Water Salinity Levels Research Articles

Heterogeneous long-term and seasonal brine evolution, and Artemia fecal pellet controls on Urmia Lake (NW Iran) salt-crust formation and mineralogy

ABSTRACT Urmia Lake resides as a substantial hypersaline lake characterized by notable fluctuations in water salinity, brine composition, and water level over long-term, annual, and seasonal intervals. Extremely rapid water elevation fall (> 7 m) in the last three decades has caused the formation of a salt crust on the lake floor. A manmade stone causeway divided the lake into two relatively deeper northern parts with minimal water inputs and a shallower southern part with maximal river inflows. Restricted water flow through the narrow water passage of the causeway leads to complex salinity processes, brine evolution, and salt-crust formation in Urmia Lake. This research analyzes the ionic composition of lake-sediment and salt-crust pore water, the mineralogy of salt crusts, and the ionic composition of both surface and deep lake waters during both the wet and dry seasons of 2019. The findings indicate that the northern and southern parts of the lake undergo stratification during wet seasons due to significant freshwater input, whereas they become homogenized during dry seasons through progressive evaporative concentration and water mixing. The spatial and temporal variations in the lake brine type (primary Na-Mg-Cl) and ionic composition contribute to the formation of a halite salt crust (NaCl > 97%) with heterogeneous mineralogy and thickness. In Urmia Lake, the variable thickness and mineralogy of the exposed marginal salt crust suggest rapid salt-crust reorganization by annual and seasonal deposition and dissolution processes. Conversely, the submerged central salt crust, with continuous thickening and constant mineralogy, remains unaffected by seasonal variations in brine type and dissolution processes. It is noteworthy to mention that Artemia (a brine shrimp) controls the mineralogy of the lake salt crust through the deposition of calcium and carbonate ions in the form of biochemical fecal pellets.

Effect of Salt Stress on Botanical Characteristics of Some Table Beet (Beta vulgaris L.) Cultivars.

Salinity inhibits the uptake of nitrogen, which slows down the growth and prevents plant reproduction. Certain ions, especially chloride, are poisonous to plants; when their concentration increases, the plant becomes poisoned and eventually perishes. The adaptability of several table beet cultivars (Beta vulgaris L.) to saline water irrigation creates new opportunities for extending beet production, increases the added economic value, and has a positive environmental impact. A pot experiment is carried out for two successive seasons, 2019/2020 and 2020/2021, to investigate the effect of irrigation with agriculture saline drainage water on the growth and biochemical traits of three selected cultivars (Detroit Dark Red, Red Ball, and Red Ace). Four levels of salinity are applied (1000, 2000, 3000, and 4000 ppm) along with tap water of 260 ppm salinity, which serves as the control. Detroit Dark Red beets show the best results among the other cultivars under consideration. Irrigation with the first level of saline water (1000 ppm) at both seasons of cultivation results in a significant increase rate in growth parameters (13-23%). The second level of salinity (2000 ppm) shows the maximum increase rate of some chemical constituents, such as ascorbic acid (16.26%), nitrogen (58.21%), phosphorus (11.94%), potassium (34.66%), and sodium (85.14%). The levels of total soluble solids (TSS), anthocyanins, proline, total sugars, water saturation deficit, and sodium increase significantly in proportion to saline water concentrations. The selected table beet mature leaves show slight variations in anatomical structure, especially in the B. vulgaris L. cv. Detroit Dark Red under the highest salinity concentration (4000 ppm) was less than that of the control and the other two cultivars. Other cultivars may be the subject in the near future to study the effect of their salinity tolerance with the aim of increasing productivity, enhancing their characteristics, and preserving the environment.

Effects of Irrigation Amount and Salinity Levels on Maize (Zea mays L.) Growth, Water Productivity and Carbon Emissions in Arid Region of Northwest China

To address the growing scarcity of freshwater resources, the use of saline water for agricultural irrigation is gaining increasing attention. This study presents findings from a two-year field experiment conducted during the 2023 and 2024 maize-growing seasons in northwestern China. The objective of the experiment was to evaluate the main and interactive effects of saline irrigation water on soil water–salt dynamics, maize growth, photosynthetic characteristics, water productivity, and carbon emissions. The experiment involved nine treatments with three irrigation amounts: 4500 m3 hm−2 (W1), 5625 m3 hm−2 (W2), and 6750 m3 hm−2 (W3), combined with three water salinity levels: 0.85 g L−1 (S1, freshwater), 3 g L−1 (S2), and 5 g L−1 (S3). Results indicated that both irrigation amount and salinity level significantly affected water–salt dynamics, with more soil accumulating in the 0–100 cm soil layer under saline irrigation water; however, this effect diminished with higher irrigation amounts. The maximum leaf area index and plant height were affected by both the irrigation amount and salinity level, as well as their interaction. Photosynthetic capacity declined with increasing salinity of the irrigation water, ultimately reducing grain yield and irrigation water use efficiency. Compared to freshwater (S1), the average maize grain yield under S2 and S3 treatments decreased by 6.28% and 15.43% in 2023 and by 7.82% and 17.48% in 2024, respectively. Additionally, for the same irrigation amount, higher salinity of the irrigation water (S2, S3) significantly reduced total soil CO2 emissions, with reductions of 10.08% and 27.53% in 2023, and 11.97% and 28.01% in 2024, respectively. In summary, to optimize the utilization of saline water, enhance maize yield, and improve soil carbon sequestration, we recommend maintaining the salinity of irrigation water below 3 g L−1, and using an irrigation amount of 6750 m3 hm−2 (W3S2) for optimal outcomes in the study area.

Determination of Salt Stress by Plant Leaf Temperature and Thermal Imaging in Black Cumin Grown Under Different Salt Sources

ABSTRACT Thermal imaging has been used in recent years to determine salinity stress in certain crops. However, no information is available on this regarding black cumin (Nigella sativa L.). The main purpose of this study was to investigate the determinability of the salt stress on black cumin by thermal imaging. The leaf temperature values were obtained by acquiring the thermal images for black cumin grown under different irrigation water salinity levels (0.6 as control, 1.5, 2.5, and 5.0 dS/m) prepared for different salt sources (CaCl2, MgCl2, NaCl, Ca(NO3)2, MgSO,4 and Na2SO4). Plant leaf temperatures averaged over all irrigation water salinity levels did not show a significant difference among salt sources. On the other hand, plant leaf temperatures independent of the salt sources significantly increased with increasing salinity levels. The order for salinity levels in terms of their effect on the leaf temperature of black cumin was determined as 5.0 dS/m > 2.5 dS/m > 1.5 dS/m ≥ 0.6 dS/m. The highest leaf temperature was obtained under 5.0 dS/m salinity level with CaCl2, MgCl2, Ca(NO3)2, MgSO4, and Na2SO4 salt sources, but the values for MgSO4 and Na2SO4 salt sources were not significantly different from those under 2.5 dS/m salinity. In addition, a strong-negative relationship between plant water consumption and leaf temperature under CaCl2 and MgSO4 and a moderate-negative relationship under MgCl2 and NaCl salt sources were determined. The results of this study showed that the plant leaf temperature values obtained by thermal imaging reflected salt stress conditions, especially under high salinity levels.

Irrigation Water Salinity Affects Solute Transport and Its Potential Factors Influencing Salt Distribution in Unsaturated Homogenous Red Soil

As a promising alternative water source to alleviate irrigation water scarcity in red soil regions in southern China, low-quality water could enhance regional water resource utilization and promote sustainable agriculture. However, its soluble salt and ions could affect soil solute distribution and transport, potentially hindering crop growth. Undoubtedly, it is necessary to understand the mechanism of solute transport in red soil under low-quality water irrigation with different water salinity levels. Therefore, a one-dimensional vertical water infiltration experiment and a solute breakthrough experiment were conducted to evaluate the solute transport (soluble salt, Na+, and Cl−) in unsaturated and saturated homogenous red soil at different salinity levels [1 (S1), 2 (S2), 3 (S3), 5 (S5), and 10 (S10) g/L] when irrigated with simulated low-quality water using analytical-grade NaCl. Moreover, the potential factors affecting salt distribution in unsaturated red soil were determined. The findings indicate positive linear relationships between accumulations of three solutes and irrigation water salinity. Generally, the depth of maximum solute concentration increased with the increase in irrigation water salinity. Soluble salt, Na+, and Cl− exhibited early breakthrough and trailing in red soil, but higher irrigation water salinity could reduce PV and retardation. A mobile and immobile water model (MIM) showed that convection was dominant in solute transport in red soil under low-quality water irrigation. D decreased as a power function with increasing irrigation water salinity, while v and R decreased linearly. Furthermore, the red soil can adsorb Cl− resulting from its special charge characteristics under low-quality water irrigation, which may be the main source of salt adsorption. Additionally, v > soil pH > βsalt primarily influenced salt distribution in the 0–40 cm soil profile. This study can provide insights into solute transport in red soil under low-quality water irrigation, facilitating soil fertility and structure, as well as low-quality water irrigation strategy optimization.

Salinity challenges and adaptive strategies in salinization-affected coastal Bangladesh: Implications for agricultural sustainability and water resource management

Abstract Salinization has become a rising global concern due to its notable effects on agriculture and freshwater resources. Coastal region of Bangladesh has been struggling with elevated levels of soil and water salinity, exacerbated by storm surges and rising sea levels. We assessed nutrient and salinity contents in agricultural and homestead lands, and the level of salinity in pond and canal water in six sub-districts in coastal Bangladesh. Finally, using household (HH) survey, focus group discussion (FGD) and key informant interview (KII), we explored the adaptive practices and challenges of salinity issues in agriculture and drinking water management. Soil nitrogen, phosphorus, and potassium contents exhibited significant variations across the sub-districts, which reflect the diversity of agricultural practices and soil management strategies. However, there was no notable difference in soil salinity across the sub-districts, which underscores the commonality of soil salinity as a pressing concern. Shyamnagar (13.99 dS m−1) recorded the highest level of pond water salinity, followed by Assasuni (13.96 dS m−1), Dacope (13.91 dS m−1), Koyra (13.58 dS m−1), Morrelganj (13.33 dS m−1), and Mongla (13.19 dS m−1) sub-districts, which highlights that water salinity decreased from exposed coast to the landward areas. Respondents in HH surveys, FGDs and KIIs identified salinity as a major challenge in agriculture and drinking water. Furthermore, climate-related stresses were recognized as significant challenges impacting crop productivity. The research highlights the feasibility of rainwater harvesting, with 89%–100% of HHs harvest rainwater in HH tanks, as an effective adaptive practice for managing drinking water. The study emphasizes the positive impact of vermicompost in reducing soil salinity levels, which is demonstrated by the 43%–88% of HHs using this practice, indicating its potential as a nature-based solution to address soil salinization. The findings underscore the need for resilient agricultural systems and sustainable water management approaches to tackle these challenges.

Effects of water quality and nitrogen on wheat productivity: Experimental and modelling study using the SALTMED model

AbstractThe effects of different water qualities and nitrogen doses need to be investigated for wheat growth to determine the optimal management strategy for sustaining wheat production potential to ensure human food security. Therefore, a 2‐year study (2020–2021 to 2021–2022) was conducted on wheat irrigated with different water qualities, including canal water (Ca), tubewell water (Tu) and mixed Ca‐Tu water (Mx), each fertilized with two nitrogen doses, that is, N75 = 75 kgN.ha−1 and N100 = 100 kgN.ha−1. Ca⨯N100 performed best, with 5.12 t.ha−1 grain yield, 11.60 t.ha−1 biomass, 102.83 cm plant height and 1.32 kg.m−3 water productivity. The best values of the root mean square error (RMSE), normalized root mean square error (NRMSE), coefficient of determination (R2) and coefficient of residual mass (CRM) were 0.11, 0.12, 0.93 and −0.004, respectively, for calibration and 0.13, 0.15, 0.87 and ±0.01, respectively, for validation of the SALTMED model. The scenario simulation was performed for additional levels of water salinity (electrical conductivity [EC] = 8 and 12 dS.m−1) and nitrogen doses (50, 125, 150 and 175 kgN.ha−1). The results revealed improvements in wheat grain yield of 107%, 16% and −6% at EC = 8 dS.m−1 and 125%, 31% and 5% at EC = 12 dS.m−1, while the improvements in biomass were 113%, 22% and −2% at EC = 8 dS.m−1 and 137%, 29% and 8% at EC = 12 dS.m−1 with increasing nitrogen doses from 50–125 kg.ha−1, 125–150 kg.ha−1 and 150–175 kg.ha−1, respectively. It is recommended that high‐quality water with the lowest possible EC and nitrogen applications of up to 150 kgN.ha−1 be adopted for wheat production in semi‐arid areas of Punjab, Pakistan.

Effects of long-term saline water irrigation on soil salinity and crop production of winter wheat-maize cropping system in the North China Plain: A case study

Fresh water shortage is a major problem for grain production in the low plain around Bohai Sea in the North China Plain. Relative abundance of shallow saline groundwater could serve as an alternative water resource for use during dry seasons. A continuous 8-year field study was conducted from 2015 to 2023 to assess the effects of salt content in irrigation water on soil salt accumulation and crop production. Fresh water (FW) with electrical conductivity (EC) at 1.6 dS/m and three levels of saline water (SW) with EC at 4.7 (SW1), 6.3 (SW2) and 7.8 dS/m (SW3) were used for irrigation. Results showed that a single irrigation event at the jointing stage of winter wheat increased grain production averagely by 18.6 %, 22.5 %, 12.9 % and 9.5 % compared with a rain-fed treatment (RF) under FW, SW1, SW2 and SW3, respectively. With an additional irrigation applied at flowering stage, both irrigations using FW increased the yield by 28.6 %, and both irrigations using SW2 increased the yield by 19.3 % compared with RF. Negative effects of salt on winter wheat overshadowed the positive effects of increased water supply under two irrigations both using SW. With an irrigation at maize sowing and the subsequent summer rainy season, the yield of maize following winter wheat was not affected by a one-time SW irrigation to the previous crop, but showed a 5.3 % yield reduction when two irrigations of SW were applied. There was no apparent salt accumulation in the top 1 m of the soil profile, but a slight increasing trend in the salt content in the 1–2 m layer of the soil profile under SW2 and SW3 irrigation. No apparent changes in soil physical properties were observed for continuous application of SW. It was suggested that SW with EC not exceeding 6.3 dS/m should be applied for a single irrigation during the winter wheat season. This practice could alleviate the fresh water shortage in this region and allow for the maintenance of a relatively stable yield of winter wheat and maize without the risk of salt accumulation in the soil.

Green Synthesis of Zinc and Iron Nanoparticles Using Psidium guajava Leaf Extract Stimulates Cowpea Growth, Yield, and Tolerance to Saline Water Irrigation

Plants use a variety of physiological, biochemical, and molecular mechanisms to mitigate salt stress impacts. Many techniques, including the application of nanoparticles (NPs), are being used to increase plant stress tolerance. To assess the growth and productivity of Vigna unguiculata L. (cowpea) plants exposed to salt stress, cowpea has been cultivated using different saline water levels and subjected to green synthesized zinc NPs (ZnNPs) and iron NPs (FeNPs) applied via foliar spraying. The cowpea plants that grew under the lowest saline water level showed the best leaf traits, leaf water content per area (LWCA), pods, and seed yields, but when salinity levels increased, the plants’ growth and productivity slightly declined. ZnNP and FeNP treatments slow down the degradation of photosynthetic pigments and greatly mitigate the negative effects of salt stress. In both stressed and unstressed plants, ZnNP treatments produced the highest osmoprotectant concentrations (proline, protein, and total carbohydrates). As a result of salt stress, cowpea seeds showed a marked decrease in dry matter and protein content, but ZnNP and FeNP treatments increased it. Conclusively, the results obtained indicated that ZnNPs and FeNPs foliar application to cowpea plants stimulated leaf pigment and polyphenol production, which in turn increased seed dry matter, seed yield, protein content, and the plants’ ability to withstand saline stress.

An insight into effect of soil salinity on vegetation dynamics in the exposed seafloor of the Aral Sea

The desiccation of the Aral Sea has precipitated significant ecological degradation, resulting in the progressive development of vegetation on the exposed seafloor. Soil salinity emerges as a pivotal determinant in this ecological succession process. Employing a comprehensive methodology integrating multi-source datasets spanning from 1986 to 2023, this study elucidates the temporal changes in vegetation dynamics and soil salinity levels. Satellite imagery (Landsat-4/5/7/8), field soil samplings, hydrological and topographic data were analyzed to understand their interactions with regression analysis. The results reveal a consistent increasing trend in the Normalized Difference Vegetation Index (NDVI) across the exposed seabed since 1986. However, NDVI demonstrates a non-linear relationship with elevation in the North Aral Sea region. Interestingly, NDVI levels near an elevation of 42 m on the exposed seabed approximate those observed during the pre-recession period in the 1960s. Conversely, in the South Aral Sea region, NDVI demonstrates a linear upward trend with increasing elevation. Furthermore, the spatial distribution of soil salinity on the exposed seabed was delineated with linear regression analysis. It revealed water salinity levels at the time of sea recession can serve as a proxy for soil salinity in cases where direct soil data is unavailable. Through establishing a robust correlation between NDVI and soil salinity, the range of stable NDVI values on the exposed seabed was delineated. Lastly, three hypothetical scenarios of rising water levels were considered to evaluate changes in stable NDVI across different elevation gradients. If the water level returns to 45 m, the salt-desert area would decrease by 4.5 × 104 km2, accounting for 23 % of the total area in 1960. At this water level, it is anticipated that lake hydrological conditions and ecological environments may restore to those observed in 1981. This study provides a long-term perspective on environmental changes in the Aral Sea region by integrating multiple data sources and analytical methods. The predictive insights from the scenario analysis offer valuable guidance for future water management and ecological restoration efforts. Compared with previous studies, it presents a detailed and comprehensive picture of the interplay between vegetation dynamics and soil salinity, highlighting the critical impact of water level changes on the region's ecosystem.

Determination of the physiological response of lettuce to different irrigation water salinities (NaCl) and leaching fractions

The Amik Plain, where the experiment was conducted, is increasingly salinised owing to improper irrigation methods, excessive irrigation, drainage and groundwater use. This situation indicates that soil salinity will increase even more in the future. The study was conducted using a factorial experimental design in potted conditions inside the greenhouse to investigate the impacts of three distinct levels of irrigation water salinity (ECi) (ECi-0= 0.5 dS m-1 (control), ECi-2= 2 dS m-1and ECi-4= 4 dS m-1) and four different leaching fraction (LF) (LF0=0%, LF10=10%, LF20=20%, LF30=30%) on stomatal conductance (gs), leaf surface temperature (LSt), chlorophyll content (SPAD), chlorophyll concentrations (Chl-a, Chl-b, and Chl-tot) and yield parameters in 'Cospirina' lettuce plants. As a result of the study, soil salinity (ECe) increased from 0.82 dS m-1 to 2.09 dS m-1 with increasing ECi. As ECi increased, plant water consumption (PWC) decreased from 8.92 to 5.71 L pot-1, yield decreased from 276 g pot-1 to 198 g pot-1, gs decreased from 266 mmol m-2 s-1 to 215 mmol m-2 s-1. LSt increased by 2.17% in ECi-2 and 6.4% in ECi-4 compared to the control. As ECe increased, yield decreased by 10% in ECi-2 and 28% in ECi-4 compared to the control treatment. Chl-tot and Chl-a were significantly affected by the increase in ECe (r2=0.96*, r2=0.99**, respectively), while Chl-b was not affected. In contrast to soil salinity, leaching fraction had a positive effect on plant physiology.

Root morphology parameters and nutrient acquisition capabilities of grafted tomato plants in root-restricted conditions are subject to salinity and rootstock characteristics

ABSTRACT A tomato cultivar ('Izmir F1') grafted onto six commercially available rootstocks ('Arnold', 'Dohkko', 'Emperador', 'He-man', 'Kaiser', and 'Suzuka') together with self-grafted plants of the tomato cultivar (Izmir/Izmir) were included in a pot experiment. Growth, root morphology and nutrient uptake parameters were evaluated under different salinity conditions (0 and 50 mM NaCl). Grafting increases root length, specific root length, and root length ratio, which enhances the capabilities of hetero-grafted plants to exploit a larger volume of soil or otherwise increase root density under root restriction conditions. Since the root traits and nutrient concentrations in hetero-grafted variants were less impacted by a change in the salinity level, the use of specific rootstocks (‘Arnold,’ ‘Dohkko,’ ‘Kaiser’) could contribute to a steadier growth and yield of tomato plants under fluctuating salinity levels in the irrigation water. The hetero-grafted tomato plants (Dohkko/Izmir, Suzuka/Izmir) demonstrated higher Na sequestration/compartmentalization capabilities than the self-grafted (Izmir/Izmir) plants which helps to maintain a more appropriate K+/Na+ ratio. By exhibiting lower translocation indexes of some heavy metals (Al, Ni, Zn, and Cd), appropriate rootstock/scion combinations might be a useful tool for reducing the risk of their accumulation in edible plant organs.

Application management of Codasal Plus 2000 on Italian Zucchini irrigated with saline water

Zucchini (Cucurbita pepo L.) is one of the main economically important vegetables in Brazil, but its production is limited in semi-arid regions due to its water requirement. This study evaluated the effect of Codasal Plus 2000 in different application management on zucchini crops irrigated with saline water. The experiment was carried out at the Federal Rural University of Semi-Árido, Mossoró-RN. A randomized block design was adopted with two salinity levels of irrigation water (S1 - 0.5 dS m-1; S2 - 5.0 dS m-1) and six application managements of Codasal Plus 2000 ((M1 - Absence (H2O); M2 - every 7 days (2 L ha-1); M3 - every 7 days (4 L ha-1); M4 - every 14 days (4 L ha-1); M5 - every 14 days (8 L ha-1); M6 - every 14 days (6 L ha-1)). Growth and production variables were evaluated. Regardless of application management, the dry mass of the vegetative part, dry mass of the fruits and total dry mass reduced by an average of 34.16%, 49.29% and 21.78. %, respectively, at the highest salinity. In fruits, the number, fresh mass and productivity were reduced by 67.75%, 21.77% and 72.48%, respectively, at the highest salinity level. Codasal Plus 2000 was unable to mitigate the negative effects of saline water.

Physiological and growth responses of Lycium barbarum seedlings to water and salt stresses

Rational exploitation and utilization of brackish water resources is the basis of sustainable agricultural development in the oasis regions of arid inland basin. As a drought-and-salt-tolerant economic crop, irrigation management at seedling stage is particularly important for the fruit yield in Lycium barbarum adulthood. The effects of three irrigation levels (the lower limits of irrigation were 80 % (full irrigation), 70 %, and 60 % of field capacity) and two salinity levels in irrigation water (1.7 (fresh water) and 5.0 dS/m) on physiology and growth of Lycium barbarum seedlings were studied through pot experiments. The results showed that water deficit treatment promoted aboveground plant growth and water use efficiency, but decreased transpiration rate of Lycium barbarum seedlings. Compared with full irrigation, the averaged leaf chlorophyll content (SPAD), base stem diameter, branch diameter, and water use efficiency of Lycium barbarum seedlings under deficit irrigation treatments were increased by 4.6 % – 6.6 %, 15.1 % – 55.5 %, 12.8 % – 41.0 %, and 22.3 % – 23.9 %, respectively, while the transpiration rate was decreased by 6.5 % – 16.1 %. Soil water content under brackish water irrigation was generally slightly higher than that under freshwater irrigation, but its soil salinity was about 5.0 times higher than that under freshwater irrigation. Compared with freshwater irrigation, brackish water irrigation decreased root biomass by 6.7 % – 9.0 % and transpiration rate by 2.5 % – 10.5 %, and increased water use efficiency by 1.9 % – 24.8 %, and meanwhile it also promoted the growth of base stem (11.4 % – 32.4 %), branch (6.4 % – 18.9 %) and leaf aera (2.2 % – 6.8 %). The lower limit of irrigation and the salinity in irrigation water imposed significant interactive effects on photosynthesis, stem and branch growth, and crop water consumption of Lycium barbarum seedlings. The analysis results of structural equation model showed that the lower limit of irrigation mainly affected water use efficiency of Lycium barbarum seedlings, while the salinity in irrigation water mainly did its root biomass. The lower limit of irrigation with 70 % field capacity may be a preferred scheme of brackish water irrigation for the planting of Lycium barbarum seedlings in arid oasis regions.

The effects of drought and salinity on KS and RAW managerial coefficients in the efficient water management in maize farms

This study aimed to investigate the simultaneous effects of drought and salinity on irrigation management coefficients in maize farms. A three-year field research was conducted in the form of a 3 × 3 factorial experiment with a randomized complete block design and three replications from 2020 to 2022 in a maize farm, in Aliabad Fashafoye, Qom province, Iran. The applied treatments included three levels of salinity (S0 = 1.8, S1 = 5.2, and S2 = 8.6 dS/m) and three levels of irrigation (W0 = 100%, W1 = 75%, and W2 = 50% of field capacity). Evapotranspiration stress coefficient (KS) due to W0S1 and W0S2 treatments was (0.975 and 0.934), (0.974 and 0.932), and (0.962 and 0.935) in 2020, 2021, and 2022, respectively. According to the results, KS decreased by increasing the salinity level of irrigation water, so a 1-unit increase in salinity level above the tolerance threshold of the crop to salinity decreased KS by 0.78 and 1.76% for S1 and S2, respectively. Moreover, each percent of volumetric moisture decrease from field capacity decreased KS by 5.9 and 13.3% in W1 and W2, respectively. Also, with the increase in the intensity of the stresses, the readily available water (RAW) of treatments decreased. The sole application of salinity stress decreased the decreasing slope of RAW by 3.2%, while the application of both stresses resulted in the decreasing slopes of 4.9, 5.7, and 7.8% at the salinity levels of S0, S1, and S2, respectively, compared to the control. The findings of this study show that the accurate estimation of crop evapotranspiration and RAW can help to improve the irrigation schedule, and the amount of irrigation water used is less than in non-stress conditions due to the reduction of total evapotranspiration and less water uptake in environmental stresses in maize farms.

Integrated biofloc technology in red tilapia aquaculture: Salinity-dependent effects on water quality, parental stock physiology, reproduction, and immune responses

The study examines the impact of integrated biofloc technology (BFT), different salinity levels, and their combined effects over 90 days on various physiological parameters. The investigation includes growth performance and feed utilization, water quality, the chemical composition of biofloc and fish, digestive enzymes, reproductive performance, stress and biochemical indicators, and antioxidant-immune responses in red tilapia (Oreochromis spp.) broodstock. The fish were initially weighed (males: n = 270; 104 ± 0.96 g; females: n = 270; 93.2 ± 0.66 g) and subsequently divided into 12 treatment groups (6 for males and 6 for females) spread across 36 separate tanks (3 tanks per treatment; 45 fish per treatment; 15 fish/tank). The treatments involved three salinity levels (18, 28, and 36 ppt) in both clear water (CW) and BFT systems. The outcomes demonstrated that fish in the 36 ppt salinity with BFT treatment demonstrated significant improvements (P < 0.05) in growth parameters (final body weight, weight gain, and specific growth rate, feed intake, and feed conversion ratio). The condition factor in BFT groups increased in all salinity situations. The survival rates of broodstock were consistently high in all experimental conditions The study found that BFT and salinity significantly impacted (P < 0.05) whole body contents (moisture, protein, lipid, and ash) in both males and females. Water quality parameters showed variations between BFT and CW, with notable impacts (P < 0.05) on dissolved oxygen and pH. The BFT and salinity influenced digestive enzyme activities (protease, amylase, and lipase) and reproductive performance (males) and the 36 ppt salinity with BFT recorded the highest values. The hemato-biochemical and antioxidant-immune responses were also impacted by BFT and salinity exposure. The study highlights the potential benefits of incorporating BFT into red tilapia aquaculture systems, particularly in optimizing growth, health, and reproductive performance under various salinity conditions, which can enhance sustainable intensification, disease control, and environmental stewardship.

Okra cultivation under irrigation with saline water and foliar application of hydrogen peroxide

Foliar application of hydrogen peroxide can induce plant defense mechanisms against salt stress, favoring plant acclimation in regions with qualitative and quantitative scarcity of water resources, such as the Brazilian semi-arid region. From this perspective, this study aimed to evaluate the effects of foliar hydrogen peroxide application on chlorophyll a fluorescence, growth, and production of okra under irrigation with saline water. The experiment was conducted under field conditions in Pombal, PB, using a randomized block design with a 5 × 3 factorial arrangement corresponding to five electrical conductivity levels of water – ECw (0.3, 1.3, 2.3, 3.3, and 4.3 dS m-1) and three hydrogen peroxide concentrations – H2O2 (0, 25, and 50 μM), with five replications. Irrigation water salinity levels up to 2.2 dS m-1 increase the maximum fluorescence of okra plants 75 days after transplanting. Foliar application of 50 µM hydrogen peroxide proved to be beneficial for plant height, stem diameter, stem dry matter, root dry matter, and total dry matter of okra when plants were grown in low-salinity water. The hydrogen peroxide concentrations of 25 and 50 µM increased the number of leaves. However, these concentrations reduced the average weight of the okra dry fruits. Foliar application with 50 µM hydrogen peroxide had a significant effect on the dry leaf phytomass of the okra cv. Clemson American 80 regardless of the electrical conductivity of irrigation water. Foliar hydrogen peroxide application at concentrations up to 50 µM intensifies the deleterious effects of salt stress on the total weight of dried okra fruits. Keywords: Abelmoschus esculentus L., acclimation, salt stress.

Yield Response of Grafted and Self-Rooted Tomato Plants Grown Hydroponically under Varying Levels of Water Salinity

Yield Response of Grafted and Self-Rooted Tomato Plants Grown Hydroponically under Varying Levels of Water Salinity

Growth and Yield of Lettuce (Lactuca sativa var. crispa) in Varying Irrigation Water Salinity and Leaching Fractions

This study aimed to determine the response of yield and yield parameters of the ‘Cospirina’ lettuce plant, known to be moderate salinity tolerant, to different levels of salt water applications and different leaching rates in the Eastern Mediterranean Region of Hatay Province, Türkiye. Lettuce was irrigated at three different irrigation water salinity levels (EC0 = 0.5 dS m-1-control, EC2 = 2 dS m-1, EC4 = 4 dS m-1) and four different leaching fractions (LF0 = 0%, LF1 = 10%, LF2 = 20%, LF3 = 30%). Irrigation water salinity was adjusted by adding different amounts of NaCl salt to the tap water (EC0, control) with an EC value of 0.5 dS m-1. Plant water consumption (PWC) increased as the leaching fraction increased but decreased as salinity increased. PWC ranged from 7.32 – 10.5 L for EC0, 7.0 – 8.46 L for EC2, and 5.0 – 6.46 L for EC4. The mean water use efficiency (WUEy) was calculated as 31.43 g L-1, 32.12 g L-1, and 34.77 g L-1 in EC0, EC2, and EC4, respectively. Lettuce yield decreased with increasing soil salinity and the leaching fraction. Yield ranged from 182 g plant-1 (EC4LF0) to 282 g plant-1 (EC0LF2). When soil salinity increased from 0.82 dS m-1 (EC0) to 1.31 dS m-1 (EC2) and 2.09 dS m-1 (EC4), yields decreased by 10% and 28%, respectively. Increasing salinity significantly decreased the root length, root width, leaf number, number of commercial leaves, leaf width, leaf length, and biomass, while commercial head length and commercial head diameter remained unaffected.

Indicators of rapid adaptation of an exotic aquatic Poaceae to increased salinity

AbstractThe invasion process and the persistence of invasive species across environments can be explained by their tolerance to stressors, such as salinization. Urochloa arrecta (Poaceae) exhibits high invasive potential and has already established in various natural and artificial aquatic ecosystems. Here, we experimentally evaluate the effects of water salinity on the traits of three exotic populations of U. arrecta derived from naturally occurring populations across a salinity gradient. Specifically, we measured the difference in the number and perimeter of intercellular spaces for individuals from the different populations across three experimental treatments of salinity. Our results demonstrate that high water salinity levels affected anatomical traits in all populations. However, the traits of freshwater populations were the more significantly impacted by increasing salinity compared with populations sampled from naturally higher occurring salinity. Populations of U. arrecta established in places with certain degree of salinity can be more resistance to salt increases compared with populations established in freshwater habitats that are more distant geographically. However, the resistance of freshwater populations to certain high salinity levels suggests that these populations may exhibit rapid adaptation and to survive under some degree of salinity, demonstrating the species' high resilience across various environments.