Salinity Prone Areas Research Articles

Delineation of fresh groundwater potentiality zones in saline coastal aquifers, Southwest Bangladesh using remote sensing and GIS approaches.

Bay of Bengal in southern Bangladesh is a major source of water from coastal aquifers, but prone to contamination by seawater intrusion,making climate-vulnerable populations and economies unfit for potable, agricultural water, adopting crops, etc. The study area located in Khulna district lies in the southwestern coast of the country is among the most vulnerable due to its salinity issues. Therefore, this study identified fresh groundwater potential zones in the southwestern coastal zones of the country suited for community usage helping coastal peoples meet their demands. This study focused on twelve thematic layers employing remote sensing and GIS with analytical hierarchy process. Here, groundwater salinity is 84% brackish to saline over 70% of the region [electric conductivity: 295-16,295 micro-Siemens/cm]. However, groundwater chloride in 88% signifies a slightly to medium salty zone. The annual average rainfall reduced surface water infiltration in 75% of the area with little to very slightly soil salinity. The fresh groundwater resource zone has classified based on its potentiality as: very high (0.52%)-for drinking, agricultural irrigation, or industrial work; high (25%)-marginal salinity suitable for agricultural or industrial uses; low (11%)-low salinity, but usable for high salt tolerant crops in irrigation; and very low (64%)-very high groundwater salinity, and not suitable for human consumption and community uses. Finally, this study will help develop sustainable groundwater resources in the coastal region and a fresh groundwater supply plan in saline-prone areas.

Role of organic amendments in improving the morphophysiology and soil quality of Setaria italica under salinity

Salinity negatively impacts soil fertility by impairing the development and physiological functions of foxtail millet plants. Organic amendments have emerged as a viable solution in the reclamation and management of salinity inflicted soils and improve the performance of crop. In this regard, a pot experiment was carried out to examine the effect of organic amendments (OAs) on soil quality and its influence on the growth and physiology of foxtail millet under saline and non-saline condition. The findings indicated that under salt stress conditions, the levels of proline, hydrogen peroxide (H2O2), and electrolyte leakage (EL) risen, whilst other physiological parameters decrease in foxtail millet. However, the addition of OAs, particularly dhaincha and biochar (BC), has shown a promising salt tolerant amendment among others. Its addition improved the growth performance of salinity-stressed plants, including plant height, fresh and dry biomass, simultaneously decreased sodium ion (Na+) and improved calcium (Ca2+), potassium (K+), and nitrate ion (NO3−). They also increased proline build up by 6–17 %, reduced H2O2 (19–38 %) and malondialdehyde (16–18 %). Furthermore, they elevated the relative water content (RWC) (25 %), chlorophyll content, and reduced EL (29–50 %). Once more, dhaincha and BC enhanced the number of rhizobia, phosphorus-solubilizing bacteria (PSB) and overall bacterial population in the soil. In saline soil, daincha and BC could enhance soil organic matter (628 %), total nitrogen (1630 %), available phosphorus (32–38 %), and exchangeable potassium (54–73 %). A potential strategy for improving setaria italica performance under salt is suggested to be the following order, dhaincha > biochar > vermicompost > duckweed. The study would assist stakeholders in these salinity-prone areas in strategizing the use of OAs to their fallow land for cultivation and agricultural activities.

MORPHOLOGICAL AND PHYSIOLOGICAL RESPONSES OF DIFFERENT COTTON GENOTYPES UNDER NORMAL AND SALT STRESS CONDITIONS

Salinity is a major abiotic stress that badly affects the growth and production of cotton worldwide. This scenario is not different in the case of Pakistan. This research was conducted to examine the effects of different salinity levels on the morpho-physiological characters of six cotton genotypes i.e. shoot and root length, fresh shoot and root weight, photosynthesis rate, and transpiration rate. A pot experiment was arranged with three salinity treatments of NaCl i.e. control (0 dS/m), T1 (4.5 dS/m), and T2 (8.5 dS/m) with three replications of each treatment. Highly significant decreases in shoot length, fresh shoot weight, fresh root weight, photosynthesis rate, and transpiration rate were observed with increasing salinity levels across all genotypes. The genotype MNH-786 showed the highest reduction in all morpho-physiological characters, indicating it was highly sensitive to salinity stress. On the other hand, FH-87 and FH-142 maintained relative performance for all discussed morpho-physiological traits under both moderate and high salinity, demonstrating that these are relatively more tolerant. These findings provided valuable insights into the salinity tolerance of cotton genotypes and highlighted the potential of FH-87 and FH-142 for cultivation in saline-prone areas and for use in breeding programs to improve salinity tolerance in cotton.

IDENTIFICATION CANDIDATE SSR, SNPs AND GENES ASSOCIATED SALT TOLERANCE IN ASIATIC COTTON (GOSSYPIUM ARBOREUM)

Soil is a vital resource for feeding the growing global population. Increased salt tolerance of perennial species used for fodder or fuel production is an important and natural method for controlling the spread of secondary salinity. This study was carried out to identify marker-trait association analysis using 7 traits and one comprehensive index of salt tolerance (CIST) and SSR and SNP markers for 215 accessions of Asiatic cotton (G. arboretum). The traits related to salt tolerance like germination rate (GR), fresh weight (FW), stem length (SL), water content (WC), chlorophyll content (ChlC), electric conduct (EC) and methylene dioxyamphetamine (MDA), of 215 cotton accessions were screened out using 150mM NaCl concentration after 7 days of seed growth. According to a comprehensive index of salt tolerance (CIST), 215 accessions were mainly categorized into four groups, and 11 accessions (top 5%) with high salinity tolerance were selected for breeding. Group 1 contained 12 accessions that were sensitive to high salt treatment (<0.6), group 2 contained 26 accessions that were moderate tolerant to salt treatment (0.6～1.5), group 3 includes 153 accession that were tolerant (1.5～2.5), and group 4 had 24 accessions that were highly tolerant to salt treatment (>2.5). The natural population of 215 accessions of G. arboretum was first classified into 3 main groups by phylogenic analysis, in which Group 2 (G2) and Group 3 (G3) represented the Yellow River and Yangtze River accessions respectively, while Group 1 (G1) contained mixed cotton accessions which belongs to different cotton growing areas in China. The grouped accessions results were largely congruent with the breeding history and ecological region, which indicates the extensive genetic diversity of G. arboretum accessions both in phenotype and genotype. The relative value (R) of the traits was used for marker-trait association analysis. Twenty-two strong SSR marker-trait associations were obtained with strict significant P value i.e. P< 0.01 and four makers including NAU1023, NAU1099, JESPR222, and NAU2783 were significantly related to salt tolerance. The marker NAU2783 was highest associated (P= 1.98E-12) with REC, and with the highest phenotype variation of 20.87%. Some markers are significantly associated with more than two traits. MUSS020 was significantly (P<0.01) related with RFW, and RMDA, NAU1375 was associated with RFW and RSL, while NAU3468 was significantly associated with RFW, RGR, and RWC. By applying the threshold of –log10 P≥4.0, the 2062 SNP markers covered all 13 chromosomes and 100 SNP markers locations that were unknown. Among these 2062 marker‐trait associations, 61 markers were associated with RGR, 187 markers were associated with RFW, 255 markers were associated with RSL, 370 markers were associated with RWC, 190 markers were associated with RChlC, 583 markers were associated with REC, 335 markers were associated with RMDA and 81 markers were associated with CIST. The nine SNP rich regions analysis revealed 143 polymorphisms that distributed 40 candidate genes and significantly associated with salt tolerance. Notably, two SNP rich regions on chromosome 7 were found to be significantly associated with two salinity related traits, RFW and RSL, by the threshold of −log10P ≥ 6.0, and two candidate genes (Cotton_A_37775 and Cotton_A_35901) related to two key SNPs (Ca7_33607751 and Ca7_77004962) were possibly associated with salt tolerance in G. arboreum. The classification information derived from these studies may be used to facilitate the development of salt tolerant cotton accessions that could give economic yield in salinity prone areas. The strong marker-trait association results might provide insights for marker-assistant selecting salt-tolerant varieties and will be useful for future cotton breeding programs.

Coastal Flood Induced Salinity Intrusion Risk Assessment Using a Spatial Multi-criteria Approach in the South-Western Bangladesh

AbstractBangladesh is extremely vulnerable to sea-level rise and other climate-induced extreme events, such as flooding, storm surge, and salinity intrusion. The south-western coastal region of Bangladesh is particularly vulnerable to salinity intrusion caused by cyclone induced storm surges and coastal floods. Salinity intrusion endanger land productivity by increasing both soil and surface water salinity. Detailed risk assessment using spatial mapping approach can contribute to mitigating the effects of salinity intrusion on natural capital and the environment. In this study, we established and evaluated a spatial multi-criteria approach for mapping the risk levels of areas to salinity intrusion impacts using field data and geospatial techniques at the local scale. We evaluated the viability of the proposed approach using Khulna District, a major coastal city and saline prone area in the south-western Bangladesh. We considered three risk components (i.e. vulnerability, exposure and hazard) with 16 relevant criteria for the study. For each criterion, an Analytical Hierarchy Process (AHP) was used to build and weight spatial raster map layers. Individual maps for each risk component were generated using a weighted sum technique, and lastly, a risk map was created by combining those. Our generated maps correctly identified relevant spatial dimensions as well as risk levels (i.e. very-high to very-low). The outcomes of our study suggest that the southern (east and west) parts of the study area are mostly susceptible to salinity intrusion due to higher storm surge impacts, lower elevation, and land use patterns than other parts. We validate our findings using a qualitative and quantitative approach. We believe that this novel approach would be useful to create risk maps that policymakers and relevant stakeholders could potentially use to evaluate risks posed by flood induced salinity intrusion in coastal regions of Bangladesh and elsewhere with similar geo-climatic context.

Comparison of the genetic basis of salt tolerance at germination, seedling, and reproductive stages in an introgression line population of rice.

Salinity is a major limitation for rice farming due to climate change. Since salt stress adversely impact rice plants at germination, seedling, and reproductive stages resulting in poor crop establishment and reduced grain yield, enhancing salt tolerance at these vulnerable growth stages will enhance rice productivity in salinity prone areas. An introgression line (ILs) population from a cross between a high yielding cultivar 'Cheniere' and a salt tolerant donor 'TCCP' was evaluated to map quantitative trait loci (QTLs) for traits associated with salt tolerance at germination, seedling, and reproductive stages. Using a genotyping-by-sequencing based high density SNP linkage map, a total of 7, 16, and 30 QTLs were identified for five germination traits, seven seedling traits, and ten reproductive traits, respectively. There was overlapping of QTLs for some traits at different stages indicating the pleiotropic effects of these QTLs or clustering of linked genes. Candidate genes identified for salt tolerance were OsSDIR1 and SERF for the seedling stage, WRKY55 and OsUBC for the reproductive stage, and MYB family transcription factors for all three stages. Gene ontology analysis revealed significant GO terms related to nucleotide binding, protein binding, protein kinase activity, antiporter activity, active transmembrane transporter activity, calcium-binding protein, and F- box protein interaction domain containing protein. The colocalized QTLs for traits at different growth stages would be helpful to improve multiple traits simultaneously using marker-assisted selection. The salt tolerant ILs have the potential to be released as varieties or as pre-breeding lines for developing salt tolerant rice varieties.

Effect of Salt Stress on the Growth, Physiology, and Mineral Nutrients of Two Penstemon Species

Penstemons are a diverse group of flowering plants valued for their ability to enhance the visual appearance of urban landscapes. Penstemon barbatus (Cav.) Roth ‘Novapenblu’ (rock candy blue® penstemon) and Penstemon strictus Benth ‘Rocky Mountain’ (rocky mountain beardtongue) are widely used in landscapes, but their tolerance to soil salinity remains poorly understood. This study aimed to investigate the effects of salinity levels at electrical conductivities (ECs) of 1.0 (nutrient solution), 2.5, 5.0, 7.5, and 10.0 dS⋅m−1 on two penstemons (P. barbatus and P. strictus). Penstemons were irrigated with nutrient or saline solution for 8 weeks and various growth and physiological data were recorded before harvest. Salinity stress degraded the visual quality of penstemon species and led to a reduction in the growth rate and biomass production. Leaf burn and necrosis were observed in penstemons because of salinity stress. The visual score of P. barbatus and P. strictus decreased with increasing EC levels in the saline solution. When irrigated with saline solution at an EC of 7.5 dS⋅m−1, Penstemon barbatus and P. strictus had severe-to-moderate foliar salt damage with average visual scores of 1.7 and 2.5, respectively (0 = dead plant; 5 = excellent plant without any foliar damage). The two penstemon species had severe foliar salt damage or were dead when irrigated with saline solution at an EC of 10.0 dS⋅m−1. There were 87% and 92% decreases in the leaf area of P. barbatus and P. strictus, respectively, when irrigated with saline solution at an EC of 10.0 dS⋅m−1 compared with those in the control. Although not statistically significant, there were 7% to 18% decreases in shoot dry weight of P. barbatus when irrigated with saline solutions at ECs of 2.5 to 10.0 dS⋅m−1 compared with control. However, P. strictus displayed declines of 13% to 31% in shoot dry weight as the salinity levels of the irrigation solution increased. As the salinity levels increased, the net photosynthetic rate (Pn), stomatal conductance (gs), and transpiration (E) rates decreased. Furthermore, sodium (Na+) and chloride (Cl−) contents of P. barbatus and P. strictus increased with the increase in salinity levels of the treatment solution. Consequently, P. barbatus and P. strictus demonstrated sensitivity to salinity stress at ECs of 7.5 and 10.0 dS⋅m−1. This study provides important insights for their effective utilization in landscaping practices within saline-prone areas.

Morpho-Physiological Response of Salt-Tolerant Chili (Capsicum annuum L.) Genotypes Under Saline Conditions

Salinity is a major challenge in crop cultivation, but tolerant genotypes can adapt physiologically to cope with stress. A pot culture experiment conducted during the period of July 2021 to June 2022 at Sher-e-Bangla Agricultural University, Dhaka, Bangladesh, evaluated the impact of salt stress on eight chili genotypes at three salinity levels (T1=3 dS/m, T2=6 dS/m, T3=9 dS/m NaCl) compared to a control (T0=0 dS/m NaCl). Varieties and stress interaction were estimated based on agromorphogenic and physiological traits. Increasing salinity levels significantly reduced plant growth traits like height, number of branches, days to first flowering, and leaf area, as well as fruit traits such as length, girth, weight, and number per plant. Among the genotypes, G4 was highly tolerant to salinity, while G5 and G6 are recommended for mild to moderately saline prone areas.

Evaluation of Local and Exotic Hybrid Genotypes of Yardlong Bean (Vigna unguiculata) in Saline Prone Area of Bangladesh

Evaluation of Local and Exotic Hybrid Genotypes of Yardlong Bean (Vigna unguiculata) in Saline Prone Area of Bangladesh

Screening of Solanum tuberosum Cultivars Salt Tolerences In vitro Condition

Aims: To evaluate the impacts of salinity on some physiological traits of potato cultivars under in Vitro conditions.
 Study Design: Completely Randomized Design using two factors.
 Place and Duration of Study: The Genetics and Plant Breeding Department, Sher-e-Bangla Agricultural University from October 2019 to January 2021.
 Methodology: Ten varieties; eight were collected from Tuber Crops Research Centre (TCRC), Agricultural Research Institute (BARI), Gazipur, and two from Sylhet were used. The varieties were BARI 29 (V1), Pechar Chokh (V2), BARI 72 (V3), Lal Shila (V4), BARI 53 (V5), BARI 25 (V6), BARI 28 (V7) and BARI 36 (V8), BARI 7 (V9) and BARI 73 (V10). Four salinity treatments including T1 (control), T2 (5 dS/m), T3 (10 dS/m), and T4 (15 dS/m) were applied to the varieties.
 Results: Varieties and salinity treatment were influenced individually in the interaction with the physiological traits of potatoes.V8 showed higher chlorophyll content (63.892%) while a minimum of 27.5% was recorded in V5. The chlorophyll content of potato varieties was increased at the lower level of salinity (T0). The accumulation of proline was observed in all varieties and treatments; however, the V7 cultivar (14.02 µmol-1FW) and T4 salinity treatment had higher accumulation. In response to salinity, the content of Na+ of potato plants rose at 0.26% in T4 while the decreasing trend was found in K+ due to salinity stress. Moreover, the highest Na+ content (0.20%) was found in V7 whereas the highest value of K+ content (0.20 %) was reported in the V4 variety.
 Conclusion: From the experiment, it has been found that BARI Alu-72(V3) performed well under 5 dS/m salinity level and 10 dS/m level because better yields were obtained from these varieties. So V3 variety is recommended for mild to moderate saline-prone areas in Bangladesh.

Morpho-physiological response of groundnut genotypes to salinity stress at early seedling stage

An experiment was conducted at the Department of Crop Botany, Faculty of Agriculture, Bangladesh Agricultural University, Mymensingh during the period from January, 2020 to June, 2020 to evaluate the morpho-physiological response of groundnut genotypes under salinity stress at early seedling stage. The four groundnut genotypes were, namely, V1= BARI Chinabadam-8, V2= Maijchar badam (Dhaka-1), V3= Binachinabadam-6 and V4= Binachinabadam-8. Two salinity levels were, namely, S1= 0 dS/m NaCl and S2= 12 dS/m NaCl used for hydroponic experiment. The treatments were designed in a Completely Randomized Design (CRD) with four replications in a factorial arrangement. The parameters of the experiment measured were root length, shoot length, number of leaves, number of leaflets, leaf area, Soil Plant Analysis Development (SPAD) value, root fresh weight, leaf fresh weight, shoot fresh weight, root dry weight, leaf dry weight, and shoot dry weight. The result indicated that there were significant differences between the genotypes and salinity stress in all of the studied parameters. Maximum root length (33.20 cm), number of leaves (7.25), number of leaflet (24.50), leaf area (128.07 cm2), SPAD value (41.67), leaf fresh weight (3.43 g) and shoot dry weight (0.11 g) were recorded in the genotype Binachinabadam-6 in a combination of control condition. On the contrary the minimum shoot length (12.17 cm), root length (16.72 cm), number of leaves (2.75), number of leaflet (15.50), leaf area (21.90 cm2), SPAD value (31.42), leaf fresh weight (0.72 g), shoot fresh weight (0.92 g), leaf dry weight (0.11 g) and shoot dry weight (0.09 g) were recorded from the genotype Binachinabadam-8 in stress condition. So, the higher susceptible genotype Binachinabadam-8 to saline conditions and the lower was Binachinabadam-6. Therefore, it may be concluded that the variety Binachinabadam-6 will be more suitable for the saline prone areas of Bangladesh.

A Study on the Phenotypic Variation of 103 Cucumber (Cucumis sativus L.) Landraces for the Development of Desirable Cultivars Suitable for the Changing Climate.

The cucumber (Cucumis sativus L.) is one of the most important vegetables in Bangladesh as well as across the globe. However, many of the important cucumber landraces have disappeared in Bangladesh due to climate change, particularly erratic rainfall, extreme temperature, salinity, and drought. Therefore, to protect against the extinction of the cucumber landraces, we collected 103 landraces in different geographical regions of Bangladesh, including drought and saline-prone areas, and studied their divergence for the future breeding programme for the development of cultivars suitable for the climate-changing situations. Data on morphological features, yield, and its components, which include 17 qualitative and quantitative traits, were recorded during the observation. Among the cucumber landraces, the Shannon–Weaver diversity index analysis revealed the presence of genetic diversity in these landraces. The biggest diversity appeared in the fruit-related characteristics, i.e., stem end fruit shape, bottom end fruit shape, fruit shape, and fruit skin colour at the table and harvest maturity. The descriptive statistics and analysis of variance expressed a wide range of variability for quantitative traits. A broad phenotypic variation was also observed for traits such as yield plant−1 [CV (%) 31.88, ranges 0.96 to 3.11 kg] and fruits plant−1 (CV (%), 28.71, ranges, 2.58 to 9.75). High heritability (broad sense) coupled with a high genetic gain was observed for yield and yield-contributing characteristics, indicating that these characteristics are controlled by additive gene effects, and they are more reliable for effective selection. The phenotypic correlation studies showed that fruit yield plant−1 exhibited a positive and significant correlation with fruits plant−1, fruit length, fruit weight, fruit width, branches plant−1, and plant height. All landraces were grouped into six clusters, and the maximum number of landraces were accommodated in cluster VI (30), followed by cluster V (22), cluster III (22), cluster IV (14), cluster I (13), and cluster II (2). Comparing cluster means with studied traits revealed that cluster III with landraces AC-14, AC-97, AC-471, AC-451, and RAI-209 were more divergent for improving average fruit weight, fruit length, and fruit width. On the other hand, cluster IV with landraces AC-201, TT-161, RAI- 217, RAI-215, and TRMR-103 were more divergent for improving average vine length, internode length, and the number of primary branches plant−1, the number of fruits plant−1, and yield plant−1. According to the MGIDI index, AC-14 (G1), AC-201 (G7), AC-471 (G24), AC-97 (G30), RAI-215 (G68) and TT-161 (G 94) may be considered to be the best parents based on their qualitative and quantitative characteristics for the future breeding programme. Moreover, crossing between the landraces, which were collected from saline and drought areas, in clusters I, V, and VI with those in other clusters could produce suitable cucumber varieties for the climatic changing situation.

Assessing Silicon-Mediated Growth Performances in Contrasting Rice Cultivars under Salt Stress.

Silicon (Si) application has great potential to improve salt tolerance in a variety of crop plants. However, it is unclear how Si influences the responses of contrasting rice cultivars when exposed to excessive salt. Here, we investigated the functions of Si in alleviating the negative effects of salt stress on two contrasting rice cultivars, namely BRRI dhan48 (salt-sensitive) and Binadhan-10 (salt-tolerant). Rice seedlings was pre-treated with three doses of Si (as silicic acid; 0, 1 and 2 mM) for 14 days at one-day interval before being exposed to salt stress (10 dSm−1) in a sustained water bath system. The results demonstrated that the seedlings of BRRI dhan48 and Binadhan-10, respectively exhibited substantial reductions in shoot height (16 and 9%), shoot fresh weight (64 and 43%) and shoot dry weight (50 and 39%) under salinity. Intriguingly, BRRI dhan48 pre-treated with 1 and 2 mM Si, respectively, showed a higher increase in shoot height (SH) (by 25.90 and 26.08%) as compared with Binadhan-10 (by 3 and 8%) under salt stress compared with their respective controls. Data revealed that a comparatively higher improvement in the growth performances of the salt-induced Si pre-treated BRRI dhan48 than that of Binadhan-10. For example, 1 and 2 mM of Si treatments significantly attributed to elevated leaf relative water content (RWC) (13 and 22%), proline (138 and 165%), chlorophyll a (42 and 44%), chlorophyll b (91 and 72%), total chlorophyll (58 and 53%) and carotenoids (33 and 29%), and recovery in the reductions of electrolyte leakage (13 and 21%), malondialdehyde content (23 and 30%) and shoot Na+/K+ ratio (22 and 52%) in BRRI dhan48 compared with Si-untreated control plants under salt stress. In addition, we found salt-tolerant Binadhan-10 also had enhanced RWC (9 and 19%), proline (12 and 26%) with pre-treatment with 1 and 2 mM of Si, respectively, under salt stress, while no significant differences were noticed in the case of photosynthetic pigments and Na+/K+ ratio. Our results showed that Si supplementation potentiated higher salt-tolerance ability in the salt-sensitive BRRI dhan48 as compared with salt-tolerant Binadhan-10. Thus, Si application could be highly beneficial in the growth recovery of the salinity-affected salt-sensitive high yielding rice cultivars in the saline-prone areas.

Effects of Salt Stress on Growth and Accumulation of NA<sup>+</sup>, K<sup>+</sup> And ca<sup>2+</sup> Ions in Different Accessions of Sesbania

Effects of salt stress on seedling growth and ion accumulation in 6 accessions of two Sesbania species viz. S. bispinosa (Jacq.) W. Wight (4 accessions: #1, #5, #7 and #59) and S. cannabina (Retz.) Poir. (2 accessions: #82 and #85), was evaluated in a hydroponic experiment under 0 (control) and 10 dS/m salinity stress. Salt stress significantly affected negatively seedling growth and different ion contents in 6 accessions of Sesbania seedling except for Na+. The relative values, per cent reduction over control, of all morphological and physiological descriptors, were significantly higher indicating superior salt tolerance in accession #59 compared to other accessions studied. The Na+ accumulation was higher in root compared to shoot; however, a reverse scenario was observed for K+ and Ca2+. No distinct difference in salt tolerance was observed between S. bispinosa and S. cannabina. Accession #59 could, therefore, be suggested for cultivation at salineprone areas of Bangladesh. However, it needs further confirmation at the farmer’s saline field condition. Bangladesh J. Bot. 51(1): 157-167, 2022 (March)

Influence of Salinity Stress on Color Parameters, Leaf Pigmentation, Polyphenol and Flavonoid Contents, and Antioxidant Activity of Amaranthus lividus Leafy Vegetables.

This is the first attempt to evaluate the impact of four salinity levels on the color parameters, pigments, polyphenols, flavonoids, and antioxidant capacities of four promising A. lividus genotypes. The color parameters, such as the yellowness/blueness (b*) and the chroma (C*); the antioxidant components, such as the polyphenols and flavonoids; and the antioxidant capacities of the leaves were remarkably increased by 39, 1, 5, 10 and 43%, respectively, at 50 mM of NaCl, and by 55, 5, 60, 34, 58 and 82%, respectively, at 100 mM NaCl concentrations. The green tower and SA6 genotypes were identified as tolerant varieties. The total phenolic content (TPC) and the total flavonoid content (TFC) played vital roles in scavenging reactive oxygen species (ROS), and they would be beneficial for the human diet and would serve as good antioxidants for the prevention of aging, and they are also essential to human health. A correlation study revealed the strong antioxidant capacities of the pigments and antioxidant components that were studied. It was revealed that A. lividus could tolerate a certain level of salinity stress without compromising the antioxidant quality of the final product. Taken together, our results suggest that A. lividus could be a promising alternative crop for farmers, especially in saline-prone areas in the tropical and subtropical regions.

Climate change, climatic extremes, and households’ food consumption in Bangladesh: A longitudinal data analysis

Bangladesh, the poster child of human-induced climate change, bears the brunt of the consequences of extreme climatic events such as floods, droughts, cyclones, salinity, and sea-level rise (SLR). In addition, the frequency and intensity of these extreme climatic events are shooting upward. They jeopardize households’ cereal food consumption in areas where the outbreak and landfall of these events are moderate and severe. Using Bangladesh—the most climate-vulnerable country globally—as a case study, this study investigates whether extreme climatic events have a heterogeneous impact on each region's agriculture through households’ food consumption. Using three rounds of nationally representative longitudinal datasets and employing a difference-in-differences (DiD) approach, results confirm that cyclone and saline-prone areas of the country are more vulnerable, followed by drought and flood-affected areas of cereal food consumption. In the long run (2011–19), Model 1 (per household cereal food consumption) was significant at the 1% and 10% levels, respectively, in the cyclone and drought-prone areas, but for flood-prone areas, it was insignificant. Moreover, analysis considering base year whole sample as control also underpinned that climate variability and their correlates negatively impact households’ basic food consumption. In the upshots findings, therefore, the study recommends intensifying agricultural research through robust budget allocation, launching crop insurance scheme and development of variety and technology sustaining in the saline, drought, and flood-prone areas along with high promotion for the adoption of the cultivars as well as strengthening of flood forecasting and early warning system.

Sodium accumulation trend in the different quality seed, cultivars, and yield potential of peanut under salinity stress

Seed quality is a crucial component of crop productivity. Therefore, it is essential to ascertain the seed harvested source for succeeding sowing to sustain productivity. Peanut (Arachis hypogaea L.) production in salinity-prone areas has abruptly decreased, which needs to be addressed on priority. Hence, we investigated the performance of contrasting seed types (seed harvested from normal and salinity grown conditions) and cultivar (TG 37A and GG 2) under different water salinity levels. Application of different salinity irrigation water levels (0.5 (control), 2, 4, and 6 dS m−1) reduced plant growth and yield attributes and increased the accumulation of sodium in both normal grown seed (NGS) and salinity grown seed (SGS) types of peanut kernel and cultivar (TG 37A and GG 2) with a successive increase in levels of salinity established since one and half-decade. This reduction was more prominent in SGS than NGS conditions for both the cultivars. However, the tested parameters were higher in cultivar GG 2 than TG 37A except 100-pod and 100-kernel mass, which were appreciably higher in cultivar TG 37A. Therefore, the reuse of SGS reduced the pod yield of peanuts (22–46%) under different water salinity levels than the NGS. Hence, the seed harvested from saline conditions should be avoided as a seed to ensure better peanut production.

Adaptive Mechanisms of Halophytes and Their Potential in Improving Salinity Tolerance in Plants.

Soil salinization, which is aggravated by climate change and inappropriate anthropogenic activities, has emerged as a serious environmental problem, threatening sustainable agriculture and future food security. Although there has been considerable progress in developing crop varieties by introducing salt tolerance-associated traits, most crop cultivars grown in saline soils still exhibit a decline in yield, necessitating the search for alternatives. Halophytes, with their intrinsic salt tolerance characteristics, are known to have great potential in rehabilitating salt-contaminated soils to support plant growth in saline soils by employing various strategies, including phytoremediation. In addition, the recent identification and characterization of salt tolerance-related genes encoding signaling components from halophytes, which are naturally grown under high salinity, have paved the way for the development of transgenic crops with improved salt tolerance. In this review, we aim to provide a comprehensive update on salinity-induced negative effects on soils and plants, including alterations of physicochemical properties in soils, and changes in physiological and biochemical processes and ion disparities in plants. We also review the physiological and biochemical adaptation strategies that help halophytes grow and survive in salinity-affected areas. Furthermore, we illustrate the halophyte-mediated phytoremediation process in salinity-affected areas, as well as their potential impacts on soil properties. Importantly, based on the recent findings on salt tolerance mechanisms in halophytes, we also comprehensively discuss the potential of improving salt tolerance in crop plants by introducing candidate genes related to antiporters, ion transporters, antioxidants, and defense proteins from halophytes for conserving sustainable agriculture in salinity-prone areas.

Salinity in drinking water and blood pressure status of adolescent school children in coastal area of Bangladesh

Background: High dietary salt intake from food is a major risk factor for raised blood pressure (BP) worldwide. In the context of Bang ladesh , information regarding salinity in water and blood pressure especially in the adolescent population is very scarce. This study was conducted to assess the blood pressure status of adolescent school children in coastal area of Bangladesh.
 Methods: A one-year school based cross-sectional study was carried out among 528 students of class 8-10 at schools of Bajua Union, Dacope Upazilla, saline prone zone of Khulna district. Relevant data were collected by using pre tested semi-structured questionnaire with face to face interview & checklist. Blood pressure was mea sured in a controlled environment and Collected water sources were analyzed by DPHE, Water Testing Laboratory. The study was conducted in the schools of Bajua Uni on, Dacope Upa zilla of the saline prone zone of Khulna district in between a one-year time frame.
 Results: Among 528 participants most of them were male (353, 66.9%) with an age of 14 years (185 , 35.0%). Most of them were read in class 8 (185 , 35.0%). Prevalence of paternal, maternal, paternal grandparents' and maternal grandparents' history of hypertension were found significant. About 72.3% regularly took extra salt during meal and 43.9% took salt preserved fish with meal. Mean of systolic blood pressure of respondents were 114.2197 ± 7.61448 mm of Hg. Mean of diastolic blood pressure of respondents were 75.1 780 ± 5.45959 mm of Hg. Mean of pulse pressure of respondents were 39.0417 ± 6.56430. Mean of mean arterial pressure of respondents were 88. I 9 I 9 ± 5.44267 mm of Hg. Sodium concentration of pond were approximately in between 500-600 mg/I, whereas in tube wells approximately in between 700-1 I 00 mg/I.
 Conclusion: Drinking water sodium is an important source of daily sodium intake , and therefore a risk factor for increased BP in salinity prone coastal areas. This adds to the cardiovascular health risks associated with food sodium intake in Southeast Asian populations. Low- saline alternative drinking water sources could effectively help to prevent high BP and hypertension-related morbidity and mortality in these coastal populations. New technologies for the supply of such alternative sources, including safeguarding the microbial quality , should be further studied.
 JOPSOM 2020; 39(1): 60-66

Bioactive Components and Radical Scavenging Activity in Selected Advance Lines of Salt-Tolerant Vegetable Amaranth.

Four selected advance lines of salt-tolerant vegetable amaranth were evaluated for proximate, nutraceuticals, pigments, phytochemicals, and antioxidants components antioxidants activity in completely randomized block design (RCBD) design in three replicates. Salt-tolerant vegetable amaranth contained adequate carbohydrates, protein, moisture, and dietary fiber. The remarkable contents of iron, manganese, copper, zinc, sodium, molybdenum, boron, potassium, calcium, magnesium, phosphorus, sulfur, betacyanins, betalains, betaxanthins, chlorophylls, ascorbic acid, polyphenols, flavonoids, and antioxidant potentiality were found in salt-tolerant vegetable amaranth. The genotypes LS7 and LS9 had abundant proximate, nutraceuticals, pigments, phytochemicals, and antioxidants compared to the genotypes LS3 and LS5. Salt-tolerant vegetable amaranth demonstrated high content of flavonoid compounds including flavonols such as rutin, kaempferol, isoquercetin, myricetin, hyperoside, and quercetin; flavanol, such as catechin; flavone such as apigenin; and flavanone, such as naringenin. For the first time, we identified one flavonol such as myricetin; one flavanol, such as catechin; one flavone such as apigenin; and one flavanone, such as naringenin in salt-tolerant vegetable amaranth. Across six flavonols, rutin and quercetin were identified as the most prominent compounds followed by isoquercetin and myricetin in selected salt-tolerant vegetable amaranths. Across the genotypes, LS7 exhibited the highest flavonols such as rutin, kaempferol, isoquercetin, myricetin, hyperoside, and quercetin as well as the highest flavanols, such as catechin; flavones such as apigenin; and flavanones, such as naringenin. It revealed from the correlation study that antioxidant components of salt-tolerant vegetable amaranth genotypes exhibited good radical quenching capacity of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and 2,2-diphenyl-1-picrylhydrazyl equivalent to Trolox. The two genotypes LS7 and LS9 of vegetable amaranth containing excellent sources of proximate, nutraceuticals, pigments, phytochemicals, and antioxidants components could be used as potent antioxidants to attaining nutrients and antioxidant sufficiency in the saline prone area of the globe. We can extract colorful juice from the genotypes LS7 and LS9 as drink purposes for consuming the nutraceuticals and antioxidant deficient community in the saline prone area around the world. However, further detail experimentation is required to confirm the standardization and stabilization of functional components of vegetable amaranth for extraction of juice as drinks.