Salt Tolerance Index Research Articles

GENETIC DIVERSITY AND ASSOCIATION ANALYSIS OF SALT TOLERANCE IN ASIATIC COTTON (GOSSYPIUM ARBOREUM) WITH MOLECULAR MARKERS

Gossypium arboreum possesses favorable characteristics that are valuable for developing superior cotton cultivars. This study was carried out to analyze genetic diversity and identify marker-trait association analysis related to salt tolerance using SSR markers for 215 accessions of G. arboreum. The salt tolerance-related traits like germination rate, fresh weight, stem length, water content, chlorophyll content, electric conductivity, and MDA of the accessions were identified using 150 mM salt for 7 days of seedling growth.
 According to the comprehensive index of salt tolerance, 215 accessions were categorized mainly into four groups. Twenty four accessions were classified as highly tolerant to salt treatment (>2.5). The natural population was classified into 3 main groups by phylogenetic analysis. The classifications of phylogenetic analysis were largely congruent with the breeding history and ecological region.
 Twenty-two strong 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 relative electric conductivity, 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) associated with relative fresh weight, and relative MDA, NAU1375 was associated with relative fresh weight and relative stem length, while NAU3468 was significantly associated with relative fresh weight, relative germination rate, and relative water content. 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.

Co-existence of halo-tolerant Pseudomonas fluorescens and Enterococcus hirae with multifunctional growth promoting traits to ameliorate salinity stress in Vigna radiata

Soil salinization has become a prominent obstacle in diverse arid and semi-arid region damaging agricultural productivity globally. From this perspective, present investigation was aimed to compare the potential compatible consortium of bio-inoculants for improving Plant Growth Promoting (PGP) attributes, anti-oxidative enzymes, grain yield and profitability of Vigna radiata in saline soil conditions. A total of 101 rhizobacterium isolated from salt affected regions of Punjab, India were screened for their ability to induce salt tolerance, multifunctional PGP traits and antagonistic activities. The 16S rRNA sequencing identified the strains LSMR-29 and LSMRS-7 as Pseudomonas flourescens and Enterococcus hirae, respectively. In-vitro compatible halo-tolerant dual inoculant (LSMR-29 + LSMRS-7) as bio-inoculants mitigated salt stress in Vigna radiata (spring mungbean) seedling with improved seed germination, biomass and salt tolerance index together with the presence of nifH, acds, pqq and ipdc gene under salinity stress as compared to single inoculants. Further, the potential of single and dual bio-inoculants were also exploited for PGP attributes in pot and field experiments. Results indicated that a significant improvement in chlorophyll content (2.03 fold), nodulation (1.24 fold), nodule biomass (1.23 fold) and leghemoglobin content (1.13 fold) with dual inoculant of LSMR-29 + LSMRS-7 over the LSMR-29 alone. The concentrations of macro & micronutrients, proline, soil enzyme activities i.e. soil dehydrogenase, acid & alkaline phosphatases and antioxidant enzymes such as superoxide dismutase, catalase and peroxidase also found to be high for LSMR-29 + LSMRS-7 as compared to un-inoculated control. The high grain yield thereby leading to Benefit: Cost (B: C) ratio at field scale was indicative of the commercial use bio-inoculants under salt affected Vigna radiata (spring mungbean) to improvement of productivity and soil health. The current finding reveals a co-inoculation of halo-tolerating Pseudomonas fluorescens and Enterococcus hirae containing ACC deaminase could prove to be novel approach for inducing salt tolerance and improving productivity of Vigna radiata (spring mungbean).

Reinforcing Pepper (<em>Capsicum annuum</em>) Growth by Gypsum and Salicylic Acid under Salinity Stress

Purpose: Salinity stress negatively affects plant growth, which leads to a decline in the food source. Low rainfall and high water evaporation rates in some regions are serious problems in the field of agriculture. In saline soil, plants are unable to absorb water. The aim was to find some amendments to reduce the toxic effects of saline soil. Research Method: In this study, a pot experiment was performed to study the ameliorative role of gypsum (G; 0.38 g per 200 g of soil) and salicylic acid (SA was sprayed on the leaves at two different times) on pepper growth. Two concentrations of NaCl (50mM and 100mM) were used for irrigation every two days. After 18 days, some growth characteristics, including shoot and root length, dry and fresh weight, salt tolerance index, leaf surface area, and chlorophyll content, were evaluated.Findings: The results showed that the application of gypsum alone and with foliar spray of SA was effective in reinforcing the pepper seedlings under salinity stress, regardless of salt concentration. Research limitations: Limited availability of some advanced instruments to collect more data.Originality/value: The investigated ameliorator can be used to improve plant growth under salinity stress.

Contribution of potassium solubilizing bacteria in improved potassium assimilation and cytosolic K+/Na+ ratio in rice (Oryza sativa L.) under saline-sodic conditions.

Sodium-induced potassium (K+) deficiency is more prevalent in salt-affected soils. Plants experience K+ starvation thus cytosolic K+/Na+ ratio is lowered, which is a prerequisite for their survival. K+ enrichment in crops can be acquired via K-solubilizing bacteria as a sustainable green agriculture approach. This study was conducted to explore potent K-solubilizing bacteria from the rhizosphere of wheat, rice, and native flora grown in salt-affected soils in two distinct regions of Pakistan. The aim of this work was to evaluate the contribution of microbial consortiums to the improvement of K+ assimilation and cytosolic K+/Na+ ratios in rice crops under saline-sodic conditions. Among 250 bacterial isolates, 9 were selected based on their salt (11% NaCl) and alkali (9) tolerance and K-solubilization indices (1.57-5.67). These bacterial strains were characterized for their plant growth-promoting traits and identified based on 16S rRNA gene sequencing. A consortium of five strains, namely, Enterobacter hormaechei, Citrobacter braakii, Pseudomonas putida, Erwinia iniecta, and Pantoea agglomerans, was used as a bio-inoculant to evaluate its role in K+ assimilation, cytosolic K+/Na+ ratio, and subsequent yield enhancement in rice grown under saline-sodic conditions. The impact of applied consortium on rice was assessed under variable salt levels (Control, 40, 80, and 120 mM) in a pot experiment and under natural saline-sodic conditions in the field. Plant agronomical parameters were significantly higher in the bacterial consortium-treated plants, with a concomitant increase in K+-uptake in root and shoot (0.56 and 0.35 mg g-1 dry wt.) of the salt-tolerant rice variety Shaheen. The root K+/Na+ ratio was significantly improved (200% in 40 mM and 126% in 80 mM NaCl) and in the shoot (99% in 40 mM and 131% in 80 mM) too. A similar significant increase was also observed in the salt-susceptible variety Kainat. Moreover, grain yield (30.39 g/1,000 grains wt.) and biomass (8.75 g) of the rice variety Shaheen, grown in field conditions, were also improved. It can be concluded that K-solubilizing bacteria can be used as bio-inoculants, contributing to growth and yield increment via enhanced K-assimilation and cytosolic K+/Na+ ratio in rice crops under salt stress.

Tuzluluk Stresinin Kolza Tohumunun (Brassica napus L.) Çimlenme ve Büyüme Özellikleri Üzerindeki Etkilerini Iyileştirmek için Askorbik Asit ile Tohum Hazırlama

This study was conducted to determine the effects of seed priming with ascorbic acid (AsA) on germination and seedling characteristics of rapeseed (Brassica napus L.) under different salinity levels. To this end, the study examined five salinity levels (0.20, 5.0, 10.0, 15.0, and 20.0 dS m-1 NaCl) and four priming doses (control, 0.5, 1.0, and 2.0 mM ascorbic acid). Salt stress negatively affected germination and some plant growth traits, such as radicle length (RL), plumule length (PL), radicle fresh weight (RFW) and plumule fresh weight (PFW), finally germination percentage (FGP), germination index (GI), mean germination time (MGT) and seedling vigor index (SVI). On the other hand, priming with AsA positively affected all parameters except FGP, PFW and salt tolerance index (STI). According to the interaction of salinity stress and priming, the highest values for GI (125.3), MGT (1.63 days), PFW (0.35 g), and STI (139.3%) were obtained at 5.0 dS m-1 salinity stress and 1.0 mM AsA dose. However, the highest value was obtained for RL (10.6 cm) and SVI (1170.7) at the control treatment and 0.5 mM AsA dose, whereas the highest value was obtained for PL (1.7 cm) at the control treatment and 1.0 mM AsA dose. Ascorbic acid at low doses (0.5 and 1.0 mM) had a positive effect on seedling germination and growth traits, while higher concentrations had a toxic effect on germination. Thus, it was concluded that priming rapeseed seeds with an AsA dose of 0.5 mM could reduce the restrictive impact of salinity stress on seed germination and seedling improvement. Further studies on the yield and growth parameters of rapeseed under salt stress by AsA application are recommended.

Comprehensive Evaluation and Transcriptome Analysis Reveal the Salt Tolerance Mechanism in Semi-Wild Cotton (Gossypium purpurascens).

Elevated salinity significantly threatens cotton growth, particularly during the germination and seedling stages. The utilization of primitive species of Gossypium hirsutum, specifically Gossypium purpurascens, has the potential to facilitate the restoration of genetic diversity that has been depleted due to selective breeding in modern cultivars. This investigation evaluated 45 G. purpurascens varieties and a salt-tolerant cotton variety based on 34 morphological, physiological, and biochemical indicators and comprehensive salt tolerance index values. This study effectively identified a total of 19 salt-tolerant and two salt-resistant varieties. Furthermore, transcriptome sequencing of a salt-tolerant genotype (Nayanmian-2; NY2) and a salt-sensitive genotype (Sanshagaopao-2; GP2) revealed 2776, 6680, 4660, and 4174 differentially expressed genes (DEGs) under 0.5, 3, 12, and 24 h of salt stress. Gene ontology enrichment analysis indicated that the DEGs exhibited significant enrichment in biological processes like metabolic (GO:0008152) and cellular (GO:0009987) processes. MAPK signaling, plant-pathogen interaction, starch and sucrose metabolism, plant hormone signaling, photosynthesis, and fatty acid metabolism were identified as key KEGG pathways involved in salinity stress. Among the DEGs, including NAC, MYB, WRKY, ERF, bHLH, and bZIP, transcription factors, receptor-like kinases, and carbohydrate-active enzymes were crucial in salinity tolerance. Weighted gene co-expression network analysis (WGCNA) unveiled associations of salt-tolerant genotypes with flavonoid metabolism, carbon metabolism, and MAPK signaling pathways. Identifying nine hub genes (MYB4, MYB105, MYB36, bZIP19, bZIP43, FRS2 SMARCAL1, BBX21, F-box) across various intervals offered insights into the transcriptional regulation mechanism of salt tolerance in G. purpurascens. This study lays the groundwork for understanding the important pathways and gene networks in response to salt stress, thereby providing a foundation for enhancing salt tolerance in upland cotton.

Morphological and physiological behaviour of sea barley (Hordeum marinum ssp marinum) genotypes originating from Soliman Sebkha under increasing salinity

Evaluation of germplasm in salt stress environment may help identifying salt-tolerant genotypes. In this study, we analyzed the genetic diversity of Hordeum marinum, genotypes originated from Soliman Sebkha in response to salinity (0, 250 and 400 mM) by measuring a set of parameters related to growth, water statue and photosynthetic activity. Results of ANOVA showed that variability of measured parameters was explained by the effects genotypes, treatment and their interaction, with treatment factor recorded the highest values. Salinity significantly reduced the photosynthetic rate and related parameters, including stomatal conductance (gs), intercellular CO2 concentration (Ci), and transpiration (E). Several indices for salt tolerance indices comprising tolerance index (TOL), stress tolerance index (STI) and Salt Tolerance (ST) were calculated based on drought biomass (ADW) under non-stressed and under stress conditions. Results showed that lower values of TOL and higher values of ST and STI indicate the superiority of the genotypes having enough plasticity to respond to extreme conditions. Principal Component Analysis clustered genotypes into sensitive (21.43%), moderately tolerant (50%), and highly tolerant (28.57%) groups, depending on their relative potential to sustain good growth under high salinity. Results indicating sufficient genetic variability for salinity tolerance among the studied genotypes, hence tolerant genotypes can be good candidates in future breeding programs.

Acetylcholine Esterase Inhibitory Effect, Antimicrobial, Antioxidant, Metabolomic Profiling, and an In Silico Study of Non-Polar Extract of The Halotolerant Marine Fungus Penicillium chrysogenum MZ945518.

Major health issues, such as the rise in oxidative stress, incidences of Alzheimer's disease, and infections caused by antibiotic-resistant microbes, have prompted researchers to look for new therapeutics. Microbial extracts are still a good source of novel compounds for biotechnological use. The objective of the current work was to investigate marine fungal bioactive compounds with potential antibacterial, antioxidant, and acetylcholinesterase inhibitory effects. Penicillium chrysogenum strain MZ945518 was isolated from the Mediterranean Sea in Egypt. The fungus was halotolerant with a salt tolerance index of 1.3. The mycelial extract showed antifungal properties against Fusarium solani with an inhibitory percentage of 77.5 ± 0.3, followed by Rhizoctonia solani and Fusarium oxysporum with percentages of 52 ± 0.0 and 40 ± 0.5, respectively. The extract also showed antibacterial activity against both Gram-negative and Gram-positive bacterial strains using the agar diffusion technique. The fungal extract was significantly more effective with Proteus mirabilis ATCC 29906 and Micrococcus luteus ATCC 9341; inhibition zones recorded 20 and 12 mm, respectively, compared with the antibiotic gentamycin, which recorded 12 and 10 mm, respectively. The antioxidant activity of the fungus extract revealed that it successfully scavenged DPPH free radicals and recorded an IC50 of 542.5 µg/mL. Additionally, it was capable of reducing Fe3+ to Fe2+ and exhibiting chelating ability in the metal ion-chelating test. The fungal extract was identified as a crucial inhibitor of acetylcholinesterase with an inhibition percentage of 63% and an IC50 value of 60.87 µg/mL. Using gas chromatography-mass spectrometry (GC/MS), 20 metabolites were detected. The most prevalent ones were (Z)-18-octadec-9-enolide and 1,2-Benzenedicarboxylic acid, with ratios of 36.28 and 26.73%, respectively. An in silico study using molecular docking demonstrated interactions between the major metabolites and the target proteins, including: DNA Gyrase, glutathione S-transferase, and Acetylcholinesterase, confirming the extract's antimicrobial and antioxidant activity. Penicillium chrysogenum MZ945518, a halotolerant strain, has promising bioactive compounds with antibacterial, antioxidant, and acetylcholinesterase inhibitory activities.

Genotypic Difference in Growth and Physiological Indices of Grain Amaranth Species under Salinity Stress

The present experiment was conducted during October to February of year 2019−20, to investigate the effect of salinity on morpho-physiological traits and identify the genotype have higher salt tolerance among ten genotypes belongs to three grain Amaranth species. Plant growth traits viz., plant height, shoot and root dry weight decreases with increase in the salinity stress level (EC of 5 and 10 dS m-1) in all the genotypes, however significant (p<0.01) genotypic difference were present among genotypes and GA-5 maintained the maximum growth under salinity. Percent decrease in SDW and RDW was lowest (10.61−23.86 and 10.37 and 26.59) in A. hypochondriachus while in A. cruentus (15.10-29.55 and 12.78-33.09) and A. caudatus (15.15−28.84 and 16.62-34.90). Salinity significantly (p<0.01) decreases the membrane stability, relative water content and leaf potassium content while, leave sodium content increases. As compared to other genotype GA-5 have maximum membrane stability (53.30), relative water content (85.40%), K+ accumulation and minimum Na+ accumulation in leaves.Morpho-physiological traits of grain Amaranthus species are significantly positively correlated with dry shoot biomass (0.649), MSI (0.770), RWC (0.768), chlorophyll (0.908), carotenoid (0.883) and leaf potassium (0.883). It might be concluded that among studied genotypes GA-5 maintained the growth and have higher physiological efficiency results into maximum salt tolerance index also morpho-physiological traits like dry weight, RWC, MSI, Chlorophyll, Carotenoid and leaf potassium content might be utilised for selection of salt tolerant Amaranth genotypes.

Exogenous Melatonin Application Induced Morpho-Physiological and Biochemical Regulations Conferring Salt Tolerance in Ranunculus asiaticus L.

This study presents the effects of exogenous melatonin application at different concentrations (50, 100, and 200 μM) on the morphological, physiological, and antioxidant defense systems of the buttercup plant under salinity stress (4.5 and 5.5 dS·m−1 EC). Expectedly, the salinity stress negatively affected the plant growth parameters, cell membrane stability, and POX enzyme activity of R. asiaticus compared to non-stressed plants. However, in a dose-dependent manner, exogenous melatonin foliar application decreased the salt stress-induced symptoms of retarded vegetative growth, physiological characteristics, and oxidative stress level. The results obtained, revealed the significant effectiveness of exogenous melatonin treatment at 200 μM concentration under salt stress conditions by enhancing the plant growth traits such as chlorophyll and carotenoids content, relative water content, proline content, peroxidase enzyme activity (POD), and by the decreased electrolyte leakage rate, and Na+ content, as well as delaying the emergence of flower buds under salinity stress. The salt tolerance index percentages (STI%) for all estimated characters are also calculated for all studied parameters. This study uncovered the beneficial effect of melatonin in reducing salt stress symptoms that can be used to reduce the salinity effect in ranunculus plant production.

The Response of Sugar Beet (Beta vulgaris L.) Genotypes at Different Ploidy Levels to Salt (NaCl) Stress

Sugar beet (Beta vulgaris L.) is cultivated in temperate climates worldwide to produce sugar. The production of sugar beet and other plants is in danger due to the world’s increasingly salinized soils. Although different sugar beet genotypes exist at various ploidy levels, most of them are diploid (2X) with 18 chromosomes. The majority of polyploid plants have different variations, morphologies, and anatomy. Diploid and polyploid plants especially have different morphology, physiology, cellularity, and biochemistry. As a result, polyploidy has been identified as an essential component in determining plant salt tolerance. To evaluate the effects of salt (NaCl) stress on sugar beet genotypes, diploid (2X), triploid (3X), and tetraploid (4X) genotypes were exposed to 0 (control), 50, and 150 mM NaCl concentrations for seven weeks. Under control conditions, the diploid (2X) genotype showed higher growth performance compared to the tetraploid (4X) and triploid (3X) genotypes, respectively. Regarding germination and early-stage growth performance, a reduction of about 50% was observed in the diploid (2X) genotype under salt stress compared to the control condition. The diploid (2X) genotype showed higher germination, a greater salt tolerance index, and better seedling growth performance than the other ploidy levels. Late-stage growth, leaf length, leaf width, leaf area, cytological findings, and total chlorophyll content were all shown to be higher and less reduced (around 30%) under salt stress in diploid (2X) genotypes. Even though all of the findings in this study showed a decrease when plants were exposed to salt (NaCl), the diploid (2X) ploidy level plants displayed more robust growth and development than the triploid (3X) and tetraploid (4X) genotypes.

Salinity responses in 24 guar genotypes are linked to multigenic regulation explaining the complexity of tolerance mechanisms in planta

AbstractGuar (Cyamopsis tetragonoloba (L.) Taub.) is an economically important, drought‐tolerant legume crop affected by moderate to high salinity. Guar has various industrial applications, including gum extracted from seeds that is widely used in the oil and natural gas industries. In this investigation, we evaluated the salinity tolerance of different guar genotypes and their relation to genetic mechanisms regulating guar responses to salinity stress. We screened 24 guar genotypes in a greenhouse lysimeter system under control (electrical conductivity (EC) = 1.46 dS m−1) and high salinity (EC = 13.65 dS m−1) treatments. Both length and biomass of shoots were significantly affected by salinity compared to roots, indicating higher shoot than root sensitivity to salinity. Twenty‐four genotypes were classified based on salt tolerance index for each trait. Tissue ion analysis revealed that roots accumulated over 10‐fold higher Na than leaves, demonstrating that guar effectively regulated the root‐to‐shoot movement of Na+. However, higher Cl concentrations in leaves than roots indicated less regulatory control of Cl− movement. Based on the morphological traits and tissue ion analysis, six genotypes (PI 164486, PI 253186, PI 26152, PI 158125, PI 179926, and PI 263698) with different responses to salinity were selected for gene expression analysis. Expression patterns of different genes showed that a complex network of component traits, including Na+ exclusion, Cl− exclusion, and tissue tolerance, regulate salinity tolerance in guar. Hence, the genetic information about different component traits will benefit guar breeders in developing new varieties that are more tolerant to salinity than current ones.

Siphoning novel sources of seedling salinity tolerance from the diverse chickpea landraces

Context Chickpea (Cicer arietinum L.) are highly sensitive to elevated salinity, particularly at initial seedling establishment stage. Seedling screening would be an effective means to identify novel sources of donors for salt tolerance. Aim This study aimed to identify salt stress tolerant genotypes at seedling stage from 50 chickpea accessions. Methods The screening of 50 chickpea accessions was done under two salinity conditions including salt stress (8 dS m−1) and control (no salt stress). Accessions were studied for morphological traits, root system architectural analysis, and CSTI (Cumulative salt tolerance index). Further, principal component analysis was conducted to validate these results for more accuracy and reliability. Key results For morphological traits, a high degree of genetic variation was seen among genotypes, and root traits were found to be the better indicators of salt stress tolerance. CSTI was used to classify the accessions; 22 (44%) were identified as salt sensitive, 21 (42%) were found to be moderately salt tolerant, and 7 (14%) had moderate to high salt tolerance. The most salt tolerant and salt sensitive genotypes were found to be ICCV10 and ILC5595, respectively. Conclusions Early seedling screening has a great potential to identify genotypes with robust root systems, which can withstand salinity. Implications We used a novel approach to classify chickpea landraces based on the combination of CSTI and principal component analysis methods. By choosing suitable donors and prospective genotypes at early growth stages, the knowledge gathered from this study may aid scientists and chickpea breeders in developing salt tolerant cultivars.

Salinity-Induced Physiological Changes in Pea (Pisum sativum L.): Germination Rate, Biomass Accumulation, Relative Water Content, Seedling Vigor and Salt Tolerance Index.

Salinity affects and limits the yield potential of pulse crops. Therefore, an experiment was conducted to evaluate the salinity-induced physiological response of field peas by estimating the germination rate (%), accumulation of biomass, relative water content, and seedling vigor and salt tolerance index. The treatments included four salinity levels (NaCl) (i.e., 0 (control), 8, 12, and 16 dS m-1, respectively) and eight field pea genotypes (i.e., BD4175, BD4182, BD4225, BD6944, BD4176, BD4193, BD4493, and BD4496). All treatments were arranged in a factorial completely randomized design and repeated four times. Results indicated that the percentage and rate of germination, percentage reduction of fresh and dry weight, relative water content, seedling vigor index, and salt tolerant index of all genotypes of field peas were influenced significantly by the different levels of salinity. The radicle and plumule of all field pea genotypes were damaged by applying 12 and 16 dS m-1 salt stress. However, among these eight pea genotypes, two genotypes, namely BD4175 and BD4225, performed better under the 8 dS m-1 level of salinity and these two genotypes may be recommended for cultivation in field conditions of saline coastal areas of Bangladesh, and can also be used in future breeding programs for the development of salt-tolerant pea cultivars.

Assessing the Suitability of Multivariate Analysis for Stress Tolerance Indices, Biomass, and Grain Yield for Detecting Salt Tolerance in Advanced Spring Wheat Lines Irrigated with Saline Water under Field Conditions

Successfully evaluating and improving the salt tolerance of genotypes requires an appropriate analysis tool to allow simultaneous analysis of multiple traits and to facilitate the ranking of genotypes across different growth stages and salinity levels. In this study, we evaluate the salt tolerance of 56 recombinant inbred lines (RILs) in the presence of salt-tolerant and salt-sensitive control genotypes using multivariate analysis of plant dry weight, measured at 75 (PDW-75) and 90 (PDW-90) days from sowing, biological yield (BY), grain yield (GY), and their salt tolerance indices (STIs). All RILs and genotypes were evaluated under the control and 15 dS m−1 for two consecutive years (2019/2020 and 2020/2021). Results showed significant main effects of salinity and genotype as well as their interactions on four plant traits. Significant genotypic differences were also found for all calculated STIs. STIs exhibited moderate to strong relationships with the four plant traits when measured under either the control or salinity conditions and between each other. The principal component analysis (PCA) showed that the most variation among all analyzed variables was explained by the first two PCs, with the PC1 and PC2 explained at 61.8–71.8% and at 28.0–38.2% of the total variation, respectively. The PC1 had positive and strong correlations with the four plant traits measured under salinity conditions and STI, YI, REI, SWPI, MRPI, MPI, GMPI, and HMPI. The PC2 had strong correlations with BY and GY measured under the control conditions and SSI, TOL, RSE, and YSI. The PC1 was able to identify the salt-tolerant genotypes, while the PC2 was able to isolate the salt-sensitive ones. Cluster analysis based on multiple traits organized 64 genotypes into four groups varied from salt-tolerant to salt-sensitive genotypes, with the salt-tolerant group attaining higher value for plant traits under salinity conditions and the STIs related to the PC1. In conclusion, the use of multivariate analysis together with the STIs that evaluated the performance of genotypes under contrasting environmental conditions will help breeders to distinguish salt-tolerant genotypes from salt-sensitive ones, even at the early growth stages of plant development.

Screening of Amaranth (Amaranthus cruentus L.) Mutant Lines for Salinity Tolerance

Aims: The present study was carried out to access the salt tolerance level of nine amaranth (Amaranthus cruentus) mutant lines selected from Benin cultivar ‘Locale’ at young plants stage in comparison with the cultivar ‘Locale’ used as control.
 Study Design: The experiment was laid out as a Completely Randomized Design with three replications.
 Place and Duration of Study: The experiment was carried out in a screening house at University of Abomey-Calavi, City of Abomey-Calavi, Republic of Benin from May to June, 2020.
 Methodology: Three-weeks old plants of the nine stable mutant lines and the control cultivar ‘Locale’ were planted in pots containing a mixture of potting soil and sand. NaCl concentrations: 0; 100; 150 and 200 mM were given by irrigation once in two days Plant growth parameters were evaluated after two weeks.
 Results: Salt effect caused a reduction of young plant growth whatever the growth parameter considered with a significant disparity (p=.001) among the genotypes. Growth of the control cultivar, lines 1, 11 and 15 was most affected under salt stress whereas that of lines 18; 23 and 16 was least affected. A significant difference (p=.01 or p=.001) was observed among the salt tolerance index of genotypes. The highest salt tolerance index was observed in the line 23 followed by lines 18 and 2; and the lowest in line 15 followed by line 17, line 10 and the control cultivar.
 Conclusion: Some variability was observed among lines for their salt resistance. Lines 23, 18 followed by line 2 appeared as the most salt resistant types whereas line 15, followed by lines 17, 10 and the control cultivar were the most salt sensitive. Thus, lines 23, 18 and 2 are promising for salt affected areas. Further studies are necessary to determine the physiological and biochemical mechanisms involved in the lines’ salt resistance.

Hydroponic and in vitro screening of wheat varieties for salt-tolerance

Salt-tolerant wheat cultivars are essential for sustainable wheat production and global food security. The present study aimed to establish a reliable screening protocol as well as successfully isolated the potential salt-tolerant wheat varieties by discerning morpho-physiological parameters with multivariate analysis. Seventeen wheat varieties were evaluated at 0, 12, 15 and 18 dSm-1 salinity levels in a hydroponic culture system at the seedling stage. Moreover, in vitro callusing responses of four selected varieties were determined to clarify the salt tolerance capability at 0, 9, 12 and 15 dSm-1 salt treatments. The seedling growth of most wheat varieties was highly interrupted and reduced by the toxic effects of salinity, however, some varieties such as BARI Gom-32, BARI Gom-33, BARI Gom-31, BARI Gom-30, and BARI Gom-28 showed the lowest reduction under all salinity stress conditions. The total salt tolerance index (TSTI) showed that the cultivar BARI Gom-33 was the most salt-tolerant followed by BARI Gom-32 and BARI Gom-30 whereas BARI Gom-25 was identified as the most sensitive. These results were strongly supported by the principal component analysis (PCA) and Ward’s Methods Euclidean based clustering. In vitro results revealed that the lowest reduction of callus induction was recorded in BARI Gom-33 which might show the greatest tolerance to salinity by improving morpho-physiological characteristics against salt stress. Therefore, the identified genotypes might be employed as donor parents to develop salt-tolerant and high-yielding cultivars in the wheat breeding programme.

Magnetopriming Actuates Nitric Oxide Synthesis to Regulate Phytohormones for Improving Germination of Soybean Seeds under Salt Stress.

In this study, the role of the signalling molecule nitric oxide (NO) in magnetopriming-mediated induction of salinity tolerance in soybean seeds is established. The cross-talk of NO with germination-related hormones gibberellic acid (GA), abscisic acid (ABA) and auxin (IAA) for their ability to reduce the Na+/K+ ratio in the seeds germinating under salinity is highlighted. Salt tolerance index was significantly high for seedlings emerging from magnetoprimed seeds and sodium nitroprusside (SNP, NO-donor) treatment. The NO and superoxide (O2•−) levels were also increased in both of these treatments under non-saline and saline conditions. NO generation through nitrate reductase (NR) and nitric oxide synthase-like (NOS-like) pathways indicated the major contribution of NO from the NR-catalysed reaction. The relative expression of genes involved in the NO biosynthetic pathways reiterated the indulgence of NR in NO in magnetoprimed seeds, as a 3.86-fold increase in expression was observed over unprimed seeds under salinity. A 23.26-fold increase in relative expression of NR genes by the NO donor (SNP) was observed under salinity, while the NR inhibitor (sodium tungstate, ST) caused maximum reduction in expression of NR genes as compared to other inhibitors [L-NAME (N(G)-nitro-L-arginine methyl ester; inhibitor of nitric oxide synthase-like enzyme) and DPI (diphenylene iodonium; NADPH oxidase inhibitor)]. The ratio of ABA/GA and IAA/GA decreased in magnetoprimed and NO donor-treated seeds, suggesting homeostasis amongst hormones during germination under salinity. The magnetoprimed seeds showed low Na+/K+ ratio in all treatments irrespective of NO inhibitors. Altogether, our results indicate that a balance of ABA, GA and IAA is maintained by the signalling molecule NO in magnetoprimed seeds which lowers the Na+/K+ ratio to offset the adverse effects of salinity in soybean seeds.

Biochemical Characterization of Halotolerant Bacillus safensis PM22 and Its Potential to Enhance Growth of Maize under Salinity Stress.

Salinity stress is one of the primary abiotic stresses limiting crop growth and yield. Plants respond to salinity stress with several morphophysiological, molecular, and biochemical mechanisms, however, these mechanisms need to be improved further to cope with salt stress effectively. In this regard, the use of plant growth-promoting (PGP) and halotolerant bacteria is thought to be very efficient for enhancing growth and salinity tolerance in plants. The current study aims to assess Bacillus safensis PM22 for its ability to promote plant growth and resistance to salt. The PM22 produced substantial amounts of exopolysaccharides, indole-3-acetic acid, siderophore, and 1-aminocyclopropane-1-carboxylic acid deaminase (ACC-deaminase) under saline conditions. Additionally, inoculation of the halotolerant bacteria PM22 reduced the severity of salinity stress in plants and increased root and shoot length at various salt concentrations (0, 180, 240, and 300 mM). Furthermore, PM22-inoculated plants showed markedly enhanced photosynthetic pigment, carotenoid, leaf relative water content, 2,2-diphenyl-1-picrylhydrazyl (DPPH) activity, salt tolerance index, total soluble sugar, total protein, and ascorbic acid contents compared to non-inoculated control maize plants. PM22 substantially increased antioxidant (enzymatic and non-enzymatic) activities in maize plants, including ascorbate peroxidase, peroxidase, superoxide dismutase, catalase, total flavonoid, and phenol levels. Maize plants inoculated with PM22 also exhibited a significant reduction in electrolyte leakage, hydrogen peroxide, malondialdehyde, glycine betaine, and proline contents compared to non-inoculated control plants. These physiological appearances were further validated by quantitative reverse transcription-polymerase chain reaction (qRT-PCR), which revealed the upregulation of expression in genes responsible for stress tolerance. In the current investigation, Bacillus safensis PM22 showed plant growth-promoting and salt tolerance attributes and can be utilized as a bio-inoculant to improve yield in salt stress affected areas.

Assessment of Genotype Stress Tolerance as an Effective Way to Sustain Wheat Production under Salinity Stress Conditions

The creation of salt-tolerant wheat genotypes can provide a basis for sustainable wheat production in areas that are particularly sensitive to the impacts of climate change on soil salinity. This study aimed to select salt-tolerant wheat genotypes that could serve as a genetic resource in breeding for salinity tolerance. A two-year experiment was established with 27 wheat genotypes, grown in salinity stress and non-stress conditions. Agronomic parameters (plant height, spike weight, number of grains per spike, thousand grain weight, and grain yield/plant) were analyzed in the phenophase of full maturity, while biochemical parameters (DPPH radical scavenging activity and total phenolic content) were tested in four phenophases. Grain yield/plant was the most sensitive parameter to salinity, with a 31.5% reduction in value. Selection based on salt tolerance indices (STI, MP, and GMP) favored the selection of the genotypes Renesansa, Harmonija, Orašanka, Bankut 1205, KG-58, and Jugoslavija. Based on YI (1.30) and stability analysis, the genotype Harmonija stands out as the most desirable genotype for cultivation in saline conditions. The presence of positive correlations between grain yield/plant and biochemical parameters, in all phenophases, enables the selection of genotypes with high antioxidant activity and high yield potential, even in the early stages of plant development.