High Salinity Levels Research Articles

Integrating Agro-Morpho-Physiological Traits and SSR Markers for Detecting the Salt Tolerance of Advanced Spring Wheat Lines under Field Conditions

To successfully enhance the salt tolerance of genotypes, it is crucial to conduct field-based trials, establish effective screening criteria and analysis tools, evaluate salt tolerance at various growth stages, and integrate phenotypic assessment-based traits with molecular markers. This study aimed to assess the salt tolerance of 16 F8 recombinant inbred lines (RILs) and eight genotypes by analyzing 13 agro-morpho-physiological traits using various analysis tools and SSR markers under both control and high salinity levels (15 dS m−1) in real field conditions. Analysis of variance (ANOVA), comparison of mean values, calculation of reduction percentage, and multivariate analysis were used to compare the assessed traits among genotypes and identify which traits are the most effective ones in describing the salt tolerance of these genotypes. A heatmap cluster analysis (HMCA) was also employed to categorize the salt tolerance of genotypes into different clusters based on the stress tolerance index (STI) for all traits. The ANOVA results revealed significant statistical differences (p ≤ 0.05) between the genotypes and salinity levels for all assessed traits in each season and their combined data. Moreover, the 150 mM NaCl treatment led to decreases in the assessed traits by 10.2% to 36.9% when compared to the control treatments. Furthermore, the mean values of assessed traits for certain genotypes were approximately one to three times greater than those of other genotypes. Principal component analysis has identified plant dry weight, green leaf area, leaf area index, and grain yield per hectare as effective screening criteria for explaining the substantial variation observed among the genotypes. The HMCA successfully grouped genotypes into three distinct clusters and distinguished the salt-tolerant genotypes from the salt-sensitive and intermediate ones. The 24 genotypes/RILs were classified into three main groups according to the allelic data of 40 SSRs associated with salt-tolerant genes. A weak yet significant correlation was observed between the similarity coefficients of agro-morpho-physiological traits and SSR markers, as determined by the Mantel test (r = 0.13, p < 0.03, and alpha = 0.05). In conclusion, this study has successfully identified several traits, particularly those associated with SSR markers, that greatly contribute to our understanding of the phenotypic and genotypic basis influencing the salt tolerance of wheat genotypes in real field conditions. Consequently, assessing these traits for a large number of wheat plant materials in a rapid and cost-effective manner will be greatly importance in breeding programs aimed at improving salt stress tolerance in this vital food crop. This will be the main focus of our forthcoming research.

Molecular characterization and phylogenetic diversity of actinomycetota species isolated from Lake Natron sediments at Arusha, Tanzania

Soda lakes are naturally occurring ecosystems characterized by extreme environmental conditions especially high pH and salinity levels but harboring valuable microbial communities with medical and biotechnological potentials. Lake Natron is one of the soda lakes situated in eastern branch of the East African Gregory Rift valley, Tanzania. In this study, the taxonomy and phylogenetic diversity of Actinomycetota species were explored in Lake Natron using molecular techniques. The sequencing of their 16S rRNA gene resulted into 13 genera of phylum Actinomycetota namely Streptomyces, Microbacterium, Nocardiopsis, Gordonia, Dietzia, Micromonospora, Microcella, Pseudarthrobacter, Nocardioides, Actinotalea, Cellulomonas, Isoptericola, and Glutamicibacter. We describe for the first time, the isolation of Streptomyces lasalocidi, S. harbinensis, S. anthocyanicus, Microbacterium aureliae, Pseudarthrobacter sp., Nocardioides sp. and Glutamicibacter mishrai from soda lake habitats. It also reports for the first time, the isolation of Gordonia spp., Microcella sp. and Actinotalea sp. from an East African Soda Lake as well as isolation of S. pseudogriseolus, S. calidiresistens and Micromonospora spp. from a Tanzania soda lake. Furthermore, two putative novel species of the phylum Actinomycetota were identified. Given that Actinomycetota are known potential sources of important biotechnological compounds, we recommend the broadening of the scope of bioprospection in future to include the novel species from Lake Natron.

Improving the Treatment of Saline Wastewater from Shrimp Farms Using Hybrid Constructed Wetlands Models toward Sustainable Development

This study investigated a feasible model for treating actual shrimp farm wastewater at a pilot scale that could be applied to farms in the Mekong Delta area. The research was carried out using a hybrid constructed wetlands (HCWs) model, which included a floating constructed wetland (FCW, total area of 1,500 m2) and a horizontal sub-surface constructed wetland (HSCW, total area of 400 m2). The HCWs were cultivated with native plants including: Scirpus littoralis Schrab, Cyperus alternifolius, and Paspalum vaginatum. These plants are all adapted to the high salinity levels of shrimp farm wastewater. The system was operated for 30 days to treat shrimp farm effluent. Results indicated that the model effectively removed organic matter and nitrogen compounds from the wastewater. The treated wastewater had low concentrations of COD (10.0-15.4 mg/L), BOD5 (7.1-12.5 mg/L), NH4+-N (0.04-1.11 mg/L), and TN (0.17-1.83 mg/L), which met the reliable conditions for reuse or safety requirements for discharge to aquatic systems. The findings of this study have significant implications for the sustainable management of shrimp farm wastewater in the Mekong Delta area. The HCWs model is a feasible and effective way to treat this type of wastewater, and it could be adapted to other regions facing similar challenges.

Reduction in Salt Stress Due to the Action of Halophilic Bacteria That Promote Plant Growth in Solanum lycopersicum.

Soil salinity is one of the most important factors reducing agricultural productivity worldwide. Halophilic plant growth-promoting bacteria (H-PGPB) represent an alternative method of alleviating saline stress in crops of agricultural interest. In this study, the following halophilic bacteria were evaluated: Bacillus sp. SVHM1.1, Halomonas sp. SVCN6, Halomonas sp. SVHM8, and a consortium. They were grown under greenhouse conditions in Solanum lycopersicum at different salinity concentrations in irrigation water (0, 20, 60, and 100 mM NaCl) to determine the effects on germination, fruit quality, yield, and concentration of osmoprotectors in plant tissue. Our results demonstrate the influence of halophilic bacteria with the capacity to promote plant growth on the germination and development of Solanum lycopersicum at higher salinity levels. The germination percentage was improved at the highest concentration by the inoculated treatments (from 37 to 47%), as were the length of the radicle (30% at 20 mM) and plumule of the germinated seed, this bacterium also increased the weight of the plumule (97% at 100 mM). They also improved the yield. The dry weight of the plant, in addition to having an influence on the quality of the fruit and the concentration of osmoprotectors (Bacillus sp. SVHM 1.1) had the greatest effect on fruit yield (1.5 kg/plant at 20 mM), by the otherhand, Halomonas sp. SVHM8 provided the best fruit quality characteristics at 100 mM. According to the above results, the efficiency of halophilic PGPB in the attenuation of salt stress in Solanum lycopersicum has been proven.

Amino acid-based biostimulant improves the productivity of Radish (Raphanus sativus L.) under saline stress


 The radish culture is highly sensitive to salinity. The use of an amino acid-based biostimulant can, therefore, be an attenuator of the deleterious effect of salinity on the radish crop. The aim was to evaluate the effectiveness of a biostimulant based on amino acids and freshwater algae extract on radish (Raphanus sativus L.) cultivated under irrigation conditions with saline water. The experiment was carried out in a greenhouse. The saline levels evaluated were 0.15, 1.8, and 2.8 dS.m-1 and four doses of biostimulant were applied (0, 2, 4, and 6 mL/L). The statistical design was completely randomized, in a 4x3 factorial scheme with 4 replications. Biometric and biomass analyses, sodium and potassium contents, and soluble solids were performed. Was observed that plants submitted to high salinity levels (2.8 dS m-1) with application of 6mL/L of the biostimulant showed high values in height (12.2 cm), stem (5mm) and tuber (6mm) diameter, leaf area (50cm2), fresh and dry mass of aerial part (3.5 g) and underground system (5.8 g). The application of the biostimulant 6 mL/L, at the salinity level of 2.8 dS.m-1, favored the increase of saline ions in the tuber of the plants. The application the biostimulant provided a higher content of soluble solids. Applications of the biostimulant in plants with saline stress showed beneficial responses in the performance of the radish, therefore the dose of 6 mL/L is recommended for a satisfactory response of the performance of the radish in saline conditions.

Potential Use of Polysaccharides Natural Polymer in Plants as an Alternative to Chemical Enhanced Oil Recovery (EOR) to Increase Oil Production in Indonesia

The decline in oil production in the past few decades has made Enhanced Oil Recovery (EOR) one of the technologies that get more attention because it has been proven to increase oil production in a field. One EOR method that is widely used today is by injecting chemicals in the form of polymers. Polymers themselves are grouped into two types, namely synthetic polymers and natural polymers or known as biopolymers. The use of synthetic polymers has limitations, especially in oil reservoirs that have high temperatures and salinity levels, therefore the development of biopolymers is an interesting thing to study, in addition to the availability of raw materials in large quantities, this type of polymer has good mechanical properties and is easy to make derivatives according to the desired properties and characters. The use of biopolymers is considered cheaper and safer because they come from natural materials so that they can be decomposed properly. Therefore, the researcher tried to make a comprehensive brief review of the reasons for the importance of using polymers in EOR activities in Indonesia, a comparison of the properties, characteristics, advantages and disadvantages of the two types of polymers, along with the progress of several research results that have been carried out previously. this research is expected to provide useful insights about the potential use of natural materials as basic materials in the process of making biopolymers, properties and characteristics that are resistant to bacteria and high salinity.

DNA metabarcoding reveals evidence of inter- and intra-guild predation by Scylla paramamosain in a marine ecosystem

IntroductionCrustacean predators exhibit diverse trophic interactions across various habitats in aquatic ecosystems. To assess their ecological roles, it is essential to understand their complete dietary spectrum. Recently, DNA-based techniques such as DNA metabarcoding and high-throughput sequencing have provided insights into trophic networks and their response to environmental drivers.MethodsIn this study, we used these methods to investigate the impact of salinity gradients on the trophic networks of mud crabs (Scylla paramamosain) in marine ecosystems.ResultsOur results revealed that mud crabs prey on a wide range of taxa, including crabs (other than the host species), fish, shrimps, and other prey factions. Salinity gradients had a significant influence on the specific prey items, such as high predation on Metapenaeus, and Trigonopterus species in high salinity sites. Notably, crabs exhibited a greater infestation of Portunion parasites in environments with high salinity levels, in contrast to environments with lower salinity levels. Ordination analysis showed that mud crabs adapt their diet according to environmental constraints.DiscussionFurthermore, the results indicate that mud crabs showed opportunistic predation behavior as they were observed preying on other Portunidae species sharing the same trophic guild. Overall, these findings demonstrate the dietary plasticity and associated parasite infestation of an important crustacean predator, and provide evidence that environmental changes may affect incidences of the associated parasites as well as the specific predator-prey interactions indirectly through fluctuations in marine ecosystems.

Exergy and energy analysis of a novel solar powered fog desalination system

A novel system that applied fogging as a desalination technique was recently published, which could be considered a further development of the humidification-dehumidification desalination system (HDH), that provides an advantage through its ability to desalinate high salinity levels. This involves spraying hot saline water at high pressure vertically upwards, creating a mist instead of large water droplets. This increases productivity since the fine mist facilitates evaporation and the low-saline mist can go upwards more than the large high-salinity droplets. However, experiments showed that this methodology, in terms of productivity, performance and cost, was between other technologies. It was noted that the performance of this system peaked at ~39 %. Therefore, in this paper, an exergy analysis of the system is presented to determine the location of the highest exergy destruction and also highlight its comparative feasibility. The results indicated that the exergetic efficiency of the system reached 17.3 % while the main source of irreversibility is the fogging process itself (~75 %). Additionally, increasing the water temperature from 33 to 76 °C increased the exergetic efficiency of the fogger from 4 % to 20 %. Therefore, the authors recommend using a combination of humidification and atomization via nozzles of larger orifices with different spraying angles.

Exploring the impact of salinity on citrus (Citrus spp.) rootstock seed germination and seedling biomass

An experiment was conducted at the screen house of the Department of Horticulture, CCS Haryana Agricultural University, Hisar, Haryana during 2018–19 and 2019–20 to assess the impact of 5 different salinity levels [0.07 (control), 2.5, 4.0, 5.5, and 7.0 dS/m] on the seed germination and biomass of 9 citrus (Citrus spp.) rootstock seedlings (Rough lemon, Pectinifera, Cleopatra mandarin, Rangpur lime, Alemow, Volkamer lemon, NRCC-4, NRCC-3 and CRH-12). Experiment consisted of 45 treatment combinations and 3 replications in a completely randomized design (CRD). Under the influence of soil salinity, the number of days taken for seed germination, seed germination percentage, fresh and dry root and shoot biomass were adversely affected across all rootstocks compared to the control treatment (0.07 dS/m). Among the tested rootstocks, Volkamer lemon exhibited the highest seed germination rate (57%), followed by Rangpur lime (53%) and CRH-12 (50%). Conversely, Pectinifera showed the lowest seed germination percentage (37%), followed by Alemow (43%) at 7 dS/m. The minimum reduction at 7 dS/m over control in fresh shoot and root and dry shoot and root biomass was observed in Rangpur lime (37.7, 16.2, 27.8 and 27.3%, respectively), followed by Volkamer lemon (38.0, 16.2, 28.3 and 28.5%, respectively). On the other hand, Pectinifera exhibited the highest reduction in biomass (51.9, 40.5, 47.0 and 43.9%, respectively), followed by Alemow (45.7, 30.9, 46.5 and 39.9%, respectively). Among all the rootstocks, Rangpur lime, Volkamer lemon and Cleopatra mandarin displayed better tolerance to salinity, exhibiting relatively lower reduction in biomass at the highest salinity level (7 dS/m) compared to the control. Cleopatra mandarin, Rough lemon and NRCC-3 showed a moderate response, while Pectinifera, NRCC-4, and Alemow were found to be less tolerant, exhibiting higher reduction in terms of count of seed germination days, seed germination percentage, fresh and dry root biomass, and shoot biomass at 7 dS/m compared to the control treatment.

Effects of Salt Tolerance Training on Multidimensional Root Distribution and Root-Shoot Characteristics of Summer Maize under Brackish Water Irrigation.

To investigate the impact of brackish water irrigation on the multidimensional root distribution and root-shoot characteristics of summer maize under different salt-tolerance-training modes, a micro-plot experiment was conducted from June to October in 2022 at the experimental station in Hohai University, China. Freshwater irrigation was used as the control (CK), and different concentrations of brackish water (S0: 0.08 g·L-1, S1: 2.0 g·L-1, S2: 4.0 g·L-1, S3: 6.0 g·L-1) were irrigated at six-leaf stage, ten-leaf stage, and tasseling stage, constituting different salt tolerance training modes, referred to as S0-2-3, S0-3-3, S1-2-3, S1-3-3, S2-2-3, and S2-3-3. The results showed that although their fine root length density (FRLD) increased, the S0-2-3 and S0-3-3 treatments reduced the limit of root extension in the horizontal direction, causing the roots to be mainly distributed near the plants. This resulted in decreased leaf area and biomass accumulation, ultimately leading to significant yield reduction. Additionally, the S2-2-3 and S2-3-3 treatments stimulated the adaptive mechanism of maize roots, resulting in boosted fine root growth to increase the FRLD and develop into deeper soil layers. However, due to the prolonged exposure to a high level of salinity, their roots below 30 cm depth senesced prematurely, leading to an inhibition in shoot growth and also resulting in yield reduction of 10.99% and 11.75%, compared to CK, respectively. Furthermore, the S1-2-3 and S1-3-3 treatments produced more reasonable distributions of FRLD, which did not boost fine root growth but established fewer weak areas (FLRD < 0.66 cm-3) in their root systems. Moreover, the S1-2-3 treatment contributed to increasing leaf development and biomass accumulation, compared to CK, whereas it allowed for minimizing yield reduction. Therefore, our study proposed the S1-2-3 treatment as the recommended training mode for summer maize while utilizing brackish water resources.

Exploring Salinity Tolerance Mechanisms in Diverse Wheat Genotypes Using Physiological, Anatomical, Agronomic and Gene Expression Analyses.

Salinity is a widespread abiotic stress that devastatingly impacts wheat growth and restricts its productivity worldwide. The present study is aimed at elucidating biochemical, physiological, anatomical, gene expression analysis, and agronomic responses of three diverse wheat genotypes to different salinity levels. A salinity treatment of 5000 and 7000 ppm gradually reduced photosynthetic pigments, anatomical root and leaf measurements and agronomic traits of all evaluated wheat genotypes (Ismailia line, Misr 1, and Misr 3). In addition, increasing salinity levels substantially decreased all anatomical root and leaf measurements except sclerenchyma tissue upper and lower vascular bundle thickness compared with unstressed plants. However, proline content in stressed plants was stimulated by increasing salinity levels in all evaluated wheat genotypes. Moreover, Na+ ions content and antioxidant enzyme activities in stressed leaves increased the high level of salinity in all genotypes. The evaluated wheat genotypes demonstrated substantial variations in all studied characters. The Ismailia line exhibited the uppermost performance in photosynthetic pigments under both salinity levels. Additionally, the Ismailia line was superior in the activity of superoxide dismutase (SOD), catalase activity (CAT), peroxidase (POX), and polyphenol oxidase (PPO) enzymes followed by Misr 1. Moreover, the Ismailia line recorded the maximum anatomical root and leaf measurements under salinity stress, which enhanced its tolerance to salinity stress. The Ismailia line and Misr 3 presented high up-regulation of H+ATPase, NHX2 HAK, and HKT genes in the root and leaf under both salinity levels. The positive physiological, anatomical, and molecular responses of the Ismailia line under salinity stress were reflected on agronomic performance and exhibited superior values of all evaluated agronomic traits.

The morpho-physiological and gene expression of East Timor’s local rice plant (Oryza sativa) response to drought and salinity stress

Abstract. Quintao G, Ubaidillah M, Hartatik S, Khofifa RAN, Siswoyo TA. 2023. The morpho-physiological and gene expression of East Timor’s local rice plant (Oryza sativa) response to drought and salinity stress. Biodiversitas 24: 4548-4556. East Timor is rich in local rice varieties, such as Silaun, Ime Buci, Me Klan, Me Likan, Me Meak, Me Taek, and Umak Klete. These varieties are tolerant to drought and salinity stress. These superior characteristics emerge as the coping strategy of the rice plants toward environmental conditions such as mountainous, upland planting areas without irrigation networks and coastal regions with high salinity levels. This study determined the tolerance response of East Timor's local rice to drought and salinity stresses. This study was designed in a Completely Randomized Design (CRD) with two factors. The first factor, i.e., rice varieties, consisted of 8 varieties, i.e., Silaun (V1), Ime Buci (V2), Me Klan (V3), Me Likan (V4), Me Meak (V5), Me Taek (V6), Umak Klete (V7), and IR-64 (V8) and the second factor was the abiotic stress treatments, namely no treatment or control (P0), 10% PEG treatment (P1), and 150 mM NaCl treatment (P2). The parameters observed were morpho-physiology and biochemical characteristics of the plants. The results showed that the Silaun local rice variety from East Timor was tolerant to drought and salinity, supported by the gene expressions for tolerance to drought and salinity stress.

Desiccation of ecosystem-critical microbialites in the shrinking Great Salt Lake, Utah (USA)

Great Salt Lake hosts an ecosystem that is critical to migratory birds and international aquaculture, yet it is currently threatened by falling lake elevation and high lakewater salinity resulting from water diversions in the upstream watershed and the enduring megadrought in the western United States. Microbialite reefs underpin the ecosystem, hosting a surface microbial community that is estimated to contribute 30% of the lake’s primary productivity. We monitored exposure, desiccation, and bleaching over time in an area of microbialite reef. During this period, lake elevation fell by 1.8 m, and salinity increased from 11.0% to 19.5% in open-water portions of the outer reef, reaching halite saturation in hydrologically closed regions. When exposed, microbialite bleaching was rapid. Bleached microbialites are not necessarily dead, however, with communities and chlorophyll persisting beneath microbialite surfaces for several months of exposure and desiccation. However, superficial losses in the mat community resulted in enhanced microbialite weathering. In microbialite recovery experiments with bleached microbialite pieces, partial community recovery was rapid at salinities ≤ 17%. 16S and 18S rRNA gene sequencing indicated that recovery was driven by initial seeding from lakewater. At higher salinity levels, eventual accumulation of chlorophyll may reflect accumulation and preservation of lake material in halite crusts vs. true recovery. Our results indicate that increased water input should be prioritized in order to return the lake to an elevation that submerges microbialite reefs and lowers salinity levels. Without quick action to reverse diversions in the watershed, loss of pelagic microbial community members due to sustained high salinity could prevent the recovery of the ecosystem-critical microbialite surface communities in Great Salt Lake.

Effects of Salinity Stress on Histological Changes, Glucose Metabolism Index and Transcriptomic Profile in Freshwater Shrimp, Macrobrachium nipponense.

Salinity is an important factor in the aquatic environment and affects the ion homeostasis and physiological activities of crustaceans. Macrobrachium nipponense is a shrimp that mainly lives in fresh and low-salt waters and plays a huge economic role in China's shrimp market. Currently, there are only a few studies on the effects of salinity on M. nipponense. Therefore, it is of particular importance to study the molecular responses of M. nipponense to salinity fluctuations. In this study, M. nipponense was set at salinities of 0, 8, 14 and 22‱ for 6 weeks. The gills from the control (0‱) and isotonic groups (14‱) were used for RNA extraction and transcriptome analysis. In total, 593 differentially expressed genes (DEGs) were identified, of which 282 were up-regulated and 311 were down-regulated. The most abundant gill transcripts responding to different salinity levels based on GO classification were organelle membrane (cellular component), creatine transmembrane transporter activity (molecular function) and creatine transmembrane transport (biological function). KEGG analysis showed that the most enriched and significantly affected pathways included AMPK signaling, lysosome and cytochrome P450. In addition, 15 DEGs were selected for qRT-PCR verification, which were mainly related to ion homeostasis, glucose metabolism and lipid metabolism. The results showed that the expression patterns of these genes were similar to the high-throughput data. Compared with the control group, high salinity caused obvious injury to gill tissue, mainly manifested as contraction and relaxation of gill filament, cavity vacuolation and severe epithelial disintegration. Glucose-metabolism-related enzyme activities (e.g., pyruvate kinase, hexokinase, 6-phosphate fructose kinase) and related-gene expression (e.g., hexokinase, pyruvate kinase, 6-phosphate fructose kinase) in the gills were significantly higher at a salinity of 14‱. This study showed that salinity stress activated ion transport channels and promoted an up-regulated level of glucose metabolism. High salinity levels caused damage to the gill tissue of M. nipponense. Overall, these results improved our understanding of the salt tolerance mechanism of M. nipponense.

Interactive effects of salinity, temperature and food web configuration on performance and harmfulness of the raphidophyte Heterosigma akashiwo

The cosmopolitan raphidophyte Heterosigma akashiwo commonly forms harmful algal blooms (HABs) in diverse estuaries discharging into Algoa Bay, South Africa, potentially leading to hypoxia, fish kills and a decline in key primary consumers. Despite the high environmental variability in these estuaries, little is known about how abiotic factors such as temperature and salinity constrain bloom formation and harmfulness of H. akashiwo. The present study therefore investigates growth, competition, and grazing interactions of H. akashiwo in laboratory experiments in response to two naturally relevant levels of salinity (15, 30) and temperature (16, 22°C), respectively. Experiments were set up with the naturally co-occurring dinoflagellate competitor Heterocapsa rotundata and two estuarine microzooplankton consumers, i.e., nauplii of the copepod Acartia tonsa and the rotifer Brachionus plicatilis. In monoculture, H. akashiwo growth was promoted at high temperature – low salinity conditions, while H. rotundata thrived under low temperature – high salinity conditions. In polyculture, H. akashiwo dominated at high temperature irrespective of the salinity regime, while at low temperature, it only dominated at low salinity and was suppressed by H. rotundata at high salinity. Grazing assays revealed highly negative effects of H. akashiwo on copepod nauplii survival and growth as well as mucus-induced immobilization, especially at high temperatures in combination with low salinity, while the estuarine adapted rotifers showed highest mortalities at the higher salinity level. The presence of H. rotundata significantly alleviated the harmful effects of H. akashiwo on both grazers, and the selectively feeding copepod nauplii actively avoided H. akashiwo when non-harmful prey was present. Overall, this study demonstrates that population dynamics and harmful effects of H. akashiwo are interactively determined by both abiotic conditions and food web configuration, implying competitor and consumer specific tolerances to the abiotic environment and their susceptibility to the harmful alga H. akashiwo.

Variability in seed salinity tolerance in an island coastal community.

Islands, with their long coastlines and increased vulnerability to sea level rise, offer compelling opportunities to investigate the salinity tolerance of coastal plants. Seeds are generally more vulnerable than other plant stages to increased stressors. The aim of this study was to characterize salinity tolerance during germination across a diverse pool of 21 species from 14 plant families found in coastal communities throughout the Hawaiian Islands in order to increase our general understanding of coastal plant ecology for conservation and restoration. Seeds of each species were exposed to unfiltered/untreated seawater (35 ppt total salinity) and two salinity treatments (10 and 20 ppt) in which the seawater was diluted with distilled water, and germination percent and timing were compared to seeds in a distilled water control. Non-germinated seeds were then tested for recovery germination. We quantified and compared germination percent, time and recovery among species and across salinity levels and tested for heterogeneity related to seed size, dormancy class, habit and threatened status. Although salinity tolerance varied considerably among species, salinity exposure generally reduced and delayed germination. The greatest effects were detected at higher salinity levels. Recovery germination overall was higher for seeds that had been exposed to higher salinity. None of the factors we explored emerged as predictors of salinity tolerance except seed mass, which tended to enhance germination at higher salinity. Species responses to salinity exposure indicate high vulnerability of coastal systems to increased salinity stress, and variability among species could lead to shifts in community assembly and composition under sea level rise. These results can help guide coastal ecosystem conservation and restoration management decisions in the face of climate change.

GROWTH PERORMANCE OF TAMARIND (Tamarindus indica L.) SEEDLINGS TO DIFFERENT LEVELS OF SALINITY AND SODICITY

Agroforestry is a viable land-use option of salt affected soils which ensure the remunerative use of this valuable resource. A two years pot study was carried out to evaluate salinity tolerance of tamarind fruit plant against different levels of salinity and sodicity. Treatments included were: T1 = ECe, 1.17 dS m-1 + SAR, 10.87, T2 = ECe, 6 dS m-1 + SAR, 25, T3 = ECe, 6 dS m-1 + SAR, 35, T4 = ECe, 6 dS m-1 + SAR, 45, T5 = ECe, 8 dS m-1 + SAR, 25, T6 = ECe, 8 dS m-1 + SAR, 35, T7 = ECe, 8 dS m-1 + SAR, 45, T8 = ECe, 10 dS m-1 + SAR, 25, T9 = ECe, 10 dS m-1 + SAR, 35, T10 = ECe, 10 dS m-1 + SAR, 45. Results revealed that no plant was survived at higher level of salinity (10 dS m-1) and sodicity (SAR 45) and complete cessation and mortality was observed in this treatment. Data of survived plants at the end of study showed that salinity and sodicity arrested the growth variables of tamarind seedlings and increasing levels of salinity-sodicity led a reduction of 3.52% to 82.47% in plant height, 1.53% to 84.61% in stem girth, 5.63% to 88.26% in number of leaves and 7.44 to 90.77 in number of branches over control (non-stress) treatment. Therefore, it was concluded that tamarind seedling can withstand and survive at salinity and sodicity level of 10 dS m-1 and SAR 35.

EVALUATION OF PEA GENOTYPES FOR SALT STRESS TOLERANCE

Pea (Pisum sativum L.), a highly nutritious vegetable, is extremely sensitive to salt stress conditions. A pot study evaluated four pea genotypes (Samrina Zard, Climax, Ambassador, and Green Arrow) by exposing them to control, 2.5, 5.0, and 7.0 dS m-1 by applying NaCl, Na2SO4, MgSO4, and CaCl2 salts. The pots under a completely randomized design (CRD) layout had four replications. Immense genetic variations occurred among the pea genotypes under salt stress. Samrina Zard showed better physiological (transpiration and photosynthesis rates, stomatal conductance, water use efficiency, and chlorophyll) and morphological traits (shoot/root length, shoot/root dry weight, number of leaves per plant, and leaf area). Genotype Samrina Zard significantly maintained the highest percentage of shoot length (14.54%), root length (28.28%), shoot dry weight (19.58%), root dry weight (36.36%), number of leaves (27.24%), and leaf area (21.59%) at a higher level of salinity 7 dS m-1 compared with the control and all other treatments. In contrast, the Ambassador genotype was categorically salt-sensitive based on the least percentage increase in shoot length (22.42%), dry weight of shoot (67.57%), dry weight of root (59.59%), number of leaves (47.69%) and leaf area (23.72%). However, salinity reduced the physiological attributes in both genotypes. Regardless of salt treatments, Samrina Zard performed better than Ambassador regarding photosynthesis (48.07%), transpiration rate (18.76%), stomatal conductance (45.42%), water use efficiency (55.88%), and chlorophyll contents (29.44%). According to study findings, Samrina Zard performed best against salinity stress.

Effect of Salinity Stress on Oxidative Stress Parameters and the Activity of Antioxidant Enzymes in Eight Durum Wheat Genotypes

This study was carried out at the Tissue Culture Laboratory, which belongs to the General Commission of Biotechnology, in order to evaluate the influence of NaCl-induced salinity stress on some oxidative parameters (MDA and H2O2) and antioxidant enzymes (CAT, APX, and SOD) in eight durum wheat genotypes (Doma1, Bouhoth11, Cham3, Bezater, Cham5, Aghamatales, Icaverve, and Icamber) in vitro, to determine the most salinity tolerant genotypes. Salinity stress was applied by adding different levels of NaCl to the growing medium (0, 50, 100, and 150 mM). The experiment was laid according to a complete randomized design (CRD) with sixteen replicates. Increasing salinity level caused an increase in both the Hydrogen peroxide (H2O2), malondialdehyde (MDA) and the activity of the investigated antioxidant enzymes (SOD، APX، CAT) compared with the control. The leaf content of both H2O2 and MDA was significantly higher in the genotype Icaverve at the salinity level of 150 mM NaCl (45.67 and 130.74 µmol g-1 fresh wt. respectively), while the activity of the enzymes SOD, APX and CAT were significantly higher in the two durum wheat genotypes, Bouhoth11 and Doma1 at the highest salinity level (150 mM NaCl). Antioxidant enzymes play a pivotal role in the defense mechanisms in the durum wheat under salinity stress conditions, and the in vitro screening tool can be effectively used to assess the genetic variability for salinity tolerance in the durum wheat crop.

Screening of Country Bean (Lablab Purpureus L.) Genotypes for Salinity Tolerance

Thirty-five country bean (Lablab purpureus L.) genotypes collected from coastal belts of Bangladesh were screened for tolerance to a high level of salinity (12 ds m-1 NaCl) in Hogland nutrient solution in a hydroponic system at vegetative growth stage. The experiment was conducted in a complete randomized design with three replications at Genetics and Plant Breeding lab, BSMRAU during January-February, 2016. The genotypes were varied in biochemical properties (proline, carbohydrates, chlorophyll contents etc.), dry root: shoot ratio, relative shoot dry weight and salt susceptibility index (SSI). Wide variation among the genotypes was noticed for root and shoot ratio (p&lt;0.05). Relative shoot length varied from 29.87- 126.04 with an average of 79.29 whereas relative root length showed wide variation with a range of 20.00-300.00. Relative root dry weight (RRDW) varied from 22.06-211.43 with a mean of 79.40 and relative shoot dry weight (RSDW) ranged from 26.57-192.66 with an average of 69.29. Relative root : shoot ratio showed a range of 0.59 to 2.51. On the basis of relative performance of root-shoot dry matter, dry leaves weight, root-shoot ratio, six genotypes were found highly tolerant, seven were moderately tolerant, sixteen were moderately susceptible and six were highly susceptible to salinity stress. Based on visual observation of plants, relative shoot dry weight (RSDW), proline content, total sugar and soil plant analysis development (SPAD) value the genotypes CB031, CB035, CB003, CB023, CB026, CB028, CB013, CB030, CB014, CB024, CB019, CB020 and CB002 were selected as tolerant for further evaluation and use in breeding work. Ann. Bangladesh Agric. (2022) 26 (2) : 19-31