[en] Highlights: • Relative abundances of ARGs and MGEs decrease during salt accumulation. • Decrease of Actinobacteria contribute to ARGs decline. • High salinity promote elimination of resistant plasmids. • High salinity hinder conjugation transfer of resistant plasmids. -- Abstract: Salt accumulation on the surface of the soil layer driven by the strong evaporation is a natural phenomenon that usually happens in the dry season, particularly on the coastal lands reclaimed from tidal flats. However, the influence of salt accumulation on the distribution profile of antibiotic resistance genes (ARGs) and mobile gene elements (MGEs) remains unclear. In this study, we sampled a wild saline soil where the salt accumulation was frequently observed to investigate the vertical distribution profiles of ARGs and MGEs. The results showed that an increasing gradient of ARGs and MGEs was observed from the top to deep layer with the decreasing of electrical conductivity (EC1:5 values) indicating the salt-influenced attenuation of ARGs in the saline soil. The competing test suggested that the attenuation of ARGs in response to salinity gradient was attributable to the elimination of the ARG-harboring plasmids, due to the reduction of the relative fitness of plasmid-harboring strains. Additionally, the network analyses showed that the attenuation of ARGs might be associated with decreased abundance of Actinobacteria. Overall, this study identifies that salinity as an abiotic stress could re-shape the distribution of ARGs, which may influence the dissemination of ARGs in the environment.

[en] Germination is one of the most important stage for the development of plants. One of the factors affecting germination is salt stress. All over the world due to increasing drought and semi-drought conditions most plants face salinity in soil. In this study, ecophysiological responses of Solanum lycopersicum “Marmande” seeds under different NaCl concentrations (% 0.5, 1, 2, 50 mM, 100 mM, 150 mM, 0.25 M, 0.45 M) were studied. Germination percentage, germination rate, total biomass, root length, green pixels and salt tolerance index (STI) were measured. The highest germination percentage and rate were observed in 0.5 % NaCl application (97.5%; 79.59) and the lowest were in 0.45 mM NaCl (2.5%; 5.88). Biomass, root length and STI reached the highest value at 50 mM NaCl application (respectively 460, 67 kg/ha, 11, 96 cm, 1,142). The biomass, root length and STI value of 2%, 0,25 M and 0,45 M NaCl applications were very low (respectively 0.001 kg/ha, 0.01, 0.001). There was no seedling development for green pixel count for 2%, 0,25 M and 0.45 M NaCl applications so the value was equal to 0, but other NaCl applications resulted in homogenic groups statistically. (author)

[en] Under inappropriate environments, plants responses by changing their metabolisms to maintain homeostasis that acclimation abilities are different among species and varieties. Saline tolerance tomato is an alternative way to overcome saline soil condition of some areas in Thailand. This study aims to select one or some saline tolerance tomato varieties from mostly used commercial ones. Six tomato variety seeds (Pethlanna, Puangphaka, Seeda, Beefeater, Seeda chompoo and TE VF 1-3-4) were grown by tissue culture technique in MS medium and MS medium supplied with 0, 5, 10, 25 and 50 mM NaCl. The Puangphaka variety was selected since it could grow in all tests NaCl concentrations with best germination time compared to the others cultivar seeds and exhibited 80-90% growth compared to control group. The seedlings were further cultivated in the same medium for 7, 14 and 21 days before they were conducted to determine stem and root superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activities as well as amount of chlorophyll. It was found that the SOD, CAT and GPx exhibited increase and decrease trends nearly the same pattern in salinity responses but with different activity levels. Inhibition of nutrient uptake could also be seen from the results. The maximum activities were 5, 0.18, 0.08, 2 and 3 U/mg protein for stem SOD, stem CAT, root CAT, stem GPx and root GPx, respectively. Furthermore, the chlorophyll A and B levels were decrease slightly except for the 21 days plants which presented considerable decrease. (author)

[en] The seed bank of salinized soil is a valuable germplasm resource for plant salt tolerance research. The study collected 468 soil samples from plant communities of 5 subtypes and 13 soil genera in saline-sodic badland of northwest China in spring, summer, and autumn, 2015, respectively. The seed from the soil samples was germinated in lab and species were identified. There were 34 species from 14 families and 31 genera that mainly belong to Chenopodiaceae, Gramineae, and Compositae. However, identification of the above ground vegetations found that there were 21 species from 9 families and 19 genera that mainly belong to Chenopodiaceae and Poaceae. The difference in species between the above ground vegetation and the soil seed bank was mainly in herbaceous plants, which had strong adaptability to salinity and alkalinity. The soil seed reserves were small and simple in species composition, with most species being indicator halophytes of desert. In spring, summer, and autumn, soil seed densities in the 5 subtypes of saline soil decreased in the order of meadow solonchaks > orthic solonchaks > dry solonchaks > bog solonchaks > alkalized solonchak. However, there was no significant difference in soil seed density between spring, summer and autumn. Soil seed bank showed a significant vertical hierarchy. The correlation between soil seed bank and aboveground vegetation is small in salinized and arid regions. (author)

[en] To investigate the effect of equilibrating time on phosphate adsorption and desorption on saline sodic soils a study was carried using three soil series from Dera Ismail Khan (Pakistan) district, namely Zindani, Tikken and Gishkori. These soils are alkaline calcareous in nature with greater Electrical Conductivity (EC) and Sodium Adsorption Ratio (SAR) values which classify them as saline sodic soils. The equilibrating time for the adsorption study was 8, 12, 16, 20, 24, 48 and 72 hours for two levels (5 mg L/sup -1/ and 100 mg L/sup -1/). For desorption study 1, 2, 3, 4 and 5 hours after 24 hours for low and high dilution. Adsorption and desorption isotherms of phosphate were developed for these soils. The Gishkori soil showed the greatest rate of adsorption as compared with the other two soils. Applying Langmuir and Freundlich models to P adsorption data revealed that Freundlich equation (R2 = 0.99) showed a better fit over the Langmuir equation (R2 =0. 97) in the three soils. The desorption curves varied similarly from each other. The amount of P adsorbed was different from that released back to the soil solution. The amount of adsorption increased with the time. Statistical analysis showed that the rate of adsorption for both 5 and 100 mg P L/sup -1/ was significantly different at P<0.05 at 16 and 20 hours and at P<0.01 beyond 20 hours. However, the rate of desorption was not significantly influenced by the equilibrating time as compared with the theoretical values of the three series. As the P - desorption curve did not coincide the P - adsorption curve, hence the availability of P to plant was adversely affected on its application. (author)

[en] The current study reported the agro-morphological evaluation of 31 barley accessions for salt tolerance at the maturity stage. Plant dry weight, tiller number, tiller length, spike number, spike length, awns length, grain number per row, grain number per spike, grain number per plant, grain weight, and thousand-kernel weight were determined after long-term salt treatments (0, 100, and 200 mM NaCl). Accessions, having different responses to salinity, were assessed through eleven agro-morphological traits. Agglomerative hierarchical classification showed three clusters. Among the tolerant cluster, Kebilli 2 and Tozeur 2 appeared the most promising accessions, and they showed the highest dry weights under control and saline conditions. Equally, they showed the most productive accessions in terms of spike number per plant, grain number per plant, and total grains weight per plant under control and salt conditions. Principal component analysis revealed that for the promising accessions, Kebilli 2 and Tozeur 2, the first both factorials explaining more than 72% of variance were related to plant dry weight, total grain weight, and spike and awn lengths. Therefore, Kebilli 2 and Tozeur 2 are highly recommended for culture in saline soils and use in hybridization programs to develop salinity-tolerant varieties.

[en] Naturally grown populations of Halophytic grass Dichanthium annulatum were collected from saline habitats for the evaluation of structural and functional adaptations in saline soils. Different populations of D. annulatum showed various adaptations i.e. decreased shoot length and shoot fresh weight, increased root length and root fresh weight in highly saline habitats. Increased epidermal thickness and cell area, enlarged storage parenchyma, broader metaxylem vessels, enhanced pith and phloem area observed in roots of highly saline populations. Thickest stem, well developed metaxylem vessels and broader cortical region was seen under severe salinity. Accumulation of organic osmotica i.e. Glycine betaine, proline, total soluble sugars and total soluble proteins contributed significantly to endure harmful consequences of saline conditions. This grass exhibited increased uptake of toxic ions like Na+, Cl- which is very harmful for growth under salt affected habitats. (author)

[en] Soil salinization is a serious environmental menace that reduces the development, growth and yield of most of the plants. Growing halophyte crops such as quinoa (Chenopodium quinoa Willd.) is a promising way of productive utilization of saline soils. The present study was conducted during 2018-19, in which we investigated the comparative salt tolerance potential of two genotypes of quinoa (Puno and A1) on the basis of growth, ionic and physiological attributes. Five-week-old seedlings of both genotypes were exposed to different levels of salinity (0, 100, 200 and 400 mM NaCl) developed in Hoagland’s nutrient solution. Results revealed that root and shoot growth, chlorophyll contents, membrane stability and relative water content remained unchanged at lower level of NaCl (100 mM). However, these attributes decreased significantly at higher level of NaCl (400 mM). The Na/sup +/ concentrations increased, whereas K+ concentrations and the ratio of K/sup +/: Na/sup +/ showed an inverse relation to the increasing salinity levels. The comparison of both genotypes indicated that physiological attributes and plant biomass were higher in A1 than Puno due to less uptake of Na+ ions and higher K/sup +/: Na/sup +/ ratio. Therefore, A1 is more suitable genotype than Puno to be grown on saline soils in arid regions of Pakistan. (author)

[en] The present experiment was designed to monitor growth and yield responses of a cotton genotype after applying salinity and boron stresses either alone or in combination and subsequent estimation of sodium-boron interaction in the cotton genotype. Treatments were set under complete randomized design (CRD) with 3 replications. Results revealed that 37.00 number of flowers/plant were found in control which was decreased by 25.24 and 34.24% by salinity-1 (75 mM NaCl) and salinity-2 (150 mM NaCl), respectively compared to control. Number of flowers/plant was improved by 46.92% by the addition of 75 mM NaCl + 12 mM B (Boron) compared with control. Number of leaves/plant of 75.66% was found in control treatment which was decreased by 16.29 and 29.07% by salinity-1 (75 mM NaCl) and salinity-2 (150 mM NaCl), respectively compared with control. Number of leaves/plants was improved by 25.08% by the application of 75 mM NaCl12 mM B compared with control. Similarly, plant height, lint weight, fresh root weight, dry root weight, root length and shoot length were improved after boron applications. Concentration of Na+ (Sodium) ion in soil analyzed for control was 4.1 meq. L-1 that increased to the level of 4.40 and 4.89 meq. L-1 by salinity-1 (75 mM NaCl) and salinity-2 (150 mM NaCl), respectively. Under boron applications, the lowest Na+ in soil were recorded 3.91 meq. L-1 for 12 mM B and 4.26 meq. L-1 for 6 mM B respectively. Similarly, the lowest Cl- (Chloride) ion in soil was recorded under boron application, while boron contents in soil was reduced under both salinity stresses. (author)

[en] Highlights: • Biochar and biochar-compost addition promoted belowground mass of P. australis. • Biochar addition significantly increased carbon content of native soil. • Both biochar and biochar-compost addition decreased soil NH₄⁺-N contents. • Biochar-compost had a stronger positive effect on P. australis than biochar alone in the saline soil. Salinity stress is common for plants growing in coastal wetlands. The addition of biochar in the soil may alleviate the negative effect of salinity through its unique physicochemical properties. To test this, we conducted a greenhouse experiment where the cosmopolitan wetland plant Phragmites australis was subjected to four salinity treatments (0, 5, 10 and 15‰) and three biochar treatments (no biochar addition, with biochar addition and with biochar-compost addition, both biochar and compost were made from P. australis) in a factorial design. Both biochar addition and biochar-compost addition to the substrate enhanced belowground mass of P. australis, application of biochar-compost significantly increased total mass by 35.5% and net photosynthesis rate of P. australis by 51.4%. Both biochar addition and biochar-compost addition significantly increased soil organic carbon content by 62.9% and 31.7%, respectively, but decreased soil ammonium nitrogen content. In the saline soil, application of the mixture of biochar-compost had a strong, and positive effect on the growth of P. australis, compared to biochar alone. Therefore, incorporation of biochar and compost might be an appropriate approach to improve the productivity of P. australis growing in coastal wetlands, where soil salinity is a common environmental stress.