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Drought stress along with soil salinity are the most common and frequently co-occurring abiotic stresses and threaten plant productivity, especially in arid and semi-arid regions of the world. The aims of this study were to investigate the interaction between soil drying (D) and salinity (S) in two forage species Medicago ciliarisTNC1.11 line and M. polymorphaTNP1.11 line. Plants were cultivated for 1 month in silty-sandy soil under two irrigation modes: 80% and 33% of field capacity (FC). The amount of the evapotranspirated water was replaced by a nutrient solution containing either 0 or 50 mM NaCl. Morphological parameters, photosynthesis, whole plant growth, water, and nutrient status (Na, K, Ca, Zn) were investigated. Under control or stressed conditions, M. ciliarisproduced more biomass when compared to M. polymorpha. The whole-plant biomass production represented 237%, 230%, 175%, and 172%, respectively, in treatment C, S, D, and D + S in M ciliariswhen compared to M polymorpha. The higher productivity correlates under all studied treatments in M. ciliariswith (i) a higher photosynthetic activity and water-use efficiency, (ii) more leaves per plant, higher number of ramifications and a longer stem, (iii) a high root water content under C, S, D + S treatments, and (iv) a high Zn accumulation in leaves. Salinity and drought applied individually negatively affect growth, photosynthesis, water, and potassium leaf content in both studied species. The effects of both constraints were not significantly additive. Salinity affects growth of the two studied species by the same manner (reduction by 64% as compared to control). The major advantage of M. ciliarisunder dry or saline conditions seems to be the general high water-use efficiency and the corresponding positive impact on the ROS risk. Besides, M ciliarisshowed a lower increase of Na+and less decrease of K+at salinity leading to an overall lower Na+/K+ratio as M. polymorpha. This shows that the selectivity of M. ciliarisis higher as the one of M. polymorpha. When compared to M. polymorpha, TNC1.11 line of M. ciliarisproduced more biomass under drought, salinity, and combined stresses; therefore, we recommend its multiplication and use by farmers as a forage candidate for the rehabilitation of soils in arid and semi-arid salinized regions.

Water deficiency has become a serious ecological problem facing all mankind, and drought has become a key factor constraining the development of agricultural production. Gaining insights into drought response mechanisms is vital for crop adaptation. We present, here, a multifactorial study from germination to vegetative drought stages in the model plant Brachypodium hybridum. A total of 200 genotypes representing 10 natural populations (Fayedh, Enfidha, Jbel Zaghouan, Haouaria, Raouad, Sejnen, Ain Drahem, El Kef, Daouar El Hej Wniss and Djerba) which represent almost all the bioclimatic regions in Tunisia were used. High variation in germination capacity under drought stress was found between studied populations. It reaches 100% at 250 mV for Djerba population and decrease up to 40% at 100 mV. Drought caused significant increase in oxidative stress. Interestingly, genotype 8/14 originated from El Kef exhibited the highest leaf H2O2content, resulting in higher leaf MDA accumulation. Consistently, no significant changes were observed in-SOD, CAT and GPX activities in both leaves and roots, relatively to unstressed state. Different profile was recorded in 6/9 originated from Raoued in which the most pronounced levels of H2O2and MDA were observed in drought stressed roots. Concurrently, root CAT activity increased by 22-fold relatively to unstressed plants. Drought stress resulted in a decrease in H2O2content, mitigation of lipid peroxidation in both leaves and roots of 6/5 genotype originated from Raoued, with a simultaneous increase in leaf and root SOD activity. This was associated with enhanced GPX activity where 75 and 40% of increase were recorded in genotype 6/5 in leaves and roots.

Silicon (Si) is not deemed sensu stricto as an essential nutrient for higher plants, but it is known for its positive impact under environmental stress conditions. The present study hypothesizes that the addition of silicon (Si) could alleviate cadmium (Cd) toxicity and reduce its accumulation in sea barley. Twenty-day-old plants were hydroponically grown under controlled conditions at two Cd levels (0 and 25 µM) with (1 mM) or without Si supply. Several aspects of the plant morphology, photosynthetic activity, membrane stability, and the status of metals (Cd, Zn, and Fe) were assessed after 17 days. Statistical analyses (Duncan’s test p≤ 0.05) indicated that most studied parameters were altered by metal treatment, reflecting Cd toxicity. Plant growth, water status, carotenoid content, chlorophyll (Chl. a/Chl. b) ratio, carotenoid/(Chl. a+ Chl. b) ratio, gas exchanges, fluorescence parameters (ETR, qP, and NPQ), membrane stability, and Zn concentration in both roots and shoots were significantly impacted by Cd. However, plants simultaneously treated with Cd and Si supply showed a significant restoration in growth parameters, water content, and photosynthetic pigments. The mitigating effect of Si was associated with higher stomatal conductance, transpiration, chlorophyll fluorescence (ETR, qP, and NPQ) values, and better membrane stability. The attenuation of Cd’s toxic effect was also explained by the fact that Si prevented Cd uptake, as Si decreased Cd content in shoot and root tissues. The current study revealed that silicon supply to sea barley, grown under Cd stress, mitigates Cd toxicity and leads the way forward for similar studies on other cereal field crops.

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Silicon (Si) is the second most abundant element in the Earth’s crust, after oxygen. Although not consistently considered an essential nutrient for plant growth, its positive impact on crop development and production, particularly under stressful conditions such as salt stress, has been well documented. This study aimed to examine the separate and combined effects of salt stress and silicon supply on sea barley (Hordeum marinumHuds.) plants. Thirty-six-day-old H. marinumplants were grown either without or with 150 mM NaCl in the absence or presence of Na2SiO3(0.5 mM). The addition of 150 mM NaCl to the growth medium significantly impaired growth parameters, pigment concentrations, lipid peroxidation, and proline and sodium contents. Simultaneous measurement of chlorophyll fluorescence and P700 redox state revealed that photosystem I (PSI) was more affected by salinity than photosystem II (PSII). The observed detrimental effects caused by salinity were significantly mitigated by silicon supplementation in the growth medium. Stress mitigation by silicon appeared to involve various parameters such as growth, chlorophyll pigment contents, lipid peroxidation, proline content, chlorophyll fluorescence (PSI and PSII machinery), and sodium content. Compared to PSII, PSI parameters (the quantum yield of non-photochemical energy dissipation in reaction centres limited by acceptor side Y(NA), maximal fluorescence yield of illuminated sample with closed PSI centres (P700m’), and oxidized PSI (P700ox)) were more sensitive to salinity. However, a more significant beneficial effect was observed for the PSI complex under silicon application. These results suggest that the advantageous effect of silicon on stressed sea barley plants was strongly associated with the crucial role of this element in protecting the photosynthetic machinery, primarily PSI, enabling this species to overcome salinity damages.

Lepidium sativumseeds were submitted to different cooking treatments (Dry heating, micowaving, grilling) and the nutritional value, the phytochemical profile and the antioxidant properties were evaluated. Domestic cooking treatments resulted in a reduction of proteins (5.07–9.44%), gross energy (2.21–3.24%), sodium (7.30-43.35%), potassium (3.34–6.76%), tanins (8.70-19.57%) and flavonoids (34.41–53.76%) and in an increase of ash content (3.39–7.16%), the DPPH scavenging activity (11.25–32.60% and the ferric reducing power (25.27–28.55%). Also, an increase of carbohydrates (4.09, 11.50%) and phosphorus (13.12, 13.13%) and a decrease of calcium (3.56, 6.50%) and phytates (9.65, 12.07%) were obtained by dry heating and grilling. Moreover, microwaving and grilling caused a decrease of iron content (23.60, 20.63%) and an augmentation of the total polyphenol content (9.37, 19.16%) and the total antioxidant capacity (16.05, 16.50%). Globally, dry heating revealed amelioration of nutritional quality and antioxidant properties and maximum nutrient and antioxidants retention.

The present work evaluates the role of silicon (Si) in barley (Hordeum vulgareL. var. Rihane) plants subjected to potassium (K+) deficiency. Plants were grown hydroponically either under K+-sufficient (+ K, 3 mM) or K+-deficient (-K, 10 µM) conditions supplied or not with 1 mM Si. Several parameters were determined in both shoots and roots [growth, macronutrients (K and Ca) and micronutrients (Fe and Zn) dynamics, protein and malondialdehyde (MDA) contents, and antioxidative enzymes activities (superoxide dismutase (SOD), catalase (CAT), and guaiacol peroxidase (GPX)]. Results showed that K+deficiency resulted in a reduction of growth and K+concentration in both shoots and roots compared to control plants. The exogenous application of Si alleviated the reduction of plant growth induced by K+deficiency but did not influence K+nutrition. Concerning Ca, Fe, and Fe nutrients, the addition of Si adjusts their uptake, translocation, and use efficiencies. Leaf MDA concentration was not affected by K+deficiency, while an increase was noted in roots. The increase of root MDA concentration was mitigated by the addition of Si. Modulation of antioxidant enzyme activities was also observed. As a whole, the data indicate the beneficial effects of Si on barley plants grown under a K+-deficient medium by modulating mineral nutrition and antioxidative response. This suggests the possible use of Si as an effective, cheap, and environmentally safe fertilizer to improve the plant’s response to K+deficiency.

Natural populations of plants may express plastic response, evolve local adaptation, or combine both mechanisms to enhance their genetic variation. Here, 79 lines from Tunisian Brachypodium hybridumpopulations were cultivated in two contrasting phosphorus (P) availability levels, and their genetic variation was investigated using forage quality traits to identify the mechanisms governing their genetic variation. Results revealed large variation among populations for most traits and separation between coastal and inland populations in both P levels. All traits revealed high heritability, and the response of most traits to P deficiency was influenced by the population effect which accounted 52.38% of the variation, indicating strong population differentiation. Although significant for most traits, only 18.13% of variation was attributed to P treatment, suggesting little plastic response to P deficiency. However, the lack of population × treatment effect for most traits suggested a common plastic response in populations. Moreover, 56.99% of variation was attributed to environmental factors with distance to coastline, precipitation seasonality, and annual precipitation being the major factors, suggesting that the strong population differentiation reflects local adaptation to specific environments. Contrary to coastal populations characterized by high levels of fiber‐related traits, the inland ones displayed high values of most energy‐related traits, suggesting that these latter were characterized by higher forage quality. Overall, our results suggested that the effect of local adaptation overrides the effect of phenotypic plasticity regarding the variation of forage quality traits, indicating a broad adaptive genetic differentiation among the populations of B. hybridumin response to P deficiency. The variation of forage quality in response to P deficiency in B. hybridum populations was analyzed.Significant population and P treatment effects in response to P deficiency were detected.Results showed broad adaptive genetic differentiation in forage quality traits.The variation of forage quality under phosphorus deficiency influenced by environment.The coastal‐inland differentiation points toward local adaptation of populations.

•A salt-tolerant bacteria strain displaying PGPR traits was isolated from a sabkha.•The PGPR strain was identified as Bacillus pumilus.•High salinity impact on wild barley growth was offset by B. pumilusinoculation.•PGPR improved plant growth and nutrient uptake while reducing oxidative damage under salinity.•Selected bacteria strain activated soil enzymes and microbial biomass C production.

Agricultural intensification necessary for global food security as well as changes in temperature and precipitation patterns expected from climate change are likely to cause further deterioration irrigated lands in various part of the world. Salinization is spreading particularly in arid and semi-arid regions and urban sprawl is forcing agricultural production into marginal areas. Many salted marginal areas could support biomass production if halophytes able to tolerate high salinity were used. This chapter presents general data on Cakile maritima, a halophyte, concerning its ecological characteristics, diversity and distribution, adaptation to environment and its potential uses as medicinal plant, for oilseed production or phytoremediation. In a second part we present what have been uncovered in C. maritimain term of mechanisms and physiological adaptations to salinity when compared to other plants.

As a result of the extreme conditions that usually occur in Mediterranean climates, the objective of this work is to study the combined and/or separate effects of saline and alkaline stresses in Portulaca oleracea. The study was carried out to determine the nutritional food potential in relation to plant physiological parameters. The results show that alkaline media in which CaCO3was present did not affect growth but exposure to 100 mM NaCl decreased it greatly. Fatty acid content increased under all stress conditions but to a higher extent with salinity; however, the protein content was increased only by alkaline media. The beneficial effect of each stress on P. oleraceais discussed in light of the physiological response, pointing out the suitability of this plant for human nutrition.

The present investigation aimed to evaluate the impact of salt treatment and domestic cooking processes on nutritional value, phytochemical contents and antioxidant properties of Lepidium sativumsprouts. The application of low to moderate concentrations of salt during germination increased the contents of ash, carbohydrate, potassium, sodium, zinc, phosphorus, total polyphenols and flavonoids, gallic acid, catechin hydrate and caffeic acid. Additionally, phytate levels were reduced at 40 mM of NaCl and the DPPH activity was enhanced at 40 and 80 mM of NaCl. Also, garden cress sprouts grown in the presence of 40 mM of NaCl and submitted to cooking treatments were characterized by an improvement in protein, fat, carbohydrate, potassium, sodium, calcium, iron, zinc, phosphorus, gallic acid, catechin hydrate, chlorogenic acid and caffeic acid contents. Cooking processes permitted a decrease in phytate contents and ameliorated the antioxidant properties as evaluated by the DPPH scavenging activity and the total antioxidant capacity. As shown in the present investigation, salt stress and domestic cooking processes might enhance the nutritional quality and the antioxidant activity and permitted to highlight the use of garden cress sprouts as functional food.

O-Methylated and glucuronosylated flavonoids were isolated from Tamarix gallicaas α-glucosidase inhibitors. Structure–activity relationship of these flavonoids suggests that catechol moiety and glucuronic acid at C-3 are factors in the increase in α-glucosidase inhibitory activity. Furthermore, rhamnetin, tamarixetin, rhamnazin, KGlcA, KGlcA-Me, QGlcA, and QGlcA-Me exhibit synergistic potential when applied with a very low concentration of acarbose to α-glucosidase from rat intestine.

Sea barely (Hordeum marinumHuds.) is known as a salinity-tolerant annual grass species. Its use in the rehabilitation of degraded arid and semiarid rangelands or in crop plant improvement programs is of great interest. In this study, we investigated the phenotypic variation within and among 150 single-seed descent families representing 10 Tunisian populations of H. marinumusing eight quantitative traits. The experiment was conducted under greenhouse conditions. For each population, seeds from 15 mother plants were evaluated with five replicates per mother plant. Our results showed significant variation within and between populations for most measured traits. Most phenotypic variation was found to occur within populations. The QSTmeasurement of differentiation between populations varied according to traits from 0.03 for number of tillers to 0.309 for the weight of aerial part, with an average of 0.149. Pairwise QSTgrouped studied populations into three major clusters; the first group included Tabarka and Sidi Othman populations showing the lowest values for spike number and weight. The second group included Lessouda, Bouficha, and Mouthul having the highest values for the number and weight of spikes, while the third group included populations Lac de Bizerte, Sebkhet Ferjouna, Bkalta, Medjez El Bab, and Soliman and had moderate spike number and weight. Furthermore, there was no significant association between population differentiation and ecogeographical parameters.

In this study, we investigated variation for tolerance to water deficit in 47 lines of Medicago truncatulaGaertn., M. ciliaris(L.) All.,and M. polymorphaL. collected from different ecogeographic regions in Tunisia. Plants were cultivated in the greenhouse under 100 and 30% of field capacity and they were harvested at the flowering stage. Nineteen morphophysiological parameters were measured for each species. Our results showed that variation of parameters were explained by the effects of species, line within species, treatment, species × treatment interaction, and treatment × line within species interaction. Drought treatment explained the most variance for the measured parameters. Of the 19 traits, 12 showed significant differences for tolerance to water deficit between M. truncatula, M. ciliaris,and M. polymorpha. M. ciliariswas the latest‐flowering and it exhibits the highest biomass under both treatments. High broad‐sense heritabilities (H2) were noted for most of parameters under control treatment and drought stress. Positive correlations were found between transpiration rate (E) and aerial and root fresh weights, and between photosynthetic rate (A) and stomatal conductance (gs), and between relative water content and number of nodules. Studied lines formed five groups based on drought response indices (DRI). A first group is formed by 23 most tolerant lines, a second group and a fourth group are constituted by 17 moderately affected lines, and a third group and a fifth group have 8 sensitive lines. Tolerant lines of three species can be good candidates in future breeding programs.

The phytochemical investigation of Tamarix africana Poir. (Tamaricaceae) shoot polar extract afforded three new sulphated flavonoids, (2S,4R)-5,7,4'-trihydroxyflavan-4-ol 5,7-disulphate (1), (2S)-5,7,4'-trihydroxyflavan 7-O-sulphate (2), and (2S)-naringenin 4'-O-sulphate (3), together with ten known compounds. Their structures were determined by spectroscopic methods including 1D and 2D NMR analysis and HRMS. Biological activities of the polar extract of T. africana shoots related to its phenolic content were also investigated. A high total phenolic content (151.1 mg GAE/g) was found in the methanol shoot extract, which exhibits strong antioxidant activities using the oxygen radical absorbance capacity method and a skin cell-based assay. Moreover, the shoot extract showed significant antiinflammatory activity, reducing nitric oxide release by 53.5% at 160 µg/mL in lipopolysaccha-ride-stimulated RAW 264.7 macrophages. Finally, T. africana shoot extract inhibited the growth of A-549 lung carcinoma cells, with an IC50 value of 34 µg/mL. [ABSTRACT FROM AUTHOR]

The effects of water deficit stress and recovery on growth, photosynthesis, physiological and biochemical parameters were investigated in the cultivated Beta vulgaris and in two Tunisian provenances (Soliman and Enfidha) of its wild relative B. macrocarpa. Seedlings were cultivated for 4 weeks under optimal or limiting water supply (respectively, 100% and 25% of field capacity, FC). After 2 weeks of treatment, a lot of stressed plants were rehydrated to 100% FC. In the Control, B. vulgaris was more productive than B. macrocarpa, whereas Enfidha provenance showed the highest biomass production (1.6- and 3-fold compared with B. vulgaris and Soliman, respectively), under water deficit stress. A partial re-establishment of growth occurred in both species upon recovery at 100% FC. The sensitivity of B. vulgaris and Soliman provenance to drought was associated with the disturbance of leaf water status and the sharp decrease in net CO2 assimilation (–66% and –82% as compared with the Control, respectively). On the contrary, the better behaviour of Enfidha provenance was related to its better photosynthetic capacity and leaf relative water content, along with a higher accumulation of amino acids (proline, glycine, and glutamine) implied in the osmotic adjustment. Leaf hexose concentration increased significantly under drought stress in both species whereas leaf sucrose concentration declined only in drought-stressed B. vulgaris and Soliman provenance. Leaf glutamate dehydrogenase activity increased under water deficit in both species despite to a higher extent in B. vulgaris. As glutamate dehydrogenase is implied in catabolism of glutamate to oxoglutarate, it might contribute to provide stressed plants with carbon skeletons. Enfidha provenance of the spontaneous species B. macrocarpa could be used in the marginal arid ecosystems in order to limit the deficit in fodder and to improve the pastoral value of these regions. In addition, this species could serve as a source of genes for genetic improvement to water deficit stress.

In Tunisian arid regions, plant life forms, ecotypes, physiological types and photosynthetic pathways (C3, C4or CAM) remain unclear. Understanding the characters of these plant species could be important for land restoration. A literature survey was conducted for 105 species from arid regions of Tunisia. These plant species belong to several ecotypes: halophytes, xerophytes, gypsophytes, psamophytes, xero-halophytes, gypso-halophytes, psamo-halophytes, psamo-xerophytes, xero-gypsophytes and hygro-halophytes. The variation of photosynthetic pathway types in the 105 studied species shows that 56.2% are C3, 41.0% are C4, 1.9% are CAM and 1.0% are C3-CAM. The C3pathway is more abundant in the halophytes, whereas the C4one is more common in the xerophytes, gypsophytes, gypso-halophytes and psamo-halophytes. The ratio of C3to C4species (C3/C4ratio) is 0.2 in the psamo-halophytes, 0.8 in the gypso-halophytes, 1.1 in the xerophytes, 1.6 in the xero-halophytes, 1.8 in the hygrohalophytes, 2.0 in the psamophytes and 3.8 in the halophytes. The annuals are mainly C3plants whereas most of perennials are C4ones. The C3/C4ratio is 1.3 in succulent species and 1.4 in non-succulent species. Thus, succulence seems not to affect the distribution of C3and C4pathways within the studied plants. This investigation shows high percentages of C4plants in plants of Tunisian arid regions. However, there are significant differences in their abundance among ecotypes. Based on C3/C4ratio, the abundance of the C4pathway is in the following order: psamo-halophytes, gypso-halophytes, xerophytes, xero-halophytes, hygro-halophytes, psamophytes, halophytes. In Tunisian arid regions, C4species are most abundant in xerophytes and less abundant in halophytes. In the Chenopodiaceae the number of C3plants is 13 and the number of C4species is 20 and in the Poaceae the number of C3was 23 and the number of C4was 19 species. Thus, the most C4proportion is in the Chenopodiaceae and Poaceae species. This confirms the fact that the Chenopodiaceae and the Poaceae were the leading families that tolerate salinity and aridity.

Rhus tripartitum(Ucria) Grande leaves and fruits were investigated for their contents in phenolic compounds, essential oils, and fatty acids. Chemical composition and antioxidant potential of these secondary metabolites were investigated using chromatographic tools and different antioxidant tests. Results displayed high amounts of phenolic compounds in leaves, concomitant with important antioxidant potentialities, probably due to their richness in phenolic acids and flavonoids as identified by reverse phase high performance liquid chromatography (RP-HPLC). Amounts of essential oils were higher in leaves. Oxygenated sesquiterpenes are exclusively synthesized by the fruits, expressing better antioxidant activities.

The aim of this study was to assess the antioxidant and antimicrobial activities in vitro of 10 extracts of the halophyte Limonium delicatulumharvested in two physiological stages, flowering and vegetative, and to determine their phenolic compounds by reverse-phase high-performance liquid chromatography. The solvent and the physiological development stage significantly affected the quantity of phenols and the biological activity; the best antioxidant and antimicrobial activities and the most phenolic compounds were found at the flowering stage. Ethanol extracts had the most total antioxidant activity, while the acetone extracts had the greatest radical scavenging capacity (IC50=2μg/mL) and the methanol extract the best inhibition of β-carotene bleaching. The ethanol extract showed the highest total antioxidant activity (177mg gallic acid equivalents/g dry weight) and antibacterial activity, mainly against Salmonella(16mm inhibition diameter). The main phenolic compounds were p-coumaric acid and chlorogenic acid.

In the present study, we compared the response to salinity of three plants from Brittany coast with contrasted ecological status: Limonium latifolium(salt marshes), Matricaria maritima(beach tops and sand dunes) and Crambe maritima(fixed dunes). Under controlled glasshouse conditions, the growth of the three plants decreased with increasing external salinity. L. latifoliumand C. maritimaexhibited the highest and lowest resistance to severe salt stress (400 mM), respectively. M. maritimacould be considered as an intermediate species, since it tolerated salinity up to 200 mM. The same observation could be made with sodium absorption and acuumulation in plant tissues, the most tolerant species (L. latifoliumbeing the least Na accumulator. Hydrogen peroxide (H2O2) and malondialdehyde (MDA), commonly produced in conditions of stress, accumulated significantly in salt treated C. maritimaand M. maritimawhile not in the tolerant L. latifolium. The latter used glutathione reductase to maintain constant H2O2levels under salt stress while peroxidases were very low and ascorbate peroxidase did not respond to salinity stimulation. The medium tolerant halophyte M. maritimaused peroxidases to protect from NaCl-induced H2O2, while the sensitive C. maritimafailed to detoxify H2O2despite a sharp increase in catalase activity. Results showed that the three coastal species differ in resistance to salinity. They also suggested that the level of plant resistance to salinity could be attributed to differing mechanisms to manage the accumulation of sodium and cope with the oxidative damages.

The progressive salinization of arable lands at a rate of 3 ha min–1worldwide is a major concern for agricultural crop production. The future of crop improvement to resist or tolerate environmental stresses requires selecting halophytes that will produce high yield and profit. A halophyte, Sulla carnosa(Hedysarum carnosumDesf.), collected from southern and central Tunisia is considered a salt‐resistance species. A group of five populations represented by 150 genotypes (30 genotypes per population) were tested under greenhouse conditions with salt treatments 0 mM (control) and 300 mM (stressed). Fifteen agronomic traits related to vegetative and reproductive growth were evaluated for their responses to salinity stress. Analysis of the population effect and genotypes within population’s effect shows that both population and genotype factors have a significant effect for almost all measured traits. The highest diversity in traits was found within progeny originating from Douiret and Kairouan populations (mean and CV across the 15 traits 48.4 and 46.5%, respectively). Level of phenotypic differentiation (Q_ST) varied according to measured traits; it ranged from 0.108 for flowering time to 0.63 for mean crown width with an average of 0.29. Means comparison and principal component analysis showed that six genotypes from different origins were ranked as salt tolerant and three others as salt sensitive. These findings indicate the potential for selecting plants or traits with improved salt tolerance within that species. The method used allows detection plants or traits with enhanced salinity tolerance after 2 mo of growth for the ability to grow at salt concentrations that prevent the growth of other plants.

Since most vegetables are commonly consumed after cooking treatments, the aim of the current study is to investigate the impact of different processing on the polyphenolic contents and antioxidant properties of two edible, medicinal and salt tolerant species, Portulaca oleraceaand Salicornia fruticosa.Results showed that microwaving increased the total phenolic content of S. fruticosaby 25% and all processing treatments permitted the enhancement of total flavonoid contents of both species. The individual phenolic contents assessed by HPLC were significantly affected by the domestic cooking methods as well as the antioxidant properties of the two species. Principal Component Analysis revealed a large variation between cooking treatments according to the phytochemical contents. The steaming process permitted the retention of the antioxidant activity for S. fruticosaas evaluated by DPPH sacvenging activity and enhanced the ferric reducing capacity for the same species. Also, steamed P. oleracearevealed the best total antioxidant capacity. Cooked vegetables consumption could be recommended as a health promoting eating.

Sulla carnosa(Desf.) is a diploid (2n= 16), allogamous, seed‐propagated species and has a vegetative shoot system characterized by an orthotropic main stem bearing some lateral plageotropic shoots. It is of interest for rangeland revegetation and production. In this study, we analyzed the genetic diversity of five S. carnosapopulations using 15 quantitative traits and nine random amplified polymorphic DNA primers. A total of 14 and 41% of the total genetic variation was found among the populations for molecular and phenotypic traits, respectively (Gst= 0.14 and Qst= 0.41). Despite the relatively high level of gene flow among populations (Nm= 3.1 or 0.065 individuals per generation), results showed a significant isolation by distance. Correlations between characters as well as with climatic region were established. The most significant positive correlations were found between features related to plant strength, while the most significant negative correlations were found between the flowering time and traits related to plant strength. When correlated to climatic region, plant height (r= –0.75, P= 0.000) and flowering date (r= –0.71, P= 0.000) showed the most significant estimates, indicating a gradual variation of these phenotypic traits. These results suggest a prominent role for natural selection in accounting for patterns of genetic differentiation of quantitative traits among natural populations of S. carnosa.

The response patterns during water deficit stress and subsequent recovery of two forage species, Medicago truncatula and Sulla carnosa, were studied. After germination and pre-treatment, seedlings were individually cultivated for two months under two irrigation modes: 100% and 33% of field capacity. Measured parameters were plant growth, water relations, leaf osmotic potential, lipid peroxidation, and leaf inorganic (Na+ and K+) and organic (proline and soluble sugars) solute contents, as well as delta-1-pyrroline-5-carboxylate synthase (P5CS) and proline dehydrogenase (PDH) activities. Our results showed that under control conditions, and in contrast to roots, no significant differences were observed in shoot biomass production between the two species. However, when subjected to water-deficit stress, M. truncatula appeared to be more tolerant than S. carnosa (reduction by 50 and 70%, respectively). In the two studied species, water-deficit stress led to an increase in root/shoot ratio and leaf proline and soluble sugar contents, and a decrease in leaf osmotic potential. Enzymatic assay revealed that in the two species, P5CS activity was stimulated whereas that of PDH was inhibited under stress conditions. Despite greater accumulation of proline, sugar, and potassium in leaves of S. carnosa, M. truncatula was more tolerant to water deficit. This was essentially due to its capacity to control tissue hydration and water-use efficiency, in addition to its greater ability to protect membrane integrity. Following stress relief, M. truncatula and S. carnosa showed partial re-establishment of growth capacity.

AbstractThe embryo growth, endosperm degradation and in situactivity of peroxidase and esterase in seeds imbibed in distilled water or 200mM NaCl were investigated in the halophyte Crithmum maritimumL. Germination was maximal (90%) in distilled water, but was fully inhibited following seed exposure to salt. The completion of the embryo growth (ca. 2mm length) leading to the radicle emergence took 6 d in distilled, but was markedly delayed in 200mM NaCl. The endosperm degradation was markedly delayed by NaCl. Esterase and peroxidase activities were less important in NaCl-imbibed than in H2O-imbibed seeds. The adverse effect of salinity on the embryo growth and the endosperm degradation could partly explain the inhibition of seed germination observed under these circumstances.

The objective of this study was to determine more indepth physiological and antioxidant responses in two Medicago ciliaris lines (a salt-tolerant line TNC 1.8 and a salt-sensitive line TNC 11.9) with contrasting responses to 100 mM NaCl. Under salt stress, both lines showed a decrease in total biomass and in the growth rate for roots, but TNC 1.8 was less affected by salt than TNC 11.9 in that it maintained leaf growth even in the presence of added salt. In both lines, salt stress mainly affected micronutrient status (Fe, Mn, Cu and Zn) rather than K nutrition, but the tolerant line TNC 1.8 accumulated more Na in leaves and less in roots compared with TNC 11.9. Salt stress decreased total soluble sugars (TSS) in all organs of the sensitive line TNC 11.9, whereas TSS was only reduced in roots of the tolerant line. The salt-induced drop in growth was linked to an increase in lipid peroxidation in roots of both lines and in leaves of the sensitive line. The salt-tolerant line TNC 1.8 was more efficient at managing salt-induced oxidative damage in leaves and to a lesser extent in roots than the salt-sensitive line TNC 11.9, by preserving higher phenolic compound and superoxide dismutase levels in both organs.

In the Mediterranean region, difficult climate conditions and inadequate land management have led to a reduction of the organic matter content of soils. As a solution, municipal solid waste (MSW) compost and sewage (S) sludge were investigated for their effectiveness in maintaining soil fertility. Clayey-loamy soil was amended with 0, 40, and 80 t ha−1of MSW compost or S sludge and cultivated with Triticum durum. Soil was sampled 15 and 70 days after sowing, and the activities of arylsulphatase, phosphatase, dehydrogenase (DH), -glucosidase (-GLU), urease, and catalase (CAT) were assayed. The wheat was harvested after 68 days, then soil properties as well as plant growth and K+and Na+contents were determined.

AbstractThe changes in biomass production, root length, mineral nutrition, potassium absorption efficiency (KAE), and potassium use efficiency (KUE) of the halophytesCatapodium rigidumandHordeum maritimumin response to potassium availability were assessed under natural conditions. Plants were cultivated in the greenhouse of the experimental station of the Biotechnology Centre of Borj Cédria (a Mediterranean coastal area) 30 km south-east of Tunis for four months from the autumn to winter of 2007–2008.H. maritimumbiomass production was not significantly affected by the K+concentration, butC. rigidumgrowth was increased significantly with increasing K+concentration in the medium. Root/shoot dry weight ratio remained constant inC. rigidum, but decreased significantly at 1000 and 3000µM K+inH. maritimum.KAE increased but KUE decreased significantly with increasing K+concentration in the medium in both species. However, KAE was higher inH. maritimumthan inC. rigidumshowing a contrasting response to K+concentration between the two species. Overall, the maintenance of a cationic balance may be explained by cation antagonism. The lower K+requirement ofH. maritimumto express its optimal growth can be attributed to its higher efficiency to acquire and transfer K+to shoots.

Different loads of municipal solid waste compost (MSWC) were applied to hyper saline salt lake soil under laboratory conditions to monitor biological soil quality. Microbial biomass-C (MBC), catalase, dehydrogenase, urease, alkaline phosphatase, arylsulfatase, and β-glycosidase activities were analyzed following 14, 30, and 50 days of incubation. In general, MBC and the oxidoreductase and hydrolase enzyme activities were significantly enhanced by addition of MSWC at 20 and 40 t ha−1doses, but they decreased at 120 t ha−1. Overall, the results show that the addition of MSWC to hyper saline soils can improve soil biological quality, in spite of its high salt content, which is an important step in any attempt to use them as biosaline agricultural soils. However, substances such as heavy metals in MSWC could limit the use of compost for this purpose; consequently, analysis of MSWC is recommended prior to its use.

AbstractTwenty-six oil samples were isolated by hydrodistillation from aerial parts of Artemisia herba-albaAsso growing wild in Tunisia (semi-arid land) and their chemical composition was determined by GC(RI), GC/MS and 13C-NMR. Various compositions were observed, dominated either by a single component (α-thujone, camphor, chrysanthenone or trans-sabinyl acetate) or characterized by the occurrence, at appreciable contents, of two or more of these compounds. These results confrmed the tremendous chemical variability of A. herba-alba.

At maturation and during seed fall and dispersal, halophyte seeds may be subjected to invasion by salt ions. How these seeds remain viable in such hostile environments is however still unclear, depending for instance on the species and the family. In the Apiaceae, the mericarp (fruit) shows a wide range of morphological and anatomical modifications, many of which may enhance the adaptation to severe environmental conditions. Therefore, structural features, ion accumulation, and long-term floating capacity were investigated in the fruit (mericarp) of the halophyte Crithmum maritimum L. The mericarp was composed of a spongy outer coat, a secretory envelope, a thin endocarp reduced to a unicellular layer delimiting the endosperm, and an embryo. Both of the secretory canals and the endocarp adhered after complete ripening of the mericarp, while the epicarp and much of the mesocarp formed the spongy coat. Assessing long-term floating ability of the fruit under laboratory conditions revealed that even after 60 d, more than 98% of C. maritimum L. mericarps still floated over seawater. Seed germination was delayed and reduced by the spongy coat. The X-ray microanalysis revealed that the spongy coat and the secretory canals contained essentially Cl and Na, while seeds, i.e. endosperm and embryo, accumulated mostly Mg, K and P. In a subsequent experiment designed to simulate salt leaching by rain, most of the salt accumulated in the spongy coat and seeds was released after 2 h imbibition in distilled water. Taken together, these results highlight the protective role of the mericarp and the likely involvement of this structure in the seed dispersal of C. maritimum L. This may ultimately have eco-physiological implications explaining the successful establishment of this halophyte in its native saline biotopes.

Batis maritimais a promising halophyte for sanddune stabilization and salinesoil reclamation. This species has also applications in herbal medicine and as an oilseed crop. Here, we address the plant response to salinity reaching up to twofold seawater concentration 0–1000 mM NaCl, with a particular emphasis on growth, water status, mineral nutrition, proline content, and photosystem II integrity. Plant biomass production was maximal at 200 mM NaCl, and the plants survived even when challenged with 1000 mM NaCl. Plant water status was not impaired by the high accumulation of sodium in shoots, suggesting that Nacompartmentalization efficiently took place in vacuoles. Concentrations of Mg2and Kin shoots were markedly lower in salttreated plants, while that of Ca2was less affected. Solublesugar and chlorophyll concentrations were hardly affected by salinity, whereas proline concentration increased significantly in shoots of salttreated plants. Maximum quantum efficiency FvFm, quantum yield of PSII PSII, and electrontransport rate ETR were maximal at 200–300 mM NaCl. Both nonphotochemical quenching NPQ and photochemical quenching qP were saltindependent. Interestingly, transferring the plants previously challenged with supraoptimal salinities 400–1000 mM NaCl to the optimal salinity 200 mM NaCl substantially restored their growth activity. Altogether, our results indicate that B. maritimais an obligate halophyte, requiring high salt concentrations for optimal growth, and surviving longterm extreme salinity. Such a performance could be ascribed to the plant capability to use sodium for osmotic adjustment, selective absorption of Kover Nain concomitance with the stability of PSII functioning, and the absence of photosynthetic pigment degradation.

Salinity and low nitrogen availability are important growthlimiting factors for most plants. Our objective was to assess the influence of nitrogen N and salt levels on the growth and mineral nutrition of three forage grasses of varying salt resistance which are widely found in Tunisian salt lands, Aeluropus littoralis, Catapodium rigidum, and Brachypodium distachyum.Their response to salt and N interaction has not been studied and further investigations are necessary. Twenty day–old plantlets were hydroponically cultivated in Hewitts nutrient solution. Half the plants were then exposed to 100 mM NaCl and the other half to no NaCl, and N was supplied at 0.5 or 5.0 mM N as NH4NO3. Plants were harvested after 60 d growth. Saline treatment 100 mM NaCl decreased growth of B. distachyuma relatively saltsensitive plant, but no significant effect was noted for A. littoralisa relatively saltresistant plant in both low– and high–N availability treatments. However, the effect of 100 mM NaCl on growth of C. rigiduma moderately saltresistant plant depended on N level. Increasing N availability and NaCl did not influence phosphate, sulfate, calcium, and magnesium concentrations in both A. littoralisand C. rigidum, but increased N supply reduced shoot sodium and chloride Cl– accumulation. Potassium acquisition in A. littoralisand C. rigidumplants was severely depressed by increasing N availability under saline and nonsaline conditions, respectively. In these species, the increase of nitrate accumulation viaN was attenuated by salinity. In contrast, total N content and allocation toward shoots were enhanced in these conditions, especially in A. littoralis,the most resistant species. It appears that increasing N availability at moderate salt levels has a beneficial effect on growth of species with high and moderate salt resistance, but not on species with low resistance to salinity.

Growth, activity of antioxidant enzymes viz. glutathione reductase GR, superoxide dismutase SOD, catalase CAT, ascorbate peroxidase APX and guaiacol peroxidase GPX, and some metabolic processes related to ammonium metabolism were investigated in a salttolerant Spatina alterniflora.In comparison to 0 mM–NaCl treatment, growth of S. alternifloraplant increased significantly at 200 mM NaCl, but was highly inhibited at 500 mM NaCl. Ammonium concentration in the leaves and roots increased 2.1–3.4 times when plants were treated with 500 mM NaCl. Under 200 mM NaCl, antioxidantenzyme activities increased, however, at 500 mM the antioxidant system was unable to compensate reactive oxygen species induced by NaCl. At this high level of salinity, ammonium production through nitrate reductase NR was inhibited, but no significant changes in the activities of glutamine synthetase GS or glutamate dehydrogenase GDH were found. We conclude that the accumulation of ammonium under high salt stress was not due to inhibition of the assimilatory activities of GS or GDH. Ammonia accumulation under high salinity may result from amino acid and protein catabolism activated by reactive oxygen species ROS andor a lack of carbon skeletons to incorporate ammonium into organic molecules due to a decrease in photosynthetic activity in saltstressed plants.

Responses of proton release to phosphorus P availability by nodulated roots of common bean Phaseolus vulgarisL. were investigated for lines BAT 477 and CocoT, inoculated with Rhizobium tropiciCIAT 899 in hydroaeroponic culture under glasshouse conditions. Phosphorus was supplied as KH2PO4at 15 and 60 mol plant–1week–115P and 60P. Proton release was higher for BAT 477 than for CocoT under both P supplies. However, it was higher for 60P than 15P, whatever the line. The ratio of proton release per unit biomass of nodulated root was higher for BAT 477 than for CocoT, independent of P deficiency. Proton release was correlated with the nodulated-root respiration for both genotypes and with the nodule respiration linked with nitrogen fixation for CocoT. Thus, the nodulation was more limited by 15P than root and shoot growth and more in CocoT than in BAT 477. It is concluded that independent of symbiotic N2fixation, proton release was higher in BAT 477 than in CocoT and that the nodulated legume releases a substantial amount of protons into its rhizosphere that is correlated with its nitrogen fixation that eventually depends upon the nodule permeability to O2diffusion.

The interactive effects of salinity and potassium (K+) availability on biomass production, water status, and ionic composition were investigated in Hordeum maritimum, an annual grass growing natively on saline soils. Plants were grown for 7 weeks on Hewitt nutrient solution supplied with NaCl (0, 100, 150, 200, and 300 mM) combined with low (0.232 mM) or high (5.8 mM) K+ levels. Independent of potassium availability, dry matter of both roots and shoots decreased consistently with increasing NaCl levels in the culture medium, in association with a significant reduction of the shoot water content. This salt-induced growth reduction did not result from a restriction of K+ nutrition, since H. maritimum expressed similar growth under both low and high K+ supply. NaCl decreased shoot K+ concentrations. This effect was more pronounced in plants grown at high K+ supply than in plants grown at low K+ supply. This result suggests that the absorption systems were strongly selective for K+, and that this selectivity was enhanced by salt.

The present study compares the demands for P of the initial nodule formation, and of the later growth and functioning of the nodulated root system in two inoculated lines of common bean (Coco blanc and BAT477). After germination and inoculation, seedlings were divided into two lots. One lot was grown under constant P supply, either 15 (low) or 250 (high) µM P, corresponding to provision of 120 and 2000 µmol P, respectively. In the second, seedlings were cultivated on the same medium supplied with 15 µM P for 24 days after germination, and then with 60 or 250 µM (total provision of P: respectively, 390 and 1530 µmol). Nodule number and biomass were significantly diminished by the low P (120 µmol) treatment, as compared with the other treatments. However, the intrinsic characteristics of the nodules (individual biomass and size, P concentration and efficiency of N fixation) did not depend on P availability. Although the bean line BAT477 was distinguished from the Coco blanc line through higher nodule number, size, biomass, and nitrogen fixation, both lines displayed analogous responses to P availability.

The growth of the halophyte Sesuvium portulacastrum, commonly known as sea purslane, is impeded by NaCl only at high (600–1000 mM) concentration. Therefore, the goal of this investigation was to identify the mechanisms which set the limit of the salt resistance of S. portulacastrum. 21-day-old cuttings were grown for 45–50 d under split-root conditions in which one half of the root system was immersed in complete nutrient solution supplemented with 800 mM NaCl, while the other half was immersed in a NaCl-free medium, containing all nutrients or being deprived of potassium or calcium or nitrogen. Using this approach, we demonstrate that K+ and N uptake was impaired in roots exposed to NaCl. Concerning Ca2+, there was no indication of uptake inhibition by NaCl. However, restriction of K+ uptake by roots was compensated by an increase in the K+-use efficiency, so that growth was not inhibited. Concerning N, our analysis shows that NO$ _3^- $ and/or NH$ _4^+ $ uptake, but not their assimilation, was limited by salt treatment. Thus, we conclude that at high salinity levels, the growth of S. portulacastrum is limited by the restrictions imposed by NaCl on N uptake, perhaps in addition to inhibiting effects of excessive Na+ accumulation in shoot.

Several studies suggest that the Fabaceae-Rhizobium symbiosis is particularly sensitive to iron (Fe) deficiency with respect to NO3^–-dependent plants. The aim of this study, which is part of a screening program for common bean tolerance to Fe deficiency, was to study genotypical differences in Fe requirement and Fe use-efficiency of common bean cultivars depending on symbiotic nitrogen fixation (SNF). Results show that ARA14 produces more whole plant dry matter and particularly more nodule biomass than Coco blanc. ARA14 is characterized by a high capacity of nitrogen fixation and a better Fe use-efficiency for the growth and the function of the nodules.

The common bean (Phaseolus vulgaris L.) is often subject to various environmental constraints in the soil. One of these constraints is salinity which is a major limitation for grain legumes yield, especially when the plant growth depends upon N$_2$ fixation. In order to confirm the variability of the response to moderate salinity, and identify the morphological and physiological criteria associated with tolerance, 9 common bean lines (BAT477, Coco blanc, DOR585, ABA16, NAG310, Flamingo, BRB17, Candide and Striker) were inoculated with Rhizobium tropici CIAT899, and grown in a glasshouse with or without 25 mM NaCl on sterilized sand. A genotypic variation in tolerance to salt was found: ABA16 and BRB17 were the most sensitive lines whereas BAT477 and Flamingo were the most tolerant. The estimated parameters of growth and symbiotic nitrogen fixation showed that (i) some lines which exhibited vigorous growth under the control treatment were greatly affected by salt treatment, (ii) the relative tolerance of some lines to salt seems to depend on the ability to maintain an adequate leaf area and to develop an abundant and efficient nodular system.

Nodulation and growth of nodules in the common bean (Phaseolus vulgaris) under salt stress. In order to determine the respective parts of the nodulation and the growth of nodules in the decrease of the nodule dry matter observed in common beans exposed to salinity, the following experiment was carried out. After germination, plants inoculated with an efficient strain of Rhizobium CIAT899 were grown in salt free medium or one containing 25 or 50 mM NaCl. In another treatment, plants were submitted later (after nodulation, 28 DAS) to 25 mM NaCl. Salt decreases the different parameters of growth. However, its effects were more pronounced in plants with early exposure to salt. The nodule DW and, to a lesser degree, growth of roots were the most affected. The mean number of nodules per plant was systematically less affected by salt than nodule DW. Also, the number of nodules per unit of root DW was generally the same or even larger in plants submitted to salt than controls. These results showed that the decrease of the nodule DW in the presence of salt is owed to an inhibition of the infection resulting more from a limitation of root growth than from a low predisposition of these organs to the infection and to a reduction of the nodule growth resulting from a restriction of the feeding of these organs with photosynthetates. This last parameter seems especially sensitive to salt.

Recent studies suggest that tocopherols could play physiological roles in salt tolerance but the mechanisms are still unknown. In this study, we analyzed changes in growth, mineral and oxidative status in vte1and vte4 Arabidopsis thalianamutants exposed to salt stress. vte1and vte4mutants lack α-tocopherol, but only the vte1mutant is additionally deficient in γ-tocopherol. Results showed that a deficiency in vitamin E leads to reduced growth and increased oxidative stress in hydroponically-grown plants. This effect was observed at early stages, not only in rosettes but also in roots. The vte1mutant was more sensitive to salt-induced oxidative stress than the wild type and the vte4mutant. Salt sensitivity was associated with (i) high contents of Na+, (ii) reduced efficiency of PSII photochemistry (Fv/Fmratio) and (iii) more pronounced oxidative stress as indicated by increased hydrogen peroxide and malondialdeyde levels. The vte 4mutant, which accumulates γ- instead of α-tocopherol showed an intermediate sensitivity to salt stress between the wild type and the vte1mutant. Contents of abscisic acid, jasmonic acid and the ethylene precursor, 1-aminocyclopropane-1-carboxylic acid were higher in the vte1mutant than the vte4mutant and wild type. It is concluded that vitamin E-deficient plants show an increased sensitivity to salt stress both in rosettes and roots, therefore indicating the positive role of tocopherols in stress tolerance, not only by minimizing oxidative stress, but also controlling Na+/K+homeostasis and hormonal balance.

Literature on the separate effects of salinity and inadequate Fe supply on plant growth and nutrient uptake, concentration, and distribution is abundant but little is known about the interactive effects of these two abiotic constraints. Here, we investigated the interactive effect of iron availability and salinity on physiological responses of cultivated and wild barley (Hordeum vulgare and H. maritimum resp.). Seedlings of both species were grown for 9 days, under complete nutrient solution with or without iron supply. Then, NaCl treatment was applied at different concentrations (0, 100, 200, and 300?mM) for 60 hours. After salt exposure, shoot water content of H. vulgare was significantly reduced as compared to H. maritimum. Furthermore, Na+ accumulation in shoots increased parallel to increasing NaCl concentration in the medium. However, the increase was significantly higher in H. vulgare than in H. maritimum. These responses were associated with lower Fe absorption efficiency photosynthetic parameters in both species. The reduction was significantly higher in cultivated than in wild barley. Moreover, phytosiderophore exudation was enhanced in both species by direct (iron free medium) or indirect iron limitation (salt-induced iron limitation). Such a stimulation of phytosiderophore release was genotype and salt level dependant.