Non-saline Conditions Research Articles

Identification of saline landscapes from an integrated SVM approach from a novel 3-D classification schema using Sentinel-1 dual-polarized SAR data

This study presented an integrated SVM classification method that investigated the relationship between intrinsic scattering attributes of the surface features and the conductivity characteristics of the soil in the newly proposed two- and three-dimensional classification (2D and 3D) schema to classify the saline landscape. The study was conducted in the Vellore district, Tamil Nadu, which is composed of heterogeneous saline landforms due to the active geological processes and anthropogenic activities. The intensity products of Sentinel-1 data (VV + VH) of C-band frequency were employed in the present study. The SVM with linear kernel has outperformed the other models, namely random forest (RF), naive Bayes (NB), and K-Nearest Neighbour (k−NN), in performing the broad level of classification from the 2D classification schema (SVMOA = 84.2%, RFOA = 80.4%, k-NNOA = 78.8%, NBOA = 68.4%). The soil EC values derived from the dielectric loss measurements (R2 = 0.79, ρ = 0.018, and α=95%) were used to introduce the integrated SVM approach in the 3D schema to further breakdown the mapped classes into non-saline (NS) (soil EC ≤ 2 ds/cm), slightly saline (SS) (soil EC = 2.1 to 4 ds/cm) and moderately saline (MS) (soil EC = 4.1 to 8 ds/cm) categories. The overall performance of the integrated SVM approach implemented for the 3D classification schema (F1 = 0.80) was found to be satisfactory, but with an associated uncertainty majorly from MS (Precision = 0.52, F1 = 0.69), SS (Recall = 0.09, F1 = 0.15), and NS waterbodies (Recall = 0.18, F1 = 0.29) as shown in the Precision-Recall graph (AUCPR3D = 0.62). However, with the promising performance level demonstrated for the other nine classes such as NS, SS, and MS wet soil (F1 = 0.92, 0.92, 0.96), healthy plants (F1 = 0.83), salt-tolerant plants under SS and MS conditions (F1 = 0.83, 0.88), and waterlogged vegetation under NS, SS, and MS conditions (F1 = 0.82, 0.83, 0.83), the proposed classification scheme becomes an effective method to map saline and non-saline features from dual-polarimetric SAR data.

Oxygen Transfer of Fine-Bubble Aeration in Activated Sludge Treating Saline Industrial Wastewater

Aeration is usually the most energy-intensive part of the activated sludge process, accounting for 50% to 80% of the total requirement. To achieve high efficiency, designers and operators of WWTPs must, therefore, consider all influencing factors, including salinity. With increasing salinity, oxygen transfer increases compared to tap water (TW), due to the inhibition of bubble coalescence. Previous saline water (SW) experiments showed that by using small slits in the diffuser membrane design, oxygen transfer and aeration efficiency increase further. In this study, we present a modified approach for considering the salt effect on oxygen transfer and assess the transferability of SW results to saline-activated sludge (sAS) conditions. Therefore, we operated a pilot-activated sludge plant over 269 days with a saline industrial wastewater influent. The oxygen transfer of disc-diffusers with two different membrane designs was measured continuously via the off-gas method. The salt concentration (cSalt) measured via ion analysis ranged between 4.9 and 11 g/L. Despite a high cSalt fluctuation, COD elimination was >90% all the time. Our results confirm previous SW results. Oxygen transfer in sAS is up to three times higher compared to non-saline conditions. Aeration efficiency shows that despite a higher pressure drop, diffusers with smaller slits are to be recommended in order to improve aeration in sAS.

Effect of saline water on growth, yield, quality and soil properties in barley (Hordeum vulgare L.)

The opportunities for salinity research are enormous due to size and diversity of the country, where all kind of soils and waters of varying quality are encountered and require solutions. Salt accumulation leads to two major stresses for the plants: osmotic stress and ionic stress. The osmotic stress firstly comes in plants when salt concentrations increase outside the roots, which leads to reduction in water uptake and subsequently plant development. The ionic stress develops when Na+ accumulation increases in plants particularly in leaves over threshold level which causes chlorosis in leaves and reduced photosynthesis and other metabolic activities. Several researchers and eminent investigators observed that higher salt concentration takes place near or immediate below the soil surface which significantly impaired the growth parameters of barley. They observed negative effect of salinity on growth and the development of barley in comparison with control treatment. Lower level of salinity upto 3 dS/m did not significantly influence the seed germination, whereas higher salinity level significantly decreased seed germination, plant height and total dry matter production. Irrigation with higher salinity levels significantly decreased tillers plant-1, spikes plant-1, 1000-grain weight, grain yield, straw yield, harvest index and leaf K: Na as compared to control treatment. Higher levels of salinity increased the total soluble sugars but decreased the protein and oil contents as compared to under non-saline conditions. EC and SAR of soil was increased with increasing levels of salinity resulting into decreased, but there was a substantial decrease in soil pH, K: Na ratio, P uptake, K content in the grain and straw as well as available N, P and K in soil.

Relationship of Selected Soil Properties with the Micronutrients in Salt-Affected Soils

The present study aimed to assess the relationship of soil properties in salt-affected soils. The soil samples were collected from 14 districts of Pakistan. Soil salinity and sodicity are the common features of the arid and semiarid regions. The effects of the salt’s interactions with soil micronutrients have not been well studied. Therefore, saline and non-saline soil samples were collected from different locations. The microelements (Fe, Cu, Mn, and Zn) were fractionated into water-soluble, exchangeable, carbonate, Fe + Mn oxide, organic, and residual fractions. Univariate and multivariate analysis (PCA) was carried out to determine the linear relationship between soil properties and micronutrients fractions. Results showed that the magnitude of micronutrients appeared to be affected by the salinity in soils. In saline soil, the Fe fractions differed in the order of residual > organic bound > Fe + Mn bound > carbonate bound > exchangeable > water soluble. Iron fractions varied in the non-saline soils as residual > Fe + Mn bound > organic bound > exchangeable > carbonate bound > water soluble. Copper concentration was higher in the residual and carbonate forms, and the amount was lower in the exchangeable and water-soluble forms under both saline and non-saline conditions. The water-soluble Mn fraction was lower, and the residual Mn fraction was proportionately higher than other forms of Mn in soils. Zinc was found mostly in the residual fraction in both saline and non-saline soils. The mobility factor of micronutrients in non-saline soil was greater than in saline soil. PCA revealed that organic matter (OM) and pH directly affected the fractionation of Cu, Mn, Zn, and Fe in soil. Thus, it could be inferred that salts can bring changes to the composition of micronutrients depending on the nature of the soil and the magnitude of salts.

Coupled effects of soil drying and salinity on soil-plant hydraulics.

Salinity and soil drying are expected to induce salt accumulation at the root-soil interface of transpiring plants. However, the consequences of this on the relationship between transpiration rate (E) and leaf xylem water potential (ψleaf-x) are yet to be quantified. Here, we used a noninvasive root pressure chamber to measure the E(ψleaf-x) relationship of tomato (Solanum lycopersicum L.) treated with (saline) or without 100-mM NaCl (nonsaline conditions). The results were reproduced and interpreted with a soil-plant hydraulic model. Under nonsaline conditions, the E(ψleaf-x) relationship became progressively more nonlinear as the soil dried (θ ≤ 0.13 cm3 cm-3, ψsoil = -0.08 MPa or less). Under saline conditions, plants exhibited an earlier nonlinearity in the E(ψleaf-x) relationship (θ ≤ 0.15 cm3 cm-3, ψsoil = -0.05 MPa or less). During soil drying, salinity induced a more negative ψleaf-x at predawn, reduced transpiration rate, and caused a reduction in root hydraulic conductance (from 1.48 × 10-6 to 1.30 × 10-6 cm3 s-1 hPa-1). The model suggested that the marked nonlinearity was caused by salt accumulation at the root surface and the consequential osmotic gradients. In dry soil, most water potential dissipation occurred in the bulk soil and rhizosphere rather than inside the plant. Under saline-dry conditions, the loss in osmotic potential at the root surface was the preeminent component of the total dissipation. The physical model of water flow and solute transport supports the hypothesis that a buildup of osmotic potential at the root-soil interface causes a large drop in ψleaf-x and limits transpiration rate under drought and salinity.

The Interactions between Arbuscular Mycorrhizal Fungi and Trichoderma longibrachiatum Enhance Maize Growth and Modulate Root Metabolome under Increasing Soil Salinity.

Trichoderma longibrachiatum sp. are free-living filamentous fungi which are common in agro-ecosystems. However, few studies thus far have examined the interaction between Trichoderma longibrachiatum and arbuscular mycorrhizal (AM) fungi in saline soil and their potential for improving plant stress tolerance. Here, single, dual-inoculated (T. longibrachiatum MF, AM fungal community or Glomus sp.), and non-inoculated maize (Zea may L.) were subjected to different salinity levels (0, 75, 150, and 225 mM NaCl) to test the synergistic effects of dual inoculants on maize plants in different salt stress conditions. Plant performance and metabolic profiles were compared to find the molecular mechanisms underlying plant protection against salt stress. The first experiment revealed that dual inoculation of an AM fungal community and T. longibrachiatum MF improved the biomass and K+/Na+ ratio in maize under non-saline conditions, and generally enhanced AM fungal growth in root and soil under all but the 225 mM NaCl conditions. However, MF inoculant did not influence the structure of AM fungal communities in maize roots. In the second experiment, dual inoculation of Glomus sp. and T. longibrachiatum MF increased maize plant biomass, K+/Na+ ratio, and AM fungal growth in root and soil significantly at both 0 and 75 mM NaCl conditions. We identified metabolic compounds differentially accumulated in dual-inoculated maize that may underline their enhanced maize plant tolerance to increasing soil salinity. Our data suggested that the combination of Glomus sp. and T. longibrachiatum leads to interactions, which may play a potential role in alleviating the stress and improve crop productivity in salt-affected soils.

Assessing impact of salinity and climate scenarios on dry season field crops in the coastal region of Bangladesh

CONTEXTSoil salinity is the main environmental limiting factor for current agricultural farming systems in the Bangladesh coastal zone. Targeting crop selection to ameliorate its impact in food production is a priority to ensure food security, diversifying crop outputs and reducing smallholders' vulnerabilities. In this context, crop growth modelling emerges as a useful tool for exploring different scenarios for crop selection. OBJECTIVEStudying spatial and -temporal heterogeneity in salinity and crop productivity under different climate scenarios. METHODSA dataset from the Polder 30 located in the Bangladesh southwest coastal zone, including different farming systems (rice-maize, rice-mungbean, rice-sunflower) comprising two years (2017–2019), was utilized, together with polder-level contiguous layers of factors (i.e., salinity, elevation, precipitation), to create clusters representing different yield-limiting conditions. Two salinity scenarios were defined and included in a long term in-silico assessment to explore dry-season field crop options (maize, sunflower, and mungbean). APSIM models for maize, sunflower and mungbean, were selected to perform all the crop simulations. RESULTS AND CONCLUSIONSBased on yield, sunflower was the most stable choice under salinity and maize was the best under non-saline conditions. Lastly, yield stability was accounted for different climate conditions, showing a large yield reduction for maize when combining low precipitation and high temperature, whereas mungbean and sunflower presented less sensitivity to different climates. SIGNIFICANCERight crop selection for the right environment, considering both salinity restrictions and climate uncertainties, is critical for long-term yield stability. The present study provides a novel framework to better match the most suitable crop under challenging salinity restrictions and climate uncertainties affecting smallholders in the coastal zone of Bangladesh.

Exogenous application of gibberellic acid and silicon to promote salinity tolerance in pea (Pisum sativum L.) through Na+ exclusion

Salinity is a worldwide problem limiting the plant growth and risking food security. This study was conducted to examine exogenous application of silicon (Si), gibberellic acid (GA3) upon the ion transport, growth, yield, and antioxidant enzymes activities of pea plant in saline conditions. Two pea varieties Meteor-FSD and Samrina Zard were pre-treated with GA3 (10-4 M) for 12 h. Plants were allowed to grow with or without silicon in washed silica sand. Ten days old seedlings were shifted in pots with 10 kg soil. Twenty-five days old plants were exposed to 0 and 5 dS m−1 sodium stress. Results showed that exogenous application of GA3 + Si was the best treatment for increasing plant biomass and yield in the presence and absence of NaCl. Furthermore, application of Si or GA3 enhanced chlorophyll content in the leaves, thereby increasing the net assimilation rate of pea varieties under NaCl stress by increasing the antioxidant enzyme activity. Treatment of Si alone or in combination with GA3 significantly reduced Na+ movement in both pea varieties. Results showed that Si has more prominent role than GA3 alone to build-up high plant biomass, yield, soluble protein content and reduction of Na+ transport. Samrina Zard variety showed higher yield, shoot and root dry weight as compared to Meteor-FSD variety in presence and absence of salt. It was concluded that Si can be used as a nutrient for pea under saline or non-saline conditions. Moreover, application of GA3 has a potential role for increasing salinity tolerance, mostly in sensitive pea varieties.

He-Ne Laser Enhances Seed Germination and Salt Acclimation in Salvia officinalis Seedlings in a Manner Dependent on Phytochrome and H2O2.

In the current study the role of H2O2 in He-Ne laser-induced effects on seed germination and post-germinative performance of Salvia officinalis seedlings was assessed under both non-stress and saline conditions. Salinity had adverse impacts on seed germination and root length and decreased seed germination tolerance index. Seed priming with H2O2 and He-Ne laser impacted the seed germination and vigoration in a dose-dependent manner. The optimal effects were gathered by energy dose of 6J/cm2 laser and concentration of 5mM H2O2. These pre-treatments enhanced seed germination due to increasing contents of total soluble and reducing sugars and the amylase activity in seeds and improved seedling performance under saline and non-saline conditions. Furthermore, Phy B transcripts were upregulated, salt-accrued oxidative stress was mitigated, and the activities of POD and CAT increased in seedlings primed with H2O2 and laser. Interestingly, applying diphenyleneiodonium (DPI as an inhibitor of NADPH oxidase activity) and N, N-dimethyl thiourea (DMTU as a H2O2 scavenger) arrested the upregulation of phy B gene and abolished stimulatory impact of laser priming on the aforementioned attributes under both non-stress and saline conditions. These novel findings suggest that H2O2 as a downstream signal modulates the impacts of He-Ne laser on seed germination, seedling performance and salt acclimation in sage seedlings, and likely phy B also is involved in these responses.

Elucidating the Effects of Combined Treatments of Salicylic Acid and l-Proline on Greenhouse-Grown Cucumber Under Saline Drip Irrigation

Salinity is one of the major abiotic stress factors that threaten crop development and sustainable food production. As a mitigation strategy, several plant growth regulators and osmoprotectants have been applied to ameliorate the negative effects of salinity stress in plants. Therefore, the current study aimed to investigate the effect of foliar applications of different concentrations of salicylic acid and proline on the growth, yield, fruit quality, and nutritional composition of cucumber crops grown under saline conditions. The three main irrigation salinity variations included electrical conductivity (EC) of 0.5 dS/m (control), EC 6.0 dS/m, and EC 12.0 dS/m. Foliar spray treatments were as follows: T1 (distilled water), T2 (1.0 mM salicylic acid), T3 (1.0 mM salicylic acid + 5.0 mM proline), and T4 (1.0 mM salicylic acid + 10 mM proline). Our results showed that foliar application of salicylic acid alone or in combination with proline under non-saline conditions improved the growth and yield of cucumber, with T4 recording the highest values. Irrigating plants with saline water (EC 6.0 and 12.0 dS/m) severely compromised cucumber's growth performance and yield, with the lowest values recorded at EC 12.0 dS/m. However, under EC 6.0 dS/m, T2 and T3 slightly ameliorated salinity stress effects regarding fruit yield, for T2, and nutritive composition of fruits, for T2 and T3. Overall, this study demonstrated that cucumber (Cucumis sativa L.) could tolerate irrigation salinity levels of up to EC 6.0 dS/m without significant detrimental effects on the growth performance, yield, and nutritional composition of fruits.

Significant response of microbial community to increased salinity across wetland ecosystems

Soil salinity can affect microbial activities and community structure, with broader implications for carbon storage and mineralization. However, a consensus on how soil microbial communities respond to elevated salinity has yet to be reached. With the increasing salinization of coastal lowlands, a comprehensive assessment of salinity-driven microbial community shifts is crucial for understanding and predicting shifts of biogeochemical processes in response to soil salinization. Here, we conducted a meta-analysis of 21 studies to investigate the changes in soil microbial communities along salinity gradients. We found a significant reduction of prokaryotic alpha-diversity indices with increasing salinity. Prokaryotic beta-diversity was altered by elevated salinity, but significant differences were only found between samples at < 1 and > 10 ppt salinity. Compared to non-saline conditions, high salt concentrations increased the relative abundance of Bacteroidetes and Proteobacteria by 17–19%, especially that of Alphaproteobacteria and Gammaproteobacteria, but generally inhibited the rest of the dominant phyla and classes. For fungi, Ascomycota was 1.3-fold more abundant in saline environments than in non-saline environments, but Basidiomycota was 21% less. This meta-analysis reveals significant changes of microbial community composition responding to environmental salinization. With strong biodiversity reduction under saline conditions, these dominant microbial groups with high-salinity niche preference will play a stronger role in regulating nutrient and energy flow, and constraining SOC dynamics.

Augmenting the Tolerance Potential of Muskmelon (Cucumis melo L.) Using Salicylic Acid

Salicylic acid (SA) is considered an important plant hormone that controls many aspects of plant growth and development, as well as resistance to biotic and abiotic stresses. In current investigations, a pot experiment consisting of four different levels of SA (0, 1, 2 and 3 mM SA) were tested on growth and physiological attributes of muskmelon (Cucumis melo L.), grown at different salinity levels (0, 50, 100 mM NaCl). Results revealed that all the morphological and physiological attributes were significantly (P&lt;0.05) adversely affected by salinity stress, whereas application of SA improved growth rate of muskmelon both in saline and non-saline conditions. SA treated plants showed higher total chlorophyll content, photosynthetic rate and stomatal regulations as compared to control plants. SA application reduced the salt deleterious effects by inhibiting toxic Na+ ions accumulation in leaf and increased K+/Na+ ratio. Among the various applied concentrations, 2 mM SA increased shoot fresh weight by (30%), dry weight (34%), leaf area (25%) and K+/Na+ ratio by (84%) as compared to control plants. Thus, 2 mM SA concentration is concluded to be the best ameliorative treatment in salt stressed environments to enhance the muskmelon production.&#x0D;

Effect of Burkholderia sp. and Pseudomonas spp. inoculation on growth, yield, and absorption of inorganic components in tomato ‘Micro-Tom’ under salinity conditions

ABSTRACT We screened four strains (Burkholderia sp. St-A, and Pseudomonas spp. St-B, St-C, and St-D) from 21 bacterial isolates isolated tomato cultivation fields based on their plant growth-promoting traits. Then, tomato (‘Micro-Tom’) seedlings inoculated with each of the four selected strains were grown under non-salinity and salinity (NaCl) treatment conditions. Under non-salinity conditions, St-C and St-D strains increased the total biomass of roots, stems, and leaves and fruit yield. Under NaCl treatment conditions, St-B, St-C, and St-D strains increased total biomass and fruit yield. In roots, Na content was not suppressed, but K, P, and water content were increased by bacterial inoculations. Correlation analysis showed a significant and positive relationship between fruit yield and root under both non-salinity and salinity conditions. This indicates that the maintenance of homeostasis and water relations in roots may contribute to the improvement of plant growth, including root and fruit yield, under salinity conditions.

Stenotrophomonas sp. SRS1 promotes growth of Arabidopsis and tomato plants under salt stress conditions

Plant Growth-Promoting Rhizobacteria (PGPR) support plant growth by alleviating plant stresses, among which those triggered by saline soils. We isolated Stenotrophomonas sp. SRS1 from salt-resistant Carex distans (distant sedge) roots to understand how this growth promotion was enabled and whether an active contribution of the bacteria and/or plant was required. Various growth assays were used to analyze the effect of bacterial inoculation on Arabidopsis thaliana and Solanum lycopersicum (cherry tomato MicroTom) growth. Furthermore, droplet microfluidics, bacterial genome mining, and bacterial and plant gene expression analysis combined with plant mutant analysis were used for in-depth analysis. SRS1 application enhanced plant growth in both saline and nonsaline environments. The fresh weight of SRS1-inoculated plants was higher than that of noninoculated plants, whereas the fresh weight ratio between SRS1-inoculated and noninoculated plants differed whether the plants were grown on agar plates, white sand or in soil. We demonstrated that the strain grew well in high salt-containing media and that, besides plant-growth-promotion-related genes, the bacterium contained various active stress genes. Interestingly, inoculation with the strain increased the induction of plant genes related to abscisic acid and auxin signaling pathways under saline conditions. SRS1 inoculation promoted the growth of Arabidopsis and MicroTom tomato under saline and nonsaline conditions, also when the plants were grown in white sand and potting soil. Overall, genetic traits related to stress alleviation, derived from both the bacteria and the plants, play a crucial role in the impact of this novel PGPR strain on plant performance.

Dryland field validation of genotypic variation in salt tolerance of chickpea (Cicer arietinum L.) determined under controlled conditions

Chickpea ( Cicer arietinum L.) is a moderately salt-susceptible grain legume species. Genotypic differences in salt tolerance/susceptibility have been identified in chickpea genotypes grown in adequately-watered soil in pots with different salt concentrations, but few studies have been conducted in saline fields. This three-year study compared the growth and yield of chickpea genotypes to determine whether genotypic differences in salt tolerance/susceptibility identified in glasshouse pot experiments applied when grown in a dryland saline field. The emergence, phenology, growth, leaf ion concentration, yield and yield components of 10–20 chickpea genotypes were compared under controlled saline and water conditions in the glasshouse, and saline and non-saline conditions in the field in a semiarid environment. In the field, soil salinity and yields varied from year to year in the non-saline and saline treatments. Genotypic differences in salt tolerance and sensitivity were observed in the controlled salt and water conditions in the glasshouse. The salt tolerant and salt sensitive check genotypes, GENESIS 836 and RUPALI, respectively, grown in all three comparison years were similarly tolerant and sensitive in the glasshouse and dryland field in all three comparison years. However, other genotypes selected for salt tolerance under controlled conditions were not observed to be tolerant in the dryland field. While salinity slowed the rate of emergence and increased the time to flowering, the variation in saline yields among genotypes was associated with aboveground biomass, filled pod number and seed number at maturity in both the glasshouse and field, but not the number of emerged plants that survived to maturity or the delay in flowering. Salinity significantly increased the leaf Na + , K + and Cl - concentrations in the glasshouse and field (except in the glasshouse in 2010). Na + increased in young and old leaves by 28–84%, but the concentrations of Na + or K + in the leaves across genotypes was not correlated with yield in saline soil. Salinity increased leaf Cl – concentrations by 80–290%; the increase in young leaves had a significant association with reduced yield among genotypes only in the glasshouse in one year. We conclude that selection under controlled soil salinity and water content in pots can identify some genotypes that are salt tolerant, but for dryland saline environments verification of their tolerance in comparable environments is essential. • Chickpeas for dryland saline sites require phenotyping in appropriate environments. • Genotypic variation in water-limited yield confounds salt tolerance in the field. • Salt tolerant chickpeas do not universally exhibit cross-tolerance for water-limited yield. • Dryland salt tolerance is associated with increased biomass and reproductive success.

Foliar Application of Salicylic Acid Improves Salt Tolerance of Sorghum (Sorghum bicolor (L.) Moench).

It has been reported that around the world, approximately 19.5% of all irrigated land and 2.1% of dry land is affected by salt stress, and these percentages continue to increase. Sorghum is the fifth most important cereal in the world and therefore research on its salt tolerance is of global importance. In our research, we focused on foliar application of salicylic acid (SA) on salt-stressed sorghum. We performed a pot experiment with two salt levels (0 and 100 mM sodium chloride NaCl) and five SA concentrations (0, 50, 100, 150 and 200 mg/L). Our results suggest that in saline conditions foliar application of SA induced an adaptive response to salinity by inducing proline accumulation as well as antioxidant enzymes activities and enhanced the protection of the photosynthetic machinery, maintained photosynthesis activities, and improved the growth of sorghum plants. These alleviation effects were depended on applied SA concentration. Under saline condition 150 mg/L, SA was the most effective for relieving the adverse effect of salt stress. Under non-saline conditions 100 mg/L SA was the best for improving sorghum growth and dry matter production. Our results demonstrated that foliar SA application is effective in improving sorghum growth under salinity.

Improvement of growth of maize by application of silicon through its suppressing effect on sodium uptake under salt stress condition

An experiment was conducted with three levels of salinity (0, 60, and 120 mM NaCl) and four levels of silicon (0, 5, 10, and 20 mM) in petridish. All the growth parameters were decreased gradually with increasing salt concentration, whereas increasing silicon concentration progressively increased the parameters up to 10 mM Si across all the salt concentrations. The beneficial role of Si was noticed both in saline and non-saline conditions. Silicon application in the growth medium dramatically reduced shoot Na content, making plants tolerant to salt stress. J. Bangladesh Acad. Sci. 45(2); 251-253: December 2021

Sorghum [Soghum bicolor (L.) Moench.] growth, and soil moisture and salt content as affected by irrigation water salinity

Information on the impact of salinity of irrigation water on soil moisture and salt content is scant in the literature. Therefore, in the present study, growth of sorghum as well as soil moisture and salt content were investigated as affected by irrigation water salinity. In this experiment, the effect of three salinity levels of irrigation water, i.e., 2, 7 and 14 dS m-1 was monitored on sorghum growth, and changes in soil moisture and salinity of soil saturated extract during the growing season. Irrigation water salinity, depending on the intensity of stress, reduced forage yield, so that 7 and 14 dS m-1 salinity decreased the fresh weight by 11% and 45% and the dry weight by 17% and 62%, respectively, compared to those in non-saline conditions. At two soil depths (0-30 cm and 30-60 cm), the lowest moisture content was observed under non-saline conditions and the highest at 14 dS m-1. The salinity of soil saturated extract was also increased with increasing salinity of irrigation water. By applying salinities of 2 and 14 dS m-1, soil salinity decreased and increased by the end of the growing season, respectively. However, soil salinity in 7 dS m-1 treatment was decreased first and then increased until the end of the growing season. At the end of the growing season, the average soil salinity in 7 and 14 dS m-1 treatments was 1.8 and 1.4 times, respectively, higher than that of the irrigation water salinity. In a nutshell, in saline conditions, more moisture remains in the soil, which may help sustain the of growth of halophytes to some extent.

EFFECT OF DIFFERENT BIOCHAR CONCENTRATION ON THE GROWTH OF THREE AGRICULTURAL PLANTS IN AFGHANISTAN

The present research was conducted in the laboratory of Badakhshan University, Afghanistan. The study was carried out for 40 days in 2021, to document the effect of biochar on the growth of three important agricultural plant species: radish, lettuce and spinach. The biochar was produced from the biomass of Oak tree under oxygen less condition. The study includes assessment of Petri plate bioassay and pot scale experiment to understand the effect of biochar under saline and non-saline conditions in order to mitigate the problem of salinity. Application of biochar has significantly increased the seed germination for all the seeds. The maximum seed germination was observed for radish &gt; lettuce &gt; spinach. NaCl has reduced the percentage of seed germination but a little increase was observed in case of radish as compared to lettuce and spinach. However, application of biochar has significantly increased its growth as compared to control plant. Both shoot and root of all three studied plants were increased with increase in BC concentrations. The maximum length of root was observed for radish &gt; lettuce &gt; spinach whereas for shoot it was lettuce &gt; radish &gt; spinach. At the same time application of 5 % biochar helped to improve the growth of both radish shoot and root. Lettuce was found sensitive to saline condition and application of biochar does not significantly improve their morphometric parameters. Spinach could be considered as moderately saline resistant species whose biomass can be improved by supplementing with biochar.

Ameliorative effects of nitric oxide on growth, physiology and biochemistry of chickpeaplants under salinity stress

Salinity is one of the major environmental constraints affecting agriculture in major regions of the world. This study was conducted to evaluate the effect of exogenous nitric oxide (NO) treatments on two chickpea cultivars (Cagatay and Inci) under salt stress conditions. Different NO doses (0. 75 and 100 μM sodium nitroprusside (SNP)) as an NO source were applied to chickpea plants grown under saline (presence of 50 and 100 mM of NaCl) and nonsaline conditions. In this study, plant shoot fresh and dry weight, root fresh and dry weight, chlorophyll a, b, total chlorophyll, chlorophyll reading value (CRV), relative water content (RWC), electrical conductivity (EC), malondialdehyde (MDA), hydrogen peroxide (H2O2), antioxidant enzyme activity [superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX)], K/Na and Ca/Na ratio were examined. Plant growth, RWC, and chlorophyll content were negatively affected by salinity conditions but exogenous NO treatment improved the parameters. EC, H2O2, and MDA content were increased with salinity conditions while exogenous NO treatment decreased the searched parameters. K/Na and Ca/Na ratios were decreased with 50 and 100 mM of NaCl treatments. Although the cultivars response to salt stress is similar in general, Inci cultivars were found to be more sensitive to salt stress than Cağatay cultivar. The present study revealed that the exogenous NO treatment supported chickpea seedlings against salinity stress by regulating uptaking mineral elements, the antioxidant enzyme activity, and RWC.