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Melatonin (N-acetyl-5-methoxytryptamine) is a molecule with a reported importance in increasing tolerance to several types of stress. The present study investigates the effect of melon (Cucumis melo L.) seed treatment with melatonin solutions (0, 10, 50 and 100 µM) at two durations (6 and 12 h) on germination and initial growth of melon plants in salt stress. Germination under salt stress (14 dS m-1 EC) suffered a decrease, which is reversed after seed treatment with melatonin and followed to 80% with 10 and 50 µM solutions. Then, considering plant growing in salt stress (8 dS m-1 EC), the best growth and physiological and biochemical responses (xylem water potential, leaf relative water content, total chlorophyll, root viability, proline, malondialdehyde content, peroxidase and catalase activity) were measured in plants derived from 50 µM seed treatment. No changes were observed at the anatomical level. Results suggest that melatonin can alleviate the effect of salt stress during seed germination and early plant growth. There is a dose-dependent response. [ABSTRACT FROM AUTHOR]

In the semiarid region of Brazil, salts found in water used in irrigation. The objective of was to analyze the influence of foliar fertilization with nitrogen as a mitigation of the salt stress of passion fruit seedlings. The design was randomized blocks, with the treatments generated from the Box's Central Composite matrix, with five electrical conductivities of irrigation water (ECw) (0.50; 0.98; 2.15; 3.32; 3.80 dS m-1) and five doses of foliar nitrogen fertilization (0.0; 0.30; 1.15; 1.97; 2.30 g L-1), with four replicates. The growth and photosynthetic pigments were evaluated Application of nitrogen doses attenuated the effect of salinity on morphophysiological aspects of passion fruit seedlings. The increase in the salinity of the water caused negative effects on the characteristics the growth and photosynthetic pigments. [ABSTRACT FROM AUTHOR]

Salinity is one of the main factors that causes losses in crops up to 50%, which puts world food security at risk. During evolution, plants have acquired defense mechanisms, which are regulated by specific genes whose main function is to counteract damage by salinity. Genetic variability in crops is necessary for stress-tolerant genotypes to occur. One of the strategies that can be used to find tolerance is the combination of mutagenesis and plant tissue culture, since thousands of plants are produced in confined spaces and short periods; in addition, with the use of selective agents such as NaCl plants can be obtained tolerant to salinity. This review will address topics related to plant tissue culture, induced mutagenesis and the combination of both as strategies to obtain salinity tolerant plants of agricultural interest. [ABSTRACT FROM AUTHOR]

Oryza sativa L. "rice" (Paceae) is one the most important crops worldwide. However, it is drastically affected by salinity. Therefore, the objective of this research was to determine the effect of salinity over the absolute growth rate (AGR) and the relative water content (RWC) of rice varieties IR-43 and amazonas. "Rice" seedlings were grown in hydroponic conditions with nutritive solution La Molina® and arranged in a factorial design. 16-day plantlets were treated with NaCl solutions 0, 100, 150 and 200 mM to determine AGR and RWC at 8-day-treatment. Salinity stress affected both variables. IR-43 was more affected when treated with 200mM NaCl, showing AGR of 12.46 and 19.04 mm/day in shoots and roots respectively; when treared with 100 mM, RWC was 73.35%. The Amazonas variety had more tolerance to salinity, with AGRs of 21.25 and 22.54 mm/day in shoots and roots treated with 200mM NaCl, respectively; and RWC was 78.47% at 100mM. The reduction in growth could be caused by changes in cell water state caused by salinity and changes in nutrient and water uptake. The differences in stress response to salinity in both rice varieties showed advantages in osmotic adjustment and regulation to maintain cell homeostasis of Amazonas over IR-43 rice varieties. [ABSTRACT FROM AUTHOR]

Blueberries (Vaccinium corymbosum L.) are the fourth most economically important berry in the world. Its consumption responds to the existing interest on the antixodant compounds contained in its fruits and that are benefitial to human health. The production of blueberries is affected by water and salinity stress. Knowning the agronomic responses of this crop to stress helps to design actions for its handling. The aim of this study was to find out the effect of water and salinity stress on the agronomic variables of blueberry plants. As dryness and salinity increase, the growth of plants and the yield of blueberry fruits are reduced. To test this hypothesis, one-year old plants were exposed to water and salinity stress, in a hydroponic system, using tezontle as a substrate and a modified Steiner universal nutrient solution. The following variables were measured: dry matter of the root, stem, leaf and fruit, foliar area, root length, and height (plant), and specific weight, and equatorial and longitudinal diameters (fruit). A randomized complete block design was used and the treatments were: 1) control, with the 100 % of the daily demand of water and with an osmotic potential (PO) of -0.027 MPa; 2) salinity stress, with two PO levels (-0.041 and -0.054 MPa), both with 100 % of the daily demand of water; 3) water stress, with 33 % (H33) and 66 % (H66) of the daily demand of water, with a PO of -0.027 MPa. ANOVA was used to analyze the results and the means were compared using a Tukey test (p≤0.05). There were four repetitions -with 20 experimental units, and three plants per each experimental unit-which were used to analyze the results. There were statistical differences (p≤0.05), as a result of salinity stress in the root length variables and in all variables in the treatments with water stress. Results indicate that blueberry plants are sensitive to water and salinity stress, which have a negative effect on the growth of this species. However, water stress has a greater impact on the growth and production of blueberry plants, unlike salinity stress, which can increase the size of the fruit when applying an osmotic potential equal to -0.41 MPa. [ABSTRACT FROM AUTHOR]

Water is a resource for agriculture, urban and industrial activities. It is insufficient in the arid climate areas in the north east of Brazil. Saline water is as an alternative to the expansion of agricultural irrigation areas. Our objective was to assess the effect of irrigation with saline water and nitrogen fertilization on sunflower (Helianthus annuus L.) cv. EMBRAPA 122-V2000 growth. This study was carried out in a greenhouse at the Campina Grande Federal University, Paraiba, Brazil, between April and July 2012. The experimental design was completely random with three replications in a 5×5 factorial arrangement; salinity levels in irrigation water, with electrical conductivity (ECa) of 0.7, 1.7, 2.7, 3.7 and 4.7 dS m-1 (25 °C) and N doses of 50, 75, 100, 125 and 150 mg kg-1 as factors, in 75 experimental units. The variables evaluated during the growth cycle were: plant height, stem diameter, number of leaves, leaf area, flowering onset, maximum inflorescence opening, inner and external flower diameter, and chlorophyll content. The results with ECa of 0.7 dS m-1 linearly decreased. The salinity of the irrigation water and nitrogen fertilization interaction was not significant in the evaluated variables, except for the plant height 15 d after sowing. The flowering variables were delayed as the salinity of the irrigation water increased and chlorophyll content decreased, but increased with N. [ABSTRACT FROM AUTHOR]

Establishment of the perennial forage legume Lotus tenuis Waldst. & Kit is difficult in central-north areas of Argentina because thermal and water stressful conditions during summer. In the present study, germination behavior and initial growth was evaluated for a naturalized population of L. tenuis from center-north of Santa Fe province and it was compared with the Aguapé commercial cultivar. Constant and alternating germination temperatures and initial growth, under controlled conditions of light and temperature, were assessed under salinity stress. Higher temperatures negatively affect the germination of both materials, under stressful and non-stressful conditions. Salinity tolerance was higher at lower constant temperature and alternating. Salinity negatively affects biomass production in initial growth although biomass allocation was not affected. The cv. Aguapé showed a better behavior than naturalized material. [ABSTRACT FROM AUTHOR]

The estuarine crustaceans are exposed to frequent and abrupt environmental salinity changes that involve adjustments at different levels in muscle tissue. The histochemical composition of fiber types of the claw closer muscle of Cyrtograpsus angulatus and Neohelice granulata (Dana, 1851) under hyper regulatory conditions was analyzed. Cryosections of the muscle were treated with myosin-adenosine triphosphatase (m-ATPase), succinic dehydrogenase (SDH), periodic acid Schiff (PAS) and Sudan Black B. The mean diameters, the relative area and the proportion of each muscle fiber type were calculated. Types I and IV would belong to 'extreme' groups, whereas types II and III would be considered 'intermediate'. Type I fibers were large and exhibited a weak reaction to all techniques; type IV fibers were small and reacted strongly to histochemical tests. Types II and III prevailed in C. angulatus whereas type II predominated in N. granulata. Type IV fibers were absent in C. angulatus and scarce in N. granulata. The claw closer muscle of N. granulata and C. angulatus exhibited differential responses under reduced salinity at a histochemical level. Therefore, the existence of different adjustment mechanisms facing salinity stress is suggested. [ABSTRACT FROM AUTHOR]

Salinity is one of the most pressing stresses today and brassinosteroids are compounds which, not only stimulate plant growth but also improve plant tolerance to salt stress. In this paper, the effect of foliar spraying with a brassinosteroid analogue (Biobras-16, BB-16) on rice seedlings under this kind of stress was evaluated. For this purpose, rice young plants cv. J-104 were sprayed with BB-16 (0; 0,01; 0,1; 1 µmol L-1), half of them was treated with NaCl (100 mmol L-1) for seven days and later, these plants were transferred to nutrient solution to assess recovery during fourteen days. The growth evaluations (shoot and root length and dry mass) were made at the beginning and the end of saline treatment and seven and fourteen days after the recovery. From the results of this experiment, the best BB-16 concentration was chosen and a second experiment, following the same methodology, was performed and, where, the growth indicators and some biochemical indicators such as malondialdehyde, proline, chlorophylls and the activities of peroxidase and catalase enzymes were determined. Results demonstrated, in general, that the foliar spraying with BB-16 0,1 µmol L-1 increased the length of rice seedlings under saline conditions what appears to be associated with increased antioxidant defenses as well as an increase of the concentration of chlorophylls, chlorophyll a fundamentally. [ABSTRACT FROM AUTHOR]

High concentrations of salts in the soil adversely affect the cultivation of Aloe vera and since it has been shown that in other plants calcium helps counteract the effects of salinity, this paper presents results on effects of the radical application Ca2+ to A. vera plants subjected to salt stress, to check if calcium improves its adaptation to salinity. For this purpose, the fresh biomass, leaf volume, number of new leaves and number and root length was measured. All variables were diminished by the application of NaCl; however, in general, supplementation with 10 mmol m-3 CaCl2 100 mmol m-3 NaCl, had positive effects on these variables, increasing, in many cases those reduced by NaCl parameters, which is good news for successfully growing aloe in areas where there are problems with dissolved salts in the soil. [ABSTRACT FROM AUTHOR]

Spirostanic analogues of brassinosteroids are synthesized, compounds in Cuba and some of their formulations have demonstrated to enhance the growth when plants grow under saline stress. Recently, a new analogue (Biobras-25) which should have a good biological activity has been synthesized. For this reason, the objective of this paper was to evaluate rice seedling growth under NaCl stress by fourteen days, when the seeds were treated with Biobras-25 or Biobras-16. Two experiments were performed, in the first one, rice seeds of cv. INCA-17 were soaked in BB-25 or BB-16 solutions (0; 0,005; 0,05 y 0,5 mg L-1) and after germination, they were placed in pots which contained Hoagland nutritive solution with the addition or not of NaCl 0,1 mol L-1 and remained during fourteen days in a growth room. At the end of the experiment, root and shoot length and dry mass were evaluated to 25 plants by treatment. Later, a second experiment was performed with the best concentrations of both formulations and, also, the growth indicators described above, leaf proline, a, b and total chlorophylls and total carotenes were determined. Results showed that both analogues exhibited a distinct behavior. Biobras-25 not only enhanced significantly seedling growth under NaCl stress but also increased significantly pigment concentration and decreased the proline content in leaves. [ABSTRACT FROM AUTHOR]

Salinity is one of the adverse environmental condition that cause high affectations to agricultural crops. The objective was to evaluate the combined effect of low doses of X-rays and different concentrations of Biobras-16 on tomato plants grown in saline conditions. The experiment was carried out at "Jorge Dimitrov" Agricultural Research Institute during the years 2009 to 2012. Fresh tomato seeds of variety cv. Vyta were exposed to X-ray doses of 20, 25 and 30 Gy and 15 days after transplantation the plants were sprayed with two concentrations (1,5 and 2,0 mg L-1) of Biobras-16. Two substrates were used, one consisting of a Vertisol soil salinized with electrical conductivity of 6 dS m-1 extract of soil saturation and Vertisol soil no salinized. The best combination of treatments was observed for 30 Gy +2,0 mg L-1, which increased significant (p≤0,05) the salt tolerance in plants, the tomato yield and its components. [ABSTRACT FROM AUTHOR]

Objective: to study the effect of co-inoculation with Ensifer meliloti and Halomonas maura of the leguminous Medicago sativa L., on growth, nutritional and functional value, grown under salinity conditions.Methods: plants of M. sativa were grown in a solution with a mixture of salts (CaSO4, MgCl, NaCl and NaHCO 3) and were co-inoculated with its specific rhizobium and the halophilic moderated bacterium H. maura. Different physiologic parameters were determined, as well as, nitrogen and minerals content. Furthermore, an assay of in vitro digestibility was carried out.Results: salinity had a negative effect on the plants; however, co-inoculation increased yield, nitrogen content, total minerals, Ca and Mg. Moreover, physiologic parameters as water potential and leghemoglobin content in fresh nodules were higher compared to those of plants inoculated only with E. meliloti. Both, salinity and bacterial treatment with E. meliloti and H. maura increased the antioxidant capacity of the legume, in dialyzates and retentates collected after an in vitro digestibility assay.Conclusion: co-inoculation of plants with E. meliloti and H. maura could improve the alfalfa yield under specific salinity conditions, increasing the nutritional and functional value of the plants. M. sativa could be considered in the formulations of nutritional supplements for the human diet. [ABSTRACT FROM AUTHOR]

Salinity is a growing threat to the productivity of soybean cultivars (Glycine max L. Merril) and different strategies have been adopted to overcome this problem. Commercial exploitation of tolerant genotypes to salinity is a good alternative to obtain economical yields in these areas. For this reason, it is important to have rapid methods to assess the tolerance to this stress especially in the early stages of growth. The aim of this study was to evaluate the salt tolerance in nine soybean genotypes. Experiments were carried out in a greenhouse under controlled conditions. The rate of salinity tolerance of germination (IG), shoot length (ILB), root length (ILR), shoot dry matter (IMSB) and root (IMSR), as well as injury of cell membrane were measured in all genotypes treated with NaCl (chloride sodium) at concentrations 0 to 150 mM. The results obtained based on physiological criteria allowed the identification of AT22 and INCASoy36 as the most tolerant cultivars compared to other genotypes, thus those genotypes seem to be promising to achieve higher productivity in areas affected by salt. [ABSTRACT FROM AUTHOR]

During their life cycle, plants are exposed to various types of external stressors, preventing the maintenance of homeostasis. Salinity is one of the main adverse factors affecting plant growth and causes great losses in the yield of many crops. In the world there are large areas of saline soils of which are largely agricultural soil. In Cuba 20% of agricultural land are at risk due to salinity; the provinces where Nicotiana tabacum is growing, are not exempt from this problem. The plants have various types of stress responses as synthesis antioxidant metabolites and enzymes which contribute to the process of acclimation The effect of salt stress on processes of photosynthesis, respiration, biomass formation and defense response systems in plants of N. tabacum `Criollo'98', excellent for the production of Habanos, was determined. The photosynthetic activity was affected in the early hours of face plants to salinity conditions imposed in hydroponics conditions (Hoagland solution supplemented with 150 mmol L -1 NaCl); however recovery was observed in a short period of time (7 d). Higher concentration of total chlorophyll and carotenoids was detected in the leaves of plants with the saline treatment, which is interpreted as a possible photosynthetic acclimation to salinity. Respiratory activity was similar in salt treated and control plants. Another answer acclimation of plants was evidenced by a greater value of root: shoot biomass ratio in salt treated plants, which could contribute to increased water uptake by the roots in these stressful conditions. The stomata of the plants under salt stress reacted partially closing, reaching values of 30 % to 50 % of the maximum apertures recorded during the diurnal cycle of control plants; this decrease in stomatal opening did not influence the CO2 fixation of stressed plants. Although it was observed an acclimation of photosynthesis in saline conditions, the leaf area and plant biomass were drastically decreased; this was associated with damage to cell membranes and changes in antioxidant enzyme activity. Catalase and guaiacol peroxidase activity in the leaves were 4 and 3-fold higher (relative to controls) after 1 and 3 h of being plants under saline treatment respectively. SOD activity decreased 3 fold relative to the control in the first hour of applying salt stress and increased to values similar to control between 3 and 52 hours later. [ABSTRACT FROM AUTHOR]

This research was done at Jorge Dimitrov Agricultural Research Institute in November 2011. The objective was to study the effect of salinity on the relative water content (RWC) and the concentration of pigments in plants of three varieties of beans (Phaseolus vulgaris L.): HOL-17 HOL-35 HOL-74, using a saline soil (CE 5.2 dS.m-1) and a non-saline soil as control. The Relative Water Content (RWC) was determined by the method described by Yamasaki and Rebello and the concentration of pigment by the methodology of Lichtenthaler and Wellburn. The results indicated a significant decrease in the RWC in the saline treatment , in the three studied varieties compared to the untreated (the control) variety. The content of chlorophyll b was affected in the three varieties under saline conditions, while HOL-17 and HOL-74 varieties exhibited a significant increase in the concentration of carotenoids, which suggests a protective mechanism of chlorophyll photooxidation induced by salt stress. [ABSTRACT FROM AUTHOR]

The chitosan is widely used in agriculture for having a strong fungistatic effect, also it has other properties such as extending the post harvest life of fruits and vegetables and stimulating the plant growth, among others. However, the use of this biopolymer for inducing salinity tolerance has been few studied, so the objective of this work was to check if chitosan-treated seeds are able to reverse the effects caused by salinity in the rice seedling growth and some biochemical indicators associated to this response. To do this, rice (Oryza sativa L.) seeds variety INCA LP-5 were treated for 24 hours with different concentrations of chitosan (0, 100 and 500 mg L-1). The germinated seeds were transferred to pots containing diluted Hoagland nutritive solution supplemented or not with NaCl 100 mmol L-1 and they were placed in a growth chamber with controlled conditions. The growth and biochemical indicators were evaluated eleven days after stress treatment. Seeds treated with chitosan 100 mg L-1 stimulated shoot length and dry matter in saline medium grown seedlings and lowered malondialdehyde and increased proline levels. Both chitosan concentrations enhanced the activities of catalase and peroxidase enzymes, although a higher effect was obtained with chitosan 500 mg L-1. [ABSTRACT FROM AUTHOR]

The ultrastructure of leaves chloroplast and root nodules from cowpea plants (Vigna unguiculata (L.) Walp.), var. IT 86 D-715, subjected to saline stress was evaluated by Transmission Electron Microscopy (TEM). Plants were exposed at 150 and 0,02 mM of NaCl treatments, considering 0,02 mM salt level as control. Native strain VIBA-1 (Bradyrhizobium liaoningense) isolated from saline soils of Cauto Valley (Cuba) was inoculated at sowing. Forty days after germination, samples of the same age and position from leaves and root nodules were taken for microscopy observations. Some ultrastructural modifications were detected by the salt effect in chloroplasts, mainly triggered by the great increase in the size of the starch granules. These modifications produced altered grana distribution. In nodule structure, when saline stress was applied, a weakness of peribacteroid membrane and high number of vesicles into infected cells were noted. Symbiosomes started deteriorating with some broken peribacteroidal membranes. A high vesiculation and degradation of some cellular organelle into uninfected cells were observed. [ABSTRACT FROM AUTHOR]

To evaluate alfalfa (Medicago sativa L.) tolerance to osmotic stress induced by polyethylene glycol 6000 (PEG6000) and salinity (NaCl), germination and growth was investigated in early seedling stages in three genotypes: Dk166, Verdor and Salina varieties. This investigation was performed using a completely randomized design with five replications: energy and power of germination, length of leaves, fresh and dry weight from roots and leaves. Results showed that germination, in which both solutions were used, was delayed in all varieties, with differences between genotypes. Seedling growth under light stress showed an increase in aerial biomass, while in severe drought and salinity stress, the varieties died except var. Salina (tolerant). PEG caused death in Verdor variety that showed more sensibility to PEG than to NaCl. In roots, the more sensitive genotypes faced to light salt stress stop their growth and under light drought stress, they increased it. Our studies allowed us to define the commercial varieties of Medicago sativa as moderately tolerant to salinity and drought the Dk166 variety; as sensitive or intolerant to salinity and drought the Verdor variety and as highly tolerant to salinity and insensitive to drought the Salinity variety. [ABSTRACT FROM AUTHOR]

The soil salinity affects food production worldwide. This shows a tendency to increase in coming years worldwide, as well as Cuban territory, where this environmental phenomenon, regardless of weather conditions, has led to processes of soil degradation, affecting crop yields of major interest in the national economy. Salt stress, causes physiological and biochemical changes in plant metabolism that determine their survival and productivity in these conditions, so plants have evolved mechanisms of tolerance. Genetic improvement offers an increase in both the recovery of underutilized areas, and yields in areas where salinity is a limiting factor or for which you work in various ways. Given that the selection of salt tolerant plants, is a long process determinedly, working in the search for efficient indicators for early selection of genotypes with better agronomic performance. These aspects are addressed in this paper focusing on the improvement as an effective tool for the selection of genotypes of different crops with better performance under salt stress. [ABSTRACT FROM AUTHOR]

Brassinosteroids are steroidal compounds which are required to plant growth and development and they are, also, implied in plant response to abiotic stress. The central objective of this paper was to evaluate if rice seed treatment with different concentrations of a natural brassinosteroid and an spirostane analog reduces the impact of salt stress in the seedling growth. Two experiments were performed, at the first one, a salt sensitive variety, J-104 was used and at the second one, a tolerant genotype, Ginés, was employed. In both experiments, the seeds were treated, for 24 hours, with different concentrations (0; 0,01; 0,1 y 1,0 µmol.L-1) of a natural brassinosteroid, 24-epibrassinolide, and an spirostanic analog of brassinosteroids, 25(R)-3α,5α, dihydroxy-5α-spirostan-6-one, which formulation is known as BIOBRAS-16. After germination, the seedlings were placed in pots containing Hoagland diluted nutritive solution with the addition or not of 100 mmol.L-1 sodium chloride. In the first experiment, the seedlings remaining during eleven days in a growth room with 12 h photoperiod and 25±2°C temperature; while in the second one, the seedlings were grown for thirteen days at a 28±2°C temperature. At the end of the experiments, root and shoot length and dry mass were evaluated. Results showed that 24-epibrassinolide and BIOBRAS-16 were able to reverse partially the seedling growth inhibition of both rice genotypes induced by the presence of sodium chloride; being the more effective treatments in the tolerant variety. [ABSTRACT FROM AUTHOR]

The present study aimed to perform biochemical studies to search possible indicators for differentiation in the early development stages of rice varieties, in relation to their degree of tolerance to saline stress. Leaf samples of two varieties with different degrees of tolerance to salinity (Pokkali and Amistad-82) and grew up in greenhouses growing in nutrient solutions simulating the salt stress (8 and 12 dS.m-1), were analyzed. At 35 days after planting, it was assessed the activity of the enzyme peroxidase, total protein content, proline and lipid peroxidation. The results showed a differential behavior of the varieties in their degree of tolerance when using the EC 12 dS.m-1 which allows using the activity of the enzyme peroxidase, proline concentration and lipid peroxidation in the discrimination of rice genotypes tolerant to salinity. [ABSTRACT FROM AUTHOR]

Salinity is a widespread root medium problem limiting productivity of cereal crops worldwide. The ability of plants to tolerate salt is determined by multiple biochemical pathways that facilitate retention and/or acquisition of water, protect chloroplast functions, and maintain ion homeostasis. Therefore, the ability of salt-sensitive ('Tajan') and salt-tolerant cultivar ('Bam') of Triticum aestivum L. to adapt to a saline environment were evaluated in a set of greenhouse experiments under salt stress during three growth stages (tillering, 50% anthesis, and 10 d after anthesis). Plants were irrigated by different saline waters with electrical conductivities of 1.3, 6, 8, 10, and 12 dS m-1 which were obtained by adding NaCl:CaCl2 in 10:1 molar ratio to fresh water. Differences in growth parameters, lipid peroxidation, superoxide dismutase (SOD) activity, and proline accumulation were tested in order to put forward the relative tolerance or sensitivity of cultivars. Results indicated that both parameters differ according to the cultivar's ability in coping oxidative stress caused by salinity. We observed a greater decline in the growth parameters and grain yield under salt stress in 'Tajan' than in 'Bam'. Malondialdehyde content was also higher in 'Tajan'. The improved performance of the 'Bam' under high salinity was accompanied by an increase in SOD (EC 1.15.1.1) activity and proline content at all growth stages. Growth parameters, lipid peroxidation and proline accumulation results are also in good correlation with supporting this cultivar is being relatively tolerant. [ABSTRACT FROM AUTHOR]

Background: Soil salinity severely affects crop yield all over the world. In a recent study, we found that homeopathic drug Natrum muriaticum 200 cH improved growth in germinating cowpea [Vigna unguiculata (L.) Walp] seeds. Aim: In the present study, we tested homeopathic drug Sepia succus, which is complementary to Nat-m on cowpea seedlings under salt stress. Methods: Cowpea seedlings grown over moist filter paper in Petri dishes were divided in 4 groups: (1) control in sterile water, (2) in 50 mM NaCl solution, (3) seeds pretreated with 90% ethanol diluted with water 1:100 and then transferred to 50 mM NaCl solution, and (4) seeds pretreated with Sep 200 cH diluted with water 1:100 and transferred to 50 mM NaCl solution. In another experiment the groups were same, but the dilution of 90% ethanol and Sep 200 cH was 1:1,000 instead of 1:100 to further reduce the ethanol content in both drug and its vehicle 90% ethanol, to minimize or abolish the effect of alcohol. The data were analyzed by ANOVA followed by Student's t-test. Results: Sep 200 cH in both 1:100 and 1:1,000 dilutions significantly increased the growth, sugar, chlorophyll, protein and water content of seedlings as compared to the untreated salt-stressed group. The effect with the 1000th dilution of Sep 200 cH was more pronounced compared to the 100th dilution. Vehicle 90% ethanol in 1:100 dilution produced some positive effects on the seedlings, but its 1000th dilution produced no such effect. Conclusions: Sep 200 cH counteracted the effects of salt stress in cowpea seedlings, and its 1000th dilution was more effective than the 100th dilution. The effect of alcohol was totally eliminated with the 1000th dilution of 90% ethanol. Therefore, the 1000th dilution could retain the drug effect and eliminate the vehicle effect. [ABSTRACT FROM AUTHOR]

Salinization of soils is one of the most alarming facts worldwide, it remarks the necessity of find natural products which omdice the saline stress tolerance on plants. On this paper, the effect of 24 epibrassinolide (EBL), a natural brassinosteroid, on growth, proline level and lipid peroxidation on rice seedlings var. J-104 (susceptible) under stress caused NaCl during seven days, was evaluated. Rice seeds were sowing on distilled water during 24 hours, then were germinated on Petri dishes and 48 hours later, were planted on flasks containing a Gley nodular ferritic hydromorphic soil, whichs were placed on a plastic basket containing Hoagland nutritive solution, to allow the normal growth of plants. At the moment of the appearance of the 3th true live (five to six weeks after planting), the treatment of salinity was imposed with NaCI (100 mmol.L-1) on Hoagland solution during seven days and in this moment leaves were sprinkled with 24 epibrassinolide (0,5; 1 and 2 µmol.L-1). Plants were maintained on Hoagland solution during 14 days to their recovering. At the moment of the salinity treatment application, at the end of the stress period, seven days after beginning of recovering period and at the end of this period, the length and biomass of radical and aereal parts of plants were measured. Proline and malondialdehyde levels were also evaluated, as well as lipid peroxidation at the end of the recovering period. The results showed that the effects of NaCI and EBL on the growth and malondialdehyde level on leaves of seedlings, depends on the temperature during the growing period. The increase of proline levels, caused by the stress due to NaCl after 14 days of recovering, diminished significatively with the application of 1 to 2 µmol.L-1 de EBL on both repetitions. [ABSTRACT FROM AUTHOR]

Salinity stress is a major and ever-present threat to crop production, especially where irrigation is necessary for agriculture. Two independent field experiments were carried out in natural non-saline (site-I; electrical conductivity [EC] < 4 dS m-1) and saline (site-II; EC = 10-13.8 dS m-1) fields to test the efficacy of different doses of Si (0, 75, and 150 mg kg-1) on two wheat (Triticum aestivum L.) cultivars with different salt susceptibility, i.e., 'Auqab-2000' (salt-sensitive) and 'SARC-5' (salt-tolerant). The crop was harvested at maturity and various ionic and yield parameters were recorded. The concomitant increase in the number of tillers, number of grains per spike, grain yield, and biological yield were observed given that Si was applied under both optimal and salt-affected field conditions. It was concluded that 'SARC-5' is better than 'Auqab-2000' under salt stress. When Si was applied, similar effects were observed in both cultivars regardless of their salt sensitivity and whether the field was saline or non-saline, and it enhanced wheat growth by improving K+:Na+, which was adversely influenced by salt stress. [ABSTRACT FROM AUTHOR]

The effect of different levels of NaCl on the seed water absorption, the germination, growing and total fresh and dry matter accumulation was studied in the floury wheat variety Cuba-C-204. Results showed that water absorption in this variety it is only significatively affected at salt-concentrations higher than 25 dS.m -1 showing the tolerance of this process to the salinity. The germination and growing indicators evaluated and accumulation of fresh and dry matter did not show significative damages at salt concentrations less than 25 dS.m-1. The regression analysis allowed to determinate the existence of negative regression between salinity and growing variables in wheat. Starting from such analysis the theorical salinity levels that diminish the growing and the accumulation of fresh and dry matter in a 50% were determined, observing a major sensibility in dry and fresh matter accumulation and plants height related to the root length. [ABSTRACT FROM AUTHOR]

With the objective to analyze the response of 12 wheat varieties to salinity at the early stages of growing was carried an experience using two different levels of NaCl. The variables plants height, root length and fresh and dry matter accumulation were evaluated. Through the Principal Component Analysis the indicators of most contribution to the total variability were established and through the Cluster analysis the varieties were collected in tree groups showing the existence of great variability for its response to saline stress. Five Cuban mutants and its progenitor CubaC-204 were placed in the group I showing the major response at the early stages of growing, wish will start to evaluate under field conditions based on yield components indicators [ABSTRACT FROM AUTHOR]

The aim of this paper was to evaluate the salt-stress tolerance of the 75 AB Citrumelo cultivar (Citrus paradisi x Poncirus trifoliata) in comparison with the Cleopatra Mandarin (Citrus retuculata) which is known worldwide due to its high stress resistance. Seedlings of both species were incubated in between paper towels damped with distilled water or 30 mM NaCl solutions. The experimental design was completely randomized with 3 replica and the data were analyzed using ANOVA and the Tukey test. After 41 days, fresh weight, relative water content (RWC), proline concentration, and mineral composition were determined. Growth in Cleopatra was more sensitive to salinity than that of the 75 AB Citrumelo cultivar, whereas relative water content kept constant in both rootstocks. The osmotic adjustment occurred by accumulating proline in leaves being its concentration higher in the 75 AB Citrumelo. The latter excluded Na+ and Cl- ions from the aerial part of the plant and limited them to the root system while the contrary was observed for Cleopatra. The 75 AB Citrumelo cultivar is more tolerant to salinity than Cleopatra and excludes both Na+ and Cl- ions from its aerial part. [ABSTRACT FROM AUTHOR]

With the objective to analyze the response of 12 wheat varieties to salinity at the early stages of plant growth, an experience was carried out using two different levels of NaCl. The variables evaluated were plant height, root length and fresh and dry matters. Through the Principal Component Analysis, indicators of the most contribution to the total variability were established and through the Cluster analysis, varieties were collected in three groups, demonstrating the existence of variability for its response to stress. Five mutants of the variety CubaC-204 were placed in group I, showing the major response at the early periods of growth, which will start to be evaluated under field conditions based on yield and its components. [ABSTRACT FROM AUTHOR]

Saline stress reduces water-absorbing capacity of plants, causing a quick growth reduction. Brassinosteroids are involved in plant tolerance to this kind of stress. This paper presents the effect of treatments with a natural brassinosteroid (24-epibrassinolide, EBR) and a brassinosteroid spirostanic analog (MH5) on seedling growth of two rice varieties in a culture medium supplemented with or without NaCl. Seeds from J-104 and INCA LP-7 germinated in a MS medium supplemented with EBR or MH5 for seven days. Seedlings were later transferred to a single MS medium or supplemented with 100 or 150 mM NaCl for 12 days. The presence of NaCl in the culture medium proved to differently affect seedling growth of those varieties and, even though treatments with EBR were capable of significantly promoting the cumulative fresh weight rate of leaves from INCA LP-7 seedlings grown in a medium supplemented with 100 mM NaCl and of roots from J-104 seedlings grown in a saline medium, absolute values of these indicators did not differ from the ones of the control treatment. [ABSTRACT FROM AUTHOR]

In the Semiarid Central Pampa Region, with low nitrogen content of the soils, about 26 % of the area cultivated with wheat is fertilized with nitrogen. However, water availability limits wheat production due to low rainfall and a very marked water deficit during winter and summer. Therefore, complementary irrigation might contribute to increase the production of this crop, but the implementation of this technology has important restrictions, due to the abundance of highly saline ground water. In order to explain the yield increases due to a higher utilization of nitrogen in wheat, in modern cultivars respect to old cultivars we studied: a) a historical sequence of wheat cultivars in the Semiarid Pampa Region with respect to vegetative growth parameters and yield and b) the yield, with response of the genotypes to nitrogen fertilization with high - salt water irrigation. The experiment was carried out in, five genotypes released between 1954 and 1989, two levels of nitrogen fertilization and two levels of water availability. Our results showed that modern cultivars had a better yield index than the old ones. The yield response to nitrogen fertilization was different and the cultivars also differed in growth and yield in response to the irrigation with saline water. The grain yield response to nitrogen fertilization, in some genotypes, may not occur when irrigation with high salt content water is applied. [ABSTRACT FROM AUTHOR]