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It is difficult to determine the photosynthetic parameters of non-flat leaves/green stems using photosynthetic instruments, due to the unusual morphology of both organs, especially for Suaeda salsa and Salicornia bigelovii as two seawater-tolerant vegetables. To solve the problem, we developed a simple, practical, and effective method to measure and calculate the photosynthetic parameters (such as P, g, E) based on unit fresh mass, instead of leaf area. The light/CO/temperature response curves of the plants can also be measured by this method. This new method is more effective, stable, and reliable than conventional methods for plants with non-flat leaves. In addition, the relative notes on measurements and calculation of photosynthetic parameters were discussed in this paper. This method solves technical difficulties in photosynthetic parameter determination of the two seawater-tolerant vegetables and similar plants. [ABSTRACT FROM AUTHOR]

Cytokinins and cell wall invertase are positive players in regulating fruit sink strength, growth, and yield under salinity as components of the same signalling cascade establishing and developing sink organs.Salinization of water and soil has a negative impact on tomato (Solanum lycopersicum L.) productivity by reducing growth of sink organs and by inducing senescence in source leaves. It has been hypothesized that yield stability implies the maintenance or increase of sink activity in the reproductive structures, thus contributing to the transport of assimilates from the source leaves through changes in sucrolytic enzymes and their regulation by phytohormones. In this study, classical and functional physiological approaches have been integrated to study the influence of metabolic and hormonal factors on tomato fruit sink activity, growth, and yield: (i) exogenous hormones were applied to plants, and (ii) transgenic plants overexpressing the cell wall invertase (cwInv) gene CIN1 in the fruits and de novo cytokinin (CK) biosynthesis gene IPT in the roots were constructed. Although salinity reduces fruit growth, sink activity, and trans-zeatin (tZ) concentrations, it increases the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) during the actively growing period (25 days after anthesis). Indeed, exogenous application of the CK analogue kinetin to salinized actively growing fruits recovered sucrolytic activities (mainly cwInv and sucrose synthase), sink strength, and fruit weight, whereas the ethylene-releasing compound ethephon had a negative effect in equivalent non-stressed fruits. Fruit yield was increased by both the constitutive expression of CIN1 in the fruits (up to 4-fold) or IPT in the root (up to 30%), owing to an increase in the fruit number (lower flower abortion) and in fruit weight. This is possibly related to a recovery of sink activity in reproductive tissues due to both (i) increase in sucrolytic activities (cwInv, sucrose synthase, and vacuolar and cytoplasmic invertases) and tZ concentration, and (ii) a decrease in the ACC levels and the activity of the invertase inhibitor. This study provides new functional evidences about the role of metabolic and hormonal inter-regulation of local sink processes in controlling tomato fruit sink activity, growth, and yield under salinity. [ABSTRACT FROM AUTHOR]

Mangroves are highly adapted to extreme environmental conditions that occur at the interface of salt and fresh water. Adaptations to the saline environment during germination are a key to mangrove survival, and thereby, its distribution. The main objective of this research was to study the effect of salinity on seed germination of selected mangrove species and the application of a hydrotime model to explain the relationship between water potential of the medium and rate of seed germination. Germination of seeds was examined at 15, 25 and 35°C in light/dark over a NaCl gradient. Germination time courses were prepared, and germination data were used to investigate whether these species behave according to the principles of the hydrotime model. The model was fitted for the germination of Acanthus ilicifolius seeds at 25°C. Final germination percentage was significantly influenced by species, osmotic potential and their interaction at 25°C. Moreover, temperature had a clear effect on seed germination (Sonneratia caseolaris and Pemphis acidula) which interacted with osmotic potential. Only A. ilicifolius seeds behaved according to the hydrotime principles and thus its threshold water potential was –1.8 MPa. Optimum germination rates for seeds of the other species occurred at osmotic potentials other than 0 MPa. The descending order of salinity tolerance of the tested species was Aegiceras corniculatum > Sonneratia caseolaris > Acanthus ilicifolius > Pemphis acidula > Allophylus cobbe , suggesting that the viviparous species (A. corniculatum) is highly salt tolerant compared with the non-viviparous species. The results revealed that seeds of the study species exhibited facultative halophytic behaviour in which they can germinate over a broad range of saline environments. Use of a hydrotime model for mangroves was limited as germination of their seeds did not meet model criteria. [ABSTRACT FROM AUTHOR]

Two Safflower (Carthamus tinctoriusL.) cultivars' seeds were used to study the influence of inoculation with mycorrhiza arbuscular fungi under salinity stress condition. Factorial experiment based on completely randomized design (three-way analysis of variance (ANOVA)) with 3 replications was used. Salinity treatment with 3 levels (0.5, 6, and 12 dS/m) and mycorrhizal arbuscular inoculation with two species (three levels consist of non-inoculation, and inoculation with Glomus intraradices and G. moseae) were applied on two cultivars of safflower (Goldasht and Padide) in this experiment. Some important biochemical, mineral, and growth traits were measured in this study. Salinity had a significant negative effect on all growth and morphological parameters including shoot and root dry weight, stem and root height. On the other hand, colonized plants showed better growth parameters under saline conditions compared with the control. The colonization of both mycorrhizal species decreased with salinity. Sugar and pigment content decreased with salinity, but their levels in colonized plants under saline conditions were higher than that in non-colonized plants. Mineral elements including phosphorus (P), nitrogen (N), and magnesium (Mg) were higher in colonized plants, while salinity decreased the absorption of these elements in both inoculated and non-inoculated plants. Higher activity of the enzymatic antioxidant means higher removal of these compounds and higher resistance to stress condition. Overall, it is clear that salinity had a negative effect on both cultivars of safflower, but these negative effects were lower in inoculated plants than in the non-inoculated ones; so, the use of mycorrhizal inoculation is a proper way to control the effect of salinity and maintain plant production. [ABSTRACT FROM AUTHOR]

We investigated the dimorphic perianth colour of Salsola vermiculata and its association with seed germination percentage, interactions with temperature, light, salinity and recovery from prior salinity exposure. Seeds with and without pink and yellow perianth were incubated at three thermal regimes, two photoperiods, and five salinity levels. Germination recovery after salinity exposure was observed on seeds that failed to germinate during the salinity study. The germination percentage and rate were significantly related to the perianth colour, the presence of perianth wings, thermal regimes and photoperiod. The presence of a perianth wing significantly reduced germination percentage and germination rate in both the pink and the yellow morph, but the yellow morph exhibited a higher germination percentage. Perianth wing removal increased germination in saline conditions. With the perianth removed, germination recovery was higher for the pink morph than for the yellow one. We suggest that by providing two different strategies for balancing germination with dormancy during favourable conditions, the presence of two morphs makes S. vermiculata more successful in highly unpredictable desert environments. [ABSTRACT FROM AUTHOR]

In the present study, a total of 70 Trichoderma spp. were isolated from the rhizosphere soils of vegetable and spice crops that were grown in Andaman and Nicobar Islands, India. Initial screening of Trichoderma spp. for salt tolerant properties showed 32 isolates were able to tolerate 10% NaCl. Furthermore, these isolates were screened for their potential plant growth-promoting characteristics such as IAA production, phosphate solubilization, and siderophore production. Among 32 isolates, nine isolates were able to produce IAA, siderophore, and solubilize phosphate. Jar trial was carried out on maize under axenic conditions at 1.67, 6.25, 11.25, 17.2, and 22.9 dS m−1 salt stress using the best nine isolates. Three isolates (TRC3, NRT2, and THB3) were effective in improving germination percentage, reducing reduction percentage of germination (RPG) and also in increasing the shoot and root length under axenic conditions. These three isolates were further tested under pot trial at 52 (sea water), 27, 15, 7, and 1.67 dS m−1. TRC3 was found to be the most effective isolate compared to the other isolates and significantly increased the physiological parameters like shoot, root length, leaf area, total biomass, and stem and leaf fresh weight at all stress levels. Similarly, total chlorophyll content also increased by TRC3 over control. All three isolates, NRT2, TRC3, and THB3 showed lower accumulation of malondialdehyde (MDA) content whereas, proline and phenol content were higher than the uninoculated control plants under both normal and saline conditions. The results suggest that these isolates could be utilized for the alleviation of salinity stress in maize. [ABSTRACT FROM AUTHOR]

Background and aims: Irrigated olives are increasingly exposed to conditions of high salinity. Salt tolerance of olives is commonly attributed to ion exclusion. Our objective was to advance understanding of salt stress response of olive roots. Methods: Nine levels of root zone salinity originating from either irrigation water salinity or leaching level were applied to bearing olive cv. Barnea trees grown in large weighing-drainage lysimeters. Minirhizotrons were used to measure count, diameter, length and age (color) of roots while analysis of sampled roots and leaves quantified ion uptake and accumulation. Results: Increased exposure to salinity caused reduction in number and length of roots and increased root turnover. The most drastic effects occurred at the first level of salt gradient. Concentration of Na and Cl was 5-10 times greater in root compared to leaf tissue. The K/Na ratio decreased tenfold as root zone salinity increased in both roots and leaves. Conclusions: Restricted ion transport from roots protected aerial tissue from ion toxicity, but at a high cost as root growth decreased and mortality rate increased. We suggest that the ionic component of salt stress is a prevailing force restricting root growth, life span and development in olives. [ABSTRACT FROM AUTHOR]

Salinity and nitrogen are two important environmental factors that affect the distribution of halophytes in their natural saline habitats. Seeds of the euhalophyte Suaeda salsa L. were harvested from plants that had been treated with 1 or 500 m m NaCl combined with 0.5 or 5 m m NO3−- N (nitrate) for 115 days in a glasshouse. Germination was evaluated under different concentrations of NaCl and nitrate. Plants exposed to high salinity (500 m m) and low nitrate (0.5 m m) tended to produce heavy seeds. Either high salinity (500 m m) or high nitrate (5 m m) increased the brown/black seed ratio. The concentrations of Na+, K+, and Cl− were higher in brown than in black seeds, and NO3− concentrations were higher in black than in brown seeds, regardless of NaCl and nitrate treatments during plant culture. Regardless of NaCl and nitrate concentrations during germination, seeds from plants grown with 0.5 m m nitrate generally germinated more rapidly than seeds from plants grown with 5 m m nitrate, and the difference was greater for black than for brown seeds. Exogenous nitrate during germination enhanced the germination of brown seeds less than that of black seeds. Producing more brown seeds and heavy black or brown seeds appears to be an adaptation of S. suaeda to saline environments. Producing more black seeds, which tend to remain dormant, should reduce competition for nitrogen and appears to be an adaptation to nitrogen-limited environments. In conclusion, nitrate provided exogenously or by mother plants to black seeds may act as a signal molecule that enhances the germination of black S. suaeda seeds. [ABSTRACT FROM AUTHOR]

The shortage of good quality water resources is becoming an important issue in arid, semi-arid, and coastal zones. Sugar beet yield declines with an increase in salinity, but its sensitivity to salts varies with the salt composition in water and the plant growth stage. The possible use of Caspian Sea water, which its salinity is well below that of open seas, is desirable for irrigation. The aim of this study was to determine effects of various Caspian Sea water regimes on sugar beet seed germination. A randomized complete block (RCB) design was used with four replications of 15 seeds per pot. Eleven different irrigation treatments of Caspian Sea water ranging from 0% to 100% were applied that each treatment indicates the percent of Caspian Sea water to the mixture with the fresh water. Seed germination percent and the mean time to germination data were obtained for 30 days. Statistical analysis revealed that seed germination was significantly affected by Caspian Sea water, particularly by the salinity levels above the electric conductivity (EC) 13 dSm−1. [ABSTRACT FROM AUTHOR]

The dehydration responsive element binding (DREB) transcription factor (TF) family comprises unique and important proteins involved in abiotic stress responses and tolerance in plants. Although DREB TFs have been well identified and characterized in a few model plants, there is no detailed information available for mulberry. In this study, 110 AP2/ERF family genes were identified based on a genome-wide analysis of the Morus genome database. Among them, 30 Morus notabilis DREB family genes ( MnDREBs) were identified. A comparative analysis with DREB gene families from other plants suggests that MnDREBs could be divided into six subgroups (A-1 to A-6) and could have similar functions in response to abiotic stresses since they have similar conserved domains/motifs within each subgroup. The expression patterns of MnDREBs were analyzed using transcriptome data of different organs from M. notabilis and the quantitative real-time polymerase chain reaction. The expression of most MnDREBs was detected in different organs and induced by various abiotic stresses, which suggest their vital roles in abiotic stress tolerance. [ABSTRACT FROM AUTHOR]

Mid- to high-latitude fjordic coastal environments experience naturally variable salinity regimes. Climate projections suggest that freshwater input into the coastal ocean will increase in the future, exposing coastal organisms to further periods of reduced salinity. This study investigated the effect of low salinity on Lithothamnion glaciale, a red coralline alga found in mid- to high-latitude fjordic regions, during a 21-day experiment. Specific measurements included: the intracellular concentration of dimethylsulphoniopropionate (DMSP, an algal secondary metabolite and major precursor to the climatically active gas dimethylsulphide), pigment composition and photosynthetic characteristics. No significant difference in intracellular DMSP concentrations was observed between treatments, suggesting that the primary function for DMSP in L. glaciale is not as a compatible solute, perhaps favouring an antioxidant role . Photosynthetic parameters (including pigment composition) exhibited a mixed response, suggesting some degree of photosynthetic resilience to reduced salinity. This study provides evidence of intracellular mechanisms adopted by L. glaciale in response to reduced salinity. This has significant implications for the survival of L. glaciale under a projected freshening scenario and provides organism-level detail to ecosystem-level projected changes should lower-salinity conditions become more frequent and more intense in the future. [ABSTRACT FROM AUTHOR]

Salinization and alkalization are worldwide problems of soil. To compare the effects of saline-alkaline stress on seedling growth between rice mutant and its wild type, we selected NaCl, Na2CO3 and NaHCO3 to simulate saline-alkaline stress, respectively, and selected two rice materials, ML04 is rice mutant and G19 is its wild type. Under saline-alkaline stress, the rice biomass sharply decreased, and the shoot fresh weight of ML04 was higher than that of G19. The saline-alkaline stress promoted the rice taking up Na+ but inhibited absorbing K+ in shoots. The Na+ and K+ contents under the alkaline stress were much more than those of under saline stress, and the Na+ content of ML04 was higher than that of G19 under alkaline stress treatments. The saline-alkaline stress reduced the root numbers (RN), total root length (TRL), root surface area (RSA), root volume (RV) and shoot length, but increased the Na+/K+ ratio and the root diameter (RD). And all these root indices of ML04 were higher than G19 under alkaline stress treatments. The high pH of alkaline salt stress might be an important reason for the severe damage to rice root system, which further limited the rice aboveground parts growth. In conclusion, the saline-alkaline stress inhibited the rice seedling growth, and most of the indices showed that the rice mutant (ML04) was much more tolerant to alkaline stress than its wild type (G19). [ABSTRACT FROM AUTHOR]

Mangroves are distributed along tropical and subtropical riverine and coastal shores. Although mangroves are highly adapted to saline environments, maintaining water uptake under saline conditions is energetically expensive. Therefore, salinity is a limiting factor for mangrove growth and productivity, and access to fresh water sources, such as rainwater and groundwater, which reduce water salinity, increase mangrove ecosystem productivity. Here, we investigated the extent of fresh water utilization by mangroves to better predict current and future mangrove productivity. We used the abundance of O isotope in stem water to assess: (1) the extent of fresh water utilization by Avicennia marina (Forssk.) Vierh across hydrological settings; and (2) whether growth, measured as increments in stem circumference, is sensitive to variation in rainfall availability. The δO isotopic composition of stem water indicated mangroves use both fresh and saline water sources for metabolic processes. However, our results suggest that the proportion of fresh water used by mangroves increases with the availability of fresh water. Growth of the main stems of trees was correlated with rainfall ( r = 0.34 and r = 0.37, P = 0.001). Our results indicate that access to fresh water is important for mangrove productivity because it enhances their growth rates. [ABSTRACT FROM AUTHOR]

A field experiment with two sets, each comprising 13 chickpea genotypes with three replications was carried out during Rabi 2012-2013 in stress and non-stress conditions. The objective of the reported research was to study the response of chickpea genotypes in drought stress and to screen the appropriate genotypes performing better in water deficit and irrigated conditions. Three genotypes TG1203, TG1221 and TG1219 exhibited best drought tolerance efficiency (92.74, 92.33 & 88.0%), good harvest index (51.6, 50.91 & 49.15%), least drought susceptibility index (0.49, 0.52 & 0.81), and minimum reduction in seed yield (7.26, 7.67 & 12.06%) in stress environment. With better yield stability, these genotypes would be recommended as drought tolerant under stress environment. [ABSTRACT FROM AUTHOR]

Basil (Ocimum Basilicum) seedlings were subjected to 0,5%,10%,20% and 40% seawater for 10 days under shade house conditions. Increasing seawater concentration led to considerable reduction in plant dry matter accumulation. However, root growth was not affected till treated with 40% seawater. Accumulations of Na+ and Cl- were correlated with decline of Ca2+ and K+ in stems, roots or both. Contents of Ca2+ and K+ in leaves increased or remained relatively unchanged with increasing salt levels. In salinity-stressed plants, Na+ were partitioned mainly in roots and more than 50% of the K+ and Ca2+were stored in leaves. Higher K+/Na+ and Ca2+/Na+ ratios in leaves rather than in roots and stems were observed in Basil plants. Scanning electron microscopy coupled with X-ray microanalysis showed that Basil leaf gland secretions contained Na+ and Ca2+. The Na+ secretion increased while Ca2+ secretion decreased with the increasing seawater concentration. These results suggested that Basil salt tolerance is associated with the compartmentation of Na+ in roots and the balance of K+, Na+ and Ca2+ in leaves as well as the salt secretion by the leaf glands. [ABSTRACT FROM AUTHOR]

A short-term experiment was conducted to investigate whether the effect of rootstock on plant response to salinity depends on the solanaceous species used as scion. Tomato cv. ‘Ikram’ and eggplant cv. ‘Black Bell’ were grafted onto two tomato interspecific hybrids (‘Beaufort’ and ‘He-Man’). Plants were grown in an open soilless cultivation system and supplied with two nutrient solutions: non-saline control and a saline solution (adding 15 mM Na2SO4, 3.7 dS m−1). Plant dry biomass production and partitioning were influenced by salinity, but its effect was depending on the rootstock/scion combination. ‘Beaufort’ eliminated the deleterious effect of salinity when tomato was used as scion, but reduced (−29.6%) the shoot biomass of eggplant. ‘He-Man’ had a different effect on scion growth under saline conditions: shoot biomass was less reduced in eggplant (−20.6%) than in tomato (−26.8%). Under salt stress, ‘Beaufort’ reduced the accumulation of Na+in tomato leaves more than in eggplant, whereas no differences were observed between tomato and eggplant grafted onto ‘He-Man’. Stem Na+accumulation followed a different pattern. The increase of Na+in the stems was similar for tomato and eggplant grafted onto ‘Beaufort’, whereas stems of tomato accumulated more Na+compared to eggplant grafted onto ‘He-Man’. The opposite response of the tested rootstocks to salt stress when the scion was either tomato or eggplant seems to be partially related to the capacity of the rootstock and scion to exclude Na+from the shoot. However, the results of nutrient accumulation within plant tissues imply that other mechanisms in addition to ion competition are involved in the salt resistance of grafted plants. [ABSTRACT FROM PUBLISHER]