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The use of plant growth-promoting rhizobacteria (PGPR) in agriculture is one of the most promising approaches to improve plants' growth under salt stress and to support sustainable agriculture under climate change. In this context, our goal was to grow and enhance quinoa growth using native rhizobacteria that can withstand salt stress. To achieve this objective, we isolated rhizobacteria from three saline localities in a semi-arid region in Tunisia, which are characterized by different halophyte species and tested their plant growth-promoting (PGP) activities. Then, we inoculated quinoa seedlings cultivated on 300 mM NaCl with the three most efficient rhizobacteria. A positive effect of the three-salt tolerant rhizobacteria on the growth of quinoa under salinity was observed. In fact, the results of principal component analysis indicated that the inoculation of quinoa by salt-tolerant PGPR under high salinity had a prominent beneficial effect on various growth and physiological parameters of stressed plant, such as the biomass production, the roots length, the secondary roots number, proline content and photosynthesis activities. Three rhizobacteria were utilized in this investigation, and the molecular identification revealed that strain 1 is related to the Bacillus inaquosorum species, strain 2 to Bacillus thuringiensis species and strain 3 to Bacillus proteolyticus species. We can conclude that the saline soil, especially the halophytic rhizosphere, is a potential source of salt-tolerant plant growth-promoting rhizobacteria (ST-PGPR), which stimulate the growth of quinoa and improve its tolerance to salinity., (© 2024 Scandinavian Plant Physiology Society.)

The aim of this study was to investigate whether silicon (Si) supply was able to alleviate the harmful effects caused by salinity stress on sorghum-sudangrass (Sorghum bicolor ×Sorghum sudanense ), a species of grass raised for forage and grain. Plants were grown in the presence or absence of 150mM NaCl, supplemented or not with Si (0.5mM Si). Biomass production, water and mineral status, photosynthetic pigment contents, and gas exchange parameters were investigated. Special focus was accorded to evaluating the PSI and PSII. Salinity stress significantly reduced plant growth and tissue hydration, and led to a significant decrease in all other studied parameters. Si supply enhanced whole plant biomass production by 50%, improved water status, decreased Na+ and Cl- accumulation, and even restored chlorophyll a , chlorophyll b , and carotenoid contents. Interestingly, both photosystem activities (PSI and PSII) were enhanced with Si addition. However, a more pronounced enhancement was noted in PSI compared with PSII, with a greater oxidation state upon Si supply. Our findings confirm that Si mitigated the adverse effects of salinity on sorghum-sudangrass throughout adverse approaches. Application of Si in sorghum appears to be an efficient key solution for managing salt-damaging effects on plants.

The aim of this study was to investigate the effect of NaCl salinity (0, 100 and 300 mM) on the individual response of the quinoa varieties Kcoito (Altiplano Ecotype) and UDEC-5 (Sea-level Ecotype) with physiological and proteomic approaches. Leaf protein profile was performed using two dimensional gel electrophoresis (2-DE). UDEC-5 showed an enhanced capacity to withstand salinity stress compared to Kcoito. In response to salinity, we detected overall the following differences between both genotypes: Toxicity symptoms, plant growth performance, photosynthesis performance and intensity of ROS-defense. We found a mirroring of these differences in the proteome of each genotype. Among the 700 protein spots reproducibly detected, 24 exhibited significant abundance variations between samples. These proteins were involved in energy and carbon metabolism, photosynthesis, ROS scavenging and detoxification, stress defense and chaperone functions, enzyme activation and ATPases. A specific set of proteins predominantly involved in photosynthesis and ROS scavenging showed significantly higher abundance under high salinity (300 mM NaCl). The adjustment was accompanied by a stimulation of various metabolic pathways to balance the supplementary demand for energy or intermediates. However, the more salt-resistant genotype UDEC-5 presented a beneficial and significantly higher expression of nearly all stress-related altered enzymes than Kcoito., (Published by Elsevier Masson SAS.)

Salinity and K + deficiency are two environmental constraints that generally occur simultaneously under field conditions, resulting in severe limitation of plant growth and productivity. The present study aimed at investigating the effects of salinity, either separately applied or in combination with K + deficiency, on growth, photosynthetic performance, secondary metabolites content, and related antioxidant capacity in Sulla carnosa. Seedlings were grown hydroponically under sufficient (6000 μM) or low (60 μM) K + supply with 100 mM NaCl (C + S and D + S treatments, respectively). Either alone or combined with K + deficiency, salinity significantly restricted the plant growth. K + deficiency further increased salt impact on the photosynthetic activity of S. carnosa, but this species displayed mechanisms that play a role in protecting photosynthetic machinery (including non photochemical quenching and antioxidant activity). In contrast to plants subjected to salt stress alone, higher accumulation of phenolic compounds was likely related to antioxidative defence mechanism in plants grown under combined effects of two stresses. As a whole, these data suggest that K + deficiency increases the deleterious effects of salt stress. The quantitative and qualitative alteration of phenolic composition and the enhancement of related antioxidant capacity may be of crucial significance for S. carnosa plants growing under salinity and K + deficient conditions., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

Salt stress is one of the most important abiotic stress factors affecting plant growth and productivity in natural ecosystems. In this study, we aimed at determining possible differences between salt tolerant and salt sensitive species in early (within 72 h) salt stress response in leaves and roots. To this purpose, we subjected three Brassicaceae species, namely two halophytes-Cakile maritima and Thellungiella salsuginea--and a glycophyte--Arabidopsis thaliana- to short-term salt stress (400 mM NaCl). The results indicate that the halophytes showed a differential osmotic and ionic response together with an early and transient oxidative burst, which was characterized by enhanced hydrogen peroxide levels and subsequent activation of antioxidant defenses in both leaves and roots. In addition, the halophytes displayed enhanced accumulation of abscisic acid, jasmonic acid (JA) and ACC (aminocyclopropane-1-carboxylic acid, the precursor of ethylene) in leaves and roots, as compared to A. thaliana under salt stress. Moreover, the halophytes showed enhanced expression of ethylene response factor1 (ERF1), the convergence node of the JA and ethylene signaling pathways in both leaves and roots upon exposure to salt stress. In conclusion, we show that the halophytes C. maritima and T. salsuginea experience an early oxidative burst, improved antioxidant defenses and hormonal response not only in leaves but also in roots, in comparison to the glycophyte A. thaliana. This differential signaling response converging, at least in part, into increased ERF1 expression in both above- and underground tissues seems to underlay, at least in part, the enhanced tolerance of the two studied halophytes to salt stress.

Cuttings of Sesuvium portulacastrum L. (Aizoaceae) were taken from plants cultivated under severe saline conditions. The obtained seedlings were grown on sand and irrigated with nutrient solution over 5 weeks under no (0 mM NaCl), moderate (200 mM NaCl), or high (400 mM NaCl) salinity conditions. A follow-up of gas exchange was performed weekly and pigment levels and patterns of fully expanded leaves were determined after 3 and 5 weeks of treatment. At the end of the 5-week period, immunoblot analysis of the main polypeptides of photosystem I and II was performed with the aim to investigate salt-induced variations in photosystem composition. Net CO2 assimilation rate (Pn) increased under salinity up to 3 weeks of treatment then decreased to reach the value of 0mM-treated plants at the end of the experiment. For stomatal conductance (gs) and intercellular CO2 concentration (Ci), the opposite occurred. These results were concomitant with an increase in practically all pigment levels, mainly under high salinity, with the exception of zeaxanthin. The de-epoxidation index (DEPS index) was much lower under saline than non-saline conditions in the 3rd week, indicating light stress in 0mM-treated plants. At the end of the experiment, this index showed much lower values with no significant differences between treatments, which coincided with no significant differences in gas exchange as well. Protein amounts of D1, CP47, and CP43 did not show noticeable variations with salt treatment, whereas LHCII underwent a slight but significant decrease (-15%) at the highest NaCl concentration. LHCI polypeptides were unaffected by the salt treatments, where conversely, the highest concentration induced a significant decrease in PsaA/B amount (-18%)., (Copyright © 2010 Elsevier GmbH. All rights reserved.)

Physiological and biochemical responses of Hordeum maritimum and H. vulgare to salt stress were studied over a 60-h period. Growth at increasing salinity levels (0, 100, 200 and 300 mM NaCl) was assessed in hydroponic culture. H. maritimum was shown to be a true halophyte via its typical behaviour at high salinity. Shoot growth of cultivated barley was gradually reduced with increasing salinity, whereas that of wild barley was enhanced at 100 and 200 mm NaCl then slightly reduced at 300 mM NaCl. The higher salt tolerance of H. maritimum as compared to H. vulgare was due to its higher capacity to maintain cell turgor under severe salinity. Furthermore, H. maritimum exhibited fine regulation of Na(+) transport from roots to shoots and, unlike H. vulgare, it accumulated less Na(+) in shoots than in roots. In addition, H. maritimum can accumulate more Na(+) than K(+) in both roots and shoots without the appearance of toxicity symptoms, indicating that Na(+) was well compartmentalized within cells and substituted K(+) in osmotic adjustment. The higher degree of salt tolerance of H. maritimum is further demonstrated by its economic strategy: at moderate salt treatment (100 mm NaCl), it used inorganic solutes (such as Na(+)) for osmotic adjustment and kept organic solutes and a large part of the K(+) for metabolic activities. Indeed, K(+) use efficiency in H. maritimum was about twofold that in H. vulgare; the former started to use organic solutes as osmotica only at high salinity (200 and 300 mm NaCl). These results suggest that the differences in salt tolerance between H. maritimum and H. vulgare are partly due to (i) differences in control of Na(+) transport from roots to shoots, and (ii) H. maritimum uses Na(+) as an osmoticum instead of K(+) and organic solutes. These factors are differently reflected in growth.

The interaction between soil drying and salinity was studied in the perennial halophyte, Sesuvium portulacastrum. Rooted cuttings were individually cultivated for three months in silty-sandy soil under two irrigation modes: 100 and 25% of field capacity (FC). The amount of the evapotranspirated water was replaced by a nutrient solution containing either 0 or 100 mM NaCl. Whole-plant growth, leaf water content, leaf water potential (Psi(w)), and Na+, K+, and proline concentrations in the tissues were measured. When individually applied, both drought and salinity significantly restricted whole-plant growth, with a more marked effect of the former stress. However, the effects of the two stresses were not additive on whole-plant biomass or on leaf expansion. Root growth was more sensitive to salt than to soil drying, the latter being even magnified by the adverse impact of salinity. Leaf water content was significantly reduced following exposure to water-deficit stress, but was less affected in salt-treated plants. When simultaneously submitted to water-deficit stress and salinity, plants displayed higher values of water and potassium use efficiencies, leaf proline and Na+ concentrations, associated with lower leaf water potential (-1.87 MPa), suggesting the ability of S. portulacastrum to use Na+ and proline for osmotic adjustment.

The main objective of the current study is to underline the effects of salicylic acid or calcium chloride seed priming on plant growth, water content, chlorophyll content and photosynthetic activity of two barley species Hordeum marinum and Hordeum vulgare exposed to salinity (0, 100 and 200 mM NaCl). Results revealed that salinity decreased shoot and root growth, transpiration rate, chlorophyll concentration, stomata conductivity and water content in plants obtained from unprimed seeds. This reduction was dependent on the saline concentration used. However, Hordeum marinum species showed tolerance by maintaining tissue hydration, growth, photosynthetic assimilation and chlorophyll biosynthesis in stressed plants compared to controls. Moreover, priming seeds with salicylic acid or calcium chloride significantly improved all the above parameters under different salt treatments, suggesting that the effectiveness of this approach mainly depends on the priming agent applied and may vary with species and stress intensity applied. [ABSTRACT FROM AUTHOR]

Exposure of plants to adverse environmental conditions reduces their growth and productivity. Currently, seed priming with phytohormones is considered one of the most reliable and cost‐effective approaches that can help alleviate the toxic effects of environmental stress. In this context, the present study aims to investigate the effect of priming alfalfa seeds with salicylic acid (SA) on oxidative stress markers, including malonyldialdehyde, protein content, activities of antioxidant enzymes, and expression of genes encoding these enzymes in leaves and roots of alfalfa (Gabes ecotype) grown under saline stress, iron deficiency, or both. Our results showed that the application of salt stress and iron deficiency separately or simultaneously induces changes in the activities of antioxidant enzymes, but these are organ‐ and stress‐dependent. The Gabes ecotype was able to increase the activities of these enzymes under salt stress to alleviate oxidative damage. Indeed, priming seeds with 100 μM SA significantly increases the enzymatic activities of APX, GPX, CAT, and SOD. Therefore, this concentration can be considered optimal for the induction of iron deficiency tolerance. Our results showed not only that Gabes ecotype was able to tolerate salt stress by maintaining high expression of the Fe‐SOD isoform, but also that the pretreatment of seeds with 100 μM SA improved the tolerance of this ecotype to iron deficiency by stimulating Fe‐SOD expression and inhibiting CAT and APXc. [ABSTRACT FROM AUTHOR]

Salinity is increasingly considered as a major environmental issue, which threatens agricultural production by decreasing yield traits of crops. Seed priming is a useful and cost‐effective technique to alleviate the negative effects of salinity and to enable a fast and uniform germination. In this context, we quantified the effects of priming with gibberellic acid (GP), calcium chloride (CP), and mannitol (MP) on seed germination of three bread wheat cultivars and investigated their response when grown at high salinity conditions (200 mM NaCl). Salt exposure strongly repressed seed imbibition and germination potential and extended germination time, whereas priming enhanced uniformity and seed vigor. Seed preconditioning alleviated the germination disruption caused by salt stress to varying degrees. Priming mitigating effect was agent‐dependent with regard to water status (CP and MP), ionic imbalance (CP), and seed reserve mobilization (GP). Na+ accumulation in seedling tissues significantly impaired carbohydrate and protein mobilization by inhibiting amylase and proteases activities but had lesser effects on primed seeds. CP attenuated ionic imbalance by limiting sodium accumulation. Gibberellic acid was the most effective priming treatment for promoting the germination of wheat seeds under salt stress. Moreover, genotypic differences in wheat response to salinity stress were observed between varieties used in this study. Ardito, the oldest variety, seems to tolerate better salinity in priming‐free conditions; Aubusson resulted the most salt‐sensitive cultivar but showed a high germination recovery under priming conditions; Bologna showed an intermediate behavior. [ABSTRACT FROM AUTHOR]

Salinity and low nitrogen availability are two major abiotic stresses that often coexist and disturb plant productivity. This study aimed at investigating the combined effects of salinity (0 and 100 mM NaCl) and nitrogen (0.5 and 5.0 mM NH4NO3) levels on the morphological parameters, the mineral status, nitrogen use efficiency, photosynthesis, and nitrate reductase (NR, E.C. 1.6.6.1) and glutamine synthetase (GS, EC 6.3.1.2) activities at Sulla carnosa.‎ Salinity enhanced growth rate (66%), the relative growth rate (RGR), root volume (RV), Na+ and Cl− accumulations and nitrogen use efficiency (NUE). It had no detrimental effect on photosynthetic assimilation rate (A) and leaf NR and GS activities under high nitrogen level condition. High nitrogen availability under saline condition enhanced growth rate, RGR, shoot/root ratio, photosynthesis activity, NR activity in roots, and the accumulation of NO3− in different plant organs and all cations and anions in roots. In brief, salinity and high nitrogen availability represented an adequate condition for optimal growth and high Na+ and NO3− accumulations at S. carnosa. This study suggested that S. carnosa could be a suitable forage legume that can be widely cultivated in the discarded, salinized and nitrogen-contaminated agricultural soils. [ABSTRACT FROM AUTHOR]

In this study, we examined the combined effect of moderate salinity (100 mM NaCl) and three phosphorus (P) levels: low, moderate and high (5 µM, 60 µM and 180 µM KH2PO4, respectively) on several physiological parameters in the facultative halophyte Aeluropus littoralis. Our results showed that plants cultivated under low P availability exhibited higher leaf hair and trichome densities, root length, and shoot soluble sugars concentrations. The response of plants to combined salinity and P deficiency was similar to that of plants cultivated under P deficiency only. Furthermore, in the absence of salt, A. littoralis plants reached maximum biomass at 180 µMP. However, in the presence of 100 mM NaCl, plants exhibited maximum growth from 60 µMP which suggests that salt supply decreased P requirements of A. littoralis plants. Moreover, salinity has no significant effect on biomass production, shoot water content and shoot potassium (K+) content when combined with 5 µMP and it significantly decreased gradually these parameters when combined with 60 µMP and 180 µMP. This was associated with higher values of P and K use efficiencies, leaf hair and trichome densities, total polyphenol content, and total antioxidant capacity in plants cultivated under combined effects of salinity and P deficiency. [ABSTRACT FROM AUTHOR]

Disentangling short‐ and long‐term neighbour effects, using both removal and observational methods within a single experiment, has strongly improved our understanding of the driving mechanisms of plant–plant interactions. However, there has been no attempt to assess two important underlying processes of their changes along gradients, either environmental‐severity (changes in target performance without neighbours) or neighbour‐traits (changes in performance with neighbours) effects, the former previously shown in alpine communities to be involved in competition and the latter in facilitation. We addressed this goal in an experiment conducted in continental saline depressions (sebkhas) from the Mediterranean arid climate of central Tunisia. We quantified short‐ and long‐term effects of dominant shrubs, transplanting three target grass species in open, nurse and removed‐nurse microhabitats of two habitats of different salinity levels in height sebkhas. The design extended greographically from central Tunisia to the Libyan border, 500 km southeastward. We used the relative interaction index to calculate short‐ and long‐term effects before and after the dry summer seasons and environmental‐severity and neighbour‐trait effects. Short‐term effects were slightly negative and long‐term effects strongly positive before the dry summer season in the two habitats. Short‐term effects switched to positive with increasing drought stress, due to an environmental‐severity effect, whereas long‐term effects decreased due to a neighbour‐trait effect. Salinity did not affect neither short‐ nor long‐term shrub effects. Soil moisture measurements showed that both changes were due to vanishing shrub soil engineering‐effects during the summer drought. We conclude that an increase in short‐term facilitation with increasing drought stress through time, apparently supporting the stress gradient hypothesis, might be due to a decrease in long‐term facilitation. Thus, we recommend using, as much as possible, both the removal and observational methods in experiments assessing changes in plant–plant interactions along stress gradients to avoid wrong conclusions. [ABSTRACT FROM AUTHOR]

The present study was conducted to determine the predictive screening parameters of quinoa salt tolerance that can be applied at early development stages, based on physiological and biochemical approaches. Four quinoa varieties (Tumeko, Red Faro, Kcoito and UDEC-5) were cultivated using hydroponic system, and treated for 2 weeks with different NaCl concentrations (0, 100, 300 and 500 mM). Salt treatment induced a decrease of plant growth depending on NaCl concentrations, plant organs and varieties. Red Faro and UDEC-5 exhibited low level of Na+ accumulation and high K/Na selectivity. UDEC-5 showed high stomatal conductance leading to high net photosynthesis, even at 500 mM NaCl. Red Faro and UDEC-5 exhibited low level of lipid peroxidation, high antioxidant activities and high proline accumulation, as an indicator of ROS defense and osmotic adjustment. This study suggested that these physiological and biochemical traits could be used as screening criteria for selecting salt tolerant genotype. [ABSTRACT FROM AUTHOR]

The considerable genetic variability of salt tolerance in Hordeum vulgare L. and its wild relative species Hordeum marinum Huds. (sea barley) is a potentially useful trait to develop well-adapted varieties to salt-affected areas. Here, two local barley (Manel and Rihane) cultivars and two local sea barley accessions (Kelbia and Soliman) were compared for their response to salt (up to 200 mM NaCl) exposure at the germination and seedling stages. Increasing salinity significantly decreased seed imbibition and seed reserve mobilization parameters (notably amylase activity), resulting in delayed germination, lower germination percentage and altered seedling root length. Interestingly, inter- and intra-specific variability was observed as cultivated barley (especially Rihane) was less salt-affected when considering final germination percentage. Yet, sea barley Soliman accession showed the highest values of seed vigor (seeds reaching the seedling stage) and efficiency of seed reserve mobilization under saline conditions. In addition, even at 200 mM NaCl, salinity impact was reversible on seeds of sea barley, in contrast with cultivated barley. Overall, while confirming the sensitivity of barley at the early developmental stages, this study provides additional criteria that would allow more accurately addressing inter-specific variability of plant behavior at this crucial step of its life cycle. [ABSTRACT FROM AUTHOR]

Soil salinity is one of the main factors limiting cereal productivity in worldwide agriculture. Exploitation of natural variation in local barley germplasm is an effective approach to overcome yield losses. Three gene pools of North African Hordeum vulgare L. grown in Tunisia, Algeria and Egypt were evaluated at the reproductive stage under control and saline conditions. Assessment of stress tolerance was monitored using morphological, yield-related traits and phenological parameters of reproductive organs showing significant genetic variation. High heritability and positive relationships were found suggesting that some traits associated with salt tolerance could be used as selection criteria. The phenotypic correlations revealed that vegetative traits including shoot biomass, tiller number and leaf number along with yield-related traits such as spike number, one spike dry weight, grain number/plant and grain number/spike were highly positively correlated with grain yield under saline conditions. Hence, these traits can be used as reliable selection criteria to improve barley grain yield. Keeping a higher shoot biomass and longer heading and maturity periods as well as privileged filling ability might contribute to higher grain production in barley and thus could be potential target traits in barley crop breeding toward improvement of salinity tolerance. Multiple selection indices revealed that salt tolerance trait index provided a better discrimination of barley landraces allowing selection of highly salt-tolerant and highly productive genotypes under severe salinity level. Effective evaluation of salt tolerance requires an integration of selection indices to successfully identify and characterize salt tolerant lines required for valuable exploitation in the management of salt-affected areas. [ABSTRACT FROM AUTHOR]

Salinity is a serious problem all over the world with an average of 830 M ha being affected. In order to investigate the screening attributes that can be used to determine early growth stage sensitivity of Thellungiella plants to salt stress, 8 Thellungiella genotypes were grown in pots containing fine sand as growth medium and subjected to five different salinity levels, i.e. 0, 200, 300 and 400 and 500 mM of NaCl. Thirteen phenotypic and physiologic traits related to vegetative growth were evaluated for their responses to salinity stress. Co-relating the different parameters; T. botschantzevii and T. halophila shown to be more tolerant than T. salsuginea. When comparing ecotypes within T. salsuginea, Altai 1 and Altai 2 ecotypes were identified as salt tolerant, Tuva and Buriatia were classified as salt sensitive and the more popular ecotype "shandong" as moderately tolerant. Furthermore, results show that salt susceptible ecotypes treated at 500 mM NaCl had 7 folds higher proline than that of tolerant genotypes treated under similar concentration. These finding indicate the potential for selecting plants or traits with improved salt tolerance within that species. Method used allows detection plants or traits within enhanced salinity tolerance after 2 months of growth for the ability to grow at salt concentration that prevents the growth of other plants. [ABSTRACT FROM AUTHOR]

Questions: Complex distal factors such as climate and topography can interact to drive direct proximal ecological gradients and vegetation zonation in geographical and ecological space, in particular salinity and soil moisture in arid climates. We pose the following questions: (a) Does increasing climate aridity alter direct water and salinity gradients along topography gradients in saline depressions in arid climates? (b) Do these effects of increasing climate aridity in turn alter vegetation life‐form zonation? (c) Does increasing climate aridity alter community composition along the zonation? Study site: Continental saline depressions of the Mediterranean arid climate of central and southern Tunisia. Methods: We sampled vegetation structure, diversity, and composition and environmental variables at five positions along the topography gradient of continental saline depressions in wet and dry conditions. Results: Climate aridity altered salinity gradients and vegetation structure but not diversity and community composition. Salinity increased with increasing aridity at the lowest positions of the depressions but decreased with increasing aridity at their highest positions. Total vegetation cover and relative abundance of therophytes decreased, whereas relative abundance of chamaephytes increased with increasing climate aridity at the upper habitats. Conclusions: Ecological factors acting at a regional scale can alter the spatial variation of other ecological factors acting at smaller spatial scales, ultimately explaining vegetation zonation in continental saline depressions. Salinity collapses with increasing aridity. We assessed how increasing climate aridity alters direct water and salinity gradients and vegetation zonation along topography gradients in saline depressions. [ABSTRACT FROM AUTHOR]

In the present study, photosynthetic parameters including gas exchanges, pigment contents, and chlorophyll fluorescence, were compared in two contrasting local Medicago truncatula lines TN6.18 and TN8.20, in response to salt added to the nutrient solution. Plants were cultivated under symbiotic nitrogen fixation (SNF) after inoculation with a reference strain Sinorhizobium meliloti 2011, a very tolerant strain to salinity (700 mM NaCl), and grown in a controlled glasshouse. On one month old plants (with active SNF), salt treatment (75 mM NaCl) was gradually applied. Photosynthesis, assimilating pigments and chlorophyll fluorescence were monitored throughout the experiment during both short and long terms, compared to control (non-saline) conditions. A genotypic variation in salt tolerance was found; TN6.18 was the more sensitive to salinity. The relative tolerance of TN8.20 was concomitant with the highest photochemical quenching coefficient (qP) affecting the maximum quantum yield of PSII (Y); the real quantum yield (ɸexc) was the most affected in the sensitive line. Moreover, stomatal and PSII reaction centers activities differed clearly between the studied lines. We found that the effect of salinity on photosynthesis of M. truncatula was related to PSII activity reduction rather than to stomatal conductance limitation. Photosynthesis was reduced by the inhibition of CO2 assimilation caused by PSII damage. This was clearly estimated by the Y, ɸexc and especially by the quantum yield of electron transport of PSII (ΦPSII). Thus, on the basis of our results on the two local M. truncatula lines, we recommend the use of chlorophyll fluorescence as non-destructive screening method to discriminate susceptible and resistant legumes to salt stress. [ABSTRACT FROM AUTHOR]

The combined effects of NaCl-salinity and phosphorus deficiency on biomass production, nutritional status, and photosynthetic activity were studied in Catapodium rigidum: an annual Poacea with fodder potential. Plants were grown in hydroponic conditions for 55 days under two phosphorus (P) supply: 5 (low) or 180 µmol KH2PO4 (sufficient), in the absence or presence of 100 mM NaCl. Obtained results demonstrated that both salinity and P deficiency treatments applied separately reduced substantially plant growth and CO2 assimilation rate with a more marked impact of salt stress. Salinity has no substantial effect on both shoot P concentrations and phosphorus acquisition efficiency independently of P availability. The highest decrease in plant growth (−91%) was observed in plants simultaneously submitted to both stresses suggesting an additive effect of the two stresses and that P deficiency increased the susceptibility of C. rigidum to salinity. This may be linked to a significant decrease in potassium acquisition (−95%), K/Na selectivity ratio (−73%), stomatal conductance (−66%), CO2 assimilation rate (−64%), and shoot water content (66%). Furthermore, plants cultivated under combined salinity and sufficient P supply displayed higher stomatal conductance, CO2 assimilation rate, K/Na selectivity ratio, and plant growth than plants cultivated under combined effects of salinity and P deficiency. These results suggest that adding P to saline soils could be an alternative for alleviating the negative effects of salinity and may ameliorate salinity tolerance. [ABSTRACT FROM AUTHOR]

The present study investigated the effect of salt stress on the development of adaptive responses and growth parameters of different coloured wheat genotypes. The different coloured wheat genotypes have revealed variation in the anthocyanin content, which may affect the development of adaptive responses under increasing salinity stress. In the early stage of treatment with salt at a lower NaCl concentration (100 mM), anthocyanins and proline accumulate, which shows rapid development of the stress reaction. A dose-dependent increase in flavonol content was observed for wheat genotypes with more intense purple-blue pigmentation after treatment with 150 mM and 200 mM NaCl. The content of Na+ and K+ obtained at different levels of salinity based on dry weight (DW) was more than 3 times greater than the control, with a significant increase of both ions under salt stress. Overall, our results demonstrated that coloured wheat genotypes with high anthocyanin content are able to maintain significantly higher dry matter production after salt stress treatment. [ABSTRACT FROM AUTHOR]

Eight barley genotypes contrasting in their salinity tolerance were assessed for their chlorophyll fluorescence, photosynthetic performance, lipid peroxidation level and ionic content. A pot experiment was conducted in Borj-Cedria (Tunisia), in a wire house with a glass roof to avoid rainfall. The assay consisted of three treatments (0, 100 and 200 mM NaCl) with eight barley genotypes following a completely randomized design. Each pot was considered as one replicate and nine replicates were used for each genotype and treatment. The salt-tolerant genotypes Kerkna and Tichedrett recorded the highest tolerance for photosynthesis and potassium accumulation, whereas the susceptible genotypes were mostly affected at severe salinity. Contrasting behavior was noted for fluorescence attributes, while PSII yield was unchanged reflecting good protection against photodamage. Photosynthetic performance, enhanced water use efficiency, maintained leaf K+and oxidative defense remain the key components for tolerance mechanisms. Salt-tolerant barley could be suitable for management of salt-affected soils. [ABSTRACT FROM PUBLISHER]

Understanding soil degradation is especially important in the Mediterranean Region where desertification is a serious problem, and soil salinization is one of the causes. Salinity reduces soil quality, limits crop productivity and brings on long term soil degradation. Therefore the restoration of degraded soils is necessary to reduce land degradation, improve soil fertility and achieve a sustainable food production. The addition of compost supplemented with the beneficial microorganism Trichoderma harzianum isolate T78 to saline soils (NaCl) was studied to determine the impact on soil microbiology, which is the key to restore and rehabilitate degraded soils. The selected Trichoderma harzianum isolate T78 showed high salt tolerance despite the low osmotolerance of the genus Trichoderma. Increasing salt concentration reduced Trichoderma sp colony-forming units (CFU) from natural soil and adversely affected soil microbial biomass C as well as dehydrogenase, β-glucosidase, phosphatase and urease activities. Simultaneous amendment of the saline soil with compost and inoculation with T. harzianum T78 improved the soil microbiological quality; the number of T. harzianum T78 CFU did not decrease as NaCl increased. As T. harzianum strain T78 is salt tolerant, increasing the relative abundance of this specific strain would contribute to the rehabilitation of saline soils. Vineyard composts supplemented with T. harzianum T78 represent a promising approach for the treatment and improvement of saline soil properties. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]