Non-saline Water Research Articles

Numerical Modeling of the Fluids Petroleum Flow Through the Supersonic Separator

In the context of increasing concerns regarding the amplification of the thermal effects of climate change, the Council of the European Union has proposed the reduction (up to the elimination) of the use of fossil fuels. For this purpose, the implementation of new ecological (renewable) fuels is being analyzed to reduce the carbon dioxide footprint, natural gas being the transition fuel. Also, in the next period, an increase in the demand for methane, the exploitation of condensate deposits, those with natural gas mixed with acid gases (containing hydrogen sulfide, carbon dioxide, and nitrogen), as well as oil deposits with associated natural gas, which will require their treatment (to eliminate saline or non-saline water, mechanical impurities, of condensate and acid gases). At the same time, the exploitation of offshore deposits in deep waters will be emphasized, which will lead to the location of treatment equipment on the seabed. The present work discusses the simulation of natural gas treatment processes, focusing on the separation from methane (in the supersonic field) of water, condensate, and acid gases.

Reverse osmosis reject water management by immobilization into alkali-activated materials

Water-intensive industries face challenges due to water scarcity and pollution. In the management of these challenges, membrane processes play an important role. However, they produce significant amounts of reject waters, in which the separated salts and pollutants are concentrated. This study aims to develop a novel management concept for reject waters using alkali activation to immobilize salts in a solid phase using metakaolin, blast furnace slag (BFS), or their mixture as precursors and to create alkali-activated materials with sufficient properties to be potentially used in construction applications. Seven different waters were used to prepare the NaOH-based alkali activator solution: deionized water, three simulated seawaters with increasing salinity, and three reverse osmosis (RO) reject waters from mining or pulp and paper industries. Overall, BFS-based samples had the highest immobilization efficiency, likely due to the formation of layered double hydroxide phases (hydrotalcite, with anion exchange capacity) and hydrocalumite (chloride-containing mineral). Moreover, high-salinity water enhanced the dissolution of precursors, prolonged the setting time, and increased the compressive strength compared with nonsaline water. Thus, the obtained materials could be used in construction applications, such as backfilling material at mines where RO concentrates are commonly produced.

The efficiency of chlorophyll fluorescence as a selection criterion for salinity and climate aridity tolerance in barley genotypes.

In the Near East and North Africa (NENA) region, crop production is being affected by various abiotic factors, including freshwater scarcity, climate, and soil salinity. As a result, farmers in this region are in search of salt-tolerant crops that can thrive in these harsh environments, using poor-quality groundwater. The main staple food crop for most of the countries in this region, Tunisia included, is barley. The present study was designed to investigate the sensitivity and tolerance of six distinct barley genotypes to aridity and salinity stresses in five different natural field environments by measuring their photosynthetic activity. The results revealed that tolerant genotypes were significantly less affected by these stress factors than sensitive genotypes. The genotypes that were more susceptible to salinity and aridity stress exhibited a significant decline in their photosynthetic activity. Additionally, the fluorescence yields in growth phases J, I, and P declined significantly in the order of humid environment (BEJ), semi-arid site (KAI), and arid environment (MED) and became more significant when salt stress was added through the use of saline water for irrigation. The stress adversely affected the quantum yield of primary photochemistry (φP0), the quantum yield of electron transport (φE0), and the efficiency by trapped excitation (ψ0) in the vulnerable barley genotypes. Moreover, the performance index (PI) of the photosystem II (PSII) was found to be the most distinguishing parameter among the genotypes tested. The PI of sensitive genotypes was adversely affected by aridity and salinity. The PI of ICARDA20 and Konouz decreased by approximately 18% and 33%, respectively, when irrigated with non-saline water. The reduction was even greater, reaching 39%, for both genotypes when irrigated with saline water. However, tolerant genotypes Souihli and Batini 100/1B were less impacted by these stress factors.The fluorescence study provided insights into the photosynthetic apparatus of barley genotypes under stress. It enabled reliable salinity tolerance screening. Furthermore, the study confirmed that the chlorophyll a fluorescence induction curve had an inflection point (step K) even before the onset of visible signs of stress, indicating physiological disturbances, making chlorophyll fluorescence an effective tool for identifying salinity tolerance in barley.

Unary adsorption of sulfonamide antibiotics onto pozzolan-tyre ash based geopolymers: Isotherms, kinetics and mechanisms

In this contribution, geopolymer composites, GP0, GP5-TA and GP10-TA, were prepared by alkaline activation and substituting pozzolan (Pz) with 0, 5 and 10 wt% of tyre ash (TA), respectively. The geopolymers were characterized using standard methods (XRD, TGA, FTIR, BET, SEM, Boehm titration and methylene blue and iodine indices) and were applied for the abatement of two sulfonamides, sulfamethoxazole (SMX) and sulfadimethoxine (SDM) in single-solute solutions. The effects of pH, salinity, initial concentration and contact time were evaluated. The incorporation of 5 and 10% TA increased the specific surface area (SSA) of pristine geopolymer (GP0) from 13.62 to 21.48 and 29.70 m2.g−1, respectively. The equilibrium data was best described by the Sips isotherm model. Salinity significantly diminished the adsorption of SMX and SDM. In aqueous medium, the geopolymers exhibited higher adsorption capacity for SDM (log Kow, 1.17) relative to SMX (log Kow, 0.86). In contrast, in saline medium, SMX uptake was higher, suggesting a cation-mediated adsorption. Adsorption of SMX was uncharacteristically independent of pH, whereas SDM uptake was significantly pH-dependent. The GP5-TA geopolymer composite exhibited the highest adsorption capacity for SMX in a saline environment (46.69 mg.g−1) and for SDM in non-saline water (107.69 mg.g−1). Adsorption rate was described by the pseudo-second order kinetic law. Adsorption mechanism was multi-mechanistic involving hydrophobic, ion exchange and charge assisted hydrogen bonding and electrostatic interactions in the case of SDM. Future works should optimize the functional groups density of active sites especially for sulfonamides in saline waters.

Evaluation of saline and magnetized water on emitter hydraulic performance and clogging in drip irrigation

The present investigation was carried out at the National Irrigation Laboratory of Agricultural Engineering Research Institute (AEnRI), Dokki, Giza, Egypt. This study was performed to investigate the hydraulic performance and clogging ratio of drip irrigation with magnetized water. Magnetized water was created by transferring water through a permanent magnet connected to a feed pipeline. Two main treatments of magnetized and non-magnetized water, as well as three sub-treatments of irrigation water salts, including fresh water (219 ppm) and the addition of 1000 and 2000 ppm to irrigation water with three replications were applied under different operating pressure (75, 100, 125 and 150 kPa). At the beginning of the experiment, results show that hydraulic parameters were almost the same for both the magnetized and the non-magnetized water and for all salinity levels. At the end of working time, the hydraulic parameters were improved for the magnetized water under salinity levels compared to the non-magnetized water. Average emitter discharge increased with roughly 2.7% and 5.6%, coefficient of variation (Cv) decreased by 0.6 and 0.91%, emission uniformity (Eu) increased about 1 and 1.1% and variation of average flow rate (qavr) decreased by 21.3 and 29.4% when 1000 and 2000 ppm were used, respectively. Magnetized water had slight effect on clogging at non-saline water at the end of experiment. At 1000 and 2000 ppm salinity levels, the clogging ratio decreased by 1.97 and 2.45% at different pressure, respectively. The results show that magnetized water treatment could effectively relieve and delay the occurrence time of clogging.

Effect of Humic acid, Cytokinin and Arginine on Growth and Yield Traits of Bean Plant Phaseolus vulgaris L. under salt stress

To achieve optimal plant growth and production under salt stress, some products were added in adequate quantities to give a good yield, especially bean plants which are sensitive to salinity. For this purpose, this experiment was carried out during the spring growing season in 2022 in Baghdad, to study the effects of humic acid, cytokinin, arginine and their interaction with 9 parameters that reflect the overall traits of vegetative growth and yield of common bean plants Phaseolus vulgaris L. var. Astraid (from MONARCH seeds, China). The factorial design with 3 replicates was used, each with 7 plants treated via foliar spraying or by addition to the soil. The first factor included three groups; H0, H1 and H2 (0, 6, 12 Kg.h-1 Humic acid). The second factor included two groups; C0, and C1 [0, 100 mg.l-1 Cytokinins], and the third factor included three groups; A0, A1 and A2 (0, 100, 200 mg.l-1 Arginine). During the period of plant growing, furrow irrigation with drip pipe irrigation was used regularly with non-saline water EC= 2.2, during the first growth stage until it reaches the stage of four true leaves then irrigated with well saline water EC=3.4 for the rest of the plant life cycle. As for the treatment with humic acid, the results revealed that H2 treatment caused significantly higher values in most the studied traits. For cytokinin treatment, the results showed that C1 treatment resulted in significantly higher values in most the studied traits. And, there was no significant difference between A0, A1, and A2 except for leaves area, shoot dry weight, and root dry weight which exerts a significant difference between (A1, A2) in comparison to control A0. Based on the results of the binary overlap among treatments, H2C1, H2A2, H2A1 and, triple overlap H2C1A2 and H2C1A1 treatments resulted in the highest values as compared to all other treatments for all the studied traits. In conclusion, the present study comes up with the following: humic acid, cytokinin, arginine, and their interactions enhance most of the plant growth parameters and the pods production of common bean plants under salt stress.

How does calcium and sodium in saline water affect the potential of different rates and size of sugarcane biochar to soil water repellency remediation?

Soil water repellency (SWR) is a growing problem in arid and semiarid regions with non-saline water limitations. The objective of this study was to investigate the potential of different rates and sizes of sugarcane biochar on reducing soil water hydrophobicity when using saline and non-saline water. Eleven sugarcane biochar application rates from 0 to 10% with two different sizes including <0.25 and 0.25–1 mm were studied. The experiment was conducted in two strongly and extremely water-repellent soil. In addition, to investigate the effect of electrolyte concentration on biochar potential for SWR reduction, calcium chloride and sodium chloride electrolyte solutions with 5 concentrations including 0, 0.15, 0.3, 0.45 and 0.6 mol L−1 were considered. The results showed that both sizes of biochar reduced the soil water repellency. While in strongly repellent soil the 4% biochar was enough to change the soil from strongly repellent to hydrophilic, in extremely water-repellent soil, the use of 8% of fine biochar and 6% of coarse biochar changed the extremely water-repellent soil to slightly hydrophobic and strongly hydrophobic respectively. Increasing the electrolyte concentration caused the expansion of soil hydrophobicity and reduced the positive effect of biochar to water repellency management. Increasing the electrolyte concentration in sodium chloride solution has a greater effect on increasing hydrophobicity than in calcium chloride solution. In conclusion, biochar could suggest as a soil-wetting agent in these two hydrophobic soils. However, the salinity of water and the its dominant ion could increase the amount of biochar for soil repellency reduction.

Role of Polyamines in the Response to Salt Stress of Tomato.

Plants irrigated with saline solutions undergo osmotic and oxidative stresses, which affect their growth, photosynthetic activity and yield. Therefore, the use of saline water for irrigation, in addition to the increasing soil salinity, is one of the major threats to crop productivity worldwide. Plant tolerance to stressful conditions can be improved using different strategies, i.e., seed priming and acclimation, which elicit morphological and biochemical responses to overcome stress. In this work, we evaluated the combined effect of priming and acclimation on salt stress response of a tomato cultivar (Solanum lycopersicum L.), very sensitive to salinity. Chemical priming of seeds was performed by treating seeds with polyamines (PAs): 2.5 mM putrescine (PUT), 2.5 mM spermine (SPM) and 2.5 mM spermidine (SPD). Germinated seeds of primed and non-primed (controls) were sown in non-saline soil. The acclimation consisted of irrigating the seedlings for 2 weeks with tap water, followed by irrigation with saline and non-saline water for 4 weeks. At the end of the growth period, morphological, physiological and biochemical parameters were determined. The positive effects of combined treatments were evident, when primed plants were compared to non-primed, grown under the same conditions. Priming with PAs improved tolerance to salt stress, reduced the negative effects of salinity on growth, improved membrane integrity, and increased photosynthetic pigments, proline and enzymatic and non-enzymatic antioxidant responses in all salt-exposed plants. These results may open new perspectives and strategies to increase tolerance to salt stress in sensitive species, such as tomato.

Effect of Recurrent Salt and Drought Stress Treatments on the Endangered Halophyte Limonium angustebracteatum Erben

Limonium angustebracteatum is an endemic halophyte from the Spanish Mediterranean coastal salt marshes. To investigate this species' ability to cope with recurrent drought and salt stress, one-year-old plants were subjected to two salt stress treatments (watering with 0.5 and 1 M NaCl solutions), one water stress treatment (complete irrigation withholding), or watered with non-saline water for the control, across three phases: first stress (30 days), recovery from both stresses (15 days), and second stress (15 days). Growth and biochemical parameters were determined after each period. The plants showed high salt tolerance but were sensitive to water deficit, as shown by the decrease in leaf fresh weight and water content, root water content, and photosynthetic pigments levels in response to the first water stress; then, they were restored to the respective control values upon recovery. Salt tolerance was partly based on the accumulation of Na+, Cl- and Ca2+ in the roots and predominantly in the leaves; ion levels also decreased to control values during recovery. Organic osmolytes (proline and total soluble sugars), oxidative stress markers (malondialdehyde and H2O2), and antioxidant compounds (total phenolic compounds and flavonoids) increased by various degrees under the first salt and water stress treatments, and declined after recovery. The analysed variables increased again, but generally to a lesser extent, during the second stress phase, suggesting the occurrence of stress acclimation acquired by the activation of defence mechanisms during the first stress period.

Redução do estresse salino em quiabeiro sob fertirrigação potássica

ABSTRACT Potassium fertigation may be a strategy to reduce saline stress in okra. The objective of this study was to analyze the effect of potassium supplementation as a salinity-attenuating agent in okra. The experiment was conducted in a greenhouse at the Federal Rural University of the Semi-Arid Region, in Mossoró-RN, Brazil. The experimental design was completely randomized, in 2x5 factorial scheme with 4 replicates. Two okra cultivars (Santa Cruz 47 and Valença) fertigated with five fertigation managements [F1= irrigation with non-saline water (0.55 dS/m) and fertigation with a standard dose of potassium (6 g/plant); F2= irrigation with saline water (3.5 dS/m) and fertigation with 6 g/plant of K, F3= irrigation with saline water (3.5 dS/m) and fertigation with 9 g/plant of K, F4= irrigation with saline water (3.5 dS/m) and fertigation with 12 g/plant of K, and F5= irrigation with saline water (3.5 dS/m) and fertigation with 15 g/plant of K]. Plants were collected 110 days after emergence and evaluated for growth variables (leaf number, leaf area, leaf dry mass, stem dry mass, total dry mass) and yield (fruit number, average fruit mass and fruit production). Potassium influenced the growth and yield characteristics of okra irrigated with saline water. The highest yields of fruits occurred at 9.56 and 10.23 g/plant of K, being 330.24 and 733.36 g/plant obtained from cultivars Santa Cruz 47 and Valença, respectively. Okra irrigated with saline water is more demanding in potassium.

Successive addition of rice straw biochar enhances carbon accumulation in soil irrigated with saline or non-saline water

Biochar has been evaluated globally to improve soil fertility and mitigate climate change. However, the long-term effects of successive biochar application on carbon (C) accumulation in soil irrigated with saline versus non-saline water (canal water) has not been investigated. A field experiment was conducted to study the effects of rice straw biochar addition rates (0, 2, 4, 8 Mg ha−1) on C storage in soil irrigated with water of different electrical conductivity [EC, dS m−1]; 0.3 (non-saline canal irrigation water; CIW), 5 (saline irrigation water; SIW5), 10 (SIW10), and 15 (SIW15) in a cotton-wheat system. Long-term irrigation with saline water of variable EC levels adversely affected soil functions, reducing above-ground biomass in cotton (12–48%) and wheat (5–27%). In contrast, plots irrigated with saline water but amended with rice straw biochar showed significant improvement in aboveground biomass (both in cotton and wheat), possibly due to its beneficial effects on soil properties such as soil EC, organic carbon, microbial population, water and nutrient availability, bulk density, soil aggregation, and proliferation of roots. Interestingly, the change in total organic C (TOC) stocks (8.5, 17, and 27.5 Mg C ha−1) after 5 years were found to be almost double the amount of biochar C added (4.3, 8.6, 17.2 Mg ha−1), indicating stabilization of belowground C inputs from the root biomass by the applied biochar and also possibly through its physical interaction with aggregates and minerals. Even though biochar application to saline water irrigated plots increased the contribution of plant-derived C to overall soil TOC stocks, it was still lower compared with canal water irrigated plots. The study conclusively established that the long-term stabilization of biogenic C through biochar has essential implications for mitigating climate change by accumulating additional C beyond the recalcitrant C contained in biochar.

Irrigation water salinity structures the bacterial communities of date palm (Phoenix dactylifera)-associated bulk soil.

The irrigation of date palms (Phoenix dactylifera) with saline groundwater is routinely practiced in the agroecosystems of arid environments because of freshwater scarcity. This leads to salts deposition in topsoil layers and increases soil salinization. However, how different irrigation sources affect soil microbiota is poorly understood. Bulk soil samples were collected from date farms receiving non-saline water and saline groundwater to examine bacterial communities using metabarcoding. Overall, bacterial diversity measures (Shannon diversity index, richness, and evenness) did not vary between irrigation sources. Bacterial communities were structured based on irrigation water sources and were significantly associated with their electrical conductivity. Of 5,155 operational taxonomic units (OTUs), 21.3% were unique to soil irrigated with saline groundwater, 31.5% received non-saline water irrigation, and 47.2% were shared. The Proteobacteria abundance was higher in soil under saline groundwater irrigation while Actinobacteriota abundance was lower. A compositional shift at the genera level was also evident; the abundance of Subgroup_10 and Mycobacterium was higher under saline groundwater irrigation. Mycobacterium was a key indicator of OTU under saline groundwater irrigation while Solirubrobacter was an indicator of non-saline water irrigation. Functional gene analyses showed enrichment of fatty acid, cell wall, and starch biosynthesis pathways in soil under saline groundwater irrigation. These findings provide insights into how “salinity filtering” influences bacterial communities, key taxa, and the potential metabolic function in soil under increasing irrigation water salinities, and have broad implications for arid agroecosystems.

Salinity of irrigation water selects distinct bacterial communities associated with date palm (Phoenix dactylifera L.) root

Saline water irrigation has been used in date palm (Phoenix dactylifera L.) agriculture as an alternative to non-saline water due to water scarcity in hyper-arid environments. However, the knowledge pertaining to saline water irrigation impact on the root-associated bacterial communities of arid agroecosystems is scarce. In this study, we investigated the effect of irrigation sources (non-saline freshwater vs saline groundwater) on date palm root-associated bacterial communities using 16S rDNA metabarcoding. The bacterial richness, Shannon diversity and evenness didn’t differ significantly between the irrigation sources. Soil electrical conductivity (EC) and irrigation water pH were negatively related to Shannon diversity and evenness respectively, while soil organic matter displayed a positive correlation with Shannon diversity. 40.5% of total Operational Taxonomic Units were unique to non-saline freshwater irrigation, while 26% were unique to saline groundwater irrigation. The multivariate analyses displayed strong structuring of bacterial communities according to irrigation sources, and both soil EC and irrigation water pH were the major factors affecting bacterial communities. The genera Bacillus, Micromonospora and Mycobacterium were dominated while saline water irrigation whereas contrasting pattern was observed for Rhizobium, Streptomyces and Acidibacter. Taken together, we suggest that date-palm roots select specific bacterial taxa under saline groundwater irrigation, which possibly help in alleviating salinity stress and promote growth of the host plant.

Assessment of a Biocompatible Additive for Hydrate Formation Kinetics along with Morphological Observations and Model Predictions

Innovative gas hydrate-based applications and hydrate flow assurance problems of oil & gas pipelines have enabled new opportunities to develop and deploy biocompatible or green low-dosage hydrate promoters and inhibitors, respectively. In this context, we evaluate the performance of a biocompatible additive, lecithin (extracted from egg yolk), for the formation kinetics of binary cyclopentane (CP)-carbon dioxide (CO2) hydrates simulating to the structure-II hydrate of natural gas. A high-pressure visual autoclave is employed in this study to map the morphological observations with the gas hydrate kinetic data. Multiple experiments are performed to examine the inhibition or promotional effect of lecithin in saline (3.0 wt % NaCl) and non-saline water systems at low pressure of 1.0 MPa while utilizing the various CP content (1.5, 3.0, and 6.0 mol%) and 500 to 5000 ppm of lecithin. Moreover, we evaluate the effect of salinity and lecithin on the thermodynamic hydrate equilibrium conditions. The results imply that the presence of lecithin retards the hydrate formation kinetics. However, no shift in the equilibrium frontier is observed. Importantly, we propose a chemical potential based kinetic model by accounting the influence of additives, vapor-liquid interfacial area, temperature and pressure on gas hydrate formation. This model has closely interpreted the experimental data of hydrate former uptake during binary hydrate formation in the presence and absence of lecithin. Our findings highlight the potential of engaging lecithin for hydrate inhibition to mitigate the flow assurance issues and also offer comprehensive insights toward integrated hydrate-based carbon capture and seawater desalination approach.

Numerical modeling and evaluation of lab-scale CO2-injection experiments based on electrical resistivity measurements

This paper presents numerical models for validating electrical resistivity (ER)-derived carbon dioxide (CO2) saturation obtained from lab-scale CO2 flooding experiments. ER assessments have generally been implemented using Archie's empirical equation, but it is only applicable to non-saline water, homogeneous medium, and non-conductive minerals. Therefore, it is necessary to develop a reliable numerical model to scale up experimental results by calibrating uncertain properties, such as capillary pressure, relative permeability, and aquifer heterogeneity. Cylindrical sandstone samples from the homogeneous Berea sandstone and heterogeneous Tako sandstone were prepared to evaluate CO2 transport within brine-saturated media. The reliability of the numerical method was verified by the trajectories of ER-derived CO2 saturation (SCO2) in the homogeneous Berea sandstone, which showed similar profiles and a root mean square error (RMSE) of 0.0503. The aquifer heterogeneity of the Tako sandstone influenced CO2 transport, i.e., its frontal velocity, by producing retardation at the less porous layers, whereas the homogeneous Berea sandstone showed consistent movement of the CO2 front. The numerical simulation of the heterogeneous Tako sandstone confirmed the effects of the less porous layers and matched the experimental profiles of SCO2, with an RMSE of 0.0421. The developed models enable validation of ER-derived SCO2 at the early stage and forecasting of the CO2 distribution in heterogeneous saline aquifers.

Biochar Reduces the Adverse Effect of Saline Water on Soil Properties and Wheat Production Profitability

The goal of this study is to assess the use of saline groundwater in combination with soil amendments to increase the efficiency of wheat production in new agricultural soil in Egypt. The experiment was conducted during the two consecutive growing seasons, 2019/2020 and 2020/2021, at the Shandaweel Agricultural Research Station, Sohag, Egypt. In this study, plants of Shandaweel 1 spring bread wheat cultivar were grown under the combinations of the two water treatments, i.e., freshwater (307.2 ppm) and saline water (3000 ppm (NaCl + MgCl2)) representing groundwater in Egypt delivered by drip irrigation and the two biochar rates, i.e., zero and 4.8 ton/ha as a soil amendment. The cob corn biochar (CCB) was synthesized by using the slow pyrolysis process (one hour at 350 °C). The results revealed that saline water reduced the grain yield ratio by 8.5%, 11.0%, and 9.7% compared to non-saline water during seasons 2019/2020 and 2020/2021 and over seasons, respectively. Concerning, combined over seasons, the biochar addition enhanced the grain yield by 5.6% and 13.8% compared to non-biochar addition under fresh and saline irrigation water conditions, respectively. Thus, the results indicated and led to a preliminary recommendation that saline groundwater is a viable source of irrigation water and that biochar seemed to alleviate salinity stress on wheat production and in reclaimed soils of Egypt.

EFFECT OF SALINE AND NON-SALINE WATER ON OKRA CROP PRODUCTION

Under the situation of acute water crises and the regular or occasional use of marginal to saline groundwater by the farming community to cultivate the crops, the research needs to be conducted on the use of marginal to saline groundwater based on the guidelines and strategies for the effective use be developed. In context of this, the experiment was conducted at the field research station of the laboratory of the Department of Land and Water Management (LWM) Faculty of Agricultural Engineering (FAE), Sindh Agriculture University (SAU) Tandojam during the year 2019. The experiment was arranged in a completely randomized design with three treatments of varying water qualities with three replications were deployed. The treatments were: W1 = non-Saline water (canal water) E.C= 1.0 dS m-1, W2 = Saline water (groundwater) EC= 4 dS/m-1and W3= Saline water (groundwater) EC= 6 dS/m-1. Okra crop was grown on ridges. The results showed that the soil EC decreased 0.76 dS/m-1 under T1, and increased 0.83 and 1.33 dS/m-1 under T2 and T3, respectively. The soil pH decreased by 0.29, 0.43, and 0.44 under T1, T2, and T3. The soil Mg increased 21.57, 22.11, and 27.03; soil SAR increased 6.15, 7.82, and 8.91; and soil ESP increased 6.51, 8.61, and 10.33 under T1, T2, and T3, respectively. The soil Ca decreased 1.34 under T1 treatment; and increased 0.30 and 10.28 under T2 and T3, respectively. The maximum yield of 18500 kg ha-1 was found with T1 followed by 17391 kg ha-1 with T2 and the lowest yield of 16836 kg ha-1 was found with T3. The highest water productivity of 1.91 kg m-3 was found with T1 treatment followed by 1.79 kg m-3 with T2 treatment and the lowest water productivity of 1.73 kg m-3 was found with T3 treatment.

Calcium supplementation in nutrient solutions to mitigate salt stress in fertigated okra

ABSTRACT The objective of this study was to evaluate the effect of calcium supplementation on saline water as a minimizing agent of saline stress in okra cultivars. The experiment was carried out in a greenhouse in Mossoró-RN using a completely randomized experimental design in a 2x5 factorial scheme with four replications. Two okra cultivars (Santa Cruz 47 and Valença) were tested fertigated with five fertigation managements [F1= irrigation with non-saline water (0.5 dS m-1) and fertigation with a standard dose of calcium (4,733.8 mg plant-1); F2, F3, F4 and F5= irrigation with saline water (3.5 dS m-1) and fertigation with increasing doses of calcium (4,733.8; 7,100.7; 9,467.7 and 11,834.5 mg plant-1, respectively)]. Plants were collected at 120 days after emergence and evaluated for growth variables (plant height, leaf number, stem diameter, leaf dry mass, stem, fruit and total) and yield (fruit number, average length of fruits, average diameter and yield). Cultivar Santa Cruz 47 presented the highest vegetative development but cultivar Valença was earlier and presented the largest number of harvests (19), allowing more harvested fruits (27 fruits per plant) and the highest yield (659 g plant-1). The cultivars were not affected by the saline level and showed little response to extra calcium fertilization.

Rice growth in a combined submergence and salinity stresses

The occurrence of submergence in agricultural land is increased by the climate change. The level of tolerance in crops depends on many factors including plant stages, duration of submergence. Level of crop tolerance to submergence is likely to decrease when other adverse factors such as salinity exist. Two experiments have been conducted to study the effect of a combined submergence and salinity on rice growth. First experiment studied the salt tolerance at early seedling stage while submerged. Split plot design was used with oxygen concentrations (with and without aeration) as the main plot and salinity levels (0.2, 50, 100 dan 150 mM NaCl) as the sub plot. Second experiment evaluated the length of submergence (one and two weeks) and salinity levels (0.2 and 50 mM NaCl) at older stages rice plants. The results showed that at early stages of seedlings, almost all growth variables have been decreased by salinity. The oxygen deficit reduced salt tolerance in rice seedlings. At older stages of rice, one-week submergence did not reduce rice growth. However, for two weeks submergence, rice submerged in saline water showed better growth compared to those submerged in non-saline water.

Calcium in the mineral nutrition of yellow passion fruit cultivated in lined pits and with saline water

ABSTRACT Nutritional status is an important tool in salinity management, because salt stress interferes with both the absorption and the assimilation of mineral nutrients by plants. The objectives of this experiment were to evaluate the effects of water salinity, lateral protection of pits against water losses and calcium doses on the leaf concentration of macronutrients and sodium of yellow passion fruit cv. BRS GA1. The treatments were arranged in a randomized block design in split plots in a 2 × (2 × 5) factorial scheme, corresponding to water salinity (0.3 and 4.0 dS m-1) in the main plot, and the combinations between lateral protection of pits (without and with) and calcium doses (0, 30, 60, 90 and 120 kg ha-1) in the subplots. Leaf concentrations of macronutrients and sodium were determined at the phenological stage of full flowering. Irrigation of yellow passion fruit with 4.0 dS m-1 water decreased the leaf concentrations of macronutrients. The lining of the pits compromised macronutrient concentration in the plants. Calcium fertilization is recommended for yellow passion fruit cultivated in Entisol with low calcium concentration at the dose of 60 kg ha-1, because it raises nitrogen and calcium concentrations in plants irrigated with non-saline water and magnesium and sulfur concentrations in those irrigated with saline water. Calcium attenuates salt stress because it promotes the accumulation of macronutrients in yellow passion fruit under saline conditions.