Influence of salinity in irrigation water on forage sorghum and soil chemical properties

Abstract

Soluble salts found in wastewater can be toxic when used for irrigation of forages. Thus, two greenhouse experiments were conducted to investigate effects of saline [CaCl₂NaCl (3:1, w:w)] treatments on soil chemical properties and ‘Dekalb FS‐5’ forage sorghum [Sorghum bicolor(L.) Moench]. Treatments for the first experiment consisted of a nonsaline control or 500 mL of a solution with an electrical conductivity (EC) of 10 dS m^?1 applied once. In the second experiment, treatments were salinity levels of 1.7,3.5,5.2,8.5, and 12.2 dS m^?1, applied in non‐nitrogenous Hoagland's solution as the sole source of irrigation. Both experiments were replicated four times. For both experiments forage sorghum was seeded in pots containing 7 kg of air‐dried Amarillo fine sandy loam soil. Sorghum survivability and plant height were measured. In the second experiment, water use by sorghum was also measured. Plants were harvested 7 wk after seeding, weighed, dried at 55°C, weighed, and ground for subsequent mineral analysis. After harvest, soil salinity, pH, and in the second experiment, extractable soil elements were determined. Soil salinity increased, while soil pH decreased, with the salinity treatments. Extracted soil calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), manganese (Mn), and cadmium (Cd) increased while sulfur (S), iron (Fe), and copper (Cu) decreased, and aluminum (Al) and zinc (Zn) exhibited no change with increasing salinity. Sorghum aerial plant and root production decreased with increasing salinity. Plant Ca, strontium (Sr), Mn, and Cd levels increased with increasing salinity. In contrast, sorghum K, P, and S levels declined with increasing salinity.     

Effect of Magnesium Chloride–Induced Salinity on Carbon Dioxide Evolution and Nitrogen Mineralization in a Silty Clay Loam Soil

A laboratory incubation experiment was conducted to evaluate the effect of magnesium chloride–induced salinity on carbon dioxide (CO₂) evolution and nitrogen (N) mineralization in a silty loam nonsaline alkaline soil. Magnesium chloride (MgCl₂) salinity was induced at 0, 4, 8, 12, 16, 20, 30, and 40.0 dS m^?1 and measured CO₂ evolution and N mineralization during 30 days of incubation. Both CO₂ evolution and N mineralization decreased significantly with increasing salinity. The cumulative CO₂ evolution decreased from 235 mg kg^?1 soil at electrical conductivity (EC) 0.65 dS m^?1 to 11.9 mg kg^?1 soil at 40 dS m^?1 during 30 days of incubation. Similarly, N mineralization decreased from 185.4 mg kg^?1 at EC 0.65 dS m^?1 to 34.45 mg kg^?1 at EC 40.0 dS m^?1 during the same period. These results suggested that increasing magnesium chloride salinity from 4 dS m^?1 adversely affect microbial activity in terms of carbon dioxide evolution and N mineralization.     

TREATED EFFLUENT AND SALINE WATER IRRIGATION INFLUENCES SOIL PROPERTIES,YIELD, WATER PRODUCTIVITY AND SODIUM CONTENT OF SNOW PEAS AND CELERY

To determine the effects of irrigation water quality, plants were irrigated with normal potable water [0.25 dS m^?1 electrical conductivity (EC), 25 mg L^?1 sodium (Na), 55 mg L^?1 chloride (Cl)], treated effluent (0.94 dS m^?1 EC, 122 mg L^?1 Na, 143 mg L^?1 Cl) and saline water with low salinity (1.24 dS m^?1 EC, 144 mg L^?1 Na and 358 mg L^?1 Cl) and high salinity (2.19 dS m^?1 EC, 264 mg L ^?1Na and 662 mg L^?1 Cl) for snow peas, and high salinity (3.07 dS m^?1 EC, 383 mg L^?1 Na and 965 mg L^?1 Cl) and very high salinity (5.83 dS m^?1 EC, 741 mg L^?1 Na and 1876 mg L^?1 Cl) for celery. The greater salts build up in the soil and ion toxicity (Cl and Na) with saline water irrigation contributed to significantly greater reduction in root and shoot biomass, water use, yield and water productivity (yield kg kL^?1 of water used) of snow peas and celery compared with treated effluent and potable water irrigation. There was 8%, 56% and 74% reduction in celery yield respectively with treated effluent, high salinity and very high salinity saline water irrigation compared with potable water irrigation. The Na concentration in snow peas shoots increased by 54%, 234% and 501% with treated effluent, low and high salinity saline water irrigation. Similarly, the increases in Na concentration in celery shoots were 19%, 35% and 82%. The treated effluent irrigation also resulted in a significant increase in soil EC, nitrogen (N) and phosphorus (P) content compared with potable water irrigation. The heavy metals besides salts build up appears to have contributed to yield reductions with treated effluent irrigation. The study reveals strong implications for the use of saline water and treated effluent for irrigation of snow peas and celery. The salt build up within the root zone and soil environment would be critical in the long-run with the use of saline water and treated effluent for irrigation of crops. To minimize the salinity level in rhizosphere, an alternate irrigation of potable water with treated effluent or low salinity level water may be better option.     

Different Levels of Irrigation Water Salinity and Biochar Influence on Faba Bean Yield,Water Productivity,and Ions Uptake

Greenhouse experiment was conducted to investigate the effect of different levels of irrigation water salinity (0.5, 2.5, 5 and 7.5 dS m^?1) and wheat straw biochar (0%, 1.25%, 2.5%, and 3.75% w/w) on growth and yield of faba been using complete randomized design with three replications. Stomatal conductance (green canopy temperature) of faba bean increased (decreased) by application of biochar at each salinity level. The results showed increasing salinity to 2.5 dS m^?1 at zero biochar application increased the seed yield through osmotic adjustment, while by declining the osmotic potential, the nutritional values of biochar caused the seed yield to increase by increasing salinity to 5 dS m^?1. The root length density and root dry weight density in 0–8 cm soil layer declined under application of 3.75% w/w biochar in all salinity levels in comparison with that obtained in 2.5% w/w biochar, due to higher saline condition of the soil as result of higher biochar application. The results showed that addition of 2.5% w/w biochar can significantly mitigate salinity stress due to its high salt sorption capacity and by increasing potassium/sodium ratio in the soil. In general, since 2.5 % w/w biochar and salinity of 5 dS m^?1 increased dry seed yield and irrigation water productivity compared with that obtained in control (B₀S_0.5), these levels are recommended to improve faba bean growth and yield; however, these levels have to be evaluated under field conditions.     

IMPACT OF SALT STRESS ON MICRONUTRIENTS IN CORDYLINE FRUTICOSA VAR. ‘RED EDGE'

This trial was carried out to study the influence of the nutrient solution on the microelements concentration and distribution in C. fruticosa var. ‘Red Edge' plants. Four treatments were tested: T₁ [control, 1.5 dS m^?1, 14.3 mmol L^?1 sodium chloride (NaCl)], T₂ (2.5 dS m^?1, 22.2 mmol L^?1 NaCl), T₃ (3.5 dS m^?1, 32.7 mmol L^?1 NaCl) and T₄ (4.5 dS m^?1, 38.2 mmol L^?1 NaCl). In roots and stems, iron (Fe) concentrations were lower in the no saline treatment. Stems accumulated more Fe with treatments T₃ and T₄. Copper concentration and extraction were not affected by salinity. The highest manganese (Mn) concentration in roots was observed in T₂, while in petioles was higher in T₃ and T₄. Manganese extraction reached higher levels in the saline treatments in roots and stems, while in petioles it was lower in T₁, T₂ and T₃. In roots, zinc (Zn) concentration was lower with the extreme treatments. Micronutrients concentration in leaves was unaffected by salinity, because an exclusion mechanism that consists on accumulation in roots and stems was developed.     

Effects of Silicon Application on Wheat Growth and Some Physiological Characteristics under Different Levels and Sources of Salinity

We investigated the effects of silicon (Si) and the levels and sources of salinity on the growth and some physiological properties of wheat (Triticum aestivum cv. Chamran) in a sandy loam soil under greenhouse conditions. Treatments comprised four Si levels (8, 50, 100 and 150 mg kg^?1 soil), four salinity levels (0.46, 4, 8 and 12 dS m^?1) and two salinity sources (sodium chloride (NaCl) and four-salt combination). Salts combination included NaCl, sodium sulfate (Na₂SO₄), calcium chloride (CaCl₂) and magnesium sulfate (MgSO₄) at a molar ratio of 4:2:2:1. The experiment was arranged as a completely randomized design in a factorial manner, with three replications. Increasing salinity level resulted in a significant decrease in shoot dry weight, chlorophyll content and catalase (CAT) activity, and it caused a marked increase in proline and glycine betaine (GB) concentrations and superoxide dismutase (SOD) enzyme activity. The stimulating effect on GB accumulation and SOD activity was more intense in NaCl-treated plants. However, the source of salinity had no significant effect on shoot dry weight, chlorophyll and proline concentrations, and CAT activity. Si application enhanced all the above-mentioned parameters, except for proline. The suppressing effect of salinity on shoot dry weight, chlorophyll concentration and CAT activity was alleviated by Si supplementation. The stimulating effects of Si fertilization on shoot dry weight and chlorophyll concentration became more pronounced at higher salinity levels. It could be concluded that a decrease in soil osmotic potential, nutrient imbalance and increasing reactive oxygen species (ROS) in salt-treated plants caused growth suppression, while Si supply decreased the deleterious effects of excess salt on wheat growth. Consequently, it appears that when wheat plants are to be grown in salt-affected soils, it is highly recommended to supply them with adequate available silicon (Si).     

EFFECTS OF MYCORRHIZAL FUNGI ON TOLERANCE CAPABILITY OF CORN GROWN UNDER SALT STRESS CONDITION

A greenhouse experiment was conducted to determine the effect of salinity on the efficacy of two arbuscular mycorrhizal fungi (AMF), Glomus mossea and natural mycorrhiza, of Glomus species, was investigated in terms of growth and nutrition of corn plant (Zea mays L). Plants were grown under different salinity levels imposed by 2.0, 2.5, 3.5, 5.0, 8.0, 12.0 dS m^?1of Hoagland's Solution [sodium chloride (NaCl), sodium sulfate (Na₂SO₄)_, Calcium dichloride (CaCl₂), and magnesium sulfate (MgSO₄) 7:9:3:1 ratio, respectively]. Both types of mycorrhizal fungi did not display significant protection in the host plant against the detrimental effects of the soil salinity. The effect of inoculation on growth varied only with the level of salinity. Maximum root colonization and spore numbers were observed in plants cultivated with low salinity levels. It was found that significant interaction between AMF x Salinity level for calcium (Ca), magnesium (Mg), iron (Fe), zinc (Zn), and manganese (Mn) of shoot, and for Zn and Mn, of root.     

Performance of Some Wheat Cultivars Under Saline Irrigation Water in Field Conditions

Most of the crop salt tolerance studies are often conducted in a glasshouse and are limited under field conditions. Therefore, the present research study was conducted under field conditions to evaluate the performance of six wheat cultivars at five salinity levels (EC 0, 3, 6, 9, and 12 dS m^?1) in split plot design with three replications. Increasing salinity significantly increased soil pH, electrical conductivity (EC), and sodium adsorption ratio (SAR). Yield parameters of different cultivars were affected more at higher salinity levels than lower in two years. Data over two years revealed that up to EC 9 dS m^?1 cultivars PBW 658 and HD 2967 performed ???better on the absolute yield basis but PBW 621 produced ?higher relative yield. At EC 12 dS m^?1, PBW 658 produced significantly higher grain yield (4.23 t ha^?1) than cultivars HD 2967 (4.11 t ha^?1) and PBW 621 (3.99 t ha^?1); therefore, should be preferred at salinity more than 9 dS m^?1.     

Sodicity Intensifies the Effect of Salinity on Grain Yield and Yield Components of Wheat

ABSTRACT

This study reports the relationship of the leaf ionic composition with the grain yield and yield components of wheat in response to salinity x sodicity and salinity alone. The study was conducted in soil culture in pots with three treatments including control (ECe 2.6 dS m^{? 1} and SAR 4.53), salinity (ECe 15 dS m^{? 1} and SAR 9.56), and salinity x sodicity (ECe 15 dS m^{? 1} and SAR 35). The soil was treated before being put in the pots and the pots were arranged in a completely randomized factorial arrangement with five replications. The seeds of three wheat genotypes were sown directly in the pots and the study was continued till the crop maturity. At booting stage, the leaf second to the flag leaf of each plant was collected and analyzed for sodium (Na⁺), potassium (K⁺), and chloride (Cl^?). At maturity, plants were harvested and data regarding grain yield and yield components were recorded. This study shows that salinity and sodicity in combination decreases the grain yield of wheat more than the salinity alone with a greater difference in the sensitive genotype. This study also shows that as for salinity, the maintenance of lower Na⁺ and higher K⁺ concentrations and higher K⁺: Na⁺ ratio in the leaves relates positively with the better development of different yield components and higher grain yield in saline sodic soil conditions. Although, the leaf Cl^? concentration was increased significantly by salinity as well as salinity x sodicity and would have affected the growth and yield, yet it does not seem to determine the genotypic tolerance or sensitivity to either salinity or salinity x sodicity.     

Effects of NaCl salinity on some leaf nutrient concentrations,non-photochemical quenching and the efficiency of the PSII photochemistry of two Iranian pomegranate varieties under greenhouse and field conditions: Preliminary results

The present research was conducted to study the responses of ‘Malas–e–Saveh’ (M) and ‘Shishe–Kab’ (Sh) Iranian pomegranates to sodium chloride (NaCl) stress under greenhouse and field conditions. Treatments included waters electrical conductivity (EC = 1.5, 3, 6, 9 and 12 dS m^?1 for greenhouse) and (EC = 1.05 as control, 4.61 and 7.46 dS m^?1 for field studies). Interactive effects of salinity × variety indicated the highest chlorophyll and leaf potassium concentration, and the lowest leaf chloride and sodium in control under greenhouse study. Non-photochemical quenching, effective quantum yield of photochemical energy conversion in PSII reduced under the highest salinity level in field, however, basal quantum yield of non-photochemical processes in PSII increased in the highest salinity. Sodium and chloride increased with increased in salinity. Calcium, magnesium and iron significantly decreased with increased in salinity. It seems that there are differences between pomegranate cultivars and Malas-e-Saveh is more tolerant compared with Shishe Kab.     

Effects of Nutrient and NaCl Salinity on Growth,Yield, Quality and Composition of Pepper Grown in Soilless Closed System

The effects of nutrient or sodium chloride (NaCl) salinity on pepper grown in closed soilless culture systems were studied. A control (2 dS m^?1) and two saline nutrient solutions (4 dS m^?1) differing in the salt sources (fertilizers or NaCl) were studied. Shoot biomass production as well as total and marketable yield were more affected by NaCl than nutrient salinity. Fruit dry matter and total soluble solids increased in both salinity treatments compared to the control. Total phenol content rose slightly (10%) with NaCl salinity, while the concentration of carotenoids was enhanced by 40% with NaCl compared to the control and nutrient salinity. The results showed that the response of pepper to salinity is both osmotic and ion specific, but a more negative effect was recorded under NaCl stress. Moreover, the highest content of antioxidant compounds in NaCl treated fruits may indicate that NaCl caused more stressful conditions than nutrient salinity.     

Differential responses of three chamomile genotypes to salinity stress with respect to physiological,morphological, and phytochemical characteristics

Effect of water salinity was studied in different Matricaria recutita L. genotypes (Isfahan, Ahvaz, and Shiraz) to understand their protective mechanisms and agronomic performance. Based on a split-plot design arranged in a randomized complete-block consisted of four salinity levels as the main plot and three genotypes as the subplots with three replications this field experiment was conducted in 36 plots with 3 m² space in the Isfahan Center for Research of Agricultural Science and Natural Resources during 2014–2015. The findings showed that the three genotypes differed in resistance to salinity and tolerance mechanisms. They have evolved different physiological, morphological, and biochemical adaptations to salt stress. The Ahvaz genotype in the absence of salt, the Isfahan genotype at 6, and the Shiraz genotype at 9 and 12 dS m^?1 sodium chloride (NaCl) were desirable, taking both quantity and quality into consideration. While preserving shoot growth, the Isfahan genotype was more tolerant to 6 dS m^?1 NaCl most likely due to peroxidase activity. The resistance of the Shiraz genotype is associated with root growth stimulation at 9 and Na compartmentation in root at 12 dS m^?1 NaCl. The Isfahan genotype had the highest oil and chamazulene content, which was not affected by salinity. The Shiraz genotype in the control treatment, the Isfahan genotype at 6 and 9 and the Ahavaz genotype at 12 dS m^?1 NaCl synthesized higher flavonoid compounds.     

INVESTIGATION OF SALINITY STRESS AND POTASSIUM LEVELS ON MORPHOPHYSIOLOGICAL CHARACTERISTICS OF SAFFRON

A greenhouse research experiment was conducted to investigate the effect of salinity stress and potassium (K) fertilization on biomass accumulation of roots and shoot of saffron plants. Treatments were four levels salinity in the form of sodium chloride (NaCl; 3.4, 6.4, 9.4 and 12.4 dS m^?1) and three levels of potassium (50, 100, and 150 % of Hoagland's nutrition solution base). Results indicated that higher levels of potassium significantly controlled the negative effects of NaCl on length and number of roots as well as fresh weight and number of leaves per plant. Increase in salinity and potassium levels caused a reduction in leaf water content, and enhancement in electrolyte leakage. It seems that in the presence of salinity increasing 50% extra potassium (Based on Hoagland's nutrient solution) in the rhizosphere of saffron can improve damaging effects of NaCl up to 9.4 dS m^?1 of soil solution.     

Response of soil microbial community and diversity to increasing water salinity and nitrogen fertilization rate in an arid soil

The scarcity of fresh water has forced farmers to use saline water (SW) for irrigation. It is important to understand the response of the soil microbial community and diversity to saline irrigation water. The objective of this study was to determine the effects of irrigation water salinity and nitrogen fertilization rates on soil physicochemical properties, microbial activity, microbial biomass, and microbial functional diversity. The field experiment consisted of a factorial design with three levels of irrigation water salinity (electrical conductivities (ECs) of 0.35, 4.61 or 8.04?dS?m^?1) and two nitrogen rates (0 and 360?kg?N?ha^?1). The results showed that the 4.61 and 8.04?dS?m^?1 treatments both reduced soil microbial biomass C (MBC), microbial biomass N (MBN), basal respiration, total phospholipid fatty acid (PLFA), bacterial PLFA, fungal PLFA, and fungal:bacterial ratios. In contrast, the SW treatments increased the MBC:MBN ratio. Nitrogen fertilization increased soil MBC, MBN, basal respiration, total PLFA, bacterial PLFA, and gram-negative bacterial PLFA. In contrast, N fertilization decreased gram-positive bacterial PLFA, fungal PLFA, and fungal:bacterial ratios. Average well color development, Richness, and Shannon's Index were always lowest in the 8.04?dS?m^?1 treatment. Carbon utilization patterns in the 8.04?dS?m^?1 treatment were different from those in the 0.35?dS?m^?1 treatment. In conclusion, five years of irrigation with brackish or SW reduced the soil microbial biomass, activity, and functional diversity, which may cause the deterioration of soil quality. Thus, the high-salinity water (EC?>?4.61?dS?m^?1) is not appropriate as a single irrigation water resource. Proper N fertilizer input may overcome some of the negative effects of salinity on soil microbial.     

Beneficial effects of silicon nutrition in alleviating salinity stress in hydroponically grown canola,Brassica napus L., plants

Abstract

Silicon (Si) is the second most abundant element in soil and effectively counteracts the effects of various abiotic stresses, such as drought, heavy metal toxicity and salinity, on plants. In the present study the ameliorating effects of Si nutrition supplied as 2?mmol?L^?1 sodium silicate were investigated on hydroponically grown canola (Brassica napus L.) plants under salinity stress (i.e. 150?mmol?L^?1 sodium chloride). Salinity decreased plant growth parameters such as tissue fresh and dry weights. These decreases were accompanied by increased lignin contents, Na⁺ ion accumulation, increased lipid peroxidation and decreased chlorophyll contents in plants. Silicon nutrition, however, enhanced plant growth parameters and led to the prevention of lignin and the Na⁺ accumulation in shoots, reduced levels of lipid peroxidation in the roots and higher levels of chlorophyll. As a result of salinity, catalase activity in the whole plant and both soluble and cell wall peroxidase activities in the shoots decreased. Silicon nutrition, however, increased the reactive oxygen species scavenging capacity of salt-stressed plants through increased catalase and cell wall peroxidase activities. Thus, silicon nutrition ameliorated the deleterious effects of salinity on the growth of canola plants through lower tissue Na⁺ contents, maintaining the membrane integrity of root cells as evidenced by reduced lipid peroxidation, increased reactive oxygen species scavenging capacity and reduced lignification.     

Soil Shrinkage Characteristics as Affected by Solution Composition and Mineral Contents

Soil-shrinkage characteristics affect fluid transport and soil mechanical properties, with broad implications for environmental flows, crop production, and civil engineering designs. We quantified mild-saline-solutions effects on soil shrinkage curves and developed pedotransfer functions to predict curve parameters. Seven soil and soil mixes were equilibrated with solutions of 0.5-to-8 dS m^?1 and 0-to-20 sodium adsorption ratios (SAR). Saturated paste rods were dried; water contents and isotropic shrinkage measured. Texture affected shape-forming factors when clay and smectite contents were >260 and 140 g kg^?1, respectively. Solutions ≥2 dS m^?1 affected the coefficient of linear extensibility for smectitic soils containing clay ≥300 g kg^?1. Solution SAR affected only the highest clay content (530 g kg^?1) and mixed mineralogy soils. However, the solution salinity levels were not high enough to affect shape factors of the shrinkage curves. Pedotransfer functions successfully described soil shrinkage with root-mean-squared-errors 1 to 4 magnitudes lower than the highest measured values.     

Influence of Salt Stress on the Nutritional State of Cordyline fruticosa var. Red Edge: Chloride,Nitrogen, and Phosphorus

This trial was carried out to study the nutritional and productive behavior generated by modifications in the salt concentration in the nutrient solution for Cordyline fruticosa var. Red Edge plants. The anions studied were chloride (Cl), nitrogen (N), and phosphorus (P). Four treatments were tested: T₁ [control, 1.5 dS m^?1, 14.3 mmol L^?1 sodium chloride (NaCl)], T₂ (2.5 dS m^?1, 22.2 mmol L^?1 NaCl), T₃ (3.5 dS m^?1, 32.7 mmol L^?1 NaCl), and T₄ (4.5 dS m^?1, 38.2 mmol L^?1 NaCl). At the end of the cultivation, leaf, petiole, shoot and root fresh and dry weights, elemental extractions, and elemental concentrations were determined. Nutrient concentrations and total plant uptake (extraction) were calculated from the dry matter. The treatment T₂ induces a blade protection mechanism, which consists on the accumulation of chloride (Cl^?) in root and vessels; so, leaf storage is reduced, avoiding damages. Petiole also contributes to this protection, acting as a salt pool. As NaCl concentration in the nutritive solution arises, N plant concentration increases significantly although there are no significant differences between T₁ and T₂. With high salinity levels, P in vessels is reduced, whereas root extraction and concentration increases. The greatest N and P extractions are observed in T₂, which is due to its higher dry matter. Chloride extractions are lower in T₁ than in the other treatments.     

RESPONSE OF LIME THYME TO SALINITY AND IONIC CONCENTRATION IN NUTRIENT SOLUTION

□ Plants from 60-day-old Lime Thyme (Thymus citriodorus) cuttings were potted in a medium of coconut fiber and peat moss and were treated with three different nutrient solutions: T1, T2, and T3. T1 was a standard nutrient solution; T2 was incremented with macronutrients up to an electrical conductivity (EC) of 2.8 dS m^?1; and T3 was the same as T1 but incremented up to an EC of 2.8 dS m^?1 with sodium chloride. The plants were then grown for 90 days in a greenhouse with natural daylight in Almería, Spain. Root growth was not affected by the treatments. The dry weight of the leaves and the total dry weight of the plants benefited from the salinity. The specific salinity of the sodium chloride negatively affected growth compared to the same salinity in the complete nutrient solution.     

EFFECT OF SALINIZATION OF SOIL ON GROWTH,WATER STATUS AND NUTRIENT ACCUMULATION IN SEEDLINGS OF ACACIA AURICULIFORMIS (FABACEAE)

Greenhouse experiments were conducted to assess the effects of salinization of soil on emergence, growth, water status, proline content, and mineral accumulation of seedlings of Acacia auriculiformis A. Cunn. ex Benth. (Fabaceae). Sodium chloride (NaCl) was added to the soil and salinity was maintained at 0.3, 3.9, 6.0, 7.9, 10.0, 12.1, and 13.9 dS m^?1. Salinity caused reduction in water potential of tissues, which resulted in internal water deficit to plants. Consequently, seedling growth significantly decreased with increase in soil salinity. Proline content in tissues increased with increase in salinity. Potassium and sodium content significantly increased in tissues as salinity increased. Nitrogen content significantly increased in tissues with salinization of soil. Phosphorus, calcium and magnesium content significantly decreased as salinity increased. Changes in tissues and whole-plant accumulation patterns of other nutrients, as well as possible mechanisms for avoidance of sodium toxicity in this tree species in response to salinity, are discussed.     

SOYBEAN RESPONSE AND ION ACCUMULATION UNDER SPRINKLER IRRIGATION WITH SODIUM-RICH SALINE WATER

The magnitude of crop growth and yield depends on the salinity level, the toxic ions present, and the irrigation system used. In order to study the effect of saline sprinkler irrigation on soybean growth and ionic accumulation in plant tissues a pot experiment was set up. There were three irrigation water quality treatments [electrical conductivity (EC) 0, 2, and 4 dS m^?1]. Soybean aerial biomass was 25% lower than the Control when irrigation salinity was 4 dS m^?1. Clearly salinity entering via leaves affected the grain filling stage and severely reduced soybean grain production (80% reduction) when salinity in irrigation water surpassed 2 dS m^?1. Sprinkler irrigation aggravates soybean's low salinity tolerance and restricts its cropping in such conditions. For early stages two linear relationships between leaf chloride (Cl^?) concentration (Y = 14.2–2x) or potassium (K⁺)/ sodium (Na⁺) ratio (Y = 5.3x?3.4) and soybean grain yield were found. Both relationships may be used as diagnostic tools for soybean growing under saline sprinkler irrigation.