Salt-tolerant Varieties Research Articles

Analysis of Effect of Compound Salt Stress on Seed Germination and Salt Tolerance Analysis of Pepper (Capsicum annuum L.).

To determine the salt tolerance and physiological mechanism of pepper (Capsicum annuum L.) at the germination stage, the Hongtianhu 101 and Xinxiang 8 varieties, which have large differences in salt tolerance, are employed as the study materials. Six mixed salt concentrations of 0, 3, 5, 10, 15, and 20 g/L derived using equal molar ratios of Na2CO3, NaHCO3, NaCl, CaCl2, MgCl2, MgSO4, and Na2SO4 are used. To determine their effects, the related indexes of seed germination, seedling growth, and physiology are measured, and salt tolerance is comprehensively evaluated using membership function analysis. The results show that as the mixed salt concentration increases, the germination potential, germination index, germination rate, seed germination vigor index, root length, and root fresh weight of the two cultivars significantly decrease, whereas the relative salt rate gradually increases. The hypocotyl length and fresh weight aboveground increase first and then decrease, while the malondialdehyde (MDA), proline (Pro) content, catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) activity decrease and then increase. The germination potential, germination index, germination rate, seed germination vigor index, root length, root fresh weight, MDA and Pro content, and CAT activity of the Hongtianhu 101 seeds are higher than those of Xinxiang 8 for all salt concentrations employed here. However, hypocotyl length, fresh weight aboveground, and relative salt rate are lower in Hongtianhu 101 than in Xinxiang 8. The comprehensive evaluation of salt tolerance reveals that the total weighted values of the two membership function indexes increase first and then decrease as the mixed salt concentration increases. Compared with 5 g/L, which has the highest membership function value, the index under salt concentrations of 3 g/L, 10 g/L, and 15 g/L decreases by 4.7%-11.1%, 25.3%-28.3%, and 41.4%-45.1%, respectively. This study provides theoretical guidance for the breeding of salt-tolerant varieties of pepper and an analysis of the physiological mechanisms involved in salt tolerance and salt-tolerant cultivation.

Lipid composition remodeling and storage lipid conversion play a critical role in salt tolerance in alfalfa (Medicago sativa L.) leaves

Alfalfa is the most important forage internationally due to its high yield and nutritional value, but its production is severely limited by soil salinization. A better understanding of alfalfa’s salt response mechanism is needed to provide guidance for breeding salt tolerant varieties. Lipidomic profiling of the salt-tolerant alfalfa cultivar Medicago sativa cv. Zhongmu-4 was performed after salt treatment. Of the 275 molecular species of lipid identified, 171 had altered levels after salt treatment. The levels of phospholipids, glycolipids, fatty acids, and sphingolipids decreased whereas lysophospholipids and glycerides accumulated in the salt treated plants. Specifically, higher PC/PE and DGDG/MGDG ratios and increased levels of FA 18:3 were observed, suggesting that changes in bilayer membrane structure integrity and fluidity maintenance occur in alfalfa leaves during salt stress. An accumulation of DAG (36:6, 36:5) and TAG (54:8, 54:9, 54:7, 54:6, 52:5, 52:6) was found, consistent with their potential role as storage substrates for membrane regeneration under salt stress. Changes in PI, LPC (16:0, 18:3, 18:2, 18:0), LPE (16:0, 18:2), and Cer (42:1;4 O, 34:1;4 O, 40:1;4 O) suggest these compounds may play a role in signal transduction under salt stress. The levels of PE, DGDG, and TAG were highly correlated (r＞0.8) with changes in salt-related physiological parameters. In addition, the apparent remodeling of lipid profiles was supported by complementary changes in gene expression, including DGD2, SQD2, FAD2, DGK, DGAT, and TAGL, that can be important candidate genes for alfalfa salt tolerance improvement. The detailed description of the changes occurring in lipid profiles and gene expression in alfalfa under salt stress provided by this study implicate lipid remodeling as an important feature of the salt-stress response, and provides a basis for the genetic improvement of alfalfa salt tolerance.

Variety-Specific Transcriptional and Alternative Splicing Regulations Modulate Salt Tolerance in Rice from Early Stage of Stress

Salt stress poses physiological drought, ionic toxicity and oxidative stress to plants, which causes premature senescence and death of the leaves if the stress sustained. Salt tolerance varied between different rice varieties, but how different rice varieties respond at the early stage of salt stress has been seldom studied comprehensively. By employing third generation sequencing technology, we compared gene expressional changes in leaves of three rice varieties that varied in their level of tolerance after salt stress treatment for 6 h. Commonly up-regulated genes in all rice varieties were related to water shortage response and carbon and amino acids metabolism at the early stage of salt stress, while reactive oxygen species cleavage genes were induced more in salt-tolerant rice. Unexpectedly, genes involved in chloroplast development and photosynthesis were more significantly down-regulated in the two salt tolerant rice varieties ‘C34’ and ‘Nona Bokra’. At the same time, genes coding ribosomal protein were suppressed to a more severe extent in the salt-sensitive rice variety ‘IR29’. Interestingly, not only variety-specific gene transcriptional regulation, but also variety-specific mRNA alternative splicing, on both coding and long-noncoding genes, were found at the early stage of salt stress. In summary, differential regulation in gene expression at both transcriptional and post-transcriptional levels, determine and fine-tune the observed response in level of damage in leaves of specific rice genotypes at early stage of salt stress.

Modeling of Irrigation Water Demand for Sustaining Crop Yield in Saline Environment

Increasing the productivity of water and making safe use of poor quality water in agriculture will play a vital role in easing competition for scarce water resources prevention of environmental degradation and provision of food security. The purpose of this study is to cover the crop water demand and supply gap with the management strategies. The comparison of actual water supplies and demand, i.e. crop water demand has been calculated and found that demand is more than supply. The daily reference evapotranspiration for Bhutana distributory is estimated using pan-Montieth method in CROPWAT model and crop-water demand has also been calculated using CROPWAT model. The supply shortfall in total Rabi seasons is 329.5 mm in 2009-10 and 162.2 in 2010-11. This gap is met by pumping ground water. Different scenario is generated after canal supply gap analysis because supply is less and demand is more and at the same, ground water quality is not so good. In some places, there is a problem of salinity or sodicity. Twelve point have been selected for soil sample from different locations of Butanadistributory. The result revealed that EC, SAR, RSC varies from 1.5 g/kg, 2.7-20 (mmoles kg-1)0.5 , 0- 8.8 mg/l. The best management strategies such as growing salt tolerant crops varieties and proper irrigation scheduling with effective conjunctive use of multiquality irrigation water, and pre-sowing water management was suggested for various scenarios of deficit canal water supply, poor soil and ground water quality, and water logging conditions for growing more food with less water of good/poor quality. This study will be helpful for engineers, researchers and farmers in taking decision on utilization of ground water, which will minimize their yield losses in scarce water supply and marginal quality of ground water.

Salt tolerance QTLs of an endemic rice landrace, Horkuch at seedling and reproductive stages

Salinity has a significant negative impact on production of rice. To cope with the increased soil salinity due to climate change, we need to develop salt tolerant rice varieties that can maintain their high yield. Rice landraces indigenous to coastal Bangladesh can be a great resource to study the genetic basis of salt adaptation. In this study, we implemented a QTL analysis framework with a reciprocal mapping population developed from a salt tolerant landrace Horkuch and a high yielding rice variety IR29. Our aim was to detect genetic loci that contributes to the salt adaptive responses of the two different developmental stages of rice which are very sensitive to salinity stress. We identified 14 QTLs for 9 traits and found that most are unique to specific developmental stages. In addition, we detected a significant effect of the cytoplasmic genome on the QTL model for some traits such as leaf total potassium and filled grain weight. This underscores the importance of considering cytoplasm-nuclear interaction for breeding programs. Finally, we identified QTLs co-localization for multiple traits that highlights the possible constraint of multiple QTL selection for breeding programs due to different contributions of a donor allele for different traits.

Coastal Wild Grapevine Accession (Vitis vinifera L. ssp. sylvestris) Shows Distinct Late and Early Transcriptome Changes under Salt Stress in Comparison to Commercial Rootstock Richter 110.

Increase in soil salinity, driven by climate change, is a widespread constrain for viticulture across several regions, including the Mediterranean basin. The implementation of salt-tolerant varieties is sought after to reduce the negative impact of salinity in grape production. An accession of wild grapevine (Vitis vinifera L. ssp. sylvestris), named AS1B, found on the coastline of Asturias (Spain), could be of interest toward the achievement of salt-tolerant varieties, as it demonstrated the ability to survive and grow under high levels of salinity. In the present study, AS1B is compared against widely cultivated commercial rootstock Richter 110, regarding their survival capabilities, and transcriptomic profiles analysis allowed us to identify the genes by employing RNA-seq and gene ontology analyses under increasing salinity and validate (via RT-qPCR) seven salinity-stress-induced genes. The results suggest contrasting transcriptomic responses between AS1B and Richter 110. AS1B is more responsive to a milder increase in salinity and builds up specific mechanisms of tolerance over a sustained salt stress, while Richter 110 maintains a constitutive expression until high and prolonged saline inputs, when it mainly shows responses to osmotic stress. The genetic basis of AS1B’s strategy to confront salinity could be valuable in cultivar breeding programs, to expand the current range of salt-tolerant rootstocks, aiming to improve the adaptation of viticulture against climate change.

Evaluation of Salicornia bigelovii Germplasm for Food Use in Egypt and the United Arab Emirates Based on Agronomic Traits and Nutritional Composition.

Climate change significantly aggravates the quality of soil and water, especially in desert regions such as the United Arab Emirates (UAE) and Egypt concluding in an alarming increase in salinity in the reservoirs of the natural resources. Saline farming rises as a promising solution, utilizing low-quality water and land resources to grow salt-tolerant varieties of conventional crops and halophytes. Samphire (Salicornia spp.) is among the most popular multi-purpose halophytes that are locally consumed in several countries around the world as a vegetable. Six Salicornia bigelovii genotypes (ICBA-2, ICBA-3, ICBA-4, ICBA-8, ICBA-9, ICBA-10) were evaluated for their agronomic performance and nutritional composition in Dubai in UAE and, for the first time, at the Red Sea Governorate in Egypt in the 2019–2020 season using saline groundwater for irrigation (ECw = 26 and 6.6 dS/m, respectively). ICBA-10 performed well in both locations with high green biomass and seed yield (10.9 kgm−2 and 116.3 gm−2, respectively, in UAE; 7.7 kgm−2 and 82.9 gm−2, respectively, in Egypt). ICBA-10 was, overall, also good in ion accumulation, total amino acids and unsaturated fatty acids content in both locations for shoots and seeds. Our results indicated that a lack of a drainage system and leaching fraction, the silt loam texture and the drip irrigation system might have contributed in the gradual accumulation of salts in the soil at Mubarak Valley at the end of the experiment at a higher level than ICBA. Apart from the agronomic parameters, higher salinity levels also affected ion accumulation, the amino acids and the fatty acids content for both shoots and seeds, whereas the proximate composition was affected to a lesser extent. Our findings on the high unsaturated fatty acids content under higher salinity corroborate the nutritional value of S. bigelovii oil. Due to its euhalophyte nature, S. bigelovii is a valuable source of minerals, amino acids and antioxidants that render it the most promising salt-loving plant for food use.

Evaluation of Salt Tolerance Mechanism and Study on Salt Tolerance Relationship of Different Salt-Tolerant Wheat Varieties.

The physiological and biochemical indexes of different salt-tolerant wheat cultivars under salt stress are affected to different degrees. The changes in physiological and biochemical indexes in salt-tolerant wheat varieties are moderate, while salt-sensitive wheat varieties have bigger changes. In this article, through comprehensive utilization of germination and seedling indoor test morphological indexes, physiological and biochemical index, and output index, combined with the evaluation mechanism of wheat's salt resistance, different salt tolerance types in the middle and lower reaches of the Yangtze River in Shandong province were studied; a collection of 100 wheat varieties and 11 wheat varieties planted over a large area were classified into three groups: strong salt resistance, medium salt resistance, and weak salt resistance. Comparative analysis of different wheat varieties' salt resistance evaluation mechanism was performed, as well as the analysis of the germination rate of wheat varieties, coleoptile growth situation, emergence rate, protect wheat seeding rate, tillering rate, seedling height, root length, seedling dry weight, wet weight, number of leaves, plant growth situation, agronomic characters of the Na+/K+ ratio, and other physiological and biochemical indexes such as salt resistance index. The evaluation mechanism of salt tolerance and the relationship of salt tolerance of different wheat varieties were obtained. The results showed that there were significant differences in salt tolerance among the 100 wheat varieties at the germination stage. Among them, three varieties, YM (Yangmai) 25, YM (Yangmai) 24, and EM (Emai) 25, had the strongest salt tolerance at the germination stage, reaching the level of the salt tolerance variety DK 961, and the salt tolerance was in the first level, while NM 17, NM 23, and other 21 varieties reached the level of the salt tolerance. These 24 varieties with strong salt tolerance at the germination stage can be used to screen the salt tolerance of wheat planted in the saline soil of Jiangsu coastal beach.

Assessment of salt tolerance potential at the germination and seedling stages in pigeonpea (Cajanus cajan L.)

Identification of salt-tolerant genotypes and their subsequent utilization in producing salt tolerant varieties would be the most appropriate and cost-effective strategy for improving the yield of pigeonpea (Cajanus cajan L.) in salt-affected areas of the country. The present study assessed fifty diverse pigeonpea genotypes for their responses to salt (NaCl) concentrations of 60, 80 and 100 mM at seed germination and seedling stage (21-days-old). The tested genotypes were assessed for their changes in 11 morpho-physiological traits under salt stress and the phenotypic scores of the genotypes were analyzed statistically. Statistically, significant variations were observed among the genotypes for all the morpho-physiological traits under study including the germination percentage and seedling survivability. The genotypic and phenotypic correlation among the traits and the Principal Component Analysis (PCA) revealed that the seedling stage of the crop and 80 mM Nacl concentration are optimum for identifying pigeonpea genotypes tolerant to salt stress under controlled conditions. Out of the 50 genotypes, 10, namely, BDN-708, AKTM 16-41, AKTE 16-09, JKM-7, TV-1, BDN-716, PT 0607-5-1, JKM-189, Phule Rajeshwary, BDN-711 and AKTE-12-04 were found to be tolerant to salt stress and rest were sensitive. The salt tolerant genotypes clustered together under UPGMA, indicating their genetic relatedness for the trait. The salt tolerant genotypes identified in this study would be useful in the development of a mapping population for mapping the salt stress, and breeding for high-yielding pigeonpea varieties with tolerance to salt stress.

A soybean sodium/hydrogen exchanger GmNHX6 confers plant alkaline salt tolerance by regulating Na+/K+ homeostasis.

Alkaline soil has a high pH due to carbonate salts and usually causes more detrimental effects on crop growth than saline soil. Sodium hydrogen exchangers (NHXs) are pivotal regulators of cellular Na+/K+ and pH homeostasis, which is essential for salt tolerance; however, their role in alkaline salt tolerance is largely unknown. Therefore, in this study, we investigated the function of a soybean NHX gene, GmNHX6, in plant response to alkaline salt stress. GmNHX6 encodes a Golgi-localized sodium/hydrogen exchanger, and its transcript abundance is more upregulated in alkaline salt tolerant soybean variety in response to NaHCO3 stress. Ectopic expression of GmNHX6 in Arabidopsis enhanced alkaline salt tolerance by maintaining high K+ content and low Na+/K+ ratio. Overexpression of GmNHX6 also improved soybean tolerance to alkaline salt stress. A single nucleotide polymorphism in the promoter region of NHX6 is associated with the alkaline salt tolerance in soybean germplasm. A superior promoter of GmNHX6 was isolated from an alkaline salt tolerant soybean variety, which showed stronger activity than the promoter from an alkaline salt sensitive soybean variety in response to alkali stress, by luciferase transient expression assays. Our results suggested soybean NHX6 gene plays an important role in plant tolerance to alkaline salt stress.

EFFECT OF SALINITY AND POTASSIUM FERTILIZER APPLICATION ON YIELD CONTRIBUTING CHARACTERISTICS OF RICE

Salt tolerant variety BR 41 was grown in kharif 2 season by pot experiment to study the effects of salinity and potassium fertilizer on agronomic characteristics of rice (Oryza sativa L.). The agronomic parameters increased with increasing salinity up to 12 dSm-1 level but with plant height. The increase in tiller number, panicle number, shoot dry matter and total grain yield was statistically significant at 5% (LSD0.05) level, whereas the increase in 1000 grain weight was significant at 1% (LSD0.01) level. Application of potassium fertilizer at different salinity levels did not produce significant change in agronomic parameters with an exception in shoot dry matter.

Marker validation for salt tolerance in Indica rice

Abstract. Suprayogi, Dewi PS, Oktaviani, E, Aisya AW. 2022. Marker validation for salt tolerance in Indica rice. Biodiversitas 23: 4517-4523. The development of salt-tolerantrice variety is of importance with concern to the use of the coastal area for rice production and, consequently, the development ofarapid and accurate method of variety selection. Molecular markers associated with Quantitative Trait Loci (QTL) for salt tolerance in rice have been reported elsewhere. This research aimed to identify molecular markers associated with salt tolerance in rice. The research was carried out from September 2020 to February 2021 at Plant Breeding and Biotechnology Laboratory, Faculty of Agriculture, Jenderal Soedirman University, Indonesia. Nine Simple Sequence Repeat (SSR) markers and one Sequence Tagged Site (STS) marker were evaluated for their association with salt tolerance. The rice varieties consisted of three salt-tolerant varieties, one salt-sensitive variety, and six commercial varieties. Nona Bokra PCR amplicon was used as a positive control for DNA band scoring. Binary data of the amplicon banding pattern were analyzed using Principal Component Analysis (PCA) to determine the grouping of the evaluated varieties about their tolerance to assigned markers. The result demonstrated that the evaluated rice varieties fell into four groups of marker resemblances. Among the evaluated SSR markers, RM 3412, RM 342, RM 8094, and Wn 11463 significantly contributed to the grouping. The present study confirmed that Wn 11463 is a strong marker for salt tolerance in rice. However, validation needs to be made on a broader range of genotypes to see the significance of RM 8094 and RM 3412 as salt tolerant markers.

Climate resilient integrated soil-crop management (CRISCM) for salt affected wheat agri-food production systems.

Maximizing opportunities for climate resilient agriculture is vital for global food security, and ecological sustainability. To explore the improvement potential of mitigation and adaptation strategies in stabilizing wheat production and increasing farm income in sodicity-prone Ghaghar Basin of Haryana, India, participatory research trials on land reclamation (gypsum/pressmud) and crop management (varieties, nutrient management and weed control) practices were undertaken during 2016-2020. Results indicated that combining gypsum and pressmud together accelerated the reclamation process (soil pH: -3.3% and ESP: -22.1%) and improved plant adaptability (RWC: 10%; MI: -15%; Pn: 40%; gS: 36%; NaK_S: -38% and NaK_R: -42%), which in turn increased wheat yield by 20% compared to unamended control. With increasing sodicity stress, salt tolerant wheat variety KRL 210 exhibited better morpho-physiological adaptation, lesser yield reduction (0.8-1.1 t ha-1) and attained 4.1% mean yield advantage compared to traditionally cultivated HD 2967. There were genotypic differences for N requirements in sodicity stressed wheat, with 173 kg ha-1 in KRL 210 and 188 kg ha-1 in HD 2967 as the economically optimum dose; further advocating for upward revision of current N recommendations beyond 150 kg N ha-1. Balanced nutrition through foliage applied K compensated the sodicity hazards with lower proportion of Na+/K+ in leaf tissues (13%), and attained higher grain yield (4%) and incremental income (34 US$ ha-1) compared to farmers' practice. Sequential use of herbicides provided affordable solution to check Phalaris minor infestation (84% WCE) and enhanced wheat productivity (5.7% higher) with incremental income of 48 US$ ha-1 compared to farmers' sole dependency on post-emergence herbicides. Synergistic integration of gypsum and pressmud-mediated sodic land reclamation, usage of stress tolerant wheat variety, 15% higher N application, foliar K-nutrition and effective P. minor control substantiate appreciable reduction in soil sodicity, improved crop resilience, and ultimately translated into 5% and 26% higher yields over the recommended and local farm practices, respectively. The key insights of this study suggest a range of opportunities wherein inputs of CRISCM could potentially stabilize the wheat production, improve farm economy and reduce environmental risks beyond what is currently being achieved with existing farm practices.

Evaluation of physiological, biochemical and yield indicators of wheat and maize genotypes exposed to sodium chloride

Aim. Study the effect of sodium chloride on the physiological and biochemical characteristics of wheat and maize genotypes, to identify varieties tolerant to salinity. To create new salt-tolerant varieties of wheat and maize, a comparative analysis of the physiological and biochemical parameters of the parental and hybrid plants was carried out. Methods. Physiological parameters such as chlorophyll content, relative water content, and PSII activity have been studied in parental forms and hybrids. Results. When studying salt-tolerance of hybrids and parental forms, differences were detected in the relative amounts of chlorophyll (a+b), carotenoids, RWC, as well as the photochemical activity of chloroplasts. The effect of salt on the amount of chlorophyll a, chlorophyll b, and carotenoids, which are the main physiological indicators, is manifested in different ways in both hybrids and parental forms. Conclusions. Based on the physiological indices determined during the grain filling stage, the highest tolerance was manifested by the parental forms, Garabagh, Gobustan, and the hybrids, ♀Garabagh×♂Gobustan, ♀Garabagh×♂Mirbashir, ♀Garabagh×♂Sharg. Under the action of salt in all genotypes of corn found a slight increase in the content of soluble sugars. The highest sugar content was observed in the hybrid Zagatala 68 x Gurur.

Genome wide association study and haplotype analysis reveals the role of HvHKT1;5 in potassium retention but not Na+ exclusion in barley (Hordeum vulgare L.)

Salinity stress is one of the major abiotic stresses which affect grain yield and quality in crops. Identifying and exploring the QTL/genes and elite alleles that control salt tolerance is crucial for breeding salt-tolerant crop varieties. In this study, a diverse panel of 214 barley ( Hordeum vulgare L.) accessions were used to identify quantitative trait loci (QTL) for salt tolerance and Na + and K + content in leaves under salt stress by MLM model and MapQTL6.0 software. Significant correlations between leaf ion content and salt tolerance were observed. One major QTL, Q.SL.2H, was identified on chromosome 2H and was responsible for the overall salinity tolerance through regulating Na + exclusion under salt stress. The other major QTL was detected on chromosome 4H that overlapped with HvHKT1;5 gene and was responsible for K + retention in leaves. Several other minor QTL were detected by MapQTL that could help in selecting salt-tolerant varieties. The haplotype analysis showed that amino acid substitutions of HvHKT1;5 in exon2 at 416 and 438 may have contributed to K + retention under salinity stress. These findings indicate the existence of two major mechanisms for salinity tolerance determined by two major QTL and challenge the accepted views on the role of HvHKT1;5 transporters in Na + exclusion in barley adaptive response to salinity stress. • A significant correlation between leaf Na + content and salt tolerance was observed. • A major QTL for salinity tolerance on 2H, conferring salinity tolerance by regulating Na + exclusion under salt stress. • Substitutions occurred at 416 and 438 of HvHKT1;5 may have significant influences on K + retention under salinity stress. • These findings challenge the accepted views on the role of HvHKT1;5 transporters in Na + exclusion in barley adaptive response to salinity stress.

English

This study was conducted at farmers’ field with three disperse replicas in three different places viz. Satkhira (AEZ-11), Koyra (AEZ-13), and Bagerhat (AEZ-11) of Khulna division in the Rabi season of 2019-2020 to determine salt tolerant varieties for maximizing mustard yield, as well as farmers’ income. Characterization was done with six varieties namely BARI Sarisha-11, BARI Sarisha-14, BARI Sarisha-16, BARI Sarisha-17, and BARI Sarisha-18 (Canola) and a control variety Tori-7 under saline stress condition in coastal area of Bangladesh. Seed Tori-7, BARI Sarisha-11, BARI Sarisha-16, and BARI Sarisha-18 (Canola) were pingol in color while BARI Sarisha-14 and BARI Sarisha-17 were yellow. The yields range of the varieties was 1.13 to 2.09 t ha-1 and oil was 41.37 to 43.40%. Variety BARI Sarisha-18 (Canola) produced the maximum yield (2.09 t ha-1) followed by BARI Sarisha-16 (1.98 t ha-1) and BARI Sarisha-11 (1.84 t ha-1). Because BARI Sarisha-18 (Canola) and BARI Sarisha-16 are suitable for coastal areas, combining this variety with a coastal area cropping pattern will increase cropping intensity, which will benefit farmers both economically and nutritionally. Key word: Mustard variety, soil salinity, tolerance, growth, yields performance.

Widespread variation in salt tolerance within freshwater zooplankton species reduces the predictability of community‐level salt tolerance

AbstractThe salinization of freshwaters is a global threat to aquatic biodiversity. We quantified variation in chloride (Cl−) tolerance of 19 freshwater zooplankton species in four countries to answer three questions: (1) How much variation in Cl− tolerance is present among populations? (2) What factors predict intraspecific variation in Cl− tolerance? (3) Must we account for intraspecific variation to accurately predict community Cl− tolerance? We conducted field mesocosm experiments at 16 sites and compiled acute LC50s from published laboratory studies. We found high variation in LC50s for Cl− tolerance in multiple species, which, in the experiment, was only explained by zooplankton community composition. Variation in species‐LC50 was high enough that at 45% of lakes, community response was not predictable based on species tolerances measured at other sites. This suggests that water quality guidelines should be based on multiple populations and communities to account for large intraspecific variation in Cl− tolerance.

Characterization of salt tolerant wheat genotypes by using morpho-physiological, biochemical, and molecular analysis.

Food security is facing a major threat from salinity and there is a need to develop salt tolerant crop varieties to ensure that the demand for food from the world’s increasing population is met. Salinity mostly occurs in arid and semi-arid regions. It may cause many adverse physiological effects on plants, i.e., toxic ion accumulation, disturbed osmotic potential, and decreased crop yield. The present study aimed to investigate the morphological, physiological, biochemical, and genetic parameters of wheat genotypes under salt stress. Six wheat genotypes were screened for salt tolerance at the seedling and maturity stage. Seeds were sown at 0 and 150 mM of salinity level. Biochemical traits, i.e., shoot/root fresh and dry weight, chlorophyll a/b and total chlorophyll contents, shoot nitrogen, shoot phosphorus, proline, and carbohydrates were measured. Wheat genotypes showed a significant increase in free amino acids, shoot nitrogen, and total soluble proteins under saline conditions. Higher Na+/K+ ratio and free amino acids were estimated under 150 mM NaCl treatment in Pasban-90 and found to be the most salt-tolerant genotype. By contrast, reduced proline, total chlorophyll, and Na+/K+ ratio were found in Kohistan-97 marking it to be sensitive to stress. Expression analysis of HKTs genes was performed to validate the results of two contrasting genotypes. The differential expression of HKT2; 1 and HKT2; 3 explained the tissue and genotype specific epigenetic variations. Our findings indicated that these selected genotypes can be further used for molecular studies to find out QTLs/genes related to salinity. This suggests that, in contrasting wheat genotypes, there is a differentially induced defense response to salt stress, indicating a functional correlation between salt stress tolerance and differential expression pattern in wheat.

Salinity-driven oxidative stress in Gerbera jamesonii cv. Bolus

Salinity adversely affects various plants’ metabolic processes, negatively influencing their productivity and crop yield. Gerbera jamesonii cv. Bolus is a commercially important ornamental plant cultivated globally throughout the year for its cut flower production in polyhouses. During polyhouse cultivation, repeated fertigation may cause salinity in Gerbera, affecting flower quality and yield, and functional alterations in the basal level of cellular antioxidative defence systems. Though several factors induce salinity in general, we focussed on NaCl as it is one of the major components of fertigation. In salt-stressed plants, monitoring altered levels of antioxidative defense systems may help better understand their physiological changes. However, little to no studies were attempted on salinity-induced oxidative damage in Gerbera till date. In the current study, we verified the salt sensitivity level of Gerbera with varying concentrations of NaCl (0-200 mM) using in vitro leaf disc approach. We measured various antioxidative enzymatic/non enzymatic defense systems besides MDA and chlorophyll content. Treatment with higher salt concentrations (above100 mM NaCl) exhibited severe bleaching in leaf discs, followed by elevated levels of H2O2, lipid peroxidation and proline. Besides, our study also revealed a decrease in the total chlorophyll content; activities of superoxide dismutase, catalase, glutathione reductase, and ascorbate peroxidase. The observed results showed that Gerbera might not tolerate higher levels of NaCl as it could be detrimental to its cellular activities. Future studies on decoding molecular networks associated with salinity stress and antioxidative defense systems may help in developing salt-tolerant varieties in Gerbera and several other ornamental plants of Asteraceae.

​Early Identification of Salt-tolerant Genotypes in Finger Millet (Eleusine coracana L.) at Germination stage by Observing the Morphological Characters

Background: The major abiotic stress limiting the plant growth and productivity across the globe is salinity. This may be overwhelmed by growing salt tolerant varieties. Hence, the present study has been figured out to sort out the salt tolerant and salt sensitive cultivars of finger millet. Methods: In this study 15 cultivars of finger millet (Eleusine coracana L.) seeds were grown at different NaCl concentrations (50 mM, 100 mM, 150 mM and 200 mM) on germination stage. Germination percentage, root length, shoot length, fresh weight, dry weight and vigour index of the seedlings were measured using different concentrations of NaCl. Result: Salt tolerant cultivars were discovered to be GPU 28, GPU 67, ML 365, Udurumallige, PYR1 and GPU 48 at 150 Mm and ML 365 at 200 Mm salt accumulation, while cultivars such as VL 400 and KM252 were very much sensitive to NaCl. Accessions with tolerance to salinity are precious genetic material for future crop improvement program.