Saline Soil Conditions Research Articles

Photosynthetic Pigments, Symbiotic Traits, Yield Attributes and Nutrient Uptake of Soybean Crop as Influenced by Soil Amendments on Degraded Vertisol of Chambal Tablelands

Background: Gypsum and organic amendments are potential ameliorants for reclamation of saline and/or sodic soil conditions to improve crop productivity and soil fertility. Application of gypsum at higher dose ( greater than 1 t ha-1) with organic amendments such as FYM, crop residue on soybean crop is largely unknown for salt affected soils. Impact of these soil amendments on soybean chlorophyll pigments, symbiotic traits, nutrient uptake, nutrient harvest index, carbohydrate equivalent yield, crop productivity and economic returns is not being addressed properly. This is particularly true for oilseed crop grown under saline conditions. Methods: A field experiment was conducted for two years (2017 and 2018) to assess the impact of amendments like gypsum, crop residue (CR), farm yard manure (FYM) with recommended dose of nitrogen-phosphorus-potassium (RNPK) fertilizer dose on soybean crop in degraded vertisol with eight treatments and three replications laid in randomized block design. Result: Results revealed that among treatments, phenological traits such as total chlorophyll (1.561 and 1.593mg g-1), carotenoid (0.156 and 0.154 mg g-1) at 30DAS (days after sowing), nodulation traits (33.6 and 32.4 nodules plant-1) and dry matter accumulation (26.2 and 23.9 g plant-1 at harvest) improved significantly in RNPK+Gypsum+CR+FYM and RNPK+Gypsum+FYM treatments respectively. Combined application of fertilizers with organic and gypsum amendments increased soybean yield by the magnitude of 49-53% compared to only fertilizer applied treatments. Higher biological yield (4169-4339 kg ha-1), carbohydrate equivalent yield (258.8-266.5 kg ha-1) and nutrient uptake (118: 8:47:11 -140: 9: 57: 12 kg ha-1N:P:K:S) were observed in RNPK+Gypsum+CR±FYM treatments. Economic analysis showed higher net returns and benefit-cost ratio in RNPK+Gypsum+CR (Rs 15247 and 1.48) and RNPK+Gypsum (Rs 14499 and 1.59) treatments.

Biochar Additions Alter the Abundance of P-Cycling-Related Bacteria in the Rhizosphere Soil of Portulaca oleracea L. under Salt Stress

Numerous reports confirm a positive impact of biochar amendments on soil enzyme activities, nutrient cycles, and, finally, plant growth and development. However, reports explaining the process behind such diverse observations are scarce. The aim of the present study was (1) to evaluate the effect of biochar on the growth of purslane (Portulaca oleracea L.) and nutrients; (2) to determine the response of rhizosphere enzyme activities linked to soil phosphorus cycling after bio-char amendment under non–saline and saline soil conditions. Furthermore, we investigate whether adding biochar to soil alters the abundance of P-cycling-related bacteria. Two rates of biochar (2% and 4%) were applied in pot experiments. Biochar addition of 2% significantly increased plant growth under non-saline and saline soil conditions by 21% and 40%, respectively. Moreover, applying biochar increased soil microbial activity as observed by fluorescein diacetate (FDA) hydrolase activity, as well as phosphomonoesterase activities, and the numbers of colony-forming units (CFU) of P-mobilizing bacteria. Soil amended with 2% biochar concentration increased total soil nitrogen (Nt), phosphorus (P), and total carbon (Ct) concentrations by 18%, 15%, and 90% under non-saline soil conditions and by 29%, 16%, and 90% in saline soil compared the control, respectively. The soil FDA hydrolytic activity and phosphatase strongly correlate with soil Ct, Nt, and P contents. The rhizosphere soil collected after biochar amendment showed a higher abundance of tricalcium phosphate-solubilizing bacteria than the control soil without biochar. Overall, this study demonstrated that 2% maize-derived biochar positively affects halophyte plant growth and thus could be considered for potential use in the reclamation of degraded saline soil.

Maize growth response to different Bacillus strains isolated from a salt-marshland area under salinity stress

Maize (Zea mays) growth performance has been hindered due to the high soil salinity. Salinity is one of the most severe abiotic stresses that has led to growth imbalance and profitability of harvests in arid and semi-arid regions. Plants have taken advantage of salt-tolerant bacteria as plant growth-promoters to enhance growth and reduce the adverse effects of salinity through the regulation of some biochemical, physiological, and molecular features. Preferences for non-chemical, eco-friendly, and economical approaches have caused the inquiry of the Bacillus genus as a joint group of plant growth-promoting rhizobacteria known to alleviate salt-stress impacts. In the present study, halotolerant Bacillus strains were isolated from salt-marshland soil and characterized for their physiological, molecular, and biochemical properties. Twenty-four bacterial isolates collected from high saline fields of salt marshland were analyzed by MALDI-TOF MS proteome analysis, which confirmed the taxonomic affiliation with Bacillus cereus, Bacillus subtilis, Bacillus atrophaeus, and Bacillus thorngiensis. Applying the isolates on maize plants as bio-inoculant bacteria obviously increased the growth parameters (P < 0.01). Pot experiments showed that isolates 74 and 90 were the most prominent strains to minimize the harmful effects of salinity. Its effects are heightening the potassium/sodium ratio and K-Na selectivity in shoots and roots measured by flame atomic absorption photometry (AAS). Accordingly, Bacillus cereus isolate 74 showed a maximum increase in dry weights of the shoot (133.89%), root (237.08%), length of the shoot (125%), and root (119.44%) compared to the control condition. Our findings suggest that bacteria isolated from marshland may be an economical and simple means to increase plant growth and resistance to high salinity soil conditions.

Evaluation of Alfalfa and Grass Species in Binary and Complex Mixtures on Performance under Soil Salinity Conditions

The effect of synergies between saline-tolerant grass and legume species grown in saline soil, on yield, quality, composition, persistence, and weed suppression was studied in 2019–2021 in a moderately saline soil located in the dark brown soil zone near Saskatoon, Saskatchewan, Canada. ‘Halo’ alfalfa (ALF), a salt-tolerant cultivar of alfalfa, was seeded in binary mixtures with ‘Revenue’ slender wheatgrass (ALF-SWG), ‘Garrison’ creeping meadow foxtail (ALF-CMF), and ‘Radisson’ smooth bromegrass (ALF-SBG). A complex mixture (quaternary) with all three grasses was also included. Four replicated treatments (n = 4) were randomly allocated to 6.2 × 1.2 m plots in spring 2019. The binary mixtures had similar or slightly better stand establishment compared to the quaternary mixture over the two years (83.3 vs. 76.9%), the quaternary stand showed greater (p = 0.01) establishment in Yr 2 than in Yr 1 (85 vs. 68.8%). There was high weed infestation in all the stands, but ALF-SWG had less weed infestation (23.8 vs. 44.1%) than ALF-CMF, especially in Yr 2 (p = 0.05). There were no significant differences among mixtures in yield, nutritional composition, and nutrient uptake. The ALF-CMF and ALF-SWG binary mixtures had 9 to 23% greater mean total DMY than the other mixtures in the moderately saline soil. The cost of establishing forage mixtures on unproductive saline land can be up to 89% recovered after only two years. The results suggested that binary mixtures of ‘Halo’ alfalfa with ‘Revenue’ slender wheatgrass or ‘Garrison’ creeping meadow foxtail could be reasonable alternatives for adequate forage production and quality, high N-use efficiency, and ultimately livestock gain per hectare, as well as for controlling soil salinity and improving soil fertility in this saline area in the dark brown soil zone.

Evaluation of the impact of potassium solubilizing bacteria on potassium efficiency and yield of canola under saline and non-saline soil conditions

ABSTRACT Canola (Brassica napus L.) is one of the most important oilseed crops used globally for nutritional and industrial purposes. In the pursuit of sustainable agriculture goals, understanding plant-microbe interactions is necessary. This study aimed to evaluate the effects of seven levels of potassium sulfate fertilizer (K2SO4; 0, 25, 50, 75, 100, 125 and 150 kg ha−1), which at each of the following five potassium solubilizing bacteria (KSB; non-inoculated, Pantoea agglomerans, Rahnella aquatilis, co-inoculation (P. agglomerans+R. aquatilis) and a commercial biofertilizer ‘PotaBarvar-2’), on potassium uptake and yield of canola under saline and non-saline soil conditions. The results indicated that among KSB treatments, the highest values for all traits were observed when P. agglomerans and R. aquatilis together were applied, which could be considered as the best KSB treatment in both soil conditions. However, grain yield was increased by 39.7% (1226.4 kg ha−1) and 51.1% (1325.0 kg ha−1); the application of K2SO4 was reduced by 13.3% (10.9 kg ha−1) and 12.4% (13.9 kg ha−1) when the co-inoculation compared to the non-inoculated treatment under non-saline and saline soil conditions, respectively. Consequently, the application of P. agglomerans and R. aquatilis together can be recommended in sustainable canola production systems, particularly under saline soil conditions.

The Content of Certain Groups of Phenolic Compounds and the Biological Activity of Extracts of Various Halophyte Parts of Spergularia marina (L.) Griseb. and Glaux maritima L. at Different Levels of Soil Salinization.

Halophyte plants are known for their resistance to harsh environmental conditions associated with excess salts in their habitats. Their resistance to salinization is due, among other things, to their high ability to detoxify free radicals, owing to the relatively high content of antioxidants. On the coast of the Baltic Sea and in the lagoons, there are several rare halophyte species included in the Red Book of the Kaliningrad Region (Russia) and the Baltic region, such as Spergularia marina (L.) Griseb. and Glaux maritima L. The aim of the research was to study the accumulation of certain groups of phenolic compounds in different parts of S. marina and G. maritima plants under conditions of weak and strong soil salinity, as well as to analyze the antioxidant, antibacterial, and fungicidal activity of extracts of the studied plant species. The present study showed an increase in total phenolic content in the roots and shoots of S. marina, and the shoots of G. maritima, in response to increased soil salinity. At the same time, the total content of flavonoids in all the studied parts of the two plant species remained unchanged. However, the content of individual flavonoids (hesperetin, epicatechin, apigenin derivative, luteolin derivative) in S. marina increased, for G. maritima there was a tendency to reduce the content of flavonoids in roots and shoots with an increase in soil salinity. There was an increase in the total content of hydroxycinnamic acids in the roots of Glaux maritima, as well as an increase in the content of protocatechuic acid in the roots and shoots of Spergularia marina. A positive relationship was established between the antioxidant activity of S. marina root extracts and the total content of phenolic compounds, as well as G. maritima shoots extracts and the total content of phenolic compounds. Extracts of S. marina showed no antibacterial activity against Escherichia coli and Bacillus subtilis, and weak fungicidal activity of stem extracts and inflorescences grown on soils, with high levels of salinities, was detected against Candida albicans. The extracts of roots and shoots from G. maritima showed weak antimicrobial and fungicidal activity.

Ecological and coenotic groups of Southern Trans-Urals vascular plants flora and biotopes phytoindication

The expert and statistical assessment of ecological and coenotic groups of Southern Trans-Urals vascular plants flora has been done for A.L. Belgards coenomorphs scheme and scheme of vascular plants flora of temperate forest zone of European Russia. Both suggested schemes of groups give adequate and similar assessment of biotopes. The proposed groups of vascular plants flora are identified in phytometer scales space definitely and can be used for regional assessment of biotopes. The best assessment of ecological flora of region is realized by combined coenomorphs and coenotic group schemes approach at the same time. The authors have established regimes of principal ecological factors that identified differentiation flora by coenotic groups and ultimate for specific groups forming in Southern Trans-Urals habitats. Sylvant coenomorph has been formed by boreal (acidic soils phytometers) and nemoral sciophytes and heliosciophytes, moreover a nemoral group must be understood as a group of shady forests on rich soils. The sylvant pine forest group is heterogeneous and not coenoticaly specific. The steppe coenotic group has been formed of obligate and facultative heliophytes of mostly dry biotopes, pratal coenomorph is heterogeneous and not coenoticaly specific and made up of humidity-meadow flora, dry-meadow coenotic group is not specific. For Southern Trans-Urals region it is recommended to use unite paludal coenomorphs but with a separation of coenotic group of oligotrophic bogs. The separation of ruderal coenomorph (phytometers of dry-meadow moistening and rich of nitrogen soils) is confirmed statistically. The authors have established regimes of principal ecological factors for stenotopic ecological and coenotic groups of Southern Trans-Urals region. For coenotic groups of Southern Trans-Urals region the authors have identified biotopical centres and biotopic and coenotic series which are associated with moistening, aeration and saline soil conditions and brightness regime.

Impact of drought and salinity on olive potential yield, oil and fruit qualities (cv. Chemlali) in an arid climate

The increase water demand for irrigation is leading to the use of low-quality water resources. The combined impact of drought and salinity on olive production sustainability, yield quality, growth, soil salinity and soil water conditions in arid areas has been little investigated. This study’s purpose was conducted to investigate the effects of the monitoring of saline water irrigation on soil properties and olive trees (cv. Chemlali) grown in an arid region of Tunisia (Sfax), on the potential yield, growth and quality of the resultant virgin olive oil in comparison to Rain-fed conditions. It is also intended to compare olive productive performance during a severe drought with, and without, irrigation and to assess recovering capacities after long driest period. Three irrigation levels were considered: (i) Full irrigation (100%ETc) with saline water 7.5 dS m-1 (FI); (ii) Full irrigation with same amount of water than the FI applied with tap water 2.46 dS m-1 (TW); and (iii) Rain-fed conditions (Dry). The results have showed that irrigation with saline water maintained the soils permeability, induced the distribution of salts outside the root zone. Additionally, it has maintained an adequate hydration of the rhizosphere through continuous and efficient leaching of salts to deep horizons. After drought period, the increase of the yield of rain-fed trees indicated 50% of recovery as compared to saline water. Irrigation with saline water reduced this gap due to drought impact. But it was 50% under that tap water; while reduction was 15% as a reduction capacity of potential yield. Hence, drought and salt stress alter the olive tree capacity and potential yield in an irreversible way if their severity is very intense. As salinity increased, there was a desirable sink in measured total phenols and flavonoids levels and a rise of oleic and linoleic acids as compared to rainfed conditions. For the triglycerides composition, triolein (OOO) was present in very large quantity in three oils, with a high content for FI (23.94%). Saline water treatment did not affect free acidity, peroxide value, K232, K270, chlorophyll, carotenoids, in contrast to Rain-fed treatment which was decreased. Olive trees permanently lost less than half of their potential yield during drought without irrigation. Irrigation with saline water seems to ensure sustainable monitoring olive yield and oil quality.

Inoculation with Azospirillum brasilense and/or Pseudomonas geniculata reinforces flax (Linum usitatissimum) growth by improving physiological activities under saline soil conditions

BackgroundSalinized soils negatively affect plant growth, so it has become necessary to use safe and eco-friendly methods to mitigate this stress. In a completely randomized design, a pot experiment was carried out to estimate the influence of the inoculation with endophytic bacterial isolates Azospirillum brasilense, Pseudomonas geniculata and their co-inoculation on growth and metabolic aspects of flax (Linum usitatissimum) plants that already grown in salinized soil.ResultsThe results observed that inoculation of salinity-stressed flax plants with the endophytes A. brasilense and P. geniculata (individually or in co-inoculation) increases almost growth characteristics (shoot and root lengths, fresh and dry weights as well as number of leaves). Moreover, contents of chlorophylls and carotenoids pigments, soluble sugars, proteins, free proline, total phenols, ascorbic acid, and potassium (K+) in flax plants grown in salinized soil were augmented because of the inoculation with A. brasilense and P. geniculata. Oppositely, there are significant decreases in free proline, malondialdehyde (MDA), hydrogen peroxide (H2O2), and sodium (Na+) contents. Regarding antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD), and ascorbate peroxidase (APX), the inoculation with the tested endophytes led to significant enhancements in the activities of antioxidant enzymes in stressed flax plants.ConclusionsThe results of this work showed that the use of the endophytic bacterial isolates Azospirillum brasilense, Pseudomonas geniculata (individually or in co-inoculation) could be regarded as an uncommon new model to alleviate salinity stress, especially in salinized soils.

Economic feasibility of subsurface drainage (SSD) to control waterlogging and soil salinity under different scenarios in the Tungabhadra project command, Karnataka, India

AbstractThe Tungabhadra irrigation command area (TBP) in Karnataka, India, has three scenarios: the head, mid and tail reach command areas. The head reach has ample good quality canal water availability, and the mid reach area has limited canal water availability. In recent decades, rice–rice monocropping in vertisols, especially by these head and mid reach farmers, has led to not only water shortages but also the development of waterlogging and secondary soil salinization in the tail (lower) reach of the command due to seepage. As the soil salinity in the head reach was less severe, a slightly wider drain spacing of 60 m was adopted over 15 ha. In the case of the mid reach, salinity was slightly higher than the head reach but slightly less than the tail reach, hence 50 m drain spacing was laid out over 24 ha. Due to the slightly higher soil salinity at the tail end of the command, a closer drain spacing of 40 m was adopted over 11 ha. In all these scenarios, the drain depth was 1.0 m. Despite differences in irrigation water availability and different soil salinity conditions, the study clearly indicated over six seasons that the SSD system is a viable solution for the reclamation of waterlogged saline soils and enhancing rice productivity in all three scenarios of the TBP command.

The effect of some soil conditioners on the yield and quality of sweet pepper grown under saline soil conditions using two sources of organic nitrogen fertilizers

Because of increased population worldwide in general and Egypt in particular , this may lead to a problem in the lack of food and fertile land area therefore, we resort to the expansion of the cultivation of salt soil. For that this experiment was carried out during two summer seasons of 2020 and 2021 at the Experimental Farm of El-Kassasein, Hort. Res. Station, Ismailia Governorate, Egypt, to study the effect of organic nitrogen sources (poultry manure and botanical compost ) and some soil conditioners ( magnetic iron at 25 and 50 kg /fed. and humic acid at 2 and 4 kg /fed.) on growth, yield and fruit quality of sweet pepper cv Top Star under sandy soil conditions. Fertilizing sweet pepper plants grown in sandy soil with 180 kg N as organic nitrogen in the form of poultry manure ( 5.521 ton /fed.) increased plant growth, N, P and K uptake by shoots, yield and its components , nitrogen use efficiency, dry matter, total soluble solids and Vit. C and decreased nitrate content in fruits compared to fertilizing with 180 kg N as organic nitrogen in the form of botanical compost (9.890 ton /fed.). Adding magnetic iron and humic acid as salt soil conditioners at different rates to sandy soil increased plant growth, N, P and K uptake by shoots, yield and its components, fruit traits, dry matter, total soluble solids and Vit. C and decreased nitrate content in fruits compared to control (without soil conditioners). Fertilizing with poultry manure at 5.521 ton /fed. and adding magnetic iron at 50 kg /fed. increased shoot dry weight, N, P and K contents and uptake by shoots, number of fruits/ plant, average fruit weight, yield / plant , total yield /fed. nitrogen use efficiency, dry matter and total soluble solids in fruits, whereas poultry manure at 5.521 ton/fed. and humic acid at 4 kg /fed. increased Vit. C and decreased nitrate contents in fruits.

Effects of simulated precipitation changes on plant community characteristics of wetland in the Yellow River Delta, China

Under the changing climate scenario, changes in precipitation regimes are expected to alter soil water and salinity conditions, with consequences on the characteristics of plant community in estuarine wetland. Here, we used a six-year (2015-2020) precipitation manipulation experiment to examine how plant community characteristics responded to precipitation changes in the Yellow River Delta. The results showed that soil electrical conductivity significantly decreased, while soil moisture significantly increased with increasing precipitation. Precipitation changes altered plant community composition. Increased precipitation reduced the absolute dominance of Suaeda glauca and Suaeda salsa, but increased that of Triarrhena sacchariflora and Imperata cylindrica. Shannon index and Margalef richness index of plant community significantly increased with increasing precipitation. Compared with the control, both decreased and increased precipitation decreased the plant community abundance, frequency and coverage. The treatment of 60% increased precipitation significantly decreased plant community frequency by 54.9%, while the 60% decreased precipitation, 40% decreased precipitation, 40% increased precipitation and 60% increased precipitation treatment significantly decreased plant abundance by 38.9%, 33.8%, 35.8% and 45.7%, respectively. The aboveground biomass significantly increased with increasing precipitation, but aboveground plant biomass under 60% increased precipitation treatment being lower than that reducing under 40% increased precipitation treatment, probably due to the negative effects of flooding stress. In addition, Margalef richness index had a significantly positive relationship with aboveground biomass. Aboveground biomass, Shannon diversity index, Margalef richness index, and Simpson diversity index were negatively related to soil electrical conductivity, and aboveground plant biomass was positively related to soil moisture. Our results revealed that precipitation changes regulate growth characteristics, species composition, and diversity of plant community by altering soil water and salinity conditions in a coastal wetland.

Salinity affects microbial composition and function in artificially induced biocrusts: Implications for cyanobacterial inoculation in saline soils

Cyanobacterial inoculation is a promising technology that can induce biocrust development, for stabilizing degraded soils in dryland environments. However, it is challenging to grow cyanobacteria in dry, saline soils, which limits the application of this technology. In this study, NaCl was added into field-collected induced biocrusts to investigate how salt affects the biocrust community. This fundamental knowledge improves our assessment of microbial salinity preference and adaptation, and can guide researchers to select the appropriate cyanobacterial inoculants for saline soil restoration. The results showed that the biocrusts induced by inoculating Microcoleus vaginatus and Scytonema javanicum could survive 1.0% salinity, although both salt and drought stresses significantly inhibited microbial biomass and metabolism (P < 0.05), and salinity led to an obvious shift in microbial community structure. Compared to salt stress, drought seems to provide a vital ecological protection for the biocrusts, allowing them to be active only under relative low salinity after hydration. In the induced biocrusts, cyanobacteria were always the dominant organisms (even 18 years since inoculation), whereas under elevated salinity, cyanobacterial communities with lower relative abundance had a higher survival percentage of M. steenstrupii and Phormidium sp. Altogether, our results showed that both prokaryotic and eukaryotic communities have obvious salinity preference in the cyanobacteria-induced biocrusts. These results suggest that cyanobacterial inoculation strategies can be adapted in response to the soil salinity conditions. Furthermore, a combined inoculation of M. steenstrupii and Phormidium sp. appears to be favorable approach that is expected to improve cyanobacterial inoculation technology in saline soils.

Plant water deficit index-based irrigation under conditions of salinity

In arid and semi-arid regions, water scarcity and soil salinization are major factors impacting sustainable agricultural production. In this study, a macroscopic root-water-uptake model was used to adapt a plant water deficit index (PWDI) for irrigation scheduling under conditions of coexisting soil water and salinity stress-causing factors. The traditional approach, estimating PWDI with average root zone soil water and salt amounts, was improved by weighting the effects of soil water and salinity according to the normalized root length density profile. An experiment growing wheat (Triticum aestivum L.) in soil columns and an experiment growing cotton (Gossypium hirsutum L.) in a salinized field were implemented to explore and quantify the effects of soil water and salinity conditions on plant water status, and thus to validate the improvement and evaluate its application, by monitoring soil water and salinity dynamics and plant growth indexes (e.g., leaf area, dry weight, leaf water potential, transpiration and yield). The results indicate that, even under conditions with equal root zone averages of soil matric and osmotic potentials, plant water status might be significantly different. In general, plants were less stressed when more water and less salinity were allocated in the upper root zone with more roots while less water and more salinity occurred in the lower root zone with less roots. By referring to some information in the soil column experiment, a numerical experiment was conducted to further demonstrate the improvement. The root-weighted approach resulted in improved PWDI estimation and thus was more reliable for irrigation scheduling, leading to higher irrigation frequency and quantity, leaf area index, biomass, yield, and transpiration, without significant decrease in water productivity. However, further improvement could be possible by considering the effects of historical soil water and salinity stresses as well as meteorological conditions on plant water status.

Synergistic Plant-Microbe Interactions between Endophytic Actinobacteria and Their Role in Plant Growth Promotion and Biological Control of Cotton under Salt Stress.

Bacterial endophytes are well-acknowledged inoculants to promote plant growth and enhance their resistance toward various pathogens and environmental stresses. In the present study, 71 endophytic strains associated with the medicinal plant Thymus roseus were screened for their plant growth promotion (PGP), and the applicability of potent strains as bioinoculant has been evaluated. Regarding PGP traits, the percentage of strains were positive for the siderophore production (84%), auxin synthesis (69%), diazotrophs (76%), phosphate solubilization (79%), and production of lytic enzymes (i.e., cellulase (64%), lipase (62%), protease (61%), chitinase (34%), and displayed antagonistic activity against Verticillium dahliae (74%) in vitro. The inoculation of strain XIEG05 and XIEG12 enhanced plant tolerance to salt stress significantly (p < 0.05) through the promotion of shoot, root development, and reduced the activities of antioxidant enzymes (SOD, POD, and CAT), compared with uninoculated controls in vivo. Furthermore, inoculation of strain XIEG57 was capable of reducing cotton disease incidence (DI) symptoms caused by V. dahliae at all tested salt concentrations. The GC-MS analysis showed that many compounds are known to have antimicrobial and antifungal activity. Our findings provide valuable information for applying strains XIEG05 and XIEG12 as bioinoculant fertilizers and biological control agent of cotton under saline soil conditions.

Applying the compositional nutrient diagnosis (CND) to pomegranate (Punica granatum cv. ‘Rabab’) under saline and calcareous soil condition

To establish the multivariate compositional nutrient diagnosis (CND) standards, and the nutrient sufficiency range in ‘Rabab’ cultivar pomegranate, the leaf nutrient concentrations and yields of 196 commercial orchards were determined. The orchard’s nutritional status was calculated and evaluated through the CND method and their compatible principal component analysis (PCA). The CND references norms were calculated as V*N = 2.587 ± 0.103, V*P = 0.124 ± 0.206, V*K = 2.232 ± 0.105, V*Ca = 3.086 ± 0.165, V*Mg = 1.367 ± 0.108, V*S = 1.357 ± 0.137, V*Fe = −1.410 ± 0.324, V*Mn = −3.165 ± 0.221, V*Zn = −4.499 ± 0.192, V*Cu = −5.265 ± 0.225, V*B = −2.884 ± 0.100, V*Rd = 6.470 ± 0.075. The corresponding optimum concentration values of nutrients were N = 1.888 ± 0.210, P = 0.164 ± 0.032, K = 1.322 ± 0.163, Ca = 3.511 ± 0.230, Mg = 0.630 ± 0.115, S = 0.649 ± 0.051 in percent and Fe = 333.588 ± 87.009, Mn = 62.647 ± 14.413, Zn = 15.471 ± 3.105, Cu = 8.118 ± 2.288, B = 89.529 ± 5.125 in mg kg−1. According to PCA analysis S, B, Fe and Cu, in the high yielding subpopulation and Ca, B, S and Mg in the low yielding subpopulation had the highest influence on the increment of fruit yield in ‘Rabab’ pomegranate orchards especially under saline and calcareous soil condition.

Evaluation of the Directly and Indirectly Effects of the Morpho-Physiological Traits of Sweet Corn Seedlings on Yield with Structural Equation Modeling Partial Least Square (SEM-PLS) Approach

Environmental stress factors have a very complex effect on the growth and growth parameters of plants. Therefore, special analytical techniques such as SEM-PLS can better understand the between observational variables and abiotic stress factors. Therefore, the present study was aimed to evaluate the, directly and indirectly, effects of the growth and biochemical parameters of sweet corn seed on yield, which seed primed with different melatonin doses and grown under different soil salinity conditions using the SEM-PLS model. Seeds of sweet corn cultivar Vega F1 were soaked in 0, 50, 100, and 200 μM of melatonin solution for 24 h, and then primed seeds were cultivated under four (0.27, 5.45, 9.00, and 12.32 dSm-1) soil salinity conditions. The study results showed that melatonin directly and positively affected growth parameters (β = 0.502, p &amp;lt;0.05). In contrast, salinity directly and negatively affected growth parameters (β = -0.689, p &amp;lt;0.05). Also, melatonin had a mostly indirect effect (β = 0.623) on biochemical components compared to direct effect (β = -0.277). The indirect effect (β = -0.855) of salinity on biochemical components was more significant than its direct effect (β = 0.244). Finally, the SEM-PLS can be used as a significant tool for understanding the benefits of melatonin and salinity’s positive or negative effects through direct and indirect relationships with the mediating variables of growth parameters and biochemical, which are essential to optimize sweet corn yield.

The effect of soil salinity and pepino mosaic virus infection on the expression of tomato defence‐related genes

AbstractTo reflect field conditions where cultivated plants are frequently exposed to multiple stresses simultaneously, the effect of salinity on the expression of defence‐related genes in tomato plants was examined in the absence and presence of pepino mosaic virus (PepMV) infection. Tomato seedlings were grown under three soil salinity regimes from the fourth day after transplantation: (a) no‐added salt (control), (b) low salinity (20 mM NaCl) and (c) high salinity (100 mM NaCl). The plants were non‐, mock‐ or PepMV‐inoculated 14 days after transplantation and systemic leaves were collected 4 days postinoculation for analysis by reverse transcription‐quantitative PCR (RT‐qPCR). In noninoculated tomato plants exposed to low and high salinity, expression of the salicylic acid (SA)‐, jasmonic acid‐, ethylene‐related genes was typically down‐regulated compared to control plants, with only a slight (nonsignificant) increase in ABA2 expression. In PepMV‐infected tomato plants, a strong induction of SA‐related genes was observed, which was compromised under low and high salt stress. The induction of PR1 gene expression by PepMV infection was the highest (an 82‐fold increase) in control plants, but was significantly less (a 20‐fold increase) under conditions of low and high soil salinity. No direct correlation between SA gene expression levels and PepMV RNA accumulation became apparent. In RT‐qPCR, the levels of PepMV genomic RNA and tomato LoxD and ACS1 RNA transcripts under mild salt stress were significantly reduced (the former 6‐fold), but under high salt stress the levels of all were similar to those in the nonstressed controls.

Salt Tolerance Strategies of Nitraria tangutorum Bobr. and Elaeagnus angustifolia Linn. Determine the Inoculation Effects of Microorganisms in Saline Soil Conditions

Increasing salinization threatens the normal growth of halophytes in saline habitats, especially at the seedling stage. Soil beneficial microorganisms have the potential to promote salt tolerance of halophytes, but less attention has been paid to the various responses between different halophytes with microbial inoculations. Here we performed pot experiments to assess the responses of Nitraria tangutorum Bobr. and Elaeagnus angustifolia Linn. to arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) inoculation in saline soil conditions. The results showed that neither a single AMF inoculation nor a single PGPR inoculation promoted the growth of N. tangutorum. In contrast, co-inoculation not only promoted biomass accumulation but also promoted the absorption of P, K+, and Ca2+ in the roots, and the accumulation of N, Na+, K+, and Ca2+ in the leaves. Co-inoculation also increased the K+/Na+ ratio in the roots as well as the Ca2+/Na+ ratio in both roots and leaves of N. tangutorum. Na+ is an important inorganic osmolyte, essential for both efficient osmoregulation and biomass accumulation in N. tangutorum. PGPR inoculation alone could not promote the growth of E. angustifolia. AMF inoculation, solely or combined with PGPR, was beneficial to the absorption of K+ and Ca2+ in the roots, the accumulation of N and K+ in the leaves, the maintenance of the K+/Na+ ratio and Ca2+/Na+ ratio in the leaves, the selective transportation of K+ and Ca2+ from roots to leaves, and the accumulation of proline and glycine betaine in the leaves of E. angustifolia. Increased nutrient absorption, ion homeostasis, and K+ and Ca2+ selective transportation in AMF-inoculated E. angustifolia helped reduce the toxic effects of Na+ and the damage caused by osmotic stress in saline soil conditions. “Plant-microbe specificity” leads to the different responses of N. tangutorum and E. angustifolia seedlings to AMF and PGPR inoculation in saline soil conditions. The different salt tolerance strategies for osmoregulation, nutrient acquisition, ion homeostasis, and ion transportation determine the differential responses in N. tangutorum and E.angustifolia to AMF and PGPR inoculations under saline soil conditions.

Determining the compositional nutrient diagnosis (CND) norms and main nutrient interactions in “Valencia” orange orchards on calcareous soils

To establish compositional nutrient diagnosis (CND) standards, in “Valencia” orange orchards (Citrus sinensis L. Osbeck), the leaf nutrient concentrations and yields of 234 commercial orchards were determined. The orchards nutritional status was evaluated through the compatible principal component analysis (PCA). The CND reference norms were calculated as V*N = 2.766 ± 0.167, V*P = 0.093 ± 0.199, V*K = 2.574 ± 0.097, V*Ca = 2.970 ± 0.217, V*Mg = 1.415 ± 0.116, V*S = 1.250 ± 0.200, V*Fe = −1.503 ± 0.212, V*Mn = −3.626 ± 0.327, V*Zn = −4.096 ± 0.431, V*Cu = −5.231 ± 0.166, V*B = −2.979 ± 0.187, V*Rd = 6.368 ± 0.074. The corresponding optimum concentration values of nutrients were N = 2.504 ± 0.348, P = 0.175 ± 0.040, K = 2.059 ± 0.227, Ca = 3.101 ± 0.664, Mg = 0.646 ± 0.071, S = 0.554 ± 0.108 in percent and Fe = 355.929 ± 80.601, Mn = 44.071 ± 14.409, Zn = 28.500 ± 12.126, Cu = 8.500 ± 1.698, B = 80.429 ± 14.516 in mg kg−1. According to PCA analysis the lower production in the “Valencia” orange orchards was mainly due to lower leaf concentration of S, Ca, B and Mg and a higher leaf concentration of K, Zn, Cu and Mn, respectively. Also, increment of leaf N and P in the high yielding subpopulation and leaf Fe in the low yielding subpopulation had significant effects on the increasing of fruit yield, especially under saline and calcareous soil conditions.