Salinity Stress Conditions Research Articles

COMBINING ABILITY FOR YIELD, OIL CONTENT, AND PHYSIO-BIOCHEMICAL CHARACTERS OF CANOLA (BRASSICA NAPUS L.) UNDER SALT STRESS CONDITIONS

Creating a half-diallel cross succeeded among seven diverse canola genotypes. The obtained 21 F1 hybrids with their seven parents underwent three salinity stress levels exposure—3.91 dsm1 (Normal), 6.24 dsm-1 (S1), and 7.81 dsm-1 (S2) —during the 2020/2021 growing seasons. Salinity treatments significantly reduced days to 50% flowering, plant height, number of primary branches, pods/plant, 1000-seed weight, seed yield/plant, seed oil content, relative water content, calcium, potassium, and the ratio between K+ and Na+ compared with a normal condition. Proline content, osmotic pressure, and Na+ were considerably higher under salinity stress conditions. Highly significant differences showed among the parents and hybrids for all traits across the tested environments. General (GCA) and specific (SCA) combining ability effects were highly significant for all attributes. The parental genotypes Serw4 and Pactol resulted as good general combiners for increased seed oil content (SOC), seed yield/plant (SYPP), and some of its components in research environments. The hybrid combinations H2/S × Serw4 and Serw4 × Serw6 were good specific combiners for days to first flower (DTF), number of primary branches (NPB), number of pods per plant (NP), a thousand seed weight (TSW), seed yield per plant (SYPP), seed oil content (SOC), proline content (ProC), Ca++, and K+/Na+. The SDS-PAGE analysis of seed proteins indicated high levels of genetic variability and revealed some vital biochemical markers for salt tolerance.

Physiological and lipidomic response of exogenous choline chloride alleviating salt stress injury in Kentucky bluegrass (Poa pratensis).

Choline participates in plant stress tolerance through glycine betaine (GB) and phospholipid metabolism. As a salt-sensitive turfgrass species, Kentucky bluegrass (Poa pratensis) is the main turfgrass species in cool-season areas. To improve salinity tolerance and investigate the effects of choline on the physiological and lipidomic responses of turfgrass plants under salinity stress conditions, exogenous choline chloride was applied to Kentucky bluegrass exposed to salt stress. From physiological indicators, exogenous choline chloride could alleviate salt stress injury in Kentucky bluegrass. Lipid analysis showed that exogenous choline chloride under salt-stress conditions remodeled the content of phospholipids, glycolipids, and lysophospholipids. Monogalactosyl diacylglycerol, digalactosyl diacylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and lysophosphatidylcholine content were increased and phosphatidic acid content were decreased in plants after exogenous choline chloride under salt treatment. Plant leaf choline content increased, but GB was not detected in exogenous choline chloride treatment plants under nonstress or salt-stress conditions. GB synthesis pathway related genes showed no clear change to choline chloride treatment, whereas cytidyldiphosphate-choline (CDP-choline) pathway genes were upregulated by choline chloride treatment. These results reveal that lipid remodeling through choline metabolism plays an important role in the salt tolerance mechanism of Kentucky bluegrass. Furthermore, the lipids selected in this study could serve as biomarkers for further improvement of salt-sensitive grass species.

Meta-analysis of microarray and RNAseq data reveal OsbZIP52 to mediate salt stress responses in sensitive, tolerant and halophyte rice varieties

The development of salt-tolerant rice has become urgent due to climate change and rising global rice consumption. A large-scale analysis using different but related platforms has become imperative to filter out candidate genes responsible for salinity tolerance and salinity stress-responsive pathways. Such genes can be used to find prospective candidate salt resistance genes in donor rice genotypes and transfer them to high-yielding rice varieties. We performed a meta-analysis to screen out candidate genes using stress-related three microarray and one RNASeq datasets from NCBI. As different genotypes of rice and different salinity stress conditions were considered in our analysis, the sensitivity of the results is expected to be multi-fold higher. Our analysis revealed the differentially expressed genes (DEGs) OsbZIP52 and OsLTP2.5 to be common between leaf and root tissues. These genes were further compared with those of the wild halophytic rice Oryza coarctata expression data in stress conditions to understand the significance of these genes. The OsbZIP52 gene homolog of Oryza coarctata was the only one found to be differentially expressed. The expression level of OsbZIP52 was quantified using RT-qPCR and observed downregulated expression in salt stress in root and leaf tissues of four rice cultivars (2 salt-tolerant and 2 salt-sensitive). Promoter and motif analysis revealed a high number of variations in promoter and motif regions of the gene in IR29 salt-sensitive rice. Expression correlation analysis and Gene Ontology study suggested that OsbZIP52 interacts with genes that are engaged in stress response and participate in stress-responsive pathways. Collectively this study increases our understanding of the differential gene expression in various stress conditions in root and leaf tissues. It also helped identify a critical regulatory transcription factor in assisting the plant in combating salinity stress.

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

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

Responses of stevia (<i>Stevia rebaudiana</i> Bertoni) to salinity conditions

The sweet herb or ka'a he'ẽ in the Guarani language (<i>Stevia rebaudiana</i> Bertoni) is a native plant of Paraguay, which produces a natural sweetener, 300 times sweeter than sucrose. The consumption of stevia has spread to numerous countries due to its beneficial properties for health. To meet the global demand for stevia, the production must be optimized through the use of improved varieties cultivated in different environmental conditions. This is an important fact, given the challenges related to climate change, such as salinity, opting for varieties that adapt to these conditions generates a positive impact on the dissemination of the crop. This research was aimed to determine the response of the Eirete variety of <i>S. rebaudiana</i> to saline stress conditions by evaluating selected biochemical and growth parameters. Vitroplants propagated in Murashige and Skoog culture medium (MS) supplemented with 0, 25, 50, 75, or 100 mM NaCl were used in the study to identify the concentration that reduced growth by 50% (GR50) and with 0, 50, 100, 150, and 200 mM NaCl to determine the concentration that caused the death of 50% of the individuals (LD50). After the evaluation of biochemical and growth parameters carried out at the dose corresponding to GR50, a significant decrease in the height, fresh and dry weight of the aerial parts, and fresh weight of the roots was found. Substantial increases in the proline concentration and the root/shoot ratio were also observed. There was no significant alteration of the dry weight of the roots and the content of soluble sugars or chlorophylls. Based on these results, it can be concluded that the development of vitroplants of <i>S. rebaudiana</i> var. Eirete is reduced by increasing concentrations of NaCl in the culture medium; however, our results suggest that stevia plants can be cultivated in moderate saline conditions.

Ethylene inhibitors improve crop productivity by modulating gene expression, antioxidant defense machinery and photosynthetic efficiency of Solanum lycopersicum L. cv. Pusa Ruby grown in controlled salinity stress conditions

Tomato is an important horticultural crop of global importance but its susceptibility to salinity stress significantly retards growth and thereby its yield. The impact of gaseous hormone, ethylene, accentuates the effect of salinity stress by negatively regulating various growth and developmental processes. Ethylene overproduction and ionic imbalance triggered by salinity stress exhibit upregulation of 1-aminocyclopropane-1-carboxylic acid synthase (ACS) and downregulation of NHX1, SOS1 and HKT1;2 under salinity stress conditions that negatively affect proline content, ROS scavenging machinery, morphometric and physiological attributes. Variation in the proline content, activation of ROS scavenging machinery, affected morphometric and physiological attributes are some discernible points in response to salinity stress induced ethylene production. Therefore, the experiment was designed to study the role of ethylene inhibitors silver nitrate (AgNO3) and cobalt chloride (CoCl2) in mitigating the negative effects of ethylene over production under salinity stress. Tomato seedlings were treated with 0 mM NaCl, 250 mM NaCl and 250 mM NaCl + 100 µM AgNO3, 250 mM NaCl + 100 µM CoCl2 for three days. The gene expression of ACS2, NHX1, SOS1 and HKT1;2, and ACS activity, endogenous ethylene level, Na+ and K+ ions concentration, proline content, antioxidant enzymes activity, photosynthetic efficiency and different morphological and yield parameters were assessed in tomato plants treated with salinity stress, and ethylene inhibitors at 45 DAS and 90 DAS. Results revealed that ethylene inhibitors might be playing the role in minimizing the ethylene and ACC load. The ACS enzyme activity and ethylene content were considerably decreased due to application of AgNO3and CoCl2. Further, the endogenous proline and K+ content, and K+/Na+ ratio were considerably increased in response to ethylene inhibitors treatment. Also, antioxidant enzymesviz., SOD, CAT, APX and GR, growth matrices, photosynthetic efficiency and yield attributes were significantly improved in treated tomato plants (salinity with ethylene inhibitors).

Preliminary agronomic evaluation of rice (Oryza sativa L.) genotypes under saline soil conditions of Yaguachi, Ecuador

Soil salinity is considered one of the main abiotic stresses that affect rice cultivation throughout the world. The main objective of this study was to carry out the preliminary agronomic evaluation of five commercial rice varieties (INIAP11, INIAP14, SFL-011, INIAP-FL-Arenillas and Fedearroz-60) under saline soil conditions in Yaguachi, Guayas, Ecuador.
 A completely randomized block design was used to estimate the agronomic response of the materials by quantifying grain yield t.ha-1 (Yield), number of tillers.m-2 (TN), plant height at harvest (PH), number of panicles.m-2 (NPM), panicle length (PL), number of grains/panicle (NGP), number of filled grains/panicle (NFG), number of vain grains (NVG), weight of 1000 grain (P1000) and content of chlorophyll at 30 (C30D) and 60 (C60D) days.
 The analysis of variance reflected a high phenotypic diversity among the varieties studied, showing adequate adaptation to the level of salinity contained in the soil used for the study. The INIAP-FL-Arenillas, INIAP14, INIAP11 and FEDEARROZ-60 varieties were the genotypes with the best responses under the study conditions, expressed in higher productivity levels.
 The results also suggest the need to continue evaluating these varieties with and without saline stress conditions, to discriminate the effect of genotype by environment interaction and confirm the level of tolerance to saline stress present in these genotypes, optimizing the selection of the appropriate germplasm in breeding programs, aiming to obtaining genotypes tolerant to saline soils.

B2 O3 nanoparticles alleviate salt stress in maize leaf growth zones by enhancing photosynthesis and maintaining mineral and redox status.

Salt stress induces significant loss in crop yield worldwide. Although the growth-stimulating effects of micronutrient nanoparticles (NPs) application under salinity have been studied, the molecular and biochemical mechanisms underlying these effects are poorly understood. The large size of maize leaf growth zones provides an ideal model system to sample and investigate the molecular and physiological bases of growth at subzonal resolution. Using kinematic analysis, our study indicated that salinity at 150 mM inhibited maize leaf growth by decreasing cell division and expansion in the meristem and elongation zones. Consistently, salinity downregulated cell cycle gene expression (wee1, mcm4, and cyclin-B2-4). B2 O3 NP (BNP) mitigated the stress-induced growth inhibition by reducing the decrease in cell division and expansion. BNP also enhanced the photosynthesis-related parameters. Simultaneously, chlorophyll, phosphoenolpyruvate carboxylase and ribulose-1,5-bisphosphate carboxylase/oxygenase were stimulated in the mature zone. Concomitant with growth stimulation by BNP, mineral homeostasis, particularly for B and Ca, was monitored. BNP reduced oxidative stress (e.g., lessened H2 O2 generation along the leaf zones and reduced lipid peroxidation in the mature zone) induced by salinity. This resulted from better maintenance of the redox status, that is, increased the glutathione-ascorbate cycle in the meristem and elongation zones, and flavonoids and tocopherol levels in the mature zone. Our study has important implications for assessing the salinity stress impact mitigated by BNP on maize growth, providing a basis to improve the resilience of crop species under salinity stress conditions.

Combining ability of plant regeneration in some bread wheat genotypes under salinity stress conditions

Combining ability of plant regeneration in some bread wheat genotypes under salinity stress conditions

Overexpression of JsFLS5 in calli improves salinity tolerance by maintaining active oxygen balance and reducing Na+ toxicity in Juglans sigillata.

The escalating global climate change significantly threatens plant growth, development, and production through salinity stress. Flavonoids, a crucial category of secondary metabolites, have been extensively studied for their role in modulating plant growth and development mechanisms in the face of biological and abiotic stress. The flavonol synthetase (FLS) gene plays a key role in the biosynthesis and accumulation of flavonoids. To investigate the correlation between salt tolerance and flavonol synthesis, JsFLS5 was overexpressed in the callus of Juglans sigillata cv. "Qianhe-7." This study shows that the upregulation of JsFLS5 significantly elevates the overall flavonoid content by modulating the expression of genes associated with flavonoid synthesis under salinity stress conditions. Additionally, the overexpressing callus exhibited enhanced resistance to salt stress compared to the wild-type callus, as evidenced by reduced levels of reactive oxygen species accumulation, electrolyte leakage, and malondialdehyde content in the overexpressing callus relative to the wild type (WT). Moreover, the overexpressing callus showed higher antioxidant enzyme activity and a more efficient ascorbic acid-glutathione cycle. Furthermore, the concentration of Na+ in the overexpressing callus was lower than WT, resulting in a decreased Na+ /K+ ratio. These findings suggest that JsFLS5 overexpression in calli effectively mitigates the oxidative damage induced by osmotic stress and reduces Na+ toxicity by enhancing flavonoid synthesis under salt stress conditions. Consequently, this study offers a novel perspective for comprehending the role of JsFLS5 in the response to abiotic stress in J. sigillata.

Effect of hypersalinic stress on hemocyte morphology and hemolymph cellular composition of the ark clam (Anadarakagoshimensis).

Bivalve mollusks as typical osmoconformers are unable to maintain a constant level of internal osmolarity in conditions of salinity stress. Adaptation to fluctuations of environmental salinity is achieved through cellular osmoregulatory responses, which are accompanied with a substantial shift in functional state of cells. In the present work we investigated the effect of hypersalinity stress on hemolymph cellular composition and morphology of the ark clam (Anadara kagoshimensis) hemocytes. Ark clams were subjected to a gradual increase of environmental salinity from 18‰ to 35‰ and 45‰ and maintained at those conditions for two days. Exposure to hypersalinity 35‰ induced changes in erythrocyte morphology and led to a decrease of their diameter. At salinity 45‰ a substantial increase of hemocyte average diameter was observed, whereas the shape of cells did not change (18‰). Hyperosmotic stress was not associated with changes in hemocyte viability as well as changes in hemolymph cellular composition. The results of the present work demonstrate high tolerance of A. kagoshimensis to short-time exposure to hypersalinic conditions.

Genetic linkage mapping and QTL identification for salinity tolerance in Indian mustard (Brassica juncea L. Czern and Coss.) using SSR markers

Soil salinity is one of the major environmental constraints that limits crop yield and nearly 7% of the total area worldwide is affected by salinity. Salinity-induced oxidative stress causes membrane damage during germination and seedling growth. Indian mustard is a major oilseed crop in India and its production and productivity are severely affected by salt stress. Breeding Brassica cultivars for salinity tolerance by conventional means is very difficult and time-consuming. Therefore, understanding the molecular components associated with salt tolerance is needed to facilitate breeding for salt tolerance in Brassica. In this investigation, quantitative trait loci (QTLs) associated with salt tolerance were identified using F2:3 mapping population developed from a cross between CS52 (salinity tolerant) and RH30 (salinity sensitive). Parents and F2:3 were evaluated under controlled and salinity stress conditions for 14 morpho-physiological traits for two consecutive generations (F2 and F2:3), explaining proportion of the phenotypic variance under control condition. Simple sequence repeat (SSR) markers were used for mapping studies. A genetic linkage map based on 42 simple sequence repeats (SSRs) markers was constructed covering 2298.5 ​cM (Haldane) to identify the loci associated with salt tolerance in Brassica juncea. Forty-one SSRs showing polymorphism in the parents (CS52 and RH30) were mapped on 8 linkage groups (C1–C8). One marker (nga 129) did not map to any of the linkage group and was excluded from mapping. Linkage group 5 (C5; 317.9 ​cM) was longest and linkage group 1 (C1, 255.0 ​cM) was shortest. Further, we identified 15 QTLs controlling 8 traits using F2:3 population. These QTLs explained 12.44–60.63% of the phenotypic variation with a LOD score range of 3.62–5.97. Out of these QTLs, QMI4.1 related to membrane injury showed 51.28% phenotypic variance with a LOD score of 3.34. QTL QBYP8.1 related to biological yield per plant showed 60.63% phenotypic variance at a LOD score of 3.62. The highest LOD score of 5.97 was recorded for QTL related to seed yield per plant (QSYP4.1). Major QTLs were QTL for biological yield per plant (QBYP8.1), QTL for siliquae per plant (QSP4.1), QTL for primary branches (QPB4.1), QTLs for seed per siliqua (QSS4.1, QSS4.2), QTL for seed yield per plant (QSYP4.1), and QTL for membrane injury (QMI8.1) which showed more than 50% phenotypic variance. These QTLs identified in our study need to be confirmed in other populations as well so that these can be used in marker-assisted selection and breeding to enhance salt tolerance in Brassica juncea.

Germination and Growth Parameters in Sorghum Cultivars (Sorghum bicolor L.) Effected by Boron Application under Salinity Stress

The aim of this research is investigating the effects of boron on the germination and growth of three sorghum cultivars at different salinity stress levels. The experiment was arranged as four replications according to the factorial experimental design in completely random blocks The three sorghum (Sorghum bicolor L.) cultivars (Erdurmuş, Uzun and Gözde 80) selected for the genetic material. NaCl compound was utilized as salt source and solutions were prepared at concentrations of 0-75-150 mM. Boron was applied as H3BO3 at 0-5-10-15 mM. In general regarding growth parameters, the values obtained in Gözde 80 cultivar were determined as the highest averages. Whereas the salinity levels effect was examined in this study, a decrease was determined in the parameters measured as the level of the stress factor increased. Salinity had a high adverse effect at the 150 mM level, and as expected the highest averages were obtained in the control treatments. Low-dose boron applications have possitive effects on germination and growth parameters in this experiment. Therewithal under salinity stress conditions, low-dose boron applications showed affirmative efficacy compared to the control of each condition. In this experiment, determined that boron applications reduce this effect under salinity stress conditions that sorghum seeds may encounter during the germination period, but the boron dose level to be applied should be properly controlled.

Correlation and Path Analysis for Yield and its Phenological, Physiological, Morphological and Biochemical Traits under Salinity Stress in Chickpea (Cicer arietinum L.)

The investigation was carried out during rabi season (November–April) of 2020–2021 in the polyhouse, Department of Genetics and Plant Breeding, Lovely Professional University, Phagwara, Punjab, India. CRD (Completely Randomize Design) were used in 3 replications with the objective to assess the performance of 20 chickpea genotypes under salinity stress conditions in order to identify genotypes that demonstrate greater tolerance to these conditions. To induce the salinity stress, NaCl salts were administer in two split doses of 120 mM during sowing and at 15 DAS. The study evaluated a range of parameters, including phenological, physiological, morphological, biochemical, and yield parameters, to examine the impact of salt stress on genotypes that exhibit varying levels of tolerance. Total proline content increment is due to increase of stress related proteins during the salinity. The yield parameters increase in non-saline conditions whereas in stress conditions, yield will get reduce. The findings revealed an increase in the total Proline content due to the production of stress-related proteins during salinity stress; however, yield parameters were negatively affected under stress conditions, with the most significant decrease observed in the 120 mM NaCl treatment group compared to the control group. ICC5439 and GNG 1581 emerged as highly tolerant chickpea genotypes under salinity stress conditions, while ICC 6050, ICC 251, ICC 252, and ICC 262 exhibited medium tolerance. In contrast, ICC253, ICC 247, and ICC 249 were found to be highly susceptible genotypes, with the remaining genotypes showing minimal tolerance and sensitivity to salinity stress.

Improvement in Physiobiochemical and Yield Characteristics of Pea Plants with Nano Silica and Melatonin under Salinity Stress Conditions

The effect of nano silica (50 mL L−1) and melatonin (75 µM) individually or in combination in foliar applications on the morphophysiological, biochemical and yield properties of pea plants under salinity stress conditions was evaluated. Salt stress caused a remarkable decrease in the growth and yield characteristics; for example, the plant dry weight, plant height, number of flowers plant−1, number of pods plant−1, weight of 100 green seeds and protein concentration in the pea plants during both seasons were decreased compared with the control. Similarly, their physiobiochemical characteristics were negatively affected; chlorophyll a, chlorophyll b and the relative water content (RWC) were significantly reduced in the stressed pea plants. However, malondialdehyde (MDA), hydrogen peroxide, the electrolyte leakage (EL%), super oxide and the antioxidant components (catalase (CAT), superoxide dismutase (SOD), peroxidase (POX) and total phenolic compounds) were significantly increased when the plants were under salt stress compared with the control plants. On the other hand, the foliar application of nano silica and melatonin individually or in combination enhanced the physiobiochemical characteristics, morphological characteristics and yield of the stressed pea plants. The best treatment was the combination treatment (nano silica + melatonin), which caused significant increases in the plant dry weight, plant height, number of flowers and pods plant−1, weight of 100 green seeds, protein concentration, chlorophyll concentrations and RWC in the stressed pea plants. Additionally, the combination treatment significantly decreased the EL%, MDA, O2⋅− and H2O2 and adjusted the upregulation of the antioxidant enzymes, proline and total phenolic compounds in the stressed plants compared with the stressed untreated pea plants. Generally, it can be suggested that the co-application of nano silica (50 mL L−1) + melatonin (75 µM) plays a positive role in alleviating the adverse impacts of salinity on pea plants by modifying the plant metabolism and regulating the antioxidant defense system as well as scavenging reactive oxygen species.

Effect of Organic Fertilizer on the Growth and Physiological Parameters of a Traditional Medicinal Plant under Salinity Stress Conditions

Foeniculum vulgare (fennel) is a medicinal and aromatic plant species from Apiaceae (Umbelliferae) and has been extensively used to treat digestive and pulmonary diseases. This plant is relatively sensitive to salinity. To investigate the effect of salinity stress at levels of 0, 40, and 80 mM NaCl in combination with 0 and 5% v/v vermicompost mixed with soil on the growth as well as the physiological and biochemical traits of two fennel landraces planted in Urmia and Shiraz areas, a factorial experiment was conducted as a randomized complete block design in three replications under greenhouse conditions. The plants were sampled in the flowering stage eleven weeks after cultivation. As the results showed, vermicompost treatment together with salinity stress could enhance the growth traits of the plants, such as the length and dry weight of shoots; leaf area and dry weight of roots; photosynthetic pigments, i.e., chlorophylls and carotenoids; membrane stability index; relative water content, soluble sugar, soluble protein, proline, total phenol, and anthocyanin in the shoots; mineral elements, i.e., phosphate, nitrate, zinc, molybdenum, magnesium, and iron in the shoots; and potassium and calcium in the shoots and roots. The interaction of vermicompost and salinity also decreased the aldehydes, total flavonoids, activity of catalase enzyme and shoot starch, soluble sugar and root proline, and sodium content of both shoots and roots. In a comparison of the two studied fennel landraces, the Shiraz landrace emerged to be less affected by salinity stress. In saline conditions, vermicompost caused a change in the physiological and biochemical parameters of both fennel landraces and improved their growth. The improvement in the growth conditions in the Urmia landrace was more obvious due to the use of vermicompost. Using vermicompost plus 40 mM NaCl salinity, the dry weight of the shoot and leaf surface of the Urmia landrace increased by about 3 and 2.5 times, respectively, and under 80 mM NaCl, the dry weight of the shoot and leaf surface increased by 2.7 and 1.2 times compared to the control. According to the experiments, it seems that vermicompost can limit the harmful effects of salinity on fennel plants by affecting photosynthetic pigments, osmolytes, phenolic compounds, antioxidants, the stability of membranes, and the availability of water and essential minerals.

The Effect of Salinity on the Chlorophyll Content of Wheat

Abiotic stress caused by salinity soil affects the development and plant growth, seed production and quality in a negative way. Salinity is an important factor influencing the quality of water. Saline stress causes negative reactions in plants both morphologically, biochemically and physiologically. The chlorophyll content is an important indicator of photosynthetic capacity of plants. Amount of chlorophyll is very influenced by nutrients reserve and by environment stress. Salinity in soil occurs as a result of the factors such as improper irrigation, lack of drainage, excessive accumulation of soluble salts. The research aims to study the behavior of an assortement of wheat varieties in terms of variability in salinity tolerance. To this end, an indirect test method for salinity tolerance, based on the determination of the influence of saline stress on chlorophyll accumulation, was pursued. Determination of chlorophyll content was performed at 7, 14, 21 days after saline stress induction. The duration of stress had the highest contribution (41.72%) to the variability of the chlorophyll content, followed by the saline (10.88%) and the varieties 7.63% respectively. At the level of the whole experiment it is observed that the chlorophyll content decreased progressively as saline stress prolongation. The change in the concentration from 200 to 240 Mm showed the highest influence on this property, materialized by a significant decrease in photosynthetic capacity. A good way to understand the plant photosynthetic regime is to determine the chlorophyll content as an indirect method. A selection criterion in screening for salt tolerance can be considered the physiological features that are positively associated with production under conditions of saline stress.

Salinity stress amelioration and morpho-physiological growth stimulation by silicon priming and biochar supplementation in Chenopodium quinoa

The effect of silicon (Si) priming and soil amendment with biochar (BC) was analysed in Chenopodium quinoa under normal and salinity stressed conditions. Reduced growth parameters, chlorophyll content, and photosynthesis under salinity stress were significantly ameliorated by Si priming and soil amendment with BC. Applied Si and BC treatment also enhanced the chlorophyll content, stomatal conductance, transpiration rate, net photosynthesis, and maximal photochemical efficiency. In addition to this, Si and/or BC amendments alleviated the oxidative damage by reducing the generation of toxic reactive oxygen species including hydrogen peroxide and superoxide. Moreover, the activities of antioxidant enzymes and the content of ascorbate and glutathione increased significantly in Si and BC treated plants reflecting efficient alleviation of oxidative damage. Besides, the content of compatible osmolytes was increased in Si and/or BC treated seedlings, thereby contributing to improved growth and salinity tolerance by maintaining higher leaf water potential and water use efficiency. Si and BC treatment increased the uptake of key mineral elements. Moreover, salinity induced decline in the nutritional components of seeds of C. quinoa were considerably increased under Si and BC treatments.

Exploration of plant growth promoting traits and regulatory mechanisms of Bacillus anthracis PM21 in enhancing salt stress tolerance in maize.

Bacillus species have been reported to reduce the negative effects of salt stress on plants; the involvement of Bacillus anthracis PM21 and the internal mechanisms involved in this process are unclear. The effects of PM21 inoculation on maize plants under salt stress were investigated in this study. The study aimed to assess the ability of Bacillus anthracis PM21 to endure high levels of salinity stress while preserving the concentration of plant growth regulators. The biomass, photosynthetic pigments, relative water content (RWC), antioxidants, osmoprotectants, inorganic ion contents, regulation of plant hormones and expression of antioxidants enzyme encoded genes were investigated under normal and salinity stress conditions. Bacillus anthracis PM21 produced a significant amount of 1-aminocyclopropane-1-carboxylate deaminase enzyme (ACC deaminase) and exopolysaccharides (EPS) under salt stress and normal conditions. PM21 also produced plant growth stimulants including indole acetic acid, gibberellic acid (GA3), kinetin, and siderophore under salinity stress and normal conditions. Under salt stress, PM21 inoculation markedly increased plant growth indices, stimulate antioxidant enzyme mechanisms, osmoprotectants, and chlorophyll content. The use of qRT-PCR to analyze the transcription of targeted genes indicated greater expression of antioxidant-encoded genes and inferred their possible function in salinity stress tolerance. Our findings shed light on the functions of PM21 and its regulatory mechanisms in plant salt stress tolerance, as well as the importance of PM21 in this process. This study will provide a thorough analysis of the theoretical framework for adopting PM21 in agricultural production as an eco-friendly method to enhance crop growth and yield under salinity stress.

Monitoring Role of Exogenous Amino Acids on the Proteinogenic and Ionic Responses of Lettuce Plants under Salinity Stress Conditions

Lettuce plants (Lactuca sativa L.) were grown under salinity stress conditions. Amino acids (histidine (His), lysine (Lys), phenylalanine (Phe), and threonine (Thr)) were individually applied to the seedlings to study their impact on the status of the photosynthetic pigments, ion absorption, proteinogenic metabolism, and peroxidase activity. Investigating the effect of exogenous amino acids on the metabolism processes showed their potential role in inducing salt stress tolerance in lettuce plants. Generally, a destructive impact on lettuce plant morphology was observed when the plants were exposed to salt stress. In contrast, the significant (p < 0.05) mitigation of salt stress was registered when EAAs were applied to the stressed seedlings while using Threonine and lysine enhanced the status of the plants under salinity stress. For the salt treatment, the maximum electric conductivity (580.2 μS/g) was reported while applying EAAs to stressed plants’ decreased EC, and the data ranged from 522 to 554 μS/g. EAAs decreased the chloride ions in the leaves by 23–30% compared to in the stressed plants. Additionally, the sodium contents were mitigated when the stressed plants were sprayed with EAAs. In contrast, applying EAAs enhanced the potassium uptake, and Thr gave the highest K+ contents (3022 μg/g). EAAs increased the chlorophyll content compared to the control except when histidine was applied, while the carotene contents significantly increased when histidine and phenylalanine were used. Endogenous amino acids are highly expressed in non-stressed lettuce plants compared to the stressed ones. Under salt stress conditions, the threonine usage increased the expression of proteinogenic amino acids except methionine and tyrosine. Compared to the salt-stressed plants, the peroxidase activity significantly decreased in the other treatments, which fell by over 32% when His, Lys, and Phe were applied.