Ameliorative Effect of Hydro Gel Substrate on Growth,Inorganic Ions,Proline, and Nitrate Contents of Bean under Salinity Stress

The effect of varying hydrogel (0, 0.5, and 1.0% w/w) supply on some agro-physiological properties, such as dry matter, nutrient contents, chlorophyll contents, proline content, and ionic balance of bean plants in different salt sources and stress due to doses were investigated. Plants were treated with eight salt sources [sodium chloride (NaCl), sodium sulfate (Na₂SO₄), calcium chloride (CaCl₂), calcium sulfate (CaSO₄), potassium chloride (KCl), potassium sulfate (K₂SO₄), magnesium chloride (MgCl₂), magnesium sulfate (MgSO₄)] and four concentrations (0, 30, 60, and 120 mM doses) for 60 days in a growth media. Salt type, doses, and hydrogel (HG) affected the soil electrical conductivity. Soil salinity affected the parameters considered, and changed the nutrient balance of plants. High salt concentration caused substantial reduction in plant growth. Different salt concentrations negatively affected plant dry weight. The highest decrease of plant root dry weight was obtained with NaCl application followed by Na₂SO₄, CaCl₂, CaSO_4, MgCl₂, MgSO₄, KCl, and K₂SO₄, and similarly NaCl, Na₂SO₄, CaCl₂, CaSO_4, KCl, K₂SO₄, MgCl₂, and MgSO₄ in root dry weight. Total chlorophyll and nitrate contents of plants decreased with increasing salt doses, and the lowest value was obtained for NaCl application. Proline contents of plants were increased with increasing salt doses, and the highest value was obtained with the NaCl application. The effects of salt concentrations in nitrogen (N), potassium (K), and phosphorus (P) content of plants were significant. The presence of salt in the growth medium induced an important decrease the macro nutrient of the root and shoot part of plant such as N, P, K, calcium (Ca), and magnesium (Mg) content, but the N and P content of root and shoot part of the plant were increased with increasing of the HG application doses. The highest N and P increases were obtained with the 1.0 HG application for all salt types for both the root and shoots of plants. The HG added to saline soil significantly improved the variables affected by high salinity and also increased plant N and P, reduced soil electricity conductivity, nitrate, proline, and electrolyte leakage of plants, enhanced plant root and shoot dry weight by allowing nutrients and water to release to the plant as needed. The results suggested that HG has great potential for use in alleviating salinity stress on plant growth and growth parameters in saline soils of arid and semi-arid areas. This HG appears to be highly effective for use as a soil conditioner in vegetable growing, to improve crop tolerance and growth in saline conditions. It is intended to confirm the results of these studies by field trials.     

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.     

VARIABILITY OF THE RESPONSE TO SODIUM CHLORIDE OF EIGHT ECOTYPES OF ARABIDOPSIS THALIANA

ABSTRACT

The variability of the sensitivity to sodium chloride (NaCl) in relation with leaf ionic content has been explored in Arabidopsis thaliana. Seedlings of eight ecotypes (WS, COL, LER, NOK0, NOK1, NOK2, NW40, and N273) were grown on a peat substrate mixed or not with 50?mM NaCl. The effect of NaCl treatment on rosette leaf dry weight after 18 days (vegetative stage) was used to establish a scale of sensitivity to salt, where COL was the most sensitive ecotype and NOK2 the more tolerant one. The tolerance to NaCl was associated to a better growth of plants, responsible for a dilution of Na⁺ in leaf tissues, and to a better supply of K⁺ to leaves. These two characteristics were responsible for maintenance of a high K/Na ratio in leaves of to the most tolerant ecotypes (NOK1, NOK2), as compared to the other ones. Responses of leaf peroxidase activity to a five-day treatment with NaCl in light and darkness conditions suggest that oxidative status is changed only in the sensitive ecotypes.     

Is salt stress of faba bean (Vicia faba) caused by Na+ or Cl– toxicity?

The effect of sodium chloride (NaCl), sodium sulfate (Na₂SO₄), and potassium chloride (KCl) on growth and ion concentrations of faba bean (Vicia faba L. cv. Troy) was studied. After 14 or 15 d of isoosmotic treatment with 100 mM NaCl or 75 mM Na₂SO₄, respectively, plants developed toxicity symptoms. These symptoms were characterized by local and nonchlorotic wilting spots, which later turned to black, necrotic spots. In contrast to NaCl or Na₂SO₄ treatment, plants treated with 100 mM KCl did not show these symptoms. The symptoms occurred on those leaves that accumulated highest concentrations of Na⁺ and showed highest Na⁺ : K⁺ ratios. Our results indicate that Na⁺ toxicity inducing K⁺ deficiency is responsible for the spot necrosis of faba bean. Additionally, chlorotic symptoms occurred. The concentrations of Na⁺ and Cl^– were determined in chlorotic leaves and in isolated chloroplasts. The reduction of chlorophyll in leaves after NaCl exposure may be explained in terms of high Cl^– concentrations in the chloroplasts and appears to depend on high Na⁺ concentrations. Chlorotic toxicity symptoms can be avoided by additional Mg²⁺ application.     

INFLUENCE OF SODIUM CHLORIDE AND CALCIUM FOLIAR SPRAY ON HYDROPONICALLY GROWN PARSLEY IN NUTRIENT FILM TECHNIQUE SYSTEM

The effects of salinity [30 or 90 mM sodium chloride (NaCl)] and calcium (Ca) foliar application on plant growth were investigated in hydroponically-grown parsley (Petroselinum crispum Mill). Increasing salinity reduced fresh weight and leaf number. Calcium alleviated the negative impacts of 30 mM NaCl on plant biomass and leaf fresh weight but not in case of 90 mM. Plant height, leaf and root dry weight and root length did not differ among treatments. Total phenols increased with calcium application, chlorophyll b reduced by salinity, while total carotenoids increased with salinity and/or Ca application. Salinity reduced nutrient uptake [nitrate (NO₃), potassium (K), phosphorus (P) and Ca] and elemental content in leaves and roots. Calcium application reduced P but increased Ca content in plant tissues. Increments of Na uptake in nutrient solution resulted in higher Na content in leaves and roots regardless Ca application. These findings suggest that calcium treatment may alleviate the negative impacts of salinity.     

Interactive effects of sodium chloride,sodium sulfate,calcium sulfate,and calcium chloride on snapbean growth,photosynthesis, and ion uptake

Excessive sodium (Na) accumulation in soil, which can be a problem for production agriculture in arid and semiarid regions, may be ameliorated by calcium (Ca). The mechanisms of Ca amelioration of Na stress in plants have received much more attention than has the effect of the anion of the Ca salt. Our objective was to determine the relative effects of the chloride (Cl^‐) and sulfate (SO₄ ^2‐) anions on Ca amelioration of Na stress. We exposed Phaseolus vulgaris L., cv. Contender seedlings growing in 1‐L styrofoam pots under greenhouse conditions to sodum chloride (NaCl) or sodium sulfate (Na₂SO₄) at concentrations of 0, 15, 30, 45, and 60 mmol/L combined with either 15 and 30 mmol/L of calcium sulfate (CaSO₄) or calcium chloride (CaCl₂). Plants in each styrofoam pot were irrigated with 300 mL of salt solution (leaching fraction = 0.25) every fourth day for four weeks. Increasing Na concentration decreased shoot dry weight, number and weight of pods, and number of nodules. The photo‐ synthesis rate was affected by all levels and types of Na salts. Calcium sulfate treatments ameliorated Na‐induced salinity in snapbeans more than did comparable CaCl₂ treatments. The thermodynamic activity of Ca, Na, and Cl was linearly related to the tissue content of each ion.     

Auswirkungen von NaCl und Na2 SO4 auf Substanzbildung,Mineralstoffgehalt und Inhaltsstoffe bei Spinat und Salat

Effect of NaCl and Na₂SO₄ on dry matter production, mineral content and organic compounds of spinach and lettuce . In water culture experiments the effect of 2,5 meq and 25 meq NaCl and Na₂SO₄ respectively on dry matter production and content of mineral elements, chloroplasts pigments and carbohydrates in lettuce (salt sensitive) and spinach (salt tolerant) has been studied. With increasing Na-supply the dry matter production was decreased in lettuce and increased in spinach. With increasing Na-supply in both species the content of K, Mg and Ca in the leaves decreased. This decrease was more pronounced with sulfate as accompanying anion (Na₂SO₄) and induced already deficiency in Ca and Mg. This induced deficiency of Mg was reflected especially in lettuce in lower contents of chloroplasts pigments. In both plant species there was no effect of the Na salt treatments on the content of phosphorus or nitrogen in roots or leaves. The carbohydrate content in both species was strongly affected by the Na salt treatments. Irrespectively of the accompanying anion this effect occured already at the low Na supply and before the dry matter production was influenced. In leaves and roots of lettuce the contents of glucose, fructose and sucrose was considerably decreased; this decrease was less expressed in the starch content. In spinach the Na supply only decreased the carbohydrate content in the roots whereas in the leaves especially the sucrose content was increased. This different effect of Na on carbohydrate content in spinach and lettuce could be an indication of different action of Na on carbohydrate metabolism, namely inhibited synthesis in lettuce and inhibited translocation in spinach. The results demonstrate that in studies on the effect of increasing Na salt concentrations besides the osmotic effects also the ion specific effects have to be carfully considered. These ion specific effects are competition of Na⁺ with other cations during uptake and the influence of Na on the cell metabolism, especially on the pathway of carbohydrates. The authors thanks Mrs. Hwie Juen Tjandraatmadja for her engaged help in various laboratory works.     

Effects of NaCl and Supplementary Potassium on Gas Exchange,Ionic Content,and Growth of Salt-Stressed Strawberry Plants

Strawberry cultivar ‘Selva’ was grown in a hydroponic culture in a heated greenhouse to study the effects of supplementary potassium (K) added to nutrient solution and applied to the plants grown at high sodium chloride (35 mmol/L) concentration. Treatments were: (1) nutrient solution alone (N); (2) N + sodium chloride (NaCl) (35 mmol/L) (NS); (3) N + NaCl + potassium sulfate (K₂SO₄; 5 mmol/L) (NSK1); (4) N + NaCl + K₂SO₄ (10 mmol/L) (NSK2). Leaf area, biomass production, and gas exchange variables (Pn, E, gs, Ci) negatively affected by salinity. In addition, ionic concentrations (sodium, chlorine, and potassium) increased by salinity treatments. Supplementary potassium had positive effects to ameliorate the harmful effects of NaCl on leaf area. Shoot growing was decreased by potassium (K) application. Ionic concentrations of this cultivar show contradictory results. Although supplementary potassium increased K accumulation, but sodium (Na) and chlorine (Cl) concentrations of plant parts was increased. These results show that potassium can be applied for this cultivar in salinity conditions.     

Genotype-Dependent Differential Responses of Three Forage Species to Calcium Supplement in Saline Conditions

Salt toxicity comprises of osmotic and ionic components both of which can severely affect root and shoot growth. In many crop species, supplemental calcium (Ca) reduces the inhibition of growth typical of exposure to salt stress. The objective of this study was to compare whole plant growth and physiological responses to interactive effect of salinity and Ca level on three forage species [African millet (AM), tall wheat grass (TW), and perennial ryegrass (PR)] differing in tolerance to sodium chloride (NaCl) salinity. Plants were grown under glasshouse condition and supplied with nutrient solution containing 0, 100, and 250 mM NaCl supplemented with 0.5, 5, or 10 mM calcium chloride (CaCl₂). Plant growth, ionic concentration, water relations, and solute (proline and glycinebetaine) concentrations of the plants were determined two weeks after the salinity treatments. At 100 mM NaCl, there was a moderate reduction in dry matter (DM) production of all three species. A drastic decrease in DM occurred at 250 mM NaCl. Supplemental Ca reduced the adverse effects of salinity on all three species. The TW showed higher shoot and root growth in 100 and 250 mM NaCl than AM and PR. It also showed the highest DM at 5 and 10 mM Ca supplement. The shoot and root DM of TW increased by about 45 and 15%, respectively compared to the control. Chemical analysis indicated that in TW, Ca restricted both uptake and transport of sodium (Na) from root to shoot. It also increased Ca and potassium (K) concentrations in both organs. The transport of K and Ca from root to shoot of AM and PR were decreased by NaCl, but were restored with increasing Ca in the medium. The opposite occurred for Na. In PR, more K uptake was observed in shoot at 250 mM NaCl with 10 mM Ca supplement. The sap osmotic potential (Ψ_S) was the highest in TW at 10 mM Ca in the presence of 250 mM NaCl. Contribution of various solutes to the difference in Ψ_S among the species from the control and 250 mM salt treatment differed greatly. Supplemental Ca induced decline in the leaf Ψ_S of TW which was predominately due to K, glycinebetaine, Na and proline accumulation. Addition of 10 mM Ca to the growth medium maintained a low Na and a high K level. Accumulation of glycinebetaine and proline in leaf contributed the NaCl tolerance of TW. The presented results suggest that supplement Ca, not only improved ionic relations but also induced plant ability in production of compatible solutes (glycinebetaine and proline) and osmotic adjustment. Accordingly, genotype dependent capacity could be found using supplemental Ca.     

EFFECT OF MIXED-SALT SALINITY ON GROWTH AND ION RELATIONS OF A QUINOA AND A WHEAT VARIETY

ABSTRACT

Salinity is among the most widespread and prevalent problems in irrigated agriculture. Many members of the family Chenopodiaceae are classified as salt tolerant. One member of this family, which is of increasing interest, is quinoa (Chenopodium quinoa Willd.) which is able to grow on poorer soils. Salinity sensitivity studies of quinoa were conducted in the greenhouse on the cultivar, “Andean Hybrid” to determine if quinoa had useful mechanisms for salt tolerant studies. For salt treatment we used a salinity composition that would occur in a typical soil in the San Joaquin Valley of California using drainage waters for irrigation. Salinity treatments (EC_i ) ranging from 3, 7, 11, to 19?dS?m^?1 were achieved by adding MgSO₄, Na₂SO₄, NaCl, and CaCl₂ to the base nutrient solution. These salts were added incrementally over a four-day period to avoid osmotic shock to the seedlings. The base nutrient solution without added salt served as the non-saline control solution (3?dS?m^?1). Solution pH was uncontrolled and ranged from 7.7 to 8.0. For comparative purposes, we also examined Yecora Rojo, a semi-dwarf wheat, Triticum aestivum L. With respect to salinity effects on growth in quinoa, we found no significant reduction in plant height or fresh weight until the electrical conductivity exceeded 11?dS?m^?1. The growth was characteristic of a halophyte with a significant increase in leaf area at 11?dS?m^?1 as compared with 3?dS?m^?1 controls. As to wheat, plant fresh and dry weight, canopy height, and leaf area did not differ between controls (3?dS?m^?1) and plants grown at 7?dS?m^?1. Beyond this threshold, however, plant growth declined. While both quinoa and wheat exhibited increasing Na⁺ accumulation with increasing salinity levels, the percentage increase was greater in wheat. Examination of ion ratios indicated that K⁺:Na⁺ ratio decreased with increasing salinity in both species. The decrease was more dramatic in wheat. A similar observation was also made with respect to the Ca²⁺:Na⁺ ratios. However, a difference between the two species was found with respect to changes in the level of K⁺ in the plant. In quinoa, leaf K⁺ levels measured at 19?dS?m^?1 had decreased by only 7% compared with controls. Stem K⁺ levels were not significantly affected. In wheat, shoot K⁺ levels had decreased by almost 40% at 19?dS?m^?1. Correlated with these findings, we measured no change in the K⁺:Na⁺ selectivity with increasing salinity in quinoa leaves and only a small increase in stems. In wheat however, K⁺:Na⁺ selectivity at 3?dS?m^?1 was much higher than in quinoa and decreased significantly across the four salinity levels tested. A similar situation was also noted with Ca²⁺:Na⁺ selectivity. We concluded that the greater salt tolerance found in quinoa relative to wheat may be due to a variety of mechanisms.     

盐渍土中盐结晶的显微研究——Ⅰ.芒硝无水芒硝的转换因素和蓬松盐土蓬松层的形成

应用偏光显微镜技术与扫描电子显微镜技术,对三种不同类型盐土的盐结晶进行观察研究。从土壤溶液的蒸发过程中,我们观察到石膏(CaSO₄·2H₂O)、芒硝(Na₂SO₄·10H₂O)、泻利盐(MgSO₄·7H₂O)、石盐(NaCl)结晶的析出过程,析出顺序受温度的影响。用这种方法可以快速确定土壤溶液中主要盐分类型。扫描电子显微镜的照片,展示出某些盐类结晶的自然特征,它们是:与土粒胶结紧密的石盐(NaCl)、由芒硝(Na₂SO₄·10H₂O)脱水转变成的无水芒硝(Na₂SO₄)、或由硫酸钠、硫酸钙形成的复盐——钙芒硝Na₂Ca(SO₄)₂。各种盐类在土壤中结晶出来形态清晰。以硫酸钠的溶解特性为例,扼要地讨论了土壤中芒硝—无水芒硝的转化条件及其对土壤结构产生的影响。     

Influence of extreme K:Na ratios and high substrate salinity on plant metabolism of crops differing in salt tolerance

Abstract

Ion‐specific initial salt effects due to supply of extreme K⁺, Na⁺, Cl or SO₄ ^2‐ combinations were studied on the carbohydrate pattern as well as on the activity of amylases, phosphorylase and invertase of two soybean varieties, Jackson and the more tolerant Lee.

Reducing sugars were little affected. Salinity increased leaf sucrose more in Jackson than in Lee, and more due to Cl^? than to SO₄ ^2‐ supply. Salinity increased the higher level of root sucrose in Lee less than the lower sucrose level in Jackson, independent of the nature of salination. Salinity increased leaf starch more in Jackson than in Lee. KCl increased leaf starch of Jackson most, Na₂SO₄. least. KCl increased leaf starch of Lee more than NaCl, while K₂SO₄ and Na₂SO₄ tended to decrease leaf starch. Only KCl stimulated amylases and phosphorylase in leaves of Jackson. Salinity changed amylases according to the starch content in leaves of Lee, while phosphorylase decreased independent of the ion combination supplied. Salinity decreased invertase in leaves of Jackson, it affected invertase in Lee only little.

It is suggested that the carbohydrate metabolism dependent and independent of ionic regulation contribute to physiological salt tolerance mechanisms of soybean varieties.     

GROWTH AND NUTRITION OF YOUNG BEAN PLANTS UNDER HIGH ALKALINITY AS AFFECTED BY MIXTURES OF AMMONIUM,POTASSIUM, AND SODIUM

High concentrations of bicarbonate (HCO^? ₃) cause alkalinity of irrigation water and are associated with suppression in plant growth and micronutrient deficiencies, such as iron (Fe) and zinc (Zn). Because reports indicate that the deleterious effects of alkalinity may be counteracted partially by supplementary potassium (K⁺) or ammonium (NH₄ ⁺) an experiment was designed to evaluate the response of bean plants (Phaseolus vulgaris L.) grown in high alkalinity conditions to varying proportions of NH₄ ⁺, K⁺, or sodium (Na⁺) (as a potential substitute for K⁺). Plants established in a growth chamber were grown in hydroponics for 21 days in solutions containing 5 mM HCO^? ₃ and a total of 5 mM of a mixture of NH₄ ⁺, K⁺, and Na⁺. The proportions of NH₄ ⁺, K⁺, and Na⁺ were designed according to mixture experiment methodology. Total N in all the mixture treatments was maintained at 10 mM by using nitrate (NO^? ₃)-N, thus the NH₄ ⁺:NO^? ₃ ratio varied according to the proportion of NH₄ ⁺ in the mixtures. Alkalinity caused suppression in plant growth and chlorophyll concentration in the younger leaves, whereas excessive NH₄ ⁺ was associated with leaf scorching and decreased leaf expansion. High proportions of K⁺ alleviated alkalinity symptoms and produced higher shoot and root dry mass provided that NH₄ ⁺ was included in the mixture. However, a proportion of NH₄ ⁺ higher than 0.333 in the mixture (>1.66 mM NH₄ ⁺) induced toxicity. The highest shoot dry mass occurred if the NH₄ ⁺:NO^? ₃ ratio was 0.19:0.81 and the NH₄ ⁺:K⁺:Na⁺ proportion was 0.38:0.38:0.24 (1.9 mM NH₄ ⁺ + 1.9 mM K⁺ + 1.2 mM Na⁺). Thus, an improvement in plant growth is achieved when NH₄ ⁺, K⁺, and Na⁺ are blended together, in spite of the high alkalinity treatment imposed. Optimum NH₄ ⁺ was associated with a decrease in solution pH and an increase in shoot Fe and Zn concentration.     

EFFECTS OF SALINITY STRESS ON PHYSIOLOGICAL PERFORMANCE OF VARIOUS WHEAT AND BARLEY CULTIVARS

An experiment with factorial arrangement of treatments on a randomized complete block (RCB) design basis with three replications was conducted in a greenhouse during Spring 2010 to investigate changes in sodium ion (Na⁺), potassium ion (K⁺), Na⁺/K⁺ and to determine proline, protein content, and superoxide dismutase (SOD) of four wheat and four barley cultivars. Three salt levels {1, control (no salt), 7, and 13 dS m^?1 [2.5 and 5 g salt [sodium chloride (NaCl) and sodium sulfate (Na₂SO₄) in 1:1 ratio] per kg of soil, respectively]} were used in this investigation. Salt stress treatments were applied 4 weeks after planting (at 2 leaf stage). Leaf samples were taken four weeks after imposition of salt treatment. The results showed that salinity caused an increased in proline and protein content, and SOD in all wheat and barley cultivars. The highest proline and protein content of barley and wheat cultivars at all salinity levels were observed in ‘Nimrooz’ and ‘Bam’ cultivars, respectively. At all salinity levels, wheat and barley cultivars ‘Kavir’ and ‘Nimrooz’, respectively, had the lowest Na⁺ content. Barley cultivar ‘Kavir’ and wheat cultivar ‘Bam’ had higher K⁺ and K⁺:Na⁺ ratios. This might be related to salt tolerance in these two cultivars. Wheat and barley cultivars showed differences with regard to proline, protein, and SOD content, Na⁺, K⁺, and K⁺:Na⁺ ratio, indicating existence of genetic diversity among the cultivars. These findings indicated that higher K⁺, K⁺:Na⁺ ratio, proline, protein, and SOD content could be the key factors, which offer advantage to barley over wheat for superior performance under saline conditions.     

PHYTOTOXICITY OF SALTS IN COMPOSTED SEWAGE SLUDGE AND CORRELATION WITH SODIUM CHLORIDE,CALCIUM NITRATE,AND MAGNESIUM NITRATE

The phytotoxicity of salts in composted sewage sludge (CSS) was evaluated. Concentrations of sodium (Na⁺), chloride (Cl^?1), calcium (Ca²⁺), and magnesium (Mg²⁺) were present at levels that would induce salt stress in plants. Nutrient imbalances were also found that would adversely affect the use of CSS as a growth medium. To further understand the phytotoxic nature of these salts, sodium chloride (NaCl), calcium nitrate [Ca(NO₃)₂] and magnesium nitrate [Mg(NO₃)₂] solutions were used to simulate the composition of salts found in CSS in an investigation of radish (Raphanus sativus L.) seed germination. High concentrations of Ca²⁺ (92.1 mmol.L^?1) and Mg²⁺ (27.4 mmol.L^?1) inhibited seed germination to an equal extent as did Na⁺ (40.6 mmol.L^?1). The lower concentration of Ca²⁺ (10 mmol.L^?1), however, significantly relieved the stress caused by NaCl. These results indicated that the composition and total amount of Na⁺, Cl^?1, Ca²⁺, and Mg²⁺ in CSS should be carefully monitored before it is used as a soil amendment or growth medium.     

Shoot growth,plant tissue elemental composition,and soil salinity following irrigation of alfalfa and tall fescue with high‐sulfate waters 1

Groundwater contaminated with sulfate (SO₄ ^2‐) at concentrations higher than allowable for drinking water might still be usable for irrigation. Objectives were to determine the growth response and mineral uptake of two forage crops irrigated with waters containing SO₄ ^2‐ at concentrations ranging from 175 to 1743 mg/L, and with electrical conductivities (EC) ranging from 1.2 to 3.6 dS/m. Plants were grown for 12 weeks in 8‐L pots containing a calcareous sandy loam and were harvested at 4, 8, or 12 weeks for plant growth measurements and tissue analysis. Digested leaves, stems, and reproductive tissues were analyzed by inductively coupled plasma (ICP) spectroscopy at each harvest, as were saturated soil paste extracts. Shoot growth of tall fescue (Festuca arundinacea Schreb.) was not affected by irrigation water treatment, whereas shoot growth of alfalfa (Medicago sativa L.) was increased by a moderate level of soil solution SO₄ ^2‐ Sulfur (S), boron (B), magnesium (Mg), sodium (Na), and zinc (Zn) concentrations in shoot tissues of both species showed a tendency to increase with increasing SO₄ ^2‐ content of irrigation water. Shoot tissue concentration of molybdenum (Mo) increased with maturation in both species, while the concentrations of B, potassium (K), manganese (Mn), Na, and Zn decreased. Soil saturated paste extract concentrations of Mg and Na increased with irrigation water Mg and Na concentrations, while Ca and S concentrations in the soil solution became saturated at the higher irrigation water concentrations of these elements.     

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.     

Effect of sodium arsenite and sodium chloride on bean plant nutrition (macronutrients)

The effects of different levels of arsenic (As) and salinity on bean plant (Phaseolus vulgaris L., cv. Buenos Aires) nutrition were investigated. We studied the processes of absorption and accumulation of macronutrient elements: nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg). The experiment was performed in soilless culture at two levels of As: 2 and 5 mg AsL^‐1 (added as sodium arsenite, NaAsO₂), and three saline levels [only sodium chloride (NaCl) was added]: 1, 2, and 4 dS‐m^‐1. Sodium arsenite and NaCl significantly affected macronutrients allocation within bean plant at concentration levels used in this study. Arsenite depressed K, Na, and Mg concentrations in root, whereas root N, and Ca levels were increased. Nitrogen, P, K, and Na concentrations were significantly higher in As‐stressed plants compared with controls. The addition of NaCl increased Ca concentration in roots and decreased that of K. Salinity tended to increase leaf concentrations of K, Na, Ca, and Mg; whereas leaf N and P levels decreased with increasing salinity.     

SELECTIVITY AND PARTITIONING OF POTASSIUM AND SODIUM IN SESAME

Net uptake and partitioning of sodium (Na⁺) and potassium (K⁺) in plants of two sesame cultivars (Sesamum indicum cv. ‘PB-1’ and cv. ‘UCR’) exposed to 20 mM sodium chloride (NaCl) were studied over a period of 28 days. Both cultivars showed a marked discrimination between K⁺ and Na⁺ during uptake. The reduction of K⁺ in the plants caused by the NaCl treatment was of similar magnitude in the two cvs. The cv. ‘UCR’ showed lower Na⁺ concentrations in the shoot tissues than ‘PB-1’ and K⁺/Na⁺ selectivity ratios were higher in cv. ‘UCR’ than in cv. ‘PB-1’. At the last sampling on day 28 there was a marked decrease of shoot growth in cv. ‘PB-1’ in comparison to the cv. ‘UCR’. Leaves of cv. ‘PB-1’ showed clear toxic symptoms, while those of cv. ‘UCR’ did not. It is concluded that Na⁺ exclusion from the shoot contributes to salt tolerance of sesame, cv. ‘UCR’.     

Influence of Salt Stress on the Nutritional State of Cordyline fruticosa var. Red Edge, 2: Sodium,Potassium, Calcium,and Magnesium

The aim of this trial was to study the nutritional behavior generated by modifications in the salt concentration in the nutrient solution used for the fertigation of Cordyline 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). There is an accumulation of sodium (Na⁺) in roots, stem, and petiole when salinity increases, which avoid leaf damages. Potassium (K) concentration increases with the intermediate saline treatments in stems and leaves but decreases when plants are fertigated with T₄. Calcium (Ca) accumulates in roots with T₃ and T₄, in stems with T₄, and in petioles and leaves with T₃. Magnesium (Mg) concentration is greater in stems, petioles, and leaves of T₄, but is greater in roots of T₃. Plants fertigated with the three saline treatments extract 1.4 times more Na⁺ than T₁ plants. The greatest K⁺ extraction is observed in T₂, followed by T₃, and T₄. T₂, T₃, and T₄ plants extracted more Ca²⁺ than T₁ plants. Finally, Mg²⁺ extractions in T₃ are twice as much as they are in T₁, while in T₄ and T₂ are much greater.