Plants In Saline Soils Research Articles

Alleviation of Salt Stress and Changes in Glycyrrhizic Acid Accumulation by Dark Septate Endophytes in Glycyrrhiza glabra Grown under Salt Stress.

This study aimed to investigate the mechanisms by which dark septate endophytes (DSE) regulate salt tolerance and the accumulation of bioactive constituents in licorice. First, the salt stress tolerance and resynthesis with the plant effect of isolated DSE from wild licorice were tested. Second, the performance of licorice inoculated with DSE, which had the best salt-tolerant and growth-promoting effects, was examined under salt stress. All isolated DSE showed salt tolerance and promoted plant growth, withCurvularia lunata D43 being the most effective. Under salt stress, C. lunata D43 could promote growth, increase antioxidant enzyme activities, enhance glycyrrhizic acid accumulation, improve key enzyme activities in the glycyrrhizic acid synthesis pathway, and induce the expression of the key enzyme gene and salt tolerance gene of licorice. The structural equation model demonstrated that DSE alleviate the negative effects of salt stress through direct and indirect pathways. Variations in key enzyme activities, gene expression, and bioactive constituent concentration can be attributed to the effects of DSE. These results contribute to revealing the value of DSE for cultivating medicinal plants in saline soils.

Improving crop salt tolerance through soil legacy effects.

Soil salinization poses a critical problem, adversely affecting plant development and sustainable agriculture. Plants can produce soil legacy effects through interactions with the soil environments. Salt tolerance of plants in saline soils is not only determined by their own stress tolerance but is also closely related to soil legacy effects. Creating positive soil legacy effects for crops, thereby alleviating crop salt stress, presents a new perspective for improving soil conditions and increasing productivity in saline farmlands. Firstly, the formation and role of soil legacy effects in natural ecosystems are summarized. Then, the processes by which plants and soil microbial assistance respond to salt stress are outlined, as well as the potential soil legacy effects they may produce. Using this as a foundation, proposed the application of salt tolerance mechanisms related to soil legacy effects in natural ecosystems to saline farmlands production. One aspect involves leveraging the soil legacy effects created by plants to cope with salt stress, including the direct use of halophytes and salt-tolerant crops and the design of cropping patterns with the specific crop functional groups. Another aspect focuses on the utilization of soil legacy effects created synergistically by soil microorganisms. This includes the inoculation of specific strains, functional microbiota, entire soil which legacy with beneficial microorganisms and tolerant substances, as well as the application of novel technologies such as direct use of rhizosphere secretions or microbial transmission mechanisms. These approaches capitalize on the characteristics of beneficial microorganisms to help crops against salinity. Consequently, we concluded that by the screening suitable salt-tolerant crops, the development rational cropping patterns, and the inoculation of safe functional soils, positive soil legacy effects could be created to enhance crop salt tolerance. It could also improve the practical significance of soil legacy effects in the application of saline farmlands.

Straw and phosphorus applications promote maize (Zea mays L.) growth in saline soil through changing soil carbon and phosphorus fractions.

Straw return has been widely recognized as an important carbon (C) enhancement measure in agroecosystems, but the C-phosphorus (P) interactions and their effects on plants in saline soils are still unclear. In this study, we investigated the effects of straw return and three P application levels, no P fertilizer (Non-P), a conventional application rate of P fertilizer (CP), and a high application rate of P fertilizer (HP), on maize growth and soil C and P fractions through a pot experiment. The results revealed that the dry matter weight of maize plant was no difference between the two straw return levels and was 15.36% higher under HP treatments than under Non-P treatments. Plant nutrient accumulations were enhanced by straw addition and increased with increasing P application rate. Straw application reduced the activities of peroxidase (POD), superoxide dismutase (SOD), catalase, and the content of malondialdehyde (MDA) in maize plants by 31.69%, 38.99%, 45.96% and 27.04%, respectively. P application decreased SOD, POD activities and MDA content in the absence of straw. The contents of easily oxidized organic carbon (EOC), particulate organic carbon (POC) and the ratio of POC/SOC in straw-added soils were 10.23%, 17.00% and 7.27% higher, respectively, than those in straw-absent soils. Compared with Non-P treatments, HP treatments led to an increase of 12.05%, 23.04% in EOC, POC contents respectively, while a decrease of 18.12% in the contribution of MAOC to the SOC pool. Straw return improved the P status of the saline soil by increasing soil available P (14.80%), organic P (35.91%) and Ca2-P contents (4.68%). The structural equation model showed that straw and P applications could promote maize growth (indicated by dry matter weight, P accumulation, antioxidant enzyme activity and MDA content) through improving soil C and P availabilities. This study provides evidence that straw return together with adequate P supply in saline soil can promote crop nutrient accumulation, attenuate the oxidation damage on crop growth, and be beneficial for SOC turnover and soil P activation.

A Si-K-Based Amendment Prepared by Coal Gangue and Plant Ash Could Improve the Growth of Maize Plants in Saline Soils

A Si-K-Based Amendment Prepared by Coal Gangue and Plant Ash Could Improve the Growth of Maize Plants in Saline Soils

Plant Growth Promoting (PGP) Performances and Diversity of Bacterial Species Isolated from Olive (Olea europaea L.) Rhizosphere in Arid and Semi-arid Regions of Morocco

Plant Growth Promoting Rhizobacteria (PGPR) play an essential role in enhancing plant growth, health and yield. In this study, we describe the isolation of PGPR associated with the olive tree (Olea europaea L.) grown in three Moroccan regions of Zouala, Errachidia, and Essaouira. In these regions, we isolated 95 PGPRs from rhizosphere of Olive trees, 78% of them were characterized by their tolerance to a salinity of 4-11%. We also found that 39% of these PGPRs were phosphate solubilizing bacteria (PSB) with a solubilization ability greater than 100 µg/mL. In fact, Pantoea agglomerans (MRC_ZO_17) and Enterobacter ludwigii (MRC_ZO_97), showed the highest phosphate solubilization rates of ~450 µg/mL and ~196 µg/mL, respectively. In addition to their ability to solubilize phosphate, various isolates had the ability to produce Indole-3-acetic acid (IAA). For instance, E. ludwigii (MRC_ZO_97) had an IAA production of ~60.48 g/mL. In the region of Zouala, characterized by relatively higher salinity and lower rate of organic matter, Firmicutes isolates account for 87% of the isolated rhizobacteria. Interestingly, we found that the olive tree-associated PGPRs vary significantly between the three sampled regions. Several rhizobacteria isolated in this study are excellent candidates for formulation as bioinocula for plants in saline soils.

Enzymatic diversity in the haloactinomycetes isolated from rhizosphere of the plants in saline soils at the periphery of Dasht-e-Kavir desert

Enzymatic diversity in the haloactinomycetes isolated from rhizosphere of the plants in saline soils at the periphery of Dasht-e-Kavir desert

Effect of a Biostimulant Based on Polyphenols and Glycine Betaine on Tomato Plants’ Responses to Salt Stress

Climate change accentuates abiotic stress conditions putting at risk several commercial cultivars particularly vulnerable to salinity in the early stages of development, which makes adopting new technologies in tune with the environment necessary to mitigate its impact. In this study, we tested the possible effects of a commercial biostimulant (BALOX®) on enhancing salt stress tolerance in salt-treated tomato plants, analysing plant growth and several stress biochemical markers: photosynthetic pigments, ion contents in roots and leaves, leaf concentrations of different osmolytes, oxidative stress markers, non-enzymatic antioxidants, and the specific activities of major antioxidant enzymes. The experimental design consisted of three soil salinity levels (non-saline, saline, and very saline), two biostimulant doses (0.4 mL and 0.8 mL of the BALOX® stock per litre of irrigation water), and the non-treated control (without biostimulant), evaluated at 30 and 60 days of treatment. The biostimulant favoured plant growth, especially at the root level and in saline soils. In addition, it helped reduce Na+ and Cl− uptake by the roots and seemed to stimulate, to some extent, K+ and Ca2+ transport to the aerial part of the plant. The BALOX® application significantly reduced the level of stress affecting the plants in saline soils, as shown by the decrease in the contents of proline and oxidative stress biomarkers and the activity of salt-induced antioxidant enzymes. Some of the biostimulant effects were also observed under low salinity conditions; therefore, in addition to enhancing salt stress responses, BALOX® appears to stimulate the growth of tomato plants through a general improvement of photosynthesis and primary metabolism.

PERTUMBUHAN DAN PRODUKSI KEDELAI AKIBAT INOKULASI Rhizobium sp. DAN BAKTERI PELARUT FOSFAT TAHAN SALIN SERTA BATUAN FOSFAT DI TANAH SALIN

<p>The purpose of this study was to examine the effect of <em>Rhizobium sp.</em> and phosphate solubilizing bacteria saline-resistant and the application of phosphate rock to the growth and production of soybean plants in saline soils. The study was carried out using a 3 x 4 factorial design on the basis of a Completely Randomized Design with 3 replications. The first factor is the treatment of <em>Rhizobium sp.</em> and phosphate solubilizing bacteria saline-resistant (CFU 109 cells/g) at 4 levels, namely F0 : 0 mg/pot, F1 : 10 mg/pot, F2 : 20 mg/pot, and F3 : 30 mg/pot. The second factor is the doses of phosphate rock with 3 levels, namely B0: 0 kg/ha, B1: 50 kg/ha, and B2: 100 kg/ha. The results showed that the inoculation treatment of <em>Rhizobium sp.</em> and phosphate solubilizing bacteria saline-resistant were not significantly different on the N uptake parameters of seeds. Treatment with different doses of rock phosphate had no significant effect on all parameters. There was no interaction between <em>Rhizobium sp.</em> and phosphate solubilizing bacteria saline-resistant with a dose of rock phosphate on all observed parameters. Inoculation of <em>Rhizobium sp.</em> and phosphate solubilizing bacteria saline-resistant and rock phosphate have not been able to significantly increase the growth and production of soybean varieties Anjasmoro in highly saline growing media with EC 6,26 dS/m, although there is a tendency to increase soybean production.</p>

Role of beneficial microbial gene pool in mitigating salt/nutrient stress of plants in saline soils through underground phytostimulating signalling molecules

Soil salinity diminishes soil health and reduces crop yield, which is becoming a major global concern. Salinity stress is one of the primary stresses, leading to several other secondary stresses that restrict plant growth and soil fertility. The major secondary stresses induced in plants under saline-alkaline conditions include osmotic stress, nutrient limitation, and ionic stress, all of which negatively impact overall plant growth. Under stressed conditions, certain beneficial soil microflora are known to have evolved phytostimulating mechanisms, such as the synthesis of osmoprotectants, siderophores, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, phosphate solubilization, and hormone production, which enhance plant growth and development while mitigating nutrient stress. Beneficial soil-borne bacterial species such as Bacillus, Pseudomonas, and Klebsiella and fungal strains such as Trichoderma, Aspergillus, Penicillium, Alternaria, and Fusarium also aid in reducing salinity stress. Phosphate-solubilizing microorganisms also assist in nutrient acquisition via both enzymatic and non-enzymatic processes. In the case of enzymatic processes, they produce different enzymes such as alkaline phosphatases and phytases, whereas non-enzymatic processes produce organic acids such as gluconic, citric, malic, and oxalic acids. The native halotolerant/halophilic soil microbial gene pool with multifunctional traits and stress-induced gene expression can be developed as suitable bio-inoculants to enhance stress tolerance and optimize plant growth in saline soils.

The physicochemical approaches of altering growth and biochemical properties of medicinal plants in saline soils.

Medicinal plants are important sources of biochemical compounds affecting human health. However, because large areas of the world are subjected to different stresses including salinity, it is important to find methods, which may control the growth and biochemical properties of medicinal plants in such conditions. Another aspect of cropping medicinal plants in saline soils is the alteration of their biochemical properties by stress. Due to the significance of planting medicinal plants in saline soils, the objective of the present review article is to investigate and analyze the physicochemical approaches including soil leaching, organic fertilization, mineral nutrition, ozonated water, magnetism, superabsorbent polymers, and zeolite, which may control the effects of salinity stress on the growth and biochemical properties (production of secondary metabolites) of medicinal plants. In our just-published review article, we investigated the biological approaches, which may affect the growth and biochemical properties of medicinal properties in saline soils. Although salinity stress may induce the production of biochemical products in medicinal plants, the use of physicochemical approaches is also recommendable for the improved growth and biochemical properties of medicinal plants in saline soils. More has yet to be indicated on the use of the physicochemical approaches, which may affect the growth and biochemical properties of medicinal plants in salt stress conditions. KEY POINTS: • Growth and physiological alteration of medicinal plants in salt stress conditions. • The physicochemical approaches of such alteration have been reviewed. • More has yet to be indicated on the approaches, which may affect such properties.

Comparative Characteristics of Germination of Some Halophyte Plants in Saline Soils of Pavlodar Region

The possibility of using halophytic plant species for remediation of saline soils in Kazakhstan is considered. In this regard, the purpose of our research is a comparative description of the germination of some halophytic plants of Pavlodar region in saline soils of European calf (salicornia europaea L.), Aksora (suaeda salsa Pall.), Tumpek sarzasan (halocnemum strobilaceum Pall.). The article aimed at selecting the most active seeds for the salt by germination indicator using some halophyte plants seeds. A comparative description of the germination of European calf (salicornia europaea L.), Aksora (suaeda salsa Pall.), Tumpek sarsazan (halocnemum strobilaceum Pall.) near Lake Maraldy of Pavlodar region was given. All of these plants have been shown to be true halophytes, and each of them can be used to reduce soil salinity. For this purpose, it can be recommended to the use European calf (salicornia europaea L.) of saline lands of not only in Pavlodar region, but in most saline areas of Kazakhstan.

Native Arbuscular Mycorrhizal Fungi Characterization from Saline Lands in Arid Oases, Northwest China.

Arbuscular mycorrhizal fungi (AMF) colonize land plants in almost every ecosystem, even in extreme conditions, such as saline soils. In the present work, we report the mycorrhizal capacity of rhizosphere soils collected in the dry desert region of the Minqin Oasis, located in the northwest of China (Gansu province), which is characterized by several halophytes. Lycium spp. and Peganum nigellastrum were used as trap plants in a greenhouse experiment to identify autochthonous AMF associated with the halophytes’ rhizospheres. Morphological observations showed the typical AMF structures inside roots. Twenty-six molecularly distinct AMF taxa were recovered from soil and root DNA. The taxonomical diversity mirrors the several AMF adapted to extreme environmental conditions, such as the saline soil of central China. Knowledge of the AMF associated with halophytes may contribute to select specific fungal isolates to set up agriculture strategies for protecting non-halophyte crop plants in saline soils.

Effect of biochar on nitrogen use efficiency, grain yield and amino acid content of wheat cultivated on saline soil

Biochar can potentially increase crop production in saline soils. However, the appropriate amount of biochar that should be applied to benefit from resource preservation and increase both grain yield (GY) and quality is not clear. A pot experiment was conducted to evaluate the effects of biochar applied at various rates (i.e., 0, 5, 10, 20, 30, 40 and 50 t/ha) on the nitrogen use efficiency (NUE), GY and amino acid (AA) contents of wheat plants in saline soils. The results showed that the application of 5–20 t/ha biochar increased wheat NUE by 5.2–37.9% and thus increased wheat GY by 2.9–19.4%. However, excessive biochar applications (more than 30 t/ha) had negative effects on both the NUE and GY of wheat. Biochar had little influence on leaf soil and plant analyzer development (SPAD) values, the harvest index or yield components. The AAs were significantly affected by biochar, depending on the application rate. Among the application rates, 5–30 t/ha biochar resulted in relatively higher (by 5.2–19.1%) total AA contents. Similar trends were observed for each of the 17 essential AAs. In conclusion, the positive effects of biochar occurred when it was applied at appropriate rates, but the effects were negative when biochar was overused.

Natural Biostimulants Improve Saline Soil Characteristics and Salt Stressed-Sorghum Performance

ABSTRACTHumus substances (HM) and Moringa oleifera leaf extract (MLE) are considered as biostimulants used for plant growing under normal and salt stress conditions. Therefore, effects of soil HM and foliar MLE applications on soil characteristics and on sorghum growth, physio-biochemical properties, and antioxidant defense system activity were investigated under salt stress using pot experiments. The experimental design was a split-split plot with three soil salinities (S1, S2, and S3) as main-plots, two HM levels (0 and 0.1 g kg‒1 soil) as subplots, and two MLE levels (0% and 3%) as sub-subplots, and each one of the 12 treatments was replicated 20 times. Saline soil properties were improved by HM. Under saline conditions, either HM or MLE increased growth characteristics, photochemical activity, contents of RNA, DNA, phytohormones, osmoprotectants and non-enzymatic antioxidants, and activities of antioxidant enzymes in sorghum plants compared to those in the untreated control plants. The interactive HM×MLE application was most effective at overcoming the harmful effects of soil salinity stress and further increased the abovementioned criteria. This study, therefore, recommends using the integrative HM+MLE treatment for growing sorghum plants in saline soils up to more than 6.12 dS m‒1 without loss in growth characteristics.

Connecting salt stress signalling pathways with salinity-induced changes in mitochondrial metabolic processes in C3 plants.

Salinity exerts a severe detrimental effect on crop yields globally. Growth of plants in saline soils results in physiological stress, which disrupts the essential biochemical processes of respiration, photosynthesis, and transpiration. Understanding the molecular responses of plants exposed to salinity stress can inform future strategies to reduce agricultural losses due to salinity; however, it is imperative that signalling and functional response processes are connected to tailor these strategies. Previous research has revealed the important role that plant mitochondria play in the salinity response of plants. Review of this literature shows that 2 biochemical processes required for respiratory function are affected under salinity stress: the tricarboxylic acid cycle and the transport of metabolites across the inner mitochondrial membrane. However, the mechanisms by which components of these processes are affected or react to salinity stress are still far from understood. Here, we examine recent findings on the signal transduction pathways that lead to adaptive responses of plants to salinity and discuss how they can be involved in and be affected by modulation of the machinery of energy metabolism with attention to the role of the tricarboxylic acid cycle enzymes and mitochondrial membrane transporters in this process.

Effect of Treatment with Saline Solution (NaCl) on Rape Plants in Presence of the Hemp Shives

The aim of this research was assessing the influence of hemp shives, like amendaments, in saline soils planted with rape (Brassica rapa L.). The growth and development assessing of rape plants in saline soils was achieved through biometric measurements for elongation and gravimetric measurements for the amount of biomass synthesized. Also, it was followed determination of the concentration of assimilating pigment (chlorophyll a, b, total carotenoid pigments) and protein content. It was found that adding hemp shives in soils with low salinity stimulated elongation and germination processes for rape. In soil with high salinity adding hemp shives determine an increase of biomass accumulation in all vegetative organs, comparative with the same salt concentration where we added the amendaments. Hemp shives can be recommended like natural amendaments for soils with high salt concentration.

Hydraulic redistribution: limitations for plants in saline soils.

Hydraulic redistribution (HR), the movement of water from wet to dry patches in the soil via roots, occurs in different ecosystems and plant species. By extension of the principle that HR is driven by gradients in soil water potential, HR has been proposed to occur for plants in saline soils. Despite the inherent spatial patchiness and salinity gradients in these soils, the lack of direct evidence of HR in response to osmotic gradients prompted us to ask the question: are there physical or physiological constraints to HR for plants in saline environments? We propose that build-up of ions in the root xylem sap and in the leaf apoplast, with the latter resulting in a large predawn disequilibrium of water potential in shoots compared with roots and soil, would both impede HR. We present a conceptual model that illustrates how processes in root systems in heterogeneous salinity with water potential gradients, even if equal to those in non-saline soils, will experience a dampened magnitude of water potential gradients in the soil-plant continuum, minimizing or preventing HR. Finally, we provide an outlook for understanding the relevance of HR for plants in saline environments by addressing key research questions on plant salinity tolerance.

Metabolic potential and community structure of endophytic and rhizosphere bacteria associated with the roots of the halophyte Aster tripolium L.

The submitted work assumes that the abundance and diversity of endophytic and rhizosphere microorganisms co-existing with the halophytic plant Aster tripolium L. growing in a salty meadow in the vicinity of a soda factory (central Poland) represent unique populations of cultivable bacterial strains.Endophytic and rhizosphere bacteria were (i) isolated and identified based on 16S rDNA sequences; (ii) screened for nifH and acdS genes; and (iii) analyzed based on selected metabolic properties. Moreover, total microbial biomass and community structures of the roots (endophytes), rhizosphere and soil were evaluated using a cultivation-independent technique (PLFA) to characterize plant–microbial interactions under natural salt conditions.The identification of the isolated strains showed domination by Gram-positive bacteria (mostly Bacillus spp.) both in the rhizosphere (90.9%) and roots (72.7%) of A. tripolium. Rhizosphere bacterial strains exhibited broader metabolic capacities, while endophytes exhibited higher specificities for metabolic activity. The PLFA analysis showed that the total bacterial biomass decreased in the following order (rhizosphere<soil<endophytes) and confirmed the dominance of Gram-positive endophytic bacteria in the roots of the halophyte.The described strain collection provides a valuable basis for a subsequent applications of bacteria in improvement of site adaptation of plants in saline soils.

Lipoic acid mitigates oxidative stress and recovers metabolic distortions in salt-stressed wheat seedlings by modulating ion homeostasis, the osmo-regulator level and antioxidant system.

Soil salinity is one of the most detrimental environmental factors affecting the growth of plants and limiting their agricultural productivity. This study investigated whether exogenous lipoic acid (LA) pretreatment plays a role in promoting salt tolerance in wheat seedlings. The seedlings were treated with LA (1.75 mmol L(-1)) and salt (100 mmol L(-1) NaCl) separately and a combination of them. Salt stress significantly reduced relative water content, leaf surface area, ribulose bisphosphate carboxylase expression, and chlorophyll content but increased the content of osmo-regulator protein, carbohydrates and proline. In addition, salinity led to an imbalance in the inorganic composition of wheat leaves. While it elevated Na(+) content compared to control, Ca content and K(+)/Na(+) ratio were reduced. Under saline conditions, despite increases in antioxidant enzyme activity and levels of antioxidant compounds (ascorbate and glutathione), the content of reactive oxygen species (superoxide anion, hydrogen peroxide) and malondialdehyde were higher than in control seedlings. LA significantly promoted osmo-regulator level and antioxidant enzyme activities compared to stressed seedlings alone. Also, it both increased levels of ascorbate and glutathione and regenerated their oxidised forms, thus contributing to maintaining cellular redox status. Similarly, LA prevented excessive accumulation of Na(+) and promoted K(+)/Na(+) ratio and Ca content. Reactive oxygen species content was significantly reduced, and the inhibitions in the above parameters markedly recovered. LA reduced salinity-induced oxidative damage and thus contributed to the growth and development of plants in saline soils by modulating ion homeostasis between plant and soil as well as in osmo-regulator content and antioxidant system.

New strains of rhizobia that nodulate regenerating messina (Melilotus siculus) plants in saline soils

Messina [Melilotus siculus (Turra) Vitman ex B.D.Jacks (syn. M. messanensis (L.) Mill.)] is the most promising annual pasture legume for saline waterlogged soils in southern Australia. Messina forms a symbiosis with the commercial Sinorhizobium medicae strain, WSM 1115, used for many annual medic (Medicago) species. However, WSM 1115 does not persist over the summer months in saline soils and fails to adequately nodulate regenerating messina plants, restricting its commercial development as a new species for agriculture. To overcome this symbiotic constraint, two field experiments (swards and rows) and a glasshouse symbiotic effectiveness experiment were undertaken to identify strains of S. medicae able to persist in saline soils and adequately nodulate regenerating messina plants. In the sward experiment, no rhizobia were detected in WSM 1115 plots in the first autumn following seed set, whereas 3519 rhizobia per g of soil were measured for strain SRDI 554. Compared with WSM 1115, SRDI 554 increased regenerating messina nodulation from 32 to 100%, the number of nodules per plant from 1.3 to 32.4 and shoot dry weights from 23.6 to 80.2 mg/plant. The row field experiment found SRDI 554 had greater saprophytic competence than WSM 1115 and increased overall mean plant nodulation from 11 to 74%. The symbiotic effectiveness experiment found plant shoot weight of the majority of S. medicae strains under non-saline conditions was similar to WSM 1115. These experiments have identified new strains of rhizobia that overcome the symbiotic constraint in regenerating messina plants in saline soils. Further evaluation, particularly in acidic saline, waterlogged soils, is required to confirm adaptation of the most promising strains to soils within the full range of messina target environments.