Increasing Salinity Levels Research Articles

Effect of Spraying with Nano Silica and Water Salinity Levels on Growth and Yield of Wheat

A field experiment was carried out during the winter season 2020-2021 at research station of the College of Agriculture, University of Al-Muthanna (Al - Bandar) to study the effect of spraying with nano silica and salinity levels of irrigation water on the growth and yield of wheat. The experiment was applied in a strip split plot design. With three replications, the spraying included three concentrations of silica (3, 6, 9 ppm) and three concentrations of irrigation water salinity (3, 6, 9 ds m−1). The results indicated that the level of 9 ppm sprayed exceeded significantly in the following traits and gave the highest means.: plant height 84.26 cm, number of tillers 354.10 m2 tillers, area of flag leaf 40.19 cm2, spike length 9.89 cm, number of spikes 288.93 m2 and yield 4.27 tons ha−1. The results also indicated that the increase in salinity level led to a decrease in the characteristics of plant height 82.22 cm, number of tillers 319.43 m2 tillers, area of flag leaf 39.93 cm2, spike length 9.19 cm, number of spikes 260.13 m2, and yield, which amounted to 3.86 tons ha−1.

RNA-seq analyses of Marine Medaka (Oryzias melastigma) reveals salinity responsive transcriptomes in the gills and livers.

Increasing salinity levels in marine and estuarine ecosystems greatly influence developmental, physiological and molecular activities of inhabiting fauna. Marine medaka (Oryzias melastigma), a euryhaline research model, has extraordinary abilities to survive in a wide range of aquatic salinity. To elucidate how marine medaka copes with salinity differences, the responses of Oryzias melastigma after being transferred to different salt concentrations [0 practical salinity units (psu), 15 psu, 30 psu (control), 45 psu] were studied at developmental, histochemical and transcriptome levels in the gill and liver tissues. A greater number of gills differentially expressed genes (DEG) under 0 psu (609) than 15 psu (157) and 45 psu (312), indicating transcriptomic adjustments in gills were more sensitive to the extreme hypotonic environment. A greater number of livers DEGs were observed in 45 psu (1,664) than 0 psu (87) and L15 psu (512), suggesting that liver was more susceptible to hypertonic environment. Further functional analyses of DEGs showed that gills have a more immediate response, mainly in adjusting ion balance, immune and signal transduction. In contrast, DEGs in livers were involved in protein synthesis and processing. We also identified common DEGs in both gill and liver and found they were mostly involved in osmotic regulation of amino sugar and nucleotide sugar metabolism and steroid biosynthesis. Additionally, salinity stresses showed no significant effects on most developmental and histochemical parameters except increased heartbeat with increasing salinity and decreased glycogen after transferred from stable conditions (30 psu) to other salinity environments. These findings suggested that salinity-stress induced changes in gene expressions could reduce the effects on developmental and histochemical parameters. Overall, this study provides a useful resource for understanding the molecular mechanisms of fish responses to salinity stresses.

Responses of the Soil Microbial Community to Salinity Stress in Maize Fields.

Simple SummarySoil microorganisms are the core of maintaining soil ecological functions. Recognition of microbial community diversity in saline soil contributes to nutrient management and crop production. Meanwhile, microbial activity is easily affected by changes in soil properties. This study addressed how the composition and diversity of bacterial and fungal communities changed under different saline conditions to identify the sensitivity of bacteria or fungi to salinity. The primary objective was to evaluate the relationship between soil’s microbial community diversity and soil’s physicochemical factors, and to explore the vital microbial predictors in salinized soil. The results showed that Firmicutes and Bacteroidetes are pivotal in salinized soil, and this finding can provide guidance for the demand for plant rhizosphere growth-promoting bacteria as a bioindicator in saline soil.To investigate the diversity and structure of soil bacterial and fungal communities in saline soils, soil samples with three increasing salinity levels (S1, S2 and S3) were collected from a maize field in Yanqi, Xinjiang Province, China. The results showed that the K+, Na+, Ca2+ and Mg2+ values in the bulk soil were higher than those in the rhizosphere soil, with significant differences in S2 and S3 (p < 0.05). The enzyme activities of alkaline phosphatase (ALP), invertase, urease and catalase (CAT) were lower in the bulk soil than those in the rhizosphere. Principal coordinate analysis (PCoA) demonstrated that the soil microbial community structure exhibited significant differences between different salinized soils (p < 0.001). Data implied that the fungi were more susceptible to salinity stress than the bacteria based on the Shannon and Chao1 indexes. Mantel tests identified Ca2+, available phosphorus (AP), saturated electrical conductivity (ECe) and available kalium (AK) as the dominant environmental factors correlated with bacterial community structures (p < 0.001); and AP, urease, Ca2+ and ECe as the dominant factors correlated with fungal community structures (p < 0.001). The relative abundances of Firmicutes and Bacteroidetes showed positive correlations with the salinity gradient. Our findings regarding the bacteria having positive correlations with the level of salinization might be a useful biological indicator of microorganisms in saline soils.

Can aged biochar offset soil greenhouse gas emissions from crop residue amendments in saline and non-saline soils under laboratory conditions?

Applying biochar in association with crop residues might optimize costs and effectiveness in the reclamation of saline soils. Here, we explored the potential effects of biochar in association with crop residue amendments on soil greenhouse gas (GHG) emissions, and microbial communities. Previously, we found that soil N2O emission significantly increased with increasing salinity levels followed by cotton straw addition. In the present study, microcosm experiments were performed to investigate the interaction of salinity (0 and 1.2% salt) with the aging of biochar following soil amendments over an incubation period of 80 days. The results indicated that N2O emissions were approximately 5–10 times higher in saline soils than in non-saline soils, and the cumulative N2O emissions following two straw amendments treatment were the highest of all the treatments. Salinity increased the contribution of nitrification to soil N2O emissions stimulated by the cotton straw amendments, and aged biochar performed better in decreasing soil N2O emissions in saline soils than in non-saline soils. In addition, aged biochar increased soil C mineralization and CO2 emissions under saline conditions. Soil CO2 and N2O emissions were affected by both soil abiotic and biotic factors under non-saline and saline conditions. Moreover, much more specific but fewer microbial groups survived and utilized crop residues under saline than non-saline conditions, and aged biochar decreased salt stress in soil microorganisms. These findings indicated that aged biochar and crop residues together would be an optimal way to address soil C storage and mitigate N2O emissions under saline conditions.

Anatomical characteristic, ionic contents and nutritional potential of Buffel grass (Cenchrus ciliaris L.) under high salinity

Cenchrus ciliaris is a potential forage grass that is widely distributed in saline desert condition across Africa, Australia and Asia. To examine anatomical characteristics relating to ionic and nutritional contents in response to salinity, Cenchrus ciliaris populations from the naturally salt-affected region of the Cholistan Desert, Pakistan were collected. The experiment was planned in a completely randomized design (CRD) with four replications and four treatment levels (0, 100, 200, and 300 mM NaCl) in a hydroponic system. After six months of growth in nutrient solution anatomical characteristics relating to ionic and nutritional traits were studied. It was hypothesized that C. ciliaris at higher salt stress must have developed some specific structural adaptations, which are responsible for better survival under high salt stress. At root level, C. ciliaris showed decreased root thickness with greater proportion of parenchyma cells in cortical region and increased sclerification in cortex and pith regions at high salinity levels, which are vital for water conservation under osmotic stress. At stem level increased stem area, cortical and vascular bundle cell area were recorded with increase in salinity level of external growth medium. Salt tolerance in C. ciliaris mainly associated with restricted uptake of toxic Na+ and Cl− ions at roots, accompanied by increased concentration of K+ and Ca++ in shoot. Under high salinities, C. ciliaris showed increased epidermis thickness, well developed bulliform cells, and increased trichome density at leaf level. All these structural modification in this species may contribute towards water conservations under physiological stress that is caused by high level of soil salinity. Various nutritional traits such as crude protein, ash content, relative feed value, and net energy of lactation slightly improved with salinity. Present study revealed nutritional potential, ionic contents and anatomical adaptations of C. ciliaris to cope with salinity. As such this species can be used to produce valuable fodder under saline desert environment.

Evaluation of Two Maize Hybrids Under Salinity Stress at Germination Stage تقييم هجينين من الذرة الشامية تحت الإجهاد الملحي خلال مرحلة الانبات

Maize (Zea mays L.) is the third most important cereal crop after wheat and rice, besides, it’s important and necessary for global food security. Maize is considered a C4 plant and is sensitive to salinity. Two maize hybrids (SC-168 and TWC-352) were evaluated morphologically and biochemically under salinity stress using levels of NaCl (0, 50, 100, 150, 200, and 250 mM) at the germination stage. The results indicated that the percentage of germination, growth characteristics, pigments in both hybrids significantly decreased with increasing of NaCl concentrations. In addition, proline increased with increasing salinity levels and then decreased at the highest levels of NaCl in both hybrids. Moreover, salinity with high levels of NaCl led to decrease activity in CAT, POX, and PPO enzymes. Finally, under salinity stress, SC-168 had greater values in germination %, growth characteristics, photosynthetic pigments, proline content, antioxidant activity compared to TWC-352. As a result, it's possible that SC-168 has a higher salt tolerance than TWC-352.

Physiological response of Bajra-Napier Hybrids and Tri-Specific Hybrid to salinity stressPhysiological response of Bajra-Napier Hybrids and Tri-Specific Hybrid to salinity stress

Physiological responses of 3 Bajra-Napier (Cenchrus spp., syn. Pennisetum spp.) hybrid varieties, viz. BNH-3, BNH-6, BNH-10, and 1 ttri-specific hybrid (TSH) were tested under different gradients of soil salinity, i.e. Control, 4, 6 and 8 dS/m electric conductivity (EC), in a pot trial. The experiment was laid out in a factorial completely randomized design with 3 replications. Shoot dry weight, root dry weight, root:shoot ratio and chlorophyll a, chlorophyll b, total chlorophyll and carotenoid concentrations were reduced with increasing salinity level as compared with Control. However, the concentration of Na+ in leaves increased and K+ concentration decreased with increasing salinity level. Physiological parameters, i.e. relative water content (RWC), membrane stability index (MSI), chlorophyll stability index, carotenoid stability index and K+: Na+ ratio, in leaves tended to be higher in the BNH-3 variety than in other varieties. Shoot dry weight showed highly positive significant correlation with RWC, MSI, K+ concentration and K+:Na+ ratio, while it was negatively correlated with Na+ concentration (P&lt;0.01) All BN hybrid varieties and the tri-specific hybrid studied were susceptible to salinity stress, showing marked reductions in growth as the level of salinity increased above 4 dS/m. However, even at salinity levels producing EC of 8 dS/m these varieties still produced 25‒44% DM yields. There are prospects for improving forage yields from saline soils by planting these hybrids but further breeding studies are warranted to identify germplasm with greater tolerance of saline conditions if these soils are to be utilized effectively to contribute more to supplying forage to support the world’s ruminant population.

Field responses of barley genotypes across a salinity gradient in an arid Mediterranean environment

Salinity is one of the most widespread abiotic stresses affecting crop growth and productivity, particularly when soil and irrigation water are salty. Field experiments were performed in an arid Mediterranean climate to investigate agronomic responses of twenty-one diverse barley genotypes to naturally occurring salinity. Three saline fields (7.72 dS/m) were irrigated with well water of three incremental salinity levels, low (5.25 dS/m), intermediate (8.35 dS/m), and high (11.12 dS/m). The results revealed considerable genotypic variability at the three salinity levels and significant genotype by salinity interaction that could be traced to specific yield components. Increasing salinity level decreased performance of all agronomic traits, but with different patterns, with yield components determined earlier being more affected than traits determined later. Days to heading exhibited a strong and negative relationship with grain yield across all salinity levels, while 1000-grain weight demonstrated the highest association with grain yield, followed by number of grains per spike, plant height, and harvest index, consistently at the three salinity levels. The genotypes were classified based on their yield indices at the three salinity levels into six groups varying from highly salt-tolerant (group A) to highly salt-sensitive genotypes (group F). Genotype-by-salinity interaction was studied based on rankings of performance across salinity levels. Close examination of yield component trends across levels allowed the identification of genotypes with different behaviors, indicating the presence of variation in potentially different mechanisms of response to salinity. This diversity of responses could be used in breeding to improve tolerance over the whole crop cycle, from plant establishment and tillering to grain filling.

The effect of salinity stress on the amount of proline, chlorophyll and sodium and potassium ions in different rice cultivars in hydroponic environment

Introduction Among the cereals, rice is the most important human food source after wheat and has a major place in human nutrition in terms of production and cultivation. This plant is susceptible to salt stress and its response to salt stress varies with growth stages, concentration and duration of impact. Materials and methods This study was carried out in factorial experiment in a completely randomized design with three replications in the research greenhouse of Sari University of Agricultural Sciences and Natural Resources in 1977-98. The first factor was 71 rice genotypes and the second factor was salinity stress with 4 levels. The germinated seeds were transferred to hydroponic medium to prepare the culture medium from Yoshida nutrient solution (Yoshida et al., 1994). Chlorophyll extraction of rice leaf by Arnon method (1997), Proline amino acid extraction from leaf tissue by Bets et al. (1973) and for determination of sodium and potassium ions from leaf by Hamada and Elnai method (1994) used. The data obtained from these traits were analyzed by SAS and SPSS statistical software and compared by means of Duncan's multiple range test and clustering of genotypes by cluster analysis of tolerant cultivars based on this. Attributes were identified. Results and discussion Results of analysis of variance for different physiological traits under salinity stress showed that genotype, salinity and their interaction effects were statistically significant at the 5% probability level for all measured traits. Comparison of mean salinity levels in all measured traits was significant at 5% probability level. It showed that proline amino acid content and leaf tissue sodium content increased with increasing salinity and zero (normal) level with minimum and salinity level 9 The highest Ds was obtained and the chlorophyll pigment and potassium content of leaf tissue decreased with increasing salinity level and the highest (zero) level and the lowest salinity level was 9 dS / m. Within plant cells, proline acts as an osmotic preserving agent between the cytoplasm and the cell vacuole, and proline protects the plant against free radical damage. In the present experiment, proline content increased significantly with increasing salinity dose. This increase was higher in tolerant cultivars than in susceptible cultivars. An important effect of increasing salinity is leaf senescence and the main factor causing leaf senescence is the decrease in chlorophyll content under salinity stress. In this study, total chlorophyll a, chlorophyll a and chlorophyll b also decreased significantly under salinity stress, which was in line with the results of Bori Boncast et al. (2013) and (Wijita et al., 2018). Higher concentrations of potassium ions in the leaves of tolerant cultivars exposed to salinity can be a adaptive response to high potassium ion storage in stomach cells in salinity stress (Fallah 2015). Aerial is one of the mechanisms of plant tolerance against salinity stress. The results of this study are in line with the results of Hong et al. (2012).Conclusions The results of this study showed that salinity stress significantly decreased chlorophyll pigment and leaf potassium ion content and significantly increased proline amino acid and sodium ion content of leaf. Mean comparison between cultivars under salinity stress showed that Shastak Mohammadi, Nemat, Tarom Ghali, GASMAL, Neda, Roshan, NONABOKRA, FL478, Dilmani and Barley at 9 dS m-1 were the most tolerant cultivars to salinity and salinity stress. Saleh, Rashti Cold, IRBLZFU, IR39595, IR29, Black tip and Dorfak at 9 dSm-1 were the most susceptible cultivars to salinity stress. Acknowledgements Thanks to Sari University of Agriculture and Natural Resources and the Genetics and Plant Breeding Laboratory for providing some of the cost of this research as well as for providing plant specimens.

Effects of different salt sources and salinity levels on emergence and seedling growth of faba bean genotypes

Suitability of poor quality water for irrigation depends on salinity level and solute concentration in the water and selected crop. Salt stress is a major potential constraint for faba bean. The present study aimed to investigate the effects of different Cl- and SO4-containing salt sources in irrigation water with different salinity levels on emergence, early seedling growth and photosynthetic capacity of six faba bean genotypes. The negative effect order of salinity level was high (3 dS/m) > medium (2 dS/m) > low (1 dS/m) > control (0.05 dS/m) for all investigated parameters except dry root weight. The negative effects of Cl-containing salt sources were higher than that of SO4-containing salt sources. The worst and the best performing genotypes were determined as III-28 and III-29 on emergence percentage at 10th DAS, I-29 and III-1 on mean emergence time, III-22 and III-1 on shoot height, III-1 and I-29 on fresh biomass weight, III-22 and III-28 on fresh shoot weight, III-29 and I-29 on fresh root weight, respectively. This study showed that faba bean genotypes have different behaviors in terms of response to the increasing salinity levels artificially makeup by using different salt sources indicating that salt response of faba bean is genotype-specific.

Effect of Hydro-priming and Salinity Stress on Germination Indices of Niger (Guizotia abyssinica Cass.)

In order to evaluate the effect of hydropriming and Salinity stress on germination indices of Niger, a factorial experiment was conducted in a randomized complete block design with four replications at seed research laboratory of Shahrekord University. Salinity treatments were applied at five levels (0, 25, 50, 100 and 150 mM NaCl). Hydropriming treatments were applied at two levels (control and 6-hour hydropriming with distilled water). Results showed that the effects of hydropriming with distilled water and salinity stress on all the studied traits were significant at P &le; 0.01. However, the interaction effects of hydropriming and salinity stress were only significant for the mean germination time, root and shoot lengths, and the allometric coefficient. The hydro prime of Niger seed resulted in the germination percentage, speed and mean germination time to be decreased significantly compared to the control treatment. The germination percentage, the time to 50% of germination, mean germination time and germination energy decreased significantly with the increasing salinity level. Hydropriming positively affected the allometric coefficient and improved its value compared to the control (non-hydropriming conditions).

Salt Stress Relief and Growth-Promoting Effect of Sweet Pepper Plants (Capsicum annuum L.) by Glutathione, Selenium, and Humic Acid Application

Three pot experiments were carried out at a private farm in Abu Homos, El-Beheira Governorate during 2018 and 2019 and 2020 growing seasons to examine the role of Glutathione, Selenium, and Humic Acid solely in the first two seasons and in combinations in the third season in elevation the impact of salinity on vegetative growth (leaves fresh weight, leaves dry weight and leaf area), chemical composition (chlorophyll, N, P, Ca, K, Na, Proline contents, K/Na ratio) and yield of sweet pepper cultivar “Madrid”. The results illustrated that the growth parameters, chemical composition and yield of sweet pepper decreased by increasing salinity level. The results of the mitigation treatments of Glutathione, Selenium, and Humic acid, showed that the application of either Selenium alone in the first two seasons or combined with Glutathione in the third season showed significant effects for increasing plant growth, nutrient contents and yield under the highest salinity level.

Effect of magnetite on anaerobic digestion treating saline wastewater: Methane production, biomass aggregation and microbial community dynamics

In this study, the effect of magnetite amendment on anaerobic digestion was investigated at three increasing salinity levels (0.5%, 1% and 2% NaCl). The amendment of magnetite enhanced the methane yield by 36.3%, 33.3% and 16.5% at low salinity (0.5% NaCl) and high salinity (1% and 2% NaCl), respectively. Meanwhile, a larger proportion of granules was obtained in the magnetite amended reactor (48.05% vs 33.16% at the end of operation). Microbial analysis suggested magnetite could induce more methanogenesis partnerships between hydrogenotrophic methanogens and syntrophic bacteria. Methanosaeta and Methanocorpusculum were the alternating dominant methanogens at low salinity and high salinity. While Streptococcus and Mesotoga were two prevalent bacteria that showed totally different transition tendency in two reactors. Additionally, the supplement of magnetite could relieve the suppression of methanogenesis-related gene expression caused by salinity, thus facilitated the higher methane production.

Data-Independent-Acquisition-Based Proteomic Approach towards Understanding the Acclimation Strategy of Oleaginous Microalga Microchloropsis gaditana CCMP526 in Hypersaline Conditions.

Salinity is one of the significant factors that affect growth and cellular metabolism, including photosynthesis and lipid accumulation, in microalgae and higher plants. Microchloropsis gaditana CCMP526 can acclimatize to different salinity levels by accumulating compatible solutes, carbohydrates, and lipids as energy storage molecules. We used proteomics to understand the molecular basis for acclimation of M. gaditana to increased salinity levels [55 and 100 PSU (practical salinity unit)]. Correspondence analysis was used for the identification of salinity-responsive proteins (SRPs). The highest number of salinity-induced proteins was observed in 100 PSU. Gene ontology enrichment analysis revealed a separate path of acclimation for cells exposed to 55 and 100 PSU. Osmolyte and lipid biosynthesis were upregulated in hypersaline conditions. Concomitantly, lipid oxidation pathways were also upregulated in hypersaline conditions, providing acetyl-CoA for energy metabolism through the tricarboxylic acid cycle. Carbon fixation and photosynthesis were tightly regulated, while chlorophyll biosynthesis was affected in hypersaline conditions. Importantly, temporal proteome analysis of salinity-induced M. gaditana revealed vital SRPs which could be used for engineering salinity resilient microalgal strains for improved productivity in hypersaline culture conditions.

Exogenous application of glutamic acid promotes cucumber (Cucumis sativus L.) growth under salt stress conditions

Salinity is expected to be the major destructive abiotic stress that causes ionic and oxidative damage leading to growth reduction and ultimately plant death. Glutamic acid (GA) is an α-amino acid that is used by almost all living beings in the biosynthsis of proteins. Therefore, in the present study, we tried to investigate the effect of foliar application of glutamic acid (GA) on cucumber (Cucumis sativus L.) under altered salinity levels. Cucumber seedlings were grown in plastic pots under greenhouse conditions by applying four levels of salinity (0, 3 dS/m, 6 dS/m and 12 dS/m) and two levels of foliar applied GA (0, 10 mM). Salinity was induced by mixing the salt and soil before seed sowing; however, exogenous GA was applied when the vine length was reached up to maximum height. Morphological characters showed disruptive response under saline conditions especially in indigenous cultivar (local cucumber represented as V1). Enhanced activities of superoxide dismutase (0.29 u g-1 FW), guaiacol peroxidase (3.51 u g-1 FW) and ascorbate peroxidase (0.39 µmol AsA.mg-1 Chl min-1) were observed in salt-stressed cucumber leaves. Both varieties showed unusual behavior for malondialdehyde in decreasing manner with increasing salinity levels (2.0333 µmol g-1 FW at 12dS/m in local cultivar; while, 1.98 µmol g-1 FW at 12dS/m in hybrid cultivar SSC-228). However, exogenously applied GA played a beneficial role in promoting all morphological parameters under stress with increasing scavenging abilities against reactive oxygen species. Foliar application of GA improved plant defense mechanism with minimum destruction. Remarked calculations showed that under salt stress, GA improved plant stress tolerance against salinity by maximizing the growth rate.

Environmental factors affecting germination of Mimosa ephedroides (Fabaceae), an endemic shrub from Monte Desert, Argentina

&#x0D; Mimosa ephedroides is an endemic shrub from western Argentina. The knowledge of the germination response of this species to different environmental factors contribute to its efficient use in ecological restoration projects. This study aimed to examine aspects of seed quality, seed dormancy, and the effect of temperature, water and saline stress on the germination of this species. Also, the effect of seed storage time on the viability and the percentage of germinated seeds were evaluated. Experiments were carried out in controlled growth chambers. Germination percentage and mean germination time were calculated. It was found that this species has non-dormant seeds. Concerning abiotic factors, the optimum temperature for germination ranged from 20 to 30 ºC, it presented high germination percentages even at moderate and severe water stress (-1.12 MPa), and the germination percentages decreased with increasing salinity levels from 300 mM NaCl. In short periods (up to 36 months), seed storage at room temperature (18ºC) was adequate, not affecting the viability and the germination power of the seeds. These results constitute a contribution to the knowledge of the autecological aspects of this endemic species, support its incorporation for restoration projects, and aid to an efficient use of native seeds for direct seeding or seedling production.&#x0D; Highlights&#x0D; &#x0D; Mimosa ephedroides seeds are non- dormant, show high viability and rapid germination (&gt;24 h).&#x0D; This shrub is able to germinate in a wide range of temperatures and under moderate and severe water stress.&#x0D; High salinity levels (&lt;300 Mm NaCl) negatively affected seed germination.&#x0D; Seed storage for short periods (&lt;5 years) at room temperature (18ºC) did not affect seed viability and germination.&#x0D;

English

Salinity stress is one of the leading abiotic stresses seriously affecting the crop productivity across the world. Early growth stages are more affected by salinity stress than terminal growth stages. Therefore, maize genotypes were evaluated for their performance in three different studies (Experiment-1: irrigation of seeds with salt solutions (distilled water, 4 dS/m, 6 dS/m and 10 dS/m) for 5 days, Experiment-2: application of different salinity treatments (distilled water, 4 dS/m, 6 dS/m and 10 dS/m) for 20 days from sowing to seedling emergence stage, Experiment-3: application of salinity stresses in hydroponic culture under four above mentioned different salinity treatments. Time to start germination (TSG), time to 50% germination (TFG) and final germination percentage (FGP) of the maize genotypes was reduced by salinity stress. Radicle length, plumule length, root and shoot length and fresh weight and chlorophyll contents were also linearly reduced in maize genotypes by increasing salinity levels. Moreover, sodium (Na+) concentration was increased in seeds and seedlings of maize genotypes whereas; potassium (K+) concentration was reduced with gradual rise in salinity levels. Principal Component Analysis (PCA) biplots facilitated the efficient assortment of susceptible, moderately susceptible, moderately tolerant and tolerant maize genotypes for each of the three studies separately. Genotype „YS-2008‟ was susceptible for seed treatment and hydroponic studies whereas, genotype „T267-5‟ was susceptible for early seedling and hydroponic studies. Genotype „C864-284‟ was tolerant in early seedling and hydroponic studies. The GGE biplot analysis indicated that „YS-2008‟ genotype was susceptible for salinity stress. Under hydroponic conditions, genotypes could effectively be discriminated by the imposition of severe salt stress (10 dS/m); however, under seed treatments and early seedling growth stages, mild stress treatments (4 dS/m) were sufficient enough to discriminate the maize genotypes. Hydroponic evaluation of genotypes is suitable and preferable under high stress conditions at early growth stages. Identified tolerant and susceptible genotypes could be effectively used in different breeding programs to develop salt tolerant new cultivars for commercial purposes. © 2021 Friends Science Publishers

Performance of Hydroponically Cultivated Geranium and Common Verbena under Salinity and High Electrical Conductivity Levels

Abiotic factors in nutrient solutions (NSs), such as salinity and high electrical conductivity (EC), may adversely alter plant growth and crop performance. However, there are medicinal/aromatic plants which can not only withstand these adverse conditions, but which can also increase their productivity or even enhance their quality in such conditions. As fresh water sources suitable for irrigation are becoming more and more limited, the use of low-quality water sources and hydroponic growing systems have been suggested as the main alternatives. Towards that direction, this study aims to evaluate the effect of high EC levels in NSs on geranium (Pelargonium graveolens L’Hér.) and common verbena (Verbena officinallis L.) plants cultivated in a soilless (perlite) hydroponics system. Plants were irrigated with a full nutrient solution of EC 2.1 dS m−1 and pH 5.8 until they reached a uniform size. Then, three treatments were applied, namely: (a) a control treatment with an EC of 2.1 dS m−1 in the NS, (b) a high-salinity NS created by adding 75 mM of NaCl (EC under 8.5 dS m−1) and (c) a concentrated NS with an EC of 8.5 dS m−1. In pelargonium, high salinity decreased the total phenolic and total flavonoid contents; antioxidant capacity; N, K, Mg and P content; as well as chlorophyll fluorescence, compared to the control treatment. On the other hand, increased salinity levels increased the Na and Ca content and stomatal resistance. In common verbena, salinity decreased total phenolic content and chlorophyll fluorescence but increased total flavonoid content; antioxidants; leaf K, P, Na, Cu and Zn content; and stomatal resistance, compared to the control. In both species, high EC did not affect polyphenols, flavonoids or antioxidants, whereas it increased stomatal resistance and nutrient accumulation in the leaves, and decreased chlorophyll fluorescence compared to the control treatment. Damage indices, indicated by lipid peroxidation, hydrogen peroxide production and the elevation of enzymes’ antioxidant activities, were evidenced in both saline- and high-EC-treated plants. In conclusion, despite having the same EC levels in the nutrient solution, it seems that ionic stress caused by high mineral concentrations in the nutrient solution had less severe effects on the tested plants than the relevant osmotic stress caused by high salinity due to the addition of NaCl in the nutrient solution.

Effect of salinity on seed germination of some tomato (Lycopersicon esculentum Mill.) varieties

Salinity adversely affects 20-30% of the irrigated area in the world. Tomato is sensitive to salinity. It is one of the most severe abiotic factors of many agricultural crops and it becoming the main problem in Ethiopia. This study was conducted to evaluate the effects of different salinity levels on the seed germination parameters of tomato varieties. It was laid out in a completely randomized design with three replicates. The treatment included four tomato varieties (Sirinka, Weyno, ARP D2, and Roma VF) and five salinity levels (1 dS m-1, 2 dS m-1, 3 dS m-1, 4 dS m-1, and control). Fifty seeds were placed in a Petri dish over a moistened germination paper for germination and seedlings and allowed to grow for 14 days. The germination rate, speed and energy of tomato seeds were significantly (p &lt; 0.001) affected by the combined effect of variety and salinity. The shortest mean germination time, the highest mean germination rate, and the highest speed of germination were recorded in the ARP D2 variety in the control treatment. The lowest first and last days of germination, and the uncertainty of germination were recorded from ARP D2. However, an increase in the days of germination and in the uncertainty of germination, and a decrease in the germination index and total germination percentage trends were observed with increasing salinity levels. The highest level of salinity (4 dS m-1) affected the germination of tomato varieties. Among the four tested tomato varieties, ARP D2 and Roma VF were tolerant to salinity.

Performance of Chrysanthemum or Chrysanthemum Morifolium Ramat (CV. Balady) in Different Saline Water Irrigated Soils and Growing Media

As a result of the decreasing availability of high-quality irrigation water, the salinity tolerance of cut flowers is of increasing importance. The influence of salinity on the growth and quality of Chrysanthemum, Chrysanthemum morifolium L. grown in two different media under four salinity levels was evaluated. C. morifolium plants were grown in plastic pots containing either zeolitic tuff or soil as potting media. Seedlings of C. morifolium were subjected to four NaCl/CaCl2 salinity levels (2, 4, 6, and 8 dS.m-1). The effect of increasing salinity level on growth, flowering characteristics, time to flower, length and diameter of flowering shoots, and the diameter of the terminal flower on each stem were evaluated. On termination of the experiment, plant height, two perpendicular canopy widths, and fresh and dry weights of shoots were measured. Results indicated that most of all measured characteristics were reduced in response to increasing salinity levels. Increasing salinity levels caused significant reductions in plant height, fresh and dry yield, and relative water content. Moreover, salinity reduced flower quality (color, size, stem thickness, and length) and yield. Also, some physiological changes occur in stomatal conductance, leaf relative water content, and chlorophyll content. C. morifolium plants showed a good salinity resistance by irrigating plants with saline water up to 4 dS.m-1. Significant differences in C. morifolium plant responses were also detected between soil and zeolitic tuff media for most tested characteristics, in which using zeolitic tuff as rowing media was better to cope with higher salinity levels than plants grown in soil. In conclusion, it is recommended to use zeolitic tuff instead of soil when water salinity is a problem in irrigation water.