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In‐depth understanding of the shifting of water status during dehydration is crucial for obtaining better quality of dried food. In this work, we report a nondestructive method to measure the water status in hot‐air dried mushroom via multispectral imaging (MSI) technology combined with chemometric methods. The low‐field nuclear magnetic resonance (LF‐NMR) measurements were performed as reference. During drying process, the moisture content changed dramatically with notable migration and conversion of different water phases. Partial least squares (PLS), back propagation neural network (BPNN), and least squares‐support vector machine (LS‐SVM) models were applied to develop quantitative models. Among all, BPNN model showed considerably better performance of prediction with coefficient of determination R2c = 0.9829, R2p = 0.9639. The results demonstrated that MSI technology combined with chemometric methods is an impressive approach for determination of the water status in hot‐air dried mushrooms, which would facilitate infield of food processing by providing applicable and appropriate platform. Practical Application: Experimental investigation of different water status during food processing. Assessment of the potential of multispectral imaging to predict water status. Usage of novel measurement method for food processors. [ABSTRACT FROM AUTHOR]

BACKGROUND: Water absorption is the dominant factor affecting the quality deterioration of dried Lentinus edodes. We therefore analyzed the effect of moisture content and dynamic water status on physical properties of the mushroom stored at water activity (aw), 0.33, 0.43, 0.67, 0.76, and 0.84 for 50 days. Moisture mobility and water status were analyzed using low‐field nuclear magnetic resonance, while hardness and microstructure were determined as texture characteristics. Meanwhile, an electronic nose and headspace solid‐phase micro‐extraction combined with gas chromatography–mass spectrometry (HS–SPME–GC–MS) were used to analyze the flavor properties of dried L. edodes. RESULTS: The results showed that bound water was the dominant water status in dried L. edodes. The content and molecular mobility of bound water increased at aw = 0.67, 0.76, and 0.84. This contributed to discoloration, hardness loss, and microstructure sparsity of dried L. edodes. The increasing content and molecular mobility of bound water aggravated the deterioration of characteristic flavor by reducing acid, aldehyde, and ketone content. CONCLUSION: Unlike immobilized or free water, bound water had a critical influence on the quality deterioration of dried L. edodes during storage. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The experiments of contact ultrasound intensified heat pump drying (CUHPD) of kiwifruit slices were conducted to investigate the effect of ultrasonic power on dehydration process and water migration of kiwifruit during CUHPD. The results clarified that contact ultrasound (CU) application could reduce the drying time of HPD significantly, and the rise of ultrasonic power had stronger reinforcing effect on dehydration rate. Weibull distribution function could simulate the dehydration process of CUHPD of kiwifruit with high precision, and the β values verified that ultrasonic power improvement could transform the moisture diffusion mechanism of CUHPD from total internal moisture diffusion control to partial internal moisture diffusion control. The Dcal values were 2.304 × 10−9~4.026 × 10−9 m2/s and increased as the rise of ultrasonic power. The scanning electron microscopy results illustrated that increasing ultrasonic power could produce more porous and spacious microstructure which was beneficial for water migration. The low-field nuclear magnetic resonance results elucidated that free water, immobilized water, and bound water in kiwifruit migrated and changed during CUHPD. Free water with the highest mobility was the most abundant water in kiwifruit, and was the first kind of water to be completely removed. With drying progressed, the contents of immobilized water and bound water gradually increased and then decreased, but they were not completely removed. The increasing in ultrasonic power was beneficial to promoting internal water migration and shortening the required dehydration time, especially for free water. Proton density images visualized that increasing ultrasonic power could significantly promote the water diffusion from internal kiwifruit outward the surface, and thereby accelerate the rate of water removal. Therefore, CU application is a suitable method to accelerate the water diffusion and moisture migration of HPD process. [ABSTRACT FROM AUTHOR]

• Leaf turgor pressure varied significantly in the azimuthal, vertical, and radial apple canopies under drip irrigation. • Water potential, leaf thickness, and solar radiation affected the variation in canopy leaf turgor. • MaxP p was optimal for soil moisture monitoring based on the XGBoost model. • The LPCP probe should be installed in the middle position of the east canopy's central layer for apple trees. Leaf turgor pressure is a relevant metric for determining plant water content. To diagnose an apple tree water shortage, it is critical to precisely establish the features of leaf turgor pressure change in the canopy. In the current study, we continually monitored the leaf turgor pressure parameter (P p) at different azimuthal, vertical, and radial locations of the apple canopy based on leaf patch clamp pressure (LPCP) probes. The results demonstrated that the P p curves on sunny and rainy days were significantly different. A peak occurred on sunny days, during which the turgor pressure remained constant around midday. Under full irrigation, there was a greater change rate and daily maximum of P p (maxP p) at the east (azimuthal), upper layer (vertical), and distal (radial) positions. While leaf turgor pressure dramatically decreased with incomplete watering, maxP p significantly increased at the central and lower layers of the east canopy, as well as on the proximal and middle of the radial parts. This spatial heterogeneity in canopy leaf turgor pressure was related to the soil water potential, midday leaf water potential, sponge tissue thickness, and canopy solar radiation. Then, the ideal drought stress indicator parameter (maxP p) and canopy turgor monitoring leaf location (the middle position of the eastern canopy central layer's radial branch) were determined by multiparameter assessment. The findings presented above serve as a theoretical foundation for the construction of an intelligent irrigation system based on apple tree water status monitoring. [ABSTRACT FROM AUTHOR]

Water loss poses a threat to the life of postharvest mushrooms. Clarifying the variation of water status in mushrooms and seeking an effective approach to postpone the water loss is of utmost urgency. This study assessed the application of electron-beam generated X-ray (EBGX) irradiation as a novel physical technology to maintain the postharvest storage quality of fresh Hericium erinaceus. Furthermore, the monitoring of changes in water distribution and migration as well as the tissue structure were conducted on irradiated (1.0, 1.5, and 2.0 kGy) samples using low-field nuclear magnetic resonance, magnetic resonance imaging, scanning electron microscopy, and transmission electron microscopy, respectively. Results indicated that the cell compartments of cytoplasm and vacuole constituted the predominant parts among the three water components in H. erinaceus matrix, whereas the water in the vacuole migrated to the cytoplasm after storage. Thereinto, the mushrooms irradiated with 1.0 kGy retarded water migration and contained more water components than those irradiated with 0, 1.5, and 2.0 kGy. Importantly, the dose of 1.0 kGy irradiation had a minimum weight loss of 2.19% and the best retention of color and texture after 9 d of storage. Additionally, low-dose irradiation with 1.0 kGy and 1.5 kGy remarkably improved the physical microstructure of H. erinaceus , while 2.0 kGy irradiation was prejudicial to the tissue structure. Taken together, the dose of 1.0 kGy was the most beneficial in maintaining postharvest quality of H. erinaceus. These findings provide insights into the changes in water status of H. erinaceus and the effects of EBGX irradiation on postharvest quality and deepen our understanding of the underlying mechanism whereby EBGX improves the freshness of H. erinaceus. [Display omitted] • E-beam generated X-ray irradiation maintained Hericium erinaceus postharvest quality. • kGy irradiation effectively retarded water loss and migration of fresh mushrooms. • kGy irradiation exhibited a minimum weight loss of 2.19% at the end of storage. • kGy irradiation has a positive impact on preserving the color and texture during storage. • Physical microstructure was improved by irradiation with doses of 1.0 and 1.5 kGy. [ABSTRACT FROM AUTHOR]

Because its impact in plant development and growth and its interaction with Na+ and Cl−, the supply of different N-forms to crops can be an easy-to-use tool with effective results on salinity tolerance. Here the effect of four N–NO 3 -/N–NH 4 + ratios (mM; 2/0, 1.6/0.4, 0.4/1.6, 0/2) on adaptation to salt conditions (15 mM NaCl in a first experiment and 40 mM NaCl in a second experiment) was studied in young lettuce (cv "Summer wonder") plants. The experiments were carried out in greenhouse and under hydroponics conditions. The results show that this cultivar tolerates and adapts to moderate salinity by deploying several structural and physiological mechanisms; (i) increasing allocation of biomass to the root, (ii) increasing root Na+ uptake and storing it in the shoot and root tissues, (iii) increasing intrinsic water use efficiency and (iv) increasing root N and P uptake. The beneficial effect of salt exposure on growth was greater when the predominant N-form was N–NO 3 -. These plants with higher tissue N–NO 3 - concentration, decreased Cl− uptake and shoot and root Cl− concentration. Regardless of salt conditions, plants with a high proportion of N–NH 4 + (1.6 mM) and a low proportion of N–NO 3 - (0.4 mM) had a greater growth and nitrogen use efficiency, that was associated with the improved uptake of nutrients, and the maintenance of water status. [Display omitted] [ABSTRACT FROM AUTHOR]

This work attempts to identify which of two species with different levels of salinity tolerance, Salvia officinalis L. or Asteriscus maritimus L., is more suitable for irrigation with reclaimed wastewater, as well as the effect of the arbuscular mycorrhiza Glomus iranicum on the plant. The experiment was carried out in a growth chamber with a first phase, where both species were irrigated with good quality water, a second phase in which the plants were irrigated with reclaimed wastewater, and a third phase in which the plants were irrigated with good quality water again (recovery). Salinity caused a reduction in leaf water potential, stomatal conductance and net photosynthesis in both species. The percentage of mycorrhization was higher in Asteriscus than in Salvia, mitigating the decrease in leaf water potential. There was osmotic adjustment in Salvia, although the proline content increased in both species. The damages produced were clearer in Salvia, in which lipid peroxidation values were higher. Likewise, the visual appearance of the leaves showed symptoms of toxicity in this species, although the mycorrhizae diminished these effects. Irrigation with good quality water induced the recovery of lipid peroxidation in both species, as well as the appearance of new leaves in Salvia.

In a vineyard, grapevines are simultaneously exposed to combinations of several abiotic (drought, extreme temperatures, salinity) and biotic stresses (phytoplasmas, viruses, bacteria). With climate change, the incidences of drought in vine growing regions are increased and the host range of pathogens with increased chances of virulent strain development has expanded. Therefore, we studied the impact of the combination of abiotic (drought) and biotic (Grapevine fanleaf virus (GFLV) infection) stress on physiological and molecular responses on the grapevine of cv. Schioppettino by studying the influence of drought and GFLV infection on plant water status of grapevines, on grapevine xylem vessel occlusion, and on expression patterns of 9-cis-epoxycarotenoid dioxygenase 1 (NCED1), 9-cis-epoxycarotenoid dioxygenase 2 (NCED2), WRKY encoding transcription factor (WRKY54) and RD22-like protein (RD22) genes in grapevines. A complex response of grapevine to the combination of drought and GFLV infection was shown, including priming in the case of grapevine water status, net effect in the case of area of occluded vessels in xylem, and different types of interaction of both stresses in the case of expression of four abscisic acid-related genes. Our results showed that mild (but not severe) water stress can be better sustained by GFLV infection rather than by healthy vines. GFLV proved to improve the resilience of the plants to water stress, which is an important outcome to cope with the challenges of global warming.

Drought and flooding conditions are increasingly common abiotic factors that affect citrus crops in both the Mediterranean Basin and Florida. Furthermore, emerging diseases, such as Huanglongbing (HLB), are a potential risk for these crops in those producing areas. This study aimed to evaluate the behavior under water-stress treatments of three new citrus rootstocks (UFR-6, B11R5T60, and 2247 x 6070-02-2) with reported tolerance of HLB, comparing them with a common commercial citrus rootstock (Carrizo citrange). Four water conditions were established: Control, Medium Water Stress (MWS), Drought, and Flooding. Chlorophyll index (SPAD), growth in height, relative growth rate, biomass (fresh and dry weight) and plant water status were evaluated. Citru rootstock response were different for each genotype; Carrizo citrange was negatively affected by all water treatments in the chlorophyll index (SPAD) and biomass production. By contrast, UFR-6 showed a positive response in SPAD and growth under MWS and Drought, B11R5T60 displayed similar behavior to Control under all water stresses, and the response of 2247 x 6070-02-2 under MWS treatment was adequate but was not under Drought or Flooding conditions. Our study describes the behavior of these promising new citrus rootstocks against water stress; B11R5T60 exhibiting the best performance. These results can be useful for the citrus industry to address water-stress problems in these crops.

Measuring seasonal plant water status is critical in choosing appropriate management strategies to ensure yields and quality of agricultural products, particularly in a context of climate change. Water status of grapevines is known to be a key factor for yield, grape composition, and wine quality. Predawn leaf water potential (PLWP) and stem water potential (SWP) proved to be simple and precise indicators for assessing grapevine water status and subsequent same-day spatial comparisons. A drawback of SWP is that it does not allow for temporal comparisons, because the measured value is impacted both by soil water availability and climatic conditions on the day of measurement. The objectives of this study are i) to provide a model that separates the effect of soil water content from the effect of climatic conditions on the SWP value and ii) to standardize the SWP value to a value under predefined reference climatic conditions in order to compare SWP values collected under different climatic conditions. SWP and PLWP were temporally assessed on three soil types in Saint-Émilion (Bordeaux, France) in 2015 and on five soil types in Margaux (Bordeaux, France) in 2018 using a pressure chamber. SWP measurements on two consecutive days with contrasting climatic conditions allowed to assess the impact of these conditions on SWP values. A large portion of the variability in SWP values was explained by PLWP. Model selection further showed that the addition of maximum air temperature and seasonality explained a significant amount of the remaining variability in SWP values. SWP values could be successfully standardized to a theoretical value under reference climatic conditions, which allows for temporal comparisons of SWP values. A plant-based measurement, such as the water potential, can be considered as the most straightforward indicator of plant water status as it integrates the effects of soil, plant, and atmospheric conditions. More precise interpretation of SWP values provides winegrowers with a tool to more adequately implement short- and long-term management strategies to adapt to drought in order to ensure yield and grape quality.

Water shortage is a major problem that limits growth and productivity of plants in arid and semi-arid regions. Protecting plants from adverse environmental conditions by using simple methods could be of great value under these conditions. In the present study, we examined water status and drought tolerance of snap bean, a drought-sensitive plant, and Jerusalem artichoke, a relatively drought tolerant plant in response to the application of salicylic acid (SA). Different levels of SA were applied and several physiological, growth, productivity and quality parameters were recorded together with the relative water content. Foliar application of SA improved growth, productivity, quality as well as some physiological parameters of snap bean and Jerusalem artichoke plants exposed to drought stress. Total chlorophyll content and relative water content were higher in plants treated with SA compared to control plants when subjected to drought stress. The specific responses of snap bean and Jerusalem artichoke to SA under drought stress as well as the possible explanations of the effects of SA are discussed.

Soil salinization is one of the most serious abiotic stress factors affecting plant productivity through reduction of soil water potential, decreasing the absorptive capacity of the roots for water and nutrients. A weighted meta-analysis was conducted to study the effects of arbuscular mycorrhizal fungi (AMF) inoculation in alleviating salt stress in C3 and C4 plants. We analyzed the salt stress influence on seven independent variables such as chlorophyll, leaf area, photosynthetic rate (Amax), stomatal conductance (Gs), transpiration rate (E), relative water content (RWC), and water use efficiency (WUE) on AMF inoculated plants. Responses were compared between C3 and C4 plants, AMF species, plant functional groups, level of salinity, and environmental conditions. Our results showed that AMF inoculated plants had a positive impact on gas exchange and water status under salt stress. The total chlorophyll contents of C3 plants were higher than C4 plants. However, C3 plants responses regarding Gs, Amax, and E were more positive compared to C4 plants. The increase in Gs mainly maintained E and it explains the increase in Amax and increase in E. When the two major AMF species (Rhizophagus intraradices and Funnelliformis mosseae) were considered, the effect sizes of RWC and WUE in R. intraradices were lower than those in F. mosseae indicating that F. mosseae inoculated plants performed better under salt stress. In terms of C3 and C4 plant photosynthetic pathways, the effect size of C4 was lower than C3 plants indicating that AMF inoculation more effectively alleviated salt stress in C3 compared to C4 plants.

The aim of this work was to study the mechanism of climatic adaptation of red currant genotypes (Ribes rubrum L.) on the basis of physiological, biochemical and agrometeorological measurements and to determine the different phenophases of plant development identify adaptive genotypes for introduction. The studies were carried out in 2014–2017. The indicators of the water status of annual shoots (water content, water retention capacity), the biochemical composition of berries (vitamin C) and phenological observations were evaluated, taking into account meteorological data. The genotypes of R. petraeum Wulf. and R. multiflorum Kit. had the longest production period. Ambiguous data on the influence of temperature on the content of ascorbic acid in berries were revealed. High temperatures (>+26 °C) contributed to a greater accumulation of ascorbic acid in the cultivars of R. vulgare Lam. High accumulations of vitamin C in the range of +25–27 °C were found in R. petraeum Wulf. and R. multiflorum Kit.. High water content and water loss contributed to early recovery from the dormant state and reduced resistance to spring temperature changes in R. vulgare Lam. Genotypes of R. vulgare Lam., and R. multiflorum Kit. are promising for growing in a zone with a temperate continental climate. The genotypes of the species R. petraeum Wulf are suitable for introduction to the areas with a continental climate. The obtained results are important for adaptive gardening.

Spraying plants with exogenous substances have gained more attention due to its potential to reduce the negative impacts of heat and water stress in a climate‐changing environment. Therefore, the effects of spraying kaolin and Ascophyllum nodosum with and without irrigation on leaf gas exchange parameters, plant water status, electrolyte leakage, cuticular waxes, plant hormones and antioxidant enzymes, proline, malondialdehyde (MDA) content and lipid peroxidation of membranes of hazelnut trees were studied. Six different treatments with kaolin (K), A. nodosum (An), irrigation (I), kaolin with irrigation (Ki), A. nodosum with irrigation (Ani) and no irrigation (control) during two consecutive years (2016–2017) were applied in a hazelnut orchard of 'Grada de Viseu' cultivar located in Moimenta da Beira region, Northern Portugal. Results showed that K and An were effective for reducing hazelnut heat and drought stress by increasing the water relative content (RWC), net CO2 assimilation (A), water use efficiency (A/gs) and reducing the leaf mass per area (LMA), electrolyte leakage (EL). Moreover, concentration of ABA, MDA, proline and lipid peroxidation of membranes, as well the average content of antioxidant enzymes, was lower, suggesting that under K and An, plants have a better physiological performance than without these two exogenous substances. Nonetheless, these benefits only appear to be significant in the second year of the experiment showing that the use of both substances to mitigate climate change adverse effects should be considered as a long‐term strategy. [ABSTRACT FROM AUTHOR]

Drought and soil salinity are the main environmental stress factors affecting plant growth and development. A certain appropriate concentration of NaCl in the soil has been suggested to show a beneficial effect on halophyte and xerophyte growth, while drought could cause severe damage to plants. Thus, under drought conditions, whether the moderate soil salinity could still stimulate all plant growth and productivity is curious. In this study, three plants with different salt tolerance, including arrowleaf saltbush (Atriplex tr-iangularis Willd.), cotton (Gossypium hirsutum L.) and soybean [Glycine max (Linn.) Merr.], were sown in soils containing different concentrations of NaCl and exposed to drought and non-drought conditions for 30 days. The shoot biomass, water potential, osmotic potential, Na+ and K+ concentrations in seedlings were measured. Both drought and salt stress could inhibit the growth of arrowleaf saltbush, cotton and soybean, but the decreases in plant height and shoot biomass under drought conditions were attenuated with the increase of NaCl concentration. The Na+ concentration in the leaves subjected to combined drought and salt stresses was significantly higher than that in leaves subjected only to drought stress. Meanwhile, the osmotic potential of the leaves was significantly lower in the former than the latter, and the RWC and cell turgor pressure in the leaves were significantly higher in the former than the latter. Our results prove that the appropriate soil salinity could alleviate the detrimental effects of drought stress on the water status and plant growth, no matter they are salt-tolerant or salt-sensitive plants. [ABSTRACT FROM AUTHOR]

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Measuring seasonal plant water status is critical in choosing appropriate management strategies to ensure yields and quality of agricultural products, particularly in a context of climate change. Water status of grapevines is known to be a key factor for yield, grape composition, and wine quality. Predawn leaf water potential (PLWP) and stem water potential (SWP) proved to be simple and precise indicators for assessing grapevine water status and subsequent same-day spatial comparisons. A drawback of SWP is that it does not allow for temporal comparisons, because the measured value is impacted both by soil water availability and climatic conditions on the day of measurement. The objectives of this study are i) to provide a model that separates the effect of soil water content from the effect of climatic conditions on the SWP value and ii) to standardize the SWP value to a value under predefined reference climatic conditions in order to compare SWP values collected under different climatic conditions. SWP and PLWP were temporally assessed on three soil types in Saint-Émilion (Bordeaux, France) in 2015 and on five soil types in Margaux (Bordeaux, France) in 2018 using a pressure chamber. SWP measurements on two consecutive days with contrasting climatic conditions allowed to assess the impact of these conditions on SWP values. A large portion of the variability in SWP values was explained by PLWP. Model selection further showed that the addition of maximum air temperature and seasonality explained a significant amount of the remaining variability in SWP values. SWP values could be successfully standardized to a theoretical value under reference climatic conditions, which allows for temporal comparisons of SWP values. A plant-based measurement, such as the water potential, can be considered as the most straightforward indicator of plant water status as it integrates the effects of soil, plant, and atmospheric conditions. More precise interpretation of SWP values provides winegrowers with a tool to more adequately implement short- and long-term management strategies to adapt to drought in order to ensure yield and grape quality. [ABSTRACT FROM AUTHOR]

Environmental sustainability of viticulture is negatively affected by prolonged droughts. In limestone dominated regions, there is limited knowledge on grapevine water status and on methods for accurate evaluation of actual water demand, necessary to appropriately manage irrigation. During a dry vintage, we monitored plant and soil water relations in old and young vines of Istrian Malvasia on Karst red soil. The vineyard with young vines was additionally subdivided into two areas, based on their soil type, 1) karst silty-clay loam, and 2) mixture of crushed rocks and karst silty-clay loam (stony soil). Seasonal changes in exploited water resources were estimated via analysis of oxygen isotope composition (δ18O) of rainfall, deep soil water, and xylem sap. We hypothesized that plants are able to thrive during drought thanks to the water stored in deep soil layers, while they rely less on superficial soil horizons. Our results show that vines growing on karstic substrates have deep roots securing the use of stable water sources during summer, with consequent favourable plant water status. In fact, both young and mature vines approached the threshold of severe water stress, but never surpassed it, as midday leaf water potentials were >−1.3 MPa in all study sites. Vines roots showed flexible water uptake, i.e. the ability to absorb water from deep or shallow soil horizons during drought and after late-summer thunderstorms, which was particularly evident in vines growing on the stony soil. In fact, precipitations of 20 mm were enough for plant water status recovery, due to fast infiltration. On the other hand, at least 50 mm of rainfall were necessary to induce water status recovery in more compact soil (karst silty-clay loam). Our findings provide new knowledge on the rooting depth and water needs of vines growing on shallow soils overlying fractured limestone bedrock. Unlabelled Image • Vines' water requirements and sourcing on limestone soils are not well understood. • Deep roots ensured the uptake of stable water resources during summer drought. • Stony soil favoured fast water infiltration and its absorption by vines roots. • Roots of young vines were sufficiently developed four years after planting. • Pre-dawn water potential estimates accurately plants water needs in karstic areas. [ABSTRACT FROM AUTHOR]

The increasing demand for tree and forest health monitoring due to ongoing climate change requires new future-oriented and nondestructive measurement techniques. Electrical resistivity (ER) tomography represents a promising and innovative approach, as it allows insights into living trees based on ER levels and ER cross-sectional distribution patterns of stems. However, it is poorly understood how external factors, such as temperature, tree water status, and electrode installation affect ER tomograms. In this study, ER measurements were carried out on three angiosperms (Betula pendula , Fagus sylvatica , Populus nigra) and three conifers (Larix decidua , Picea abies , Pinus cembra) exposed to temperatures between −10 and 30°C and to continuous dehydration down to −6.3 MPa in a laboratory experiment. Additionally, effects of removal of peripheral tissues (periderm, phloem, cambium) and electrode installation were tested. Temperature changes above the freezing point did not affect ER distribution patterns but average ER levels, which increased exponentially and about 2.5-fold from 30 to 0°C in all species. In contrast, freezing of stems caused a pronounced raise of ER, especially in peripheral areas. With progressive tree dehydration, average ER increased in all species except in B. pendula , and measured resistivities in the peripheral stem areas of both angiosperms and conifers were clearly linearly related to the tree water status. Removal of the periderm resulted in a slight decrease of high ER peaks. Installation of electrodes for a short period of 32–72 h before conducting the tomography caused small distortions in tomograms. Distortions became serious after long-term installation for several months, while mean ER was only slightly affected. The present study confirms that ER tomography of tree stems is sensitive to temperature and water status. Results help to improve ER tomogram interpretation and suggest that ER analyses may be suitable to nondestructively determinate the hydraulic status of trees. They thus provide a solid basis for further technological developments to enable presymptomatic detection of physiological stress in standing trees. [ABSTRACT FROM AUTHOR]

Maintaining greater photosynthetic performance is important to improve drought resistance in soybean. However, photosynthetic response mechanisms to drought via the interaction between root and shoot remain to be clarified. Here, we investigated the roles of roots and shoots in photosynthetic responses to water stress. Grafted plants of drought-tolerant cultivar L14 and drought-sensitive cultivar L21 were grown in the pot-culture experiments. Some photosynthetic and physiological traits were measured after water-stress treatments during a podding stage. The L14 as rootstock showed a stronger growth vigor under water stress, leading to increases in some photosynthetic traits. Although the photosynthesis of L21 scion was improved by grafting onto L14 rootstock, it was still lower than that of L14 scion. This indicated that not only the greater water absorption capacity via roots but also the physiological property of leaves conferred a higher photosynthetic capacity and drought resistance in soybean. [ABSTRACT FROM AUTHOR]

• Mechanism of Al tolerance in Al-tolerant ET8 wheat is effective in dry soil. • Drought aggravates aluminum toxicity in Al-sensitive ES8 wheat. • Al in ES8 roots is increasing despite drought induced decrease in water. • ET8 had 3 times lower root Al than ES8 line at a similar water uptake from dry soil. In field conditions crops growth are usually under influence of many abiotic stresses that simultaneously affect their growth. Due to large areas of cultivated lands that are prone to anthropogenic or natural acidification and increasing frequency of drought events the exposure of crops to the simultaneous action of aluminum (Al) toxicity and water deficit is a serious threat decreasing food productivity. The effect of simultaneous soil drought and aluminum toxicity on wheat was studied to determine whether complex alteration within plants in response to drought affects the mechanism of Al tolerance in wheat. Al-tolerant (ET8) and Al-sensitive (ES8) wheat (Triticum aestivum L.) near isogenic lines (NILs) were grown in acid and limed soil under controlled laboratory conditions with precisely controlled water deficit. Although both NILs of contrasting resistivity to Al were characterized by similar root biomass in soil of pH 4.2, the tolerant line was characterized by 60% longer roots. This effect resulted from enhanced contribution of the thick root fractions in ES8. The NILs response to the drought in acid soil was characterized by the higher transpiration from ET8 than ES8 leaves irrespectively of leaf order and the effect was stronger with soil drying. The gap in the performance of both NILs in acid soil was increasing with the decrease in soil water potential. It was also shown that aluminum uptake through root surface area is increasing with the decrease in water uptake and the effect was most pronounced for sensitive line grown in acid soil. [ABSTRACT FROM AUTHOR]

To investigate the interactive effects of drought, heat and elevated atmospheric CO2 concentration ([CO2]) on plant water relations and grain yield in wheat, two wheat cultivars with different drought tolerance (Gladius and Paragon) were grown under ambient and elevated [CO2], and were exposed to post‐anthesis drought and heat stress. The stomatal conductance, plant water relation parameters, abscisic acid concentration in leaf and spike, and grain yield components were examined. Both stress treatments and elevated [CO2] reduced the stomatal conductance, which resulted in lower leaf relative water content and leaf water potential. Drought induced a significant increase in leaf and spike abscisic acid concentrations, while elevated [CO2] showed no effect. At maturity, post‐anthesis drought and heat stress significantly decreased the grain yield by 21.3%–65.2%, while elevated [CO2] increased the grain yield by 20.8% in wheat, which was due to the changes of grain number per spike and thousand grain weight. This study suggested that the responses of plant water status and grain yield to extreme climatic events (heat and drought) can be influenced by the atmospheric CO2 concentration. [ABSTRACT FROM AUTHOR]

Photosynthetic carbon (C) fixation and its partitioning in the plant-soil system are responsible for soil C sequestration and nutrient cycling. These microbially-mediated biogeochemical processess are impacted strongly by soil nutrient availability and soil moisture, which are being altered by global environmental change. We studied the interactive effects of fertilization (fertilized vs unfertilized) and water regime (high-water vs low-water level) on plant C fixation and rhizodeposition, and the subsequent microbial processing of plant-derived C substrates in mesocosms planted with the wetland sedge Carex acuta. We used a 13CO 2 pulse-labelling approach to track assimilates in plants, microbial phospholipid fatty acids (PLFA) and soils for 7 days. Fertilizer × water regime interactions affected the dynamics of root 13C efflux, microbial utilization and final 13C sequestration in the soil. Plants growing in high-water unfertilized soils rapidly exuded a greater proportion of 13C into the rhizosphere, but the temporal increase in soil 13C was lower than in the other treatments. In contrast, the greatest temporal increase in soil 13C was observed in high-water fertilized systems. This occurred because fertilized plants were more productive and fixed more C, which resulted in larger root biomass with faster turnover and consequently larger amounts of 13C immobilized in the high-water fertilized soils than high-water unfertilized soils. The composition of microbial communities processing the C rhizodeposits was dynamic during the 7 d study. Initially, the exuded 13C was processed mainly by bacteria, while fungal PLFA became progressively more enriched after 7 d. This indicates that fungi were the main recipients of C in rhizodeposits at this time, regardless of nutrient availability or soil water regime. In summary, fertilization of the C. acuta sedge wetland stimulated above- and belowground production and selected for a smaller but more active microbial community dominated by fungi. Fertilization enhanced soil C sequestration of recently fixed photosynthates in this wet sedge grassland. • Ecosystem C partitioning is affected by fertilization and soil water status. • Rhizodeposition responds to fluctuations in soil fertility and water levels. • Structure of the active microbial community is related to short-term C rhizodeposits. • Fungi are primary recipients of recent rhizodeposits regardless of soil water level. [ABSTRACT FROM AUTHOR]

• A collaborative approach was used to compare water potential measurement methods. • Time of the day (predawn, mid-morning and noon) and mode (stem vs. leaf) were compared. • Discrimination Ratio (DR) was used to determine the discrimination ability of each. • Leaf water potential was less discriminant than predawn or stem water potential at any time. Water potential is considered to be the "gold-standard" measure for plant water status determination. However, there are some discrepancies on how and at what time of the day water potential measurements should be performed in order to obtain meaningful information. The aim of this work is to evaluate the discrimination ability of water potential measurements in grapevines depending on the time of the day and of the measurement procedure (leaf vs. stem). To do so, a meta-analysis was performed using >78,000 measurements of water potential data obtained in field irrigation experiments, provided by 13 research teams working in this subject in Spain. For each measurement day and experiment, Discrimination Ratio (DR) was calculated and used to determine the discrimination ability of each method, and then pooled for comparison. The measurement procedure with the greatest DR can be hypothesised to be the most suitable under the average working conditions. Leaf water potential showed lower DR mean values than predawn or stem water potential. The climatic conditions and the cultivar may affect to the discrimination ability, although the abovementioned trend was always maintained. Leaf water potential in vineyards should therefore be replaced, as a general rule, by either stem or predawn water potential readings, without a clear pre-eminence of the performance of predawn and stem water potential measurements. Building a common dataset and its subsequent meta-analysis has been proved to be an efficient and robust tool to compare plant measurements, and should be implemented for other species and/or measurement procedures. [ABSTRACT FROM AUTHOR]

• Lutheria splendens and Aechmea aquilega are epiphytic tank bromeliad. • Leaf absorbing trichomes and roots have different functions in resource uptake in the two species. • The root system of L. splendens only plays a negligible role in resources uptake. • The root system of A. aquilega does contribute to water and nutrient uptake. The water and nutrient uptake mechanisms used by vascular epiphytes have been the subject of a few studies. While leaf absorbing trichomes (LATs) are the main organ involved in resource uptake by bromeliads, little attention has been paid to the absorbing role of epiphytic bromeliad roots. This study investigates the water and nutrient uptake capacity of LATs vs. roots in two epiphytic tank bromeliads Aechmea aquilega and Lutheria splendens. The tank and/or the roots of bromeliads were watered, or not watered at all, in different treatments. We show that LATs and roots have different functions in resource uptake in the two species, which we mainly attributed to dissimilarities in carbon acquisition and growth traits (e.g., photosynthesis, relative growth rate, non-structural carbohydrates, malate), to water relation traits (e.g., water and osmotic potentials, relative water content, hydrenchyma thickness) and nutrient uptake (e.g., 15N-labelling). While the roots of A. aquilega did contribute to water and nutrient uptake, the roots of L. splendens were less important than the role played by the LATs in resource uptake. We also provide evidenced for a synergistic effect of combined watering of tank and root in the Bromelioideae species. These results call for a more complex interpretation of LATs vs. roots in resource uptake in bromeliads. [ABSTRACT FROM AUTHOR]

This study was conducted to determine the effect of exogenous cyclitol (dl-cyclopentane-1,2,3-triol) on barley (Hordeum vulgare L.) during the alleviation of drought stress by using proteomics and physiological approaches. With the relative water content, water potential declined in barley depending on time under drought stress. This decline was lower in cyclitol-treated plants than in untreated plants. The stomatal pore width and open stoma number were higher in cyclitol-treated barley than in untreated plants under drought stress. The abscisic acid (ABA) and proline levels increased with the severity of drought in most treatments. The ABA level was lower in cyclitol-treated plants than in untreated plants under drought stress. Cyclitol treatments reduced O 2. − fluorescence in leaf cells under drought stress. Total differentially expressed proteins were identified in cyclitol treatment under stressful and unstressful conditions. Photosynthesis (approx. 49%) and energy metabolism (approx. 27%) were upregulated by cyclitol treatment under drought. Moreover, CML42, acting as a negative ABA regulator, also increased by cyclitol treatment. This increase may be important in controlling stomata movements under drought stress. Our results suggest that exogenous cyclitol enhances the drought tolerance of barley seedlings by modulating the photosynthesis, energy pathway, biosynthesis, and signal transduction. [ABSTRACT FROM AUTHOR]

Under drought and soil salinity, plants usually respond to accumulate inorganic and organic osmolytes for adaptation, that would induce changes in energy consumption strategy of plants. Moderate soil salinity would enable plants to lower energy consumption for osmotic adjustment by passively absorbing more Na+. This action would keep more energies for growth of drought-stressed plants. Thus, Na+ accumulation might be an energy-efficient strategy for plants to cope with drought was speculated. To support this speculation, we assessed the effects of soil salinity on osmotic adjustment and energy utilization under drought in this study. Our results indicated that the ratio and content of inorganic osmolytes was significantly higher under drought-saline stress (D + S) than those under single drought stress (D), while the osmolarity and contents of organic osmolytes of D + S were significantly lower than those of D. This indicated that moderate soil salinity could enable soybean seedlings to consume relatively lower energies to produce less organic osmolytes and accumulate more inorganic ions for osmotic adjustment coping with drought. Meanwhile the water content, cell turgor, ash content, and specific leaf area and biomass of D + S were significantly higher than those of D, but the leaf construction cost of D + S was significantly lower than those of D. This suggested that moderate soil salinity could enhance water retention, and reduce the photoassimilate and energy consumption of droughty soybean seedlings. This work would help to understand the positive effects of moderate soil salinity on plant growth on the level of osmotic adjustment and energy consumption strategy. • Salt-treated plants can lower energy consumption for osmotic adjustment under drought. • Moderate soil salinity can enhance water retention of soybean seedlings under drought. • Moderate soil salinity can reduce the cost of soybean seedlings coping with drought. [ABSTRACT FROM AUTHOR]

Highlights • Spatial extrapolation of localized grapevine water status measurements is studied. • An existing empirical approach (SPIDER) is analysed using a mechanistic model. • The empirical approach is validated by the mechanistic model. • New insights on the validity domain of spatial extrapolation are found. • This work strengthens the relevancy of SPIDER for precision viticulture application. Abstract This work is devoted to precision agriculture and more precisely to the spatial monitoring of water status in viticulture. An empirical approach was introduced in 2008 based on the extrapolation across a domain (vineyard block, vineyard, region) of vine water status observations from a reference site using a simple statistical model, called SPIDER, and proved efficient in many studies. Once the extrapolation model is calibrated, this approach leads to a concentration of measurements for one site only (reference site) while providing an estimate of the grapevine water status at a larger spatial scale. It is a promising hybrid approach based both on regular (but targeted) measurements and on modelling. However, so far only empirical guidelines for its practical use have been provided. Moreover, the limits of validity (spatial, temporal, etc.) of such an approach are not known. This work intends to use a mechanistic model based on grapevine water balance modelling to study to what extent a simulated water status can be spatially extrapolated at the field scale. The water balance model was calibrated on two datasets (different cultivars and weather data) and used to analyse the performances of SPIDER. The results confirmed the relevance of the empirical approach (SPIDER) based on water status spatial extrapolation with a low error level on the two datasets studied. The use of the water balance model also helped define the validity domain of SPIDER: it confirmed the importance of having dominantly dry conditions and revealed the possibility of recovering good prediction quality after strong rainfall or irrigation. This study globally demonstrates the relevance of spatial extrapolation of the vine water status from a reference site with a linear regression model and provides new insights on the properties of the predictions for application in viticulture either at the within-field level or at larger scale. [ABSTRACT FROM AUTHOR]

Soil salinization is one of the most serious abiotic stress factors affecting plant productivity through reduction of soil water potential, decreasing the absorptive capacity of the roots for water and nutrients. A weighted meta-analysis was conducted to study the effects of arbuscular mycorrhizal fungi (AMF) inoculation in alleviating salt stress in C3 and C4 plants. We analyzed the salt stress influence on seven independent variables such as chlorophyll, leaf area, photosynthetic rate (Amax), stomatal conductance (Gs), transpiration rate (E), relative water content (RWC), and water use efficiency (WUE) on AMF inoculated plants. Responses were compared between C3 and C4 plants, AMF species, plant functional groups, level of salinity, and environmental conditions. Our results showed that AMF inoculated plants had a positive impact on gas exchange and water status under salt stress. The total chlorophyll contents of C3 plants were higher than C4 plants. However, C3 plants responses regarding Gs, Amax , and E were more positive compared to C4 plants. The increase in G s mainly maintained E and it explains the increase in Amax and increase in E. When the two major AMF species (Rhizophagus intraradices and Funnelliformis mosseae) were considered, the effect sizes of RWC and WUE in R. intraradices were lower than those in F. mosseae indicating that F. mosseae inoculated plants performed better under salt stress. In terms of C3 and C4 plant photosynthetic pathways, the effect size of C4 was lower than C3 plants indicating that AMF inoculation more effectively alleviated salt stress in C3 compared to C4 plants. [ABSTRACT FROM AUTHOR]

Highlights • Girdling eliminates shoot-to-root ABA transport, altering plant physiology. • Girdling decreased stomatal conductance by increasing leaf xylem ABA concentration. • Girdling decreased root ABA concentration of well-watered plants. • Soil-drying induced root ABA accumulation requires shoot-to-root ABA transport. • Soil water content better explained variation in [ABA] than tissue water status. Abstract To understand the impact of shoot-to-root ABA transport on water potential of, and xylem ABA concentration in, different plant tissues during soil drying, soybean (Glycine max cv. Siverka) plants were subjected to drought and girdling in a factorial experiment. Girdling was achieved by surgically excising the phloem tissue from just above the cotyledonary node. After girdling and withholding water, ABA concentrations were determined in xylem saps extracted from individual leaves, detached shoots and de-topped roots, after measuring stomatal conductance (g s), tissue water potentials, and root ABA concentrations. Soil drying decreased water potential throughout the plant and approximately doubled xylem ABA concentrations, coinciding with stomatal closure. Girdling slightly enhanced water potential, especially in droughted plants. Girdling diminished the soil-drying induced increase in xylem sap ABA concentration, and completely prevented root tissue ABA accumulation. Furthermore, girdling decreased root ABA concentration and increased leaf xylem ABA concentration of well-watered (WW) plants. Stomatal conductance declined linearly with leaf water potential only in intact plants, while g s declined as leaf xylem ABA concentration increased, independently of girdling. Thus shoot to root ABA transport not only determines (soil-drying induced) root ABA accumulation, but also limits ABA accumulation in the shoot to maintain stomatal opening of WW plants. [ABSTRACT FROM AUTHOR]

Wine growing needs to adapt to confront climate change. In fact, the lack of water becomes more and more important in many regions. Whereas vineyards have been located in dry areas for decades, so they need special resilient varieties and/or a sufficient water supply at key development stages in case of severe drought. With climate change and the decrease of water availability, some vineyard regions face difficulties because of unsuitable variety, wrong vine management or due to the limited water access. Decision support tools are therefore required to optimize water use or to adapt agronomic practices. This study aimed at monitoring vine water status at a large scale with Sentinel-2 images. The goal was to provide a solution that would give spatialized and temporal information throughout the season on the water status of the vines. For this purpose, thirty six plots were monitored in total over three years (2018, 2019 and 2020). Vine water status was measured with stem water potential in field measurements from pea size to ripening stage. Simultaneously Sentinel-2 images were downloaded and processed to extract band reflectance values and compute vegetation indices. In our study, we tested five supervised regression machine learning algorithms to find possible relationships between stem water potential and data acquired from Sentinel-2 images (bands reflectance values and vegetation indices). Regression model using Red, NIR, Red-Edge and SWIR bands gave promising result to predict stem water potential (R2=0.40, RMSE=0.26).

Cadmium (Cd) contamination harms plant growth and human health. The application of hemin (ferroprotoporphyrin IX) can effectively relieve abiotic stresses in plants. This work investigates the effects of hemin on alleviating Cd toxicity and enhancing Cd tolerance in maize seedlings. In this study, maize seedlings were cultivated in nutrient solutions, with a combination of CdCl2 (464 μmol L−1) and hemin (100 μmol L−1). We measured plant growth status, water status, Cd concentration, and Cd distribution in maize seedlings. The results indicated that Cd stress increased Cd accumulation in plants and inhibited plant growth. However, hemin alleviated the growth inhibition and improved water balance, root morphology, and root vitality under Cd stress. Additionally, hemin increased 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), total phenolic content, and phenylalanine ammonia lyase (PAL) activity to enhance tolerance to Cd stress. Hemin reduced Cd concentration, the translocation factor (TF), and the bioconcentration factor (BCF) in maize seedlings under Cd stress. Furthermore, hemin increased Cd concentrations in the cell wall and the soluble fraction of seedling roots, which helped reduce Cd transport from root to shoot. In summary, exogenous hemin could be used for alleviating adverse impacts on maize seedling induced by Cd stress.

Halophytes are capable of coping with excessive NaCl in their tissues, although some species may differ in their degree of salt tolerance. In addition, it is not clear whether they can tolerate other confounding factors and impurities associated with non-conventional waters. The experiment was performed in a greenhouse with Crithmum maritimum and Atriplex halimus plants, growing on soil and irrigated with two different water types: reclaimed wastewater (RWW) (EC: 0.8–1.2 dS m−1) and reverse osmosis brine (ROB) (EC: 4.7–7.9 dS m−1). Both species showed different physiological and nutritional responses, when they were irrigated with ROB. Atriplex plants reduced leaf water potential and maintained leaf turgor as consequence of an osmotic adjustment process. Atriplex showed higher intrinsic water use efficiency than Crithmum, regardless of the type of water used. In Crithmum, the water status and photosynthetic efficiency were similar in both treatments. Crithmum presented a higher leaf accumulation of B and Ca ions, while Atriplex a higher amount of K, Mg, Na and Zn. Crithmum plants irrigated with ROB presented higher concentrations of 1-aminocyclopropane-1-carboxylic acid and trans-zeatin-glucoside, whereas abscisic acid concentration was lower. Atriplex showed a lower concentration of trans-zeatin-riboside and scopoletin. The characteristics associated to water irrigation did not influence negatively the development of any of these species, which confirms the use of brine as an alternative to irrigate them with conventional waters.

• The effects of summer pruning (elimination of suckers) on olive were evaluated. • In summer, it determined higher relative water content (RWC) and greater photosynthetic activity. • At harvest, it determined a higher fruit oil content on a dry-weight basis. • The extracted oil was less rich in phenolic compounds and was more herbaceous and fruitier, and less bitter and spicy. • Overall, the results indicate that summer pruning can have effects similar to irrigation. An investigation was carried out in 2017 in central Italy, in an adult olive orchard with trees of the cultivar Leccino, spaced 5 × 5 m, trained to a vase and pruned biennially. The aim was to evaluate the effects of summer pruning (i.e. eliminating suckers, in the central part of the canopy, in the non-pruning year), on the water status and physiology of the leaves, on the yield/tree, and on fruit characteristics and oil quality. Unpruned trees were used as the control. During the investigation (July-October), rainfall was low (less than 100 mm) and the orchard was not irrigated. During the summer, the leaves of summer-pruned trees had higher relative water content (RWC) and greater photosynthetic activity than those of control trees. Summer-pruned trees had similar yield, but higher oil content on a dry-weight basis. Oil qualitative parameters (free acidity, peroxide value and spectrophotometric absorbances in the ultra-violet) were similar, whereas the total content of phenolic compounds was higher in control trees. The oils from summer-pruned trees were more herbaceous and fruity, and less bitter and spicy than oils from control trees. The results show that in situations where there is considerable formation of suckers, such as in the case of biennial, triennial or plurennial pruning, summer pruning can contribute to improving tree water status and the physiological condition, favoring photosynthetic activity. This practice also has effects on fruit oil content and oil quality, producing more aromatic and less bitter and spicy oil. Overall, the results indicate that summer pruning can have effects similar to irrigation. [ABSTRACT FROM AUTHOR]

• This is the first study estimating the plant water content (PWC) in chrysanthemum using leaf-based hyperspectral reflectance. • The upper leaf layer is optimal for chrysanthemum PWC estimations. • The PLSR outperforms vegetation spectral indices for PWC estimations. • Hyperspectral remote sensing allows managers to have overview of chrysanthemum water status. Water plays an important role in the growth process of cut chrysanthemum (Chrysanthemum morifolium Ramat.). Accurate monitoring of plant water content (PWC) is a vital guarantee for the high-quality production of cut chrysanthemums. Hyperspectral remote sensing technology has been widely used in precision agriculture due to its rapid, convenient, and nondestructive advantages, but relatively little is known about its use for predicting the PWC of cut chrysanthemums. Therefore, this study aimed to evaluate the performance of hyperspectral reflectance from different leaf layers for estimating the PWC of cut chrysanthemums. A hyperspectral spectroradiometer was used to collect hyperspectral reflectance data (350-2500 nm) from three leaf layers at different critical growth periods. Immediately following the spectra measurements, cut chrysanthemum canopies were sampled for PWC. Spectral index and partial least square regression (PLSR) were then used to establish PWC estimation models of cut chrysanthemums. The results showed that the first leaf layer (LL 1) was the optimal leaf layer for estimating the PWC of cut chrysanthemum. The new proposed two-band spectral index, NDVI-LL 1 (R 2280 , R 1885), exhibited moderate prediction capability for PWC cut chrysanthemum (R2=0.54658, RMSE=0.02352). Moreover, compared with the spectral index model, the model using the PLSR-LL 1 showed the best performance for estimating the cut chrysanthemum PWC (R2=0.93510, RMSE=0.00887). Our results can provide technical support for spectral monitoring of PWC and precise irrigation in cut chrysanthemums. [ABSTRACT FROM AUTHOR]

To elucidate the mechanism behind the heterogeneity in the water distribution during the drying process of medicinal chrysanthemum (Imperial chrysanthemum), and thereby optimize the drying process, this study introduced an innovative approach by incorporating tempering into the drying process and evaluated the effects of hot air drying (HAD), infrared-assisted hot air drying (IR-HAD), and tempering-incorporated IR-HAD (TD+IR-HAD) on the water status, microstructure, and phytochemicals of dried chrysanthemums. Results showed a significant difference in the rate of dehydration between the central and marginal parts of chrysanthemums. The highest difference in moisture content value (1.34 g water/g dry matter) was observed between these two parts for samples subjected to 2.5 h of IR-HAD drying. Consequently, the sample subjected to 2.5 h of IR-HAD drying was selected for tempering. After the optimal tempering treatment (12 h), the samples were subjected to an additional 0.5 h of IR-HAD drying. This incorporated drying method (TD+IR-HAD) effectively reduced the drying time and energy consumption. Transverse relaxation curves and microstructural observations further confirmed that these reductions were related to the enhancement of water mobility and the formation of microchannels during tempering. As a result, chrysanthemums dried using TD+IR-HAD showed increased contents of chlorogenic acid, luteolin, total phenolic, total flavonoid, antioxidant capacity, and the number of volatile compounds compared to HAD and IR-HAD. Overall, these results highlight the potential of TD+IR-HAD as a promising drying technique for enhancing the value and applications of medicinal chrysanthemums in industrial settings. [Display omitted] • The water status and distribution in chrysanthemums were first investigated. • The central part of the chrysanthemum showed a lower dehydration rate. • Tempering enhanced water mobility and promoted water redistribution in samples. • The required drying time and energy consumption were reduced by tempering. • Tempering effectively preserved phytochemicals and volatiles in dried samples. [ABSTRACT FROM AUTHOR]

To better interpret summer maize stomatal conductance (gs) variation under conditions of changing water status at different growth stages, three water stress indicators, soil water content (SWC), leaf-air temperature difference (ΔT) and leaf level water stress index (CWSIL) were employed in Jarvis model, which were JS, JT and JC models respectively. Measurements of gs were conducted in a summer maize field experiment during the year 2012–2013. In the insufficient irrigation experiment, three levels of irrigation amount were applied at four different growth stages of summer maize. We constructed three scenarios to evaluate the performance of the three water stress indicators for estimating maize gs in a modified Jarvis model. Results showed that JT and JC models had better simulation accuracy than the JS model, especially at the late growth stage (Scenario 1) or considering the plant recovery compensation effects (Scenario 2). Scenario 3 indicated that the more environmental factors were adopted, the better prediction performance would be for JS model. While for JT model, two environmental factors (photosynthesis active radiation (PAR), and vapor pressure deficit (VPD)) seemed good enough to obtain a reliable simulation. When there were insufficient environmental data, CWSIL would be the best option. This study can be useful to understand the response of plant stomatal to changing water conditions and will further facilitate the application of the Jarvis model in various environments.

The aim of this study is to compare the water and photosynthetic characteristics of two xerophilic ecotypes of Atriplex halimus (L.). Seeds collected from two different sites Djelfa and Oran are germinated in controlled greenhouse. After 6 months, the plantlets were treated 21 days with increasing concentrations of abscisic acid (0M, 10-6 M and 10-3 M). The results show that ecotype of Djelfa reduced water loss through transpiration because of high stomatal resistance. Consequently the content of chlorophyll a and b decrease significantly compared to Oran ecotype which show an increase of the osmotic potential and relative water content. Osmotic adjustment to reduce dehydration and maintain a good photosynthesis seems efficient in Oran ecotype.

The main challenge encountered by Mediterranean winegrowers is water management. Indeed, with climate change, drought events are becoming more intense each year, dragging the yield down. Moreover, the quality of the vineyards is affected and the level of alcohol increases. Remote sensing data are a potential solution to measure water status in vineyards. However, important questions are still open such as which spectral, spatial, and temporal scales are adapted to achieve the latter. This study aims at using hyperspectral measurements to investigate the spectral scale adapted to measure their water status. The final objective is to find out whether it would be possible to monitor the vine water status with the spectral bands available in multispectral satellites such as Sentinel-2. Four Mediterranean vine plots with three grape varieties and different water status management systems are considered for the analysis. Results show the main significant domains related to vine water status (Short Wave Infrared, Near Infrared, and Red-Edge) and the best vegetation indices that combine these domains. These results give some promising perspectives to monitor vine water status.

The efficient use of water in the vineyard requires knowledge of the crop’s response to irrigation in terms of production and quality and the interaction of the same with the environmental conditions. In this work, the behavior of a trellis system vineyard in cv. Tempranillo, located in the south-west of Spain, was analyzed for three years in relation to different irrigation strategies based on crop evapotranspiration (ETc), and with two levels of crop load established by early cluster thinning. The response of the vineyard to the same irrigation strategy varied depending on the characteristics of the year. The vineyard’s biomass production increased in a linear trend as annual water status improved. However, during pre-veraison, the water status had a more significant impact on the harvest by affecting bud fertility. The increase in individual cluster weight only partially compensated the loss of yield caused by cluster thinning. The year’s characteristics highly conditioned the response to the irrigation treatment and, together with cluster thinning, modified the characteristics of the musts, although the response was varied.

Soil salinity has emerged as one of the most prominent threats to modern intensive farming systems, and it has necessitated the cultivation of halophytes to ensure food security and human nutrition. Peucedanum japonicum Thunb. is an edible wild plant with medicinal value that is widely distributed along the Pacific coast of western Japan. However, the adaptive mechanisms of this plant with respect to salt stress tolerance have not yet to be elucidated. The purpose of this study was to compare the physiological responses of P. japonicum to salt stress with those of barley (Hordeum vulgare), which is considered a salinity-tolerant plant. Seedlings of both species at the same height were exposed to different concentrations (0, 50, 75, and 150 mM) of NaCl for 16 days, after which the leaves were analyzed with respect to different physiological parameters. The results revealed a maintenance of leaf growth in P. japonicum compared with that in barley, the growth of which was severely impaired at low concentrations of NaCl (50 and 75 mM). In response to salt stress, a higher suppression of Na+ and Cl− assimilations was observed in P. japonicum than in barley under all NaCl treatments. Moreover, P. japonicum showed a greater ability to maintain leaf K+ and Ca2+ concentrations, whereas barley exhibited a significant reduction in the concentrations of these ions under saline conditions. Thus, the superior salinity tolerance of P. japonicum could be attributed to a more efficient maintenance of ionic balances. Taken together, our results indicate that P. japonicum may be classified as a halophyte, given its superior regulation of K+, Ca2+, SO4−, and sucrose concentrations and lower NO3− concentrations compared with those of barley.

Irrigation management continues to be an important issue for tomato cultivation, especially in plant factories. Accurate and timely assessment of tomato leaf water status is a key factor in enabling appropriate irrigation, which can save nutrition solution and labor. In recent decades, hyperspectral imaging has been widely used as a nondestructive measurement method in agriculture to obtain plant biological information. The objective of this research was to establish an approach to obtain the tomato leaf water status—specifically, the relative water content (WC) and equivalent water thickness (MC)—for five different tomato cultivars in real time by using hyperspectral imaging. The normalized difference vegetation index (NDVI) and two-band vegetation index (TBI) analyses were performed on the tomato leaf raw relative reflection (RAW), the inversion-logarithm relative reflection (LOG), and the first derivative of relative reflection (DIFF) from wavelengths of 900 nm to 1700 nm. The best regression model for WC assessment was obtained by TBI regression using DIFF at wavelengths of 1410 nm and 1520 nm, and the best regression model for MC assessment was obtained by NDVI regression using RAW at wavelengths of 1300 nm and 1310 nm. Higher model performance was obtained with MC assessment than with WC assessment. The results will help improve our understanding of the relationship between hyperspectral reflectance and leaf water status.

Exposure to solar radiation is a determining factor of grape composition. Flavonol synthesis is upregulated by solar radiation leaving a fingerprint on flavonol profile. This study aimed to test the factors affecting flavonol accumulation and profile and their potential as an indicator to assess the overall exposure of red wine grape berry to solar radiation. We performed three experiments to study the response of flavonol accumulation and profile to (1) three different solar radiation exclusion treatments during berry development; (2) canopy porosity and leaf area index (LAI); and (3) spatial variability of water status, vigor and ripening and cultural practices in commercial vineyards. Results showed a strong relationship between global radiation, inverse dormant pruning weights or canopy porosity (inversely proportional to LAI) and % kaempferol or % quercetin. Furthermore, the increase in concentration of the above two flavonols was associated with a reduction of % myricetin. Total flavonol content, % kaempferol, % quercetin, and % myricetin had significant correlations with inverse dormant pruning weights, but these were less sensitive to over-ripening or water deficits. Flavonol profile was associated to site hydrology (wetness index) through changes in vigor, and to LAI; and responded to shoot thinning or fruit-zone leaf removal. These results support the reliability of the flavonol profile as an assessment parameter for studies aiming to discuss canopy architecture or the effect of solar radiation on grapevine berries.