polycarpa. Significant intra-specific differences occurred among leaf traits (leaf area, SLA) in A. lentiformis populations. In contrast, populations varied in their stem xylem structural traits (mean vessel wall thickness, mean vessel diameter, maximum vessel length) among A. polycarpa populations. Many of these differences were associated with soil salinity in A. lentiformis , and with minimum seasonal water potential in A. polycarpa. Overall, both saltbush species showed high intra- and inter-specific trait variation. This could be a critical consideration in understanding the evolution of these native species and has important implications for their conservation and restoration. [ABSTRACT FROM AUTHOR]

In Spain, almost all pistachios are grown under water-stress conditions. Pistachio plants have sophisticated mechanisms to avoid or tolerate stress. It is known that the rootstock affects responses to water stress in the cultivar grafted onto it. The traditional belief is that Pistacia terebinthus L. is the rootstock best adapted to rainfed conditions. This study examined the effect of rootstock on stress traits, photosynthetic rate, transpiration, stomatal conductance, chlorophyll, polyphenol concentrations, and growth in plants of Pistacia vera L. cv. Kerman grafted onto P. terebinthus, P. atlantica, and UCB-1. These responses were classified into constituent traits and characteristics of the plant's adaptation to water stress. The latter was induced by adding PEG 6000 to the nutrient solution. Plants grafted onto P. terebinthus showed more constituent traits, while plants grafted onto UCB-1 showed a greater number of drought-responsive traits. Plants grafted onto P. atlantica showed similar adaptative traits to those observed in UCB-1 but lower values of transpiration and net photosynthesis. Although it is likely that plants grafted onto P. terebinthus survive longer under extreme drought conditions, under moderate stress conditions, their yield is probably lower than that of plants grafted onto UCB-1 under the same moderate stress conditions. [ABSTRACT FROM AUTHOR]

Instrumentation plays a key role in modern horticulture. Thus, the microtensiomenter, a new plant-based sensor that continuously monitors trunk water potential (Ψtrunk) can help in irrigation management decisions. To compare the response of the Ψtrunk with other continuous tree water status indicators such as the sap flow rate, the difference between canopy and air temperatures, or the variations of the trunk and fruit diameter, all the sensors were installed in 2022 in a commercial orchard of ‘Honeycrisp’ apple trees with M.9 rootstocks in Washinton State (USA). From the daily evolution of the Ψtrunk, five indicators were considered: predawn, midday, minimum, daily mean, and daily range (the difference between the daily maximum and minimum values). The daily range of Ψtrunk was the most linked to the maximum daily shrinkage (MDS; R2 = 0.42), the canopy-to-air temperature (Tc-Ta; R2 = 0.32), and the sap flow rate (SF; R2 = 0.30). On the other hand, the relative fruit growth rate (FRGR) was more related to the minimum Ψtrunk (R2 = 0.33) and the daily mean Ψtrunk (R2 = 0.32) than to the daily range of Ψtrunk. All indicators derived from Ψtrunk identified changes in tree water status after each irrigation event and had low coefficients of variation and high sensitivity. These results encourage Ψtrunk as a promising candidate for continuous monitoring of tree water status, however, more research is needed to better relate these measures with other widely studied plant-based indicators and identify good combinations of sensors and threshold values.

Many arid lands across the globe are experiencing more frequent and extreme droughts due to warmer temperatures resulting from climate change, less predictable precipitation patterns, and decreased soil moisture. Approximately 60-90% of household water is used for urban landscape irrigation in the western United States, necessitating the establishment of landscapes using drought-tolerant plants that conserve water. Shepherdia ×utahensis (hybrid buffaloberry) is a drought-tolerant plant with dense leaf trichomes (epidermal appendages) that may limit excessive water loss by transpiration. However, little is known about how S. ×utahensis regulates leaf heat balance when transpirational cooling is limited. The objective of this research was to investigate the effects of substrate water availability on plant growth and development and trichome density of S. ×utahensis. Ninety-six clonally propagated plants were grown using an automated irrigation system, and their substrate volumetric water contents were controlled at 0.05-0.40 m3·m-3 for 2 months. Results showed that water stress impaired plant growth and increased the proportion of visibly wilted leaves. Shepherdia ×utahensis acclimates to drought by reducing cell dehydration and canopy overheating, which may be accomplished through decreased stomatal conductance, smaller leaf development, leaf curling, increased leaf thickness, and greater root-to-shoot ratio. Leaf trichome density increased when stem water potential decreased, resulting in greater leaf reflectance of visible light. Cell and leaf expansion were restricted under water stress, and negative correlations were exhibited between epidermal cell size and trichome density. According to our results, plasticity in leaves and roots aids plants in tolerating abiotic stresses associated with drought. Acclimation of S. ×utahensis to water stress was associated with increased trichome density due to plasticity in cell size. Dense trichomes on leaves reflected more lights which appeared to facilitate leaf temperature regulation.

In semi‐arid regions where drought and wildfire events often co‐occur, such as in Southern California chaparral, relationships between plant hydration, drought‐ and fire‐adapted traits may explain landscape‐scale wildfire dynamics. To examine these patterns, fire scientists and plant physiologists quantify hydration in plants via mass‐based metrics of water content, including live fuel moisture, or pressure‐based metrics of physiological status, such as xylem water potential; however, relationships across these metrics, plant traits and flammability remain unresolved.To determine the impact of hydration on tissue‐level flammability (leaves and stems), we conducted laboratory dehydration tests across wet and dry seasons in which we simultaneously measured xylem water potential, live fuel moisture and flammability. We tested two widespread chaparral shrubs, Adenostoma fasciculatum and Ceanothus megacarpus.Live fuel moisture showed a threshold‐type relationship with tissue flammability (increased ignitability and combustibility at specific hydration levels) that aligned with drought‐response traits (turgor loss point) and fire behaviour (increased fire likelihood and spread) identified at the landscape scale. Water potential was the better predictor of flammability in linear statistical models.A. fasciculatum was more flammable than C. megacarpus, and both species were more flammable during the wet growing season, suggesting seasonal growth or drought‐related tissue characteristics other than moisture content, such as lignin or chemical content, are critical for determining flammability.Our results suggest a mechanism for landscape‐scale increases in flammability at specific levels of drought stress. Integration of drought‐related traits, such as the turgor loss point, might improve models of wildfire risk in drought‐ and fire‐prone systems. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

The cultivation of mango in Mediterranean-type climates is challenged by the depletion of freshwater. Polyploids are alternative genotypes with potential greater water use efficiency, but field evaluations of the anatomy and physiology of conspecific adult polyploid trees under water stress remain poorly explored. We combined field anatomical evaluations with measurements of leaf water potential (Ψl) and stomatal conductance (Gs) comparing one diploid and one autotetraploid tree per treatment with and without irrigation during dry summers (when fruits develop). Autotetraploid leaves displayed lower Ψl and Gs in both treatments, but the lack of irrigation only affected Gs. Foliar cells of the adaxial epidermis and the spongy mesophyll contained linear pectin epitopes, whereas branched pectins were localized in the abaxial epidermis, the chloroplast membrane, and the sieve tube elements of the phloem. Cell and fruit organ size was larger in autotetraploid than in diploid mango trees, but the sugar content in the fruits was similar between both cytotypes. Specific cell wall hygroscopic pectins correlate with more stable Ψl of autotetraploid leaves under soil water shortage, keeping lower Gs compared with diploids. These preliminary results point to diploids as more susceptible to water deficits than tetraploids. [ABSTRACT FROM AUTHOR]

Several Xylella fastidiosa subsp. fastidiosa (ST1) strains that cause Pierce's disease were isolated from grapevine in Spain. In this study, we applied an approach to assess PD susceptibility among 24 different well-known Vitis vinifera subsp. vinifera cultivars and five rootstocks belonging to different species of the genus Vitis. Both were commonly commercialized, representing about 75% of the cultivated area in Spain. This method incorporated disease severity, disease progression, and water potential from the stem xylem. The trials were carried out under field and greenhouse conditions. The virulence of the Xff strain XYL 2055/17 was significantly higher than that of strain XYL 2177/18. However, while this difference in strain virulence did not seem to modify the susceptibility profiles of the cultivars, disease severity could be climate dependent. This work established two significantly different groups of European cultivars of grapevine characterized by high and low susceptibility to Xff ST1: cultivars with high susceptibility, including reference cultivars such as Tempranillo and Tempranillo Blanco, and cultivars with high resistance, such as Hondarrabi Zuri and Cabernet Sauvignon. Cultivar susceptibility was independent of the rootstock on which they were grafted. No conclusive data were found regarding the potential of water loss as an early detection test prior to symptom onset. This study provides a framework with which to advance cultivar susceptibility studies under different environmental conditions. [ABSTRACT FROM AUTHOR]

Some chewing larvae are capable of inducing galls in the host vascular cylinder, e.g. Dasineura sp. (Cecidomyiidae) on Peumus boldus stems. Due to the medicinal and economic importance of P. boldus, the anatomical and functional implications of establishment of Dasineura sp. on P. boldus stems were investigated. We asked if establishment of Dasineura sp. in P. boldus stems induces abnormalities at the cellular and organizational level of the vascular system that increase during gall development in favour of the hydric status of the gall.Anatomical alterations induced in the stems during gall development were determined. Cytohistometric analyses in mature galls were compared to non‐galled stems, and water potential and leaf area of non‐galled stems were compared with galled stems.Dasineura sp. establishes in the vascular cambium, leading to delignification and rupture of xylem cells, inhibiting formation of phloem and perivascular sclerenchyma. Gall diameter increases together with larval feeding activity, producing a large larval chamber and numerous layers of nutritive tissue, vascular parenchyma, and sclerenchyma. These anatomical alterations do not affect the leaf area of galled stems but favour increased water flow towards these stems.The anatomical alterations induced by Dasineura sp. in P. boldus stems guarantee water and nutrient supply to the gall and larva. After the inducer exits stems, some host branches no longer have vascular connections with the plant body. [ABSTRACT FROM AUTHOR]

The sunflower (Helianthus annuus L.) is a commercially important cut flower requiring research into postharvest factors such as recutting, water uptake, stem number, cooling rate, and storage temperature to maximize vase life. Stems of 'Sunbright' sunflowers were either recut before or after a drying period up to 48 h. Water uptake, stem quality, and microbial counts were determined 4 days after rehydration. Water potential was determined on five corresponding leaves per treatment. The effects of stem number per vase were evaluated with either 1, 3, 5, or 10 stems. Effects of cooling rate were determined by temperatures of 5 ℃ for 3 days in the dark, 5 ℃ for 2 days in the dark preceded by 24 h at either 20 ℃ with light or 32 ℃ in a shaded area outdoors, or were maintained in a shaded area at 32 ℃ for 3 days. Hydration and storage temperature effects were determined by either transferring to a postharvest environment, 20 ℃ cooler for 2 h, immediate storage for 2 days at 5 ℃, or 3 days at 5 ℃ after recutting the basal stem. Allowing stems to dry up to 48 h reduced vase life by 2.3 days or less. Vase life was unaffected by harvesting into water or by the number of stems in a vase but was affected by temperature such that the longest vase life of 13.2 days occurred when stems were stored for 3 days at 5 ± 0.5 ℃ followed by postharvest evaluation at 20 ± 1 ℃. [ABSTRACT FROM AUTHOR]

In a context of climate change, deciphering signaling pathways driving plant adaptation to drought, changes in water availability, and salt is key. A crossing point of these plant stresses is their impact on plant water potential (Ψ), a composite physico-chemical variable reflecting the availability of water for biological processes such as plant growth and stomatal aperture. The Ψ of plant cells is mainly driven by their turgor and osmotic pressures. Here we investigated the effect of a variety of osmotic treatments on the roots of Arabidopsis plants grown in hydroponics. We used, among others, a permeating solute as a way to differentiate variations on turgor from variations in osmotic pressure. Measurement of cortical cell turgor pressure with a cell pressure probe allowed us to monitor the intensity of the treatments and thereby preserve the cortex from plasmolysis. Transcriptome analyses at an early time point (15 min) showed specific and quantitative transcriptomic responses to both osmotic and turgor pressure variations. Our results highlight how water-related biophysical parameters can shape the transcriptome of roots under stress and provide putative candidates to explore further the early perception of water stress in plants. [ABSTRACT FROM AUTHOR]

The irrigation of crops represents 70% of the world's water use. For crops grown in high-altitude tropical climates, due to the decrease in rainfall with increasing altitude, along with the effects of global warming, it is necessary to propose alternatives for sustainable fruit production with reduced water consumption. This study was carried out in Sesquilé, Colombia (South America), at an altitude of 2595 m a.s.l. for two successive years with pear trees, var. Triunfo de Viena. The objective of this work was to determine the effect of regulated deficit irrigation (RDI) on the absolute and relative growth rates of the equatorial diameter of the fruits, the fresh and dry weights, the number of fruits, the yield per tree and the water potential of the fruits. In 2014, during the rapid growth phase of the fruit, one group of plants was irrigated at 100% of the crop evapotranspiration (ETc) (control), another at 74% and a third group at 60%. In 2015, the three groups were irrigated at 100%, 48% and 27% of the ETc. The use of RDI did not significantly affect the growth of the fruits. This study showed that the 'Triunfo de Viena' pear tree not only has sufficient adaptive reserves, but also has good ecological plasticity under water stress conditions in high-altitude tropical climates. In cases where water is a limiting factor for pear tree production, RDI can obtain production rates similar to those of a regularly irrigated crop, as long as this technique is used and implemented in phenological states of low sensitivity to water stress without exceeding the tolerance limits of the plants to the stressor. [ABSTRACT FROM AUTHOR]

Droughts in a warming climate have become more common and more extreme, making understanding forest responses to water stress increasingly pressing. Analysis of water stress in trees has long focused on water potential in xylem and leaves, which influences stomatal closure and water flow through the soil-plant-atmosphere continuum. At the same time, changes of vegetation water content (VWC) are linked to a range of tree responses, including fluxes of water and carbon, mortality, flammability, and more. Unlike water potential, which requires demanding in situ measurements, VWC can be retrieved from remote sensing measurements, particularly at microwave frequencies using radar and radiometry. Here, we highlight key frontiers through which VWC has the potential to significantly increase our understanding of forest responses to water stress. To validate remote sensing observations of VWC at landscape scale and to better relate them to data assimilation model parameters, we introduce an ecosystem-scale analog of the pressure-volume curve, the non-linear relationship between average leaf or branch water potential and water content commonly used in plant hydraulics. The sources of variability in these ecosystem-scale pressure-volume curves and their relationship to forest response to water stress are discussed. We further show to what extent diel, seasonal, and decadal dynamics of VWC reflect variations in different processes relating the tree response to water stress. VWC can also be used for inferring belowground conditions-which are difficult to impossible to observe directly. Lastly, we discuss how a dedicated geostationary spaceborne observational system for VWC, when combined with existing datasets, can capture diel and seasonal water dynamics to advance the science and applications of global forest vulnerability to future droughts.

Rain cracking (hereinafter referred to as macrocracking) severely impacts the production of sweet cherry (Prunus avium). Calcium (Ca) sprays can reduce macrocracking, but the reported responses to Ca sprays are variable and inconsistent. The objective of this study was to establish the physiological mechanism through which Ca reduces macrocracking in sweet cherry fruit. Six spray applications of 50 mM CaCl2 had no effect on macrocracking (assessed using a standardized immersion assay) despite a 28% increase in the Ca-to-dry mass ratio. Similarly, during another experiment, there was no effect of up to nine Ca sprays on macrocracking, although the Ca-to-dry mass ratio increased as the number of applications increased. In contrast, CaCl2 spray applications during simulated rain (in a fog chamber) significantly reduced the proportion of macrocracked fruit. Additionally, immersion of fruit in CaCl2 decreased macrocracking in a concentration-dependent manner. Monitoring macrocrack extension using image analysis revealed that the rate of macrocrack extension decreased markedly as the CaCl2 concentration increased. This effect was significant at concentrations as low as 1 mM CaCl2. Decreased anthocyanin leakage, decreased epidermal cell wall swelling, and increased fruit skin stiffness and fracture force contributed to the decrease in macrocracking. There was no effect of CaCl2 on the cuticle deposition rate. Our results demonstrated that Ca decreased macrocracking when applied to a wet fruit surface either by spraying on wet fruit or by incubation in solutions containing CaCl2. Under these circumstances, Ca had direct access to the cell wall of an extending macrocrack. The mode of action of Ca in reducing macrocracking is primarily decreasing the rate of crack extension at the tip of a macrocrack.

The classification of species as iso- or anisohydric has been widely used to assess their behavior under drought conditions. This behavior depends on the water use strategy adopted in terms of their position along a continuum, where isohydry and anisohydry represent the two extremes. This study was conducted in an experimental vineyard during the summer months of 2021 and 2022. Pre-dawn (Ψpd) and stem (Ψst) water potentials, stomatal conductance (gs), and leaf-to-air vapor pressure deficit (VPDL) measurements were performed on 24 grapevine varieties according to successive soil hydration–drying cycles. The following three metrics were used to assess their behavior during drought: slope σ-Ψpd, hydroscape, and conductance surface (CS). The CS is a new metric that we developed and used in this study for the first time. The results revealed that the categorization of some varieties varied depending on the metric used. Considering the set of parameters of all metrics, the varieties were classified into three groups. Two of the groups included varieties whose behavior seemed to conform to the iso- and anisohydric patterns, respectively, while a third group consisted of varieties that exhibited a mixed iso-anisohydric behavior. This last group was the most interesting due to its high ability to optimize the water use. Our findings suggest that the iso/anisohydry concept alone is, in most cases, insufficient for explaining grapevine water use behavior. Furthermore, this is the first study reporting knowledge on the water use behavior of 17 varieties, for which there are no previous studies related to this subject matter.

Tomato is a demanding crop in terms of handling, mainly because irrigation has a strong influence on fruit production and quality. Salinity changes the absorption, transport, assimilation, and distribution of nutrients in the plant. In general, such effects are analyzed using statistical tests. However, fuzzy models allow simulations between points that are not verified in agricultural experimentation. Currently, systems with artificial intelligence have excelled in the field of applied sciences, particularly fuzzy systems applied to mathematical modeling. The objective of this research was to use fuzzy modeling to analyze the biometric variables during the development of hybrid tomatoes under two different conditions: the first concerning different water tensions in the soil and the second concerning different salinity doses in irrigation. To this end, two models were developed based on an experiment carried out at São Paulo State University (UNESP), School of Agriculture, Botucatu, São Paulo State, Brazil. Both models sought to estimate the values of biometric variables of the tomato crop. Thus, two models were developed: Model 1 regarded water tensions and days after sowing (DAS), while Model 2 featured salinity and DAS. Fuzzy models provided results that verified the effects of irrigation and salinity layers. Two Fuzzy Rule-Based Systems (FRBS), an input processor with two variables, a set of linguistic rules defined from statistical procedures with percentiles, the Mamdani fuzzy inference method, and the center of gravity method to defuzzification were elaborated for this purpose. The range between −25 and −10 kPa (for Model 1) and between 0.08 and 3 dS m−1 (for Model 2) provided the development within the ideal parameters for the complete development of the plant cycle. The use of fuzzy logic has shown effectiveness in evaluating the development of tomato crops, thus showing potential for use in agricultural sciences. Moreover, the created fuzzy models showed the same characteristics of the experiment, allowing their use as an automatic technique to estimate ideal parameters for the complete development of the plant cycle. The development of applications (software) that provide the results generated by the artificial intelligence models of the present study is the aim of future research.

Seed germination is a complex physiological process influenced by abiotic stresses such as drought, temperature, salinity along with other biological and physical means. Halothermal time model (HaloTT) permitted quantitative assessment of seed germination at different water potential (ψ) and temperature (T). The present study aimed to evaluate the reliability of HaloTT model and to find cardinal temperature values for seed germination of Oats under various Ts and ψs. Avena sativa L. Var. Swan seeds were incubated at seven constant Ts under five various ψs prepared through sodium chloride (NaCl) at Plant Physiology Lab., University of Peshawar, Pakistan. The cardinal Ts measured through HaloTT model for Oats seed germination were 10, 30 and 40 °C for the base (Tb), optimum (To) and ceiling (Tc) temperatures correspondingly in distilled water (0 MPa). The maximum halotime constant (θHalo) was recorded as 48 MPa °Ch−1 at 30 °C in distilled water (0 MPa). The highest value of halotime and thermal time of germination rate was observed at -2.0 MPa at 40 °C. Germination percentage (GP), germination rate index (GRI), germination energy (GE), coefficient of velocity of germination (CVG), timson germination index (TGI), mean germination rate (MGR) and coefficient of variation of germination time (CVt) was observed maximum in 0 MPa at 30 °C, while minimum in -2.0 MPa at 40 °C. Contrarily the high rate of mean germination time (MGT) and time to 50 % germination (T50 %) was reported in -2.0 MPa and -1.5 MPa at 10 and 40 °C, while in distilled water (0 MPa) is lowest at 25 and 30 °C. Thus, we concluded that HaloTT model precisely interpret germination responses to various ψs across different Ts and may be used as an accurate and simple method to predict germination parameters under natural field conditions.

In this paper, we propose a novel approach for analyzing the effects of water regime on grapevine canopy status using robotics as an aid for monitoring and mapping. Data from an unmanned aerial vehicle (UAV) and a ground mobile robot are used to obtain multispectral images and multiple vegetation indexes, and the 3D reconstruction of the canopy, respectively. Unlike previous works, sixty vegetation indexes are computed precisely by using the projected area of the vineyard point cloud as a mask. Extensive experimental tests on repeated plots of Pinot gris vines show that the GDVI, PVI, and TGI vegetation indexes are positively correlated with the water potential: GDVI (R2=0.90 and 0.57 for the stem and pre-dawn water potential, respectively), PVI (R2=0.90 and 0.57), TGI (R2=0.87 and 0.77). Furthermore, the canopy volume and the canopy area projected on the ground are impacted by the water status, as well as stem and pre-dawn water potential measurements. The results obtained in this work demonstrate the feasibility of the proposed approach and the potential of robotic technologies, supporting precision viticulture.

This study investigated the relationship between water potential (Ψ) and the cation-induced inhibition of methane production in anaerobic digesters. The Ψ around methanogens was manipulated using polyethylene glycol (PEG) in a batch anaerobic reactor, ranging from −0.92 to −5.10 MPa. The ultimate methane potential (Bu) decreased significantly from 0.293 to 0.002 Nm3 kg−1-VSadded as Ψ decreased. When Ψ lowered from −0.92 MPa to −1.48 MPa, the community distribution of acetoclastic Methanosarcina decreased from 59.62% to 40.44%, while those of hydrogenotrophic Methanoculleus and Methanobacterium increased from 17.70% and 1.30% to 36.30% and 18.07%, respectively. These results mirrored changes observed in methanogenic communities affected by cation inhibition with KCl. Our findings strongly indicate that the inhibitory effect of cations on methane production may stem more from the water stress induced by cations than from their direct toxic effects. This study highlights the importance of considering Ψ dynamics in understanding cation-mediated inhibition in anaerobic digesters, providing insights into optimizing microbial processes for enhanced methane production from organic substrates.

Modeling plants for biomass production and metal uptake from surrounding environment is strongly dependent on the moisture content of soil. Therefore, experiments were conducted to find out how soil moisture affects the phenotypic traits, photosynthetic efficiency, metabolic profile, and metal accumulation in the hyperaccumulating ecotype of Sedum alfredii (S. alfredii). A total of six water potential gradients were set: 0 ~ −15 kPa (T1), −15 ~ −30 kPa (T2), −30 ~ −45 kPa (T3), −45 ~ −60 kPa (T4), −60 ~ −75 kPa (T5), and −75 ~ −90 kPa (T6). Different water potential treatments had a significant effect on plant growth and metal uptake efficiency. Compared to T3, T2 was more effective in promoting plant growth and development, with an increase in biomass of 23% and 17% in both fresh weight (FW) and dry weight (DW), respectively. T2 and T3 had the highest cadmium (Cd) content in the shoot (280.2 mg/kg) and (283.3 mg/kg), respectively, whereas T1 had the lowest values (204.7 mg/kg). Cd availability for plants in the soil was affected by moving soil moisture cycles. Changes in soil moisture that were either too high or too low compared to the ideal soil water content for S. alfredii growth resulted in a significant reduction in Cd accumulation in shoots. Tryptophan, phenylalanine, and other amino acids were accumulated in T5, whereas only tryptophan and phenylalanine slightly increased in T1. Sugars and alcohols such as sucrose, trehalose, mannitol, galactinol, and mannobiose increased in T5, while they decreased significantly in T1. Interestingly, in contrast to T1, the two impaired metabolic pathways in T5 (galactose and starch metabolism) were identified to be glucose metabolic pathways. These findings provide scientific information (based on experiments) to improve biomass production and metal uptake efficiency in hyperaccumulating ecotype of S. alfredii for phytoremediation-contaminated agricultural fields. [ABSTRACT FROM AUTHOR]

The establishment of Artemisia tridentata, a keystone species of the sagebrush steppe, is often limited by summer drought. Symbioses with arbuscular mycorrhizal fungi (AMF) can help plants to cope with drought. We investigated this possible effect on A. tridentata seedlings inoculated with native AMF and exposed to drought in greenhouse and field settings. In greenhouse experiments, AMF colonization increased intrinsic water use efficiency under water stress and delayed the decrease in photosynthesis caused by drought, or this decrease occurred at a lower soil water content. In the field, we evaluated the effect of AMF inoculation on colonization, leaf water potential, survival, and inflorescence development. Inoculation increased AMF colonization, and the seedlings experienced water stress, as evidenced by water potentials between −2 and −4 MPa and reduced stomatal conductance. However, survival remained high, and no differences in water potentials or survival occurred between treatments. Only the percentage of plants with inflorescence was higher in inoculated than non-inoculated seedlings. Overall, the greenhouse results support that AMF colonization enhances drought tolerance in A. tridentata seedlings. Yet, the significance of these results in increasing survival in nature remains to be tested under more severe drought than the plants experienced in our field experiment. [ABSTRACT FROM AUTHOR]