A pot experiment was conducted to evaluate the beneficial effect of foliar application of glycine betaine (10mM), grain presoaking in salicylic acid (0.05 M) and their interaction on drought tolerance of two wheat ( Triticum aestivum L.) cultivars (sensitive, Sakha 94 and resistant, Sakha 93). Osmotic pressure, some osmolytes concentration and grain yield were determined. Water stress caused an increase in osmotic pressure, proline, total soluble nitrogen, total soluble sugars, organic acids, ions (Na +, K +, Ca +2, Mg +2 and Cl -) content as well as Na +/K + ratio in cell sap flag leaves of both wheat cultivars. The resistant variety had higher values of osmotic pressure, proline, organic acids and ions content than the sensitive one. On the other hand, water stress induced marked decrease (P<0.05) in grain yield. The applied chemicals mitigated the effect of water stress on the used wheat cultivars. The effect was more pronounced with glycine betaine + salicylic acid treatment. The applied chemicals increased the osmotic pressure, the osmolytes concentrations as well as the grain yield. Furthermore, the osmotic pressure of flag leaf sap appeared to depend on proline, TSN, TSS, organic acids and the ions content. The economic yield (grain yield) was positively correlated with proline, keto-acids and osmotic pressure but negatively correlated with TSN, TSS and citric acid.
Журнал стресс-физиологии и биохимии / Journal of Stress Physiology & Biochemistry
2013. — Выпуск 3
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Effect of different concentrations of heavy metals such as Cadmium, Chromium, Mercury and Lead was studied by cultivating rooted propagules of Boerhavia diffusa for a period of twenty days in Hoagland nutrient medium artificially contaminated with known concentration of those heavy metal ions. Concentrations of the metals selected to impart visible symptoms of growth retardation and to permit survival for prolonged period are 30 µM cadmium chloride (CdCl 2), 400 µM potassium dichromate (K 2Cr 2O 7), 10 µM mercuric chloride (HgCl 2), and 600 µM lead acetate (CH 3-COO) 2 Pb. More or less uniform growth performance was shown by the plants irrespective of the differences of concentration of the heavy metals. However, parameters such as root - and stem length, stomatal - and tolerance index varied among the treatments. Significant differences were observed in the heavy metal accumulation potential among metals and between plant parts such as root, stem and leaf and the pattern was dependent on growth period.
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Corypha umbraculifera L. is a monocarpic palm, which usually flowers after 30-60 years of growth. In C. umbraculifera seeds are the only propagating unit, but the germination rate is very low and seeds are highly recalcitrant. In this context, it was imperative to investigate the desiccation sensitivity, physiological and biochemical changes accompanying the desiccation and germination in C. umbraculifera seeds. Therefore, to make a detailed study, freshly collected C. umbraculifera seeds were desiccated at room temperature for a period of 35 d and physiological and biochemical changes during desiccation and germination were monitored at an interval of 7 d. It was observed that there was a sharp decline in the moisture content of the seed as desiccation proceeded. As the desiccation period progressed, the germination percentage decreased which was below 50% after 35 d. The dry weight percentage of the embryo and endosperm increased with the desiccation period and the increase in dry weight of embryo was significant in comparison with the endosperm. Total protein content of embryo was more compared to that of the endosperm. Peroxidase activity in the embryo was increased up to 28 d of desiccation and decreased further. The endosperm registered a gradual reduction of peroxidase activity during desiccation. In contrast, SOD activity in the embryo was comparatively higher in the fresh seeds and further declined during desiccation, while that of the endosperm remained almost unaltered. The results give a strong indication that desiccation in C. umbraculifera is accompanied by abundant activity of peroxidase in embryo, thereby viability is retained up to 35 days. Whereas, feeble activity of SOD is not seen to be linked with seed viability of C. umbraculifera.
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This investigation aimed to evaluate five upland cotton ( Gossypium hirsutum L.) (Aleppo118, Aleppo33/1, Aleppo90, Raqqa5, and Deir-Ezzor22) varieties based on physiological indices and genetic variation using AFLP marker. These varieties were evaluated under control and saline conditions (50, 100 & 200 mM NaCl) for 56 days. Various physiological indices were detected in this investigation. In this respect, Deir-Ezzor22 variety differed by showing high salt tolerance relative to the other tested varieties. Otherwise, PCR amplification with 7 AFLP PCs primer combinations revealed that Deir-Ezzor22 variety characterized by 15 unique positive markers compared to the other tested varieties. Based on physiological study and AFLP technique, it can be concluded that genetic variation detected by AFLP marker supported the physiological indices among the tested cotton varieties. These varieties present considerable interest for genetic studies and plant improvement.
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In this study physiological, certain blood hormones and immune status of male and female Broad Breasted White turkeys were recorded under cold stress. Birds were acclimated two weeks prior to the start of experiment and later divided into two groups. Control group (n=12 with equal number from each sex) was maintained at an environmental temperature of 27-30 °C and Test group (n=12 with equal number from each sex) was housed in a designed chamber were the temperature (10±1°C) remained stable at least for 5-6 hours in a day. After 3 consecutive days (72 hours) of temperature treatment Phytohaemagglutinin-P (PHA-P) at the dose rate of 0.5 mg in 0.1 ml PBS were injected to the patagium of both control and test group of birds to study the cell mediated immune response by measuring the dermal swelling in response to inflammatory reaction after 24 hours of injection of Phytohaemagglutinin-P (PHA-P). After 96 hours of cold treatment the blood samples were collected from the wing vein to analyze the blood hormonal levels using standard protocols. The physiological parameters like respiration rate, rectal temperature and surface temperature were recorded at the morning hours of the day during experimental period. Significant difference (p≤0.01) between treatments were observed in body temperatures, respiration rate, Heterophil%, H/L ratio, Wing web thickness, T4 and cortisol levels.
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Seed priming techniques have been used to increase germination, improve germination uniformity and seedling establishment under stressed conditions. Seed priming was used in Rye Mountain ( Secale montanum ) to increase seed germination and tolerance on stress exposure. Rye seeds were treated with various priming agents for different time and temperatures. The effect of priming was assessed on germination characteristics on subsequent exposure to drought (PEG -14 bar) stress for 7 days. Seed priming treatments significantly (p≤ 0.01) affected, Germination percentage (GP), normality seedling percentage (NSP), germination Index (GI), germination uniformity (GU), means time to germination (MTG), coefficient of velocity of germination (CVG), seedling vigour index (SVI) and coefficient of allometry(AC). Seed priming with gibberelic acid (GA) and salicylic acid (SA) (p≤ 0.01) increased germination characteristics as the compared to the unprimed. Seed priming with concentrations 25, 50 ppm of GA for 15 h at 10 ◦C and 25 ppm of SA for 12 h at 10 ◦C, may be considered as optimal treatment for priming of Secale montanum seeds in drought stress conditions. Also priming increased catalase (CAT) and ascorbate peroxidase (APX) as compared to the unprimed.
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Drought is one of the complex environmental factors affecting growth and yield of sorghum in arid and semi-arid areas of the world. Sixteen elite sorghum ( Sorghum bicolor (L) Moench) genotypes were evaluated for their genetic potential to drought tolerance at callus induction and plant regeneration stage for drought tolerance. The non-ionic water soluble polymer polyethylene glycol (PEG) of molecular weight 6000 was used as osmoticum to simulate water stress. The factorial experiment was laid down in a completely randomized design which comprised of a combination of two factors (genotypes and five PEG stress level; 0, 0.5, 1.0, 1.5, and 2.0% (w/v) treatments). Data were recorded for callus induction efficiency, callus fresh weight, embryogenic callus percentage and plant regeneration percentage. Significant differences were observed among the genotypes, treatments and their interactions for the evaluated plant traits suggesting a great amount of variability for drought tolerance in sorghum. The correlation analysis also revealed strong and significant association between embryogenic callus percent and plant regeneration percent as well as between embryogenic callus percent and plant regeneration percent. By taking into consideration all the measured traits, Mann Whitney rank sum test revealed that 76T1#23 and Teshale followed by Meko, Gambella-1107 and Melkam showed better drought stress tolerance. Therefore they are recommended to be used as parents for genetic analysis, gene mapping and improvement of drought tolerance while Chelenko, Hormat and Raya appear to be drought sensitive.
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Phenylalanine ammonia lyase (PAL) is a biochemical marker of the environmental stress and plays a pivotal role in phenolic synthesis. The lower ROS level and oxidative damage was observed in grafted plants and the rootstocks have a profound influence on the biochemical composition, especially phenolic compounds. Regarding the importance of the effect rootstocks have on scion in pistachio trees, this study was carried out to assess and compare three pistachio cultivars ("Ahmadaghaii", "Ohadi" and "Kallehghuchi") on three rootstocks (Mutica, Ahli, Sarakhs). PAL activity, phenolic compounds, flavonoid and anthocyanin contents in leaves, flowers and fruits were measured toward the selection of the most suitable and compatible rootstock/scion resistant to environmental stresses. The results showed that PAL activity was different among the cultivars and organs. A positive correlation was observed between PAL activity and phenolic compounds in the leaves and flowers of Mutica- Ahmadaghaii, suggesting that it is more resistant than the others to environmental stresses. PAL activity and total phenolics in fruits of pistachio suffered a decrease when the maturation processes began. The hulls of the pistachio fruits contained high levels of phenolic compounds especially in Mutica-Ahmadaghaii) suggesting its function as a protective layer and a defense chemical against ultraviolet radiation and pathogen. Our results indicated the presence of a number of bioactive compounds in kernels with the highest amount belonging to Mutica- Ahmadaghaii, and therefore it is concluded that pistachio rootstocks may affect the antioxidant compounds in kernels.
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Agrobacterium tumefaciens infection and antibiotic wash are the critical steps of Agrobacterium mediated plant transformation procedure, most time responsible for lower transformation efficiency due to necrosis and phytotoxicity caused by biotic stress of Agrobacterium and abiotic stress by antibiotics respectively. Ammi majus Egyptian origin medicinal plant and Pearl millet cereal grain crop were studied for their stress responses to Agrobacterium mediated transformation (AMT). Agrobacterium strains LBA4404 (O.D.=0.6-0.8) and EHA105 (O.D.=0.2-0.4) were used for transformation experiments to infect calli of Ammi majus and embryogenic calli of Pearl millet respectively. Incase of antibiotic wash, Cefotaxime 500 mg L -1 was used for LBA4404 infected Ammi majus calli and Timentin 300 mg L -1 was used for EHA105 infected embryogenic calli of Pearl millet. Effects of Agrobacterium infection, antibiotic and NaOCl washes on Agrobacterium removal and both explants physiological changes during transformation experimental procedures were studied. At the end of the experiments explants survival efficiency of Ammi majus and pearl millet were 8% and 5% respectively. Biotic and abiotic stress factors responsible for lower efficiency were investigated with various other factors and strategies were discussed which are need to be considered for higher transformation events and target tissue survival.
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Saline soils are defined as those that contain sufficient soluble salts in the root zone to impair plant growth. Wheat is one of the three major cereals dominating world agriculture to date. Durum wheat is the hardest wheat and the concept of durum wheat quality is complex and confusing. Quality factors such as protein content, gluten strength and color have different priorities in various durum wheat markets. Changes in the grain quality of ten durum wheat cultivars under salt stress studied at the greenhouse condition. A factorial experiment was carried out based on completely randomized design with three replications. Treatments were salinity including 0, 60 and 120 mM and ten durum wheat cultivars (Boomer, PGS, 71135, 61130,605, C1351, KND, KDM, Haurani and G1252). Biochemical grain reserves such total protein and carbohydrate content, gluten, phosphorous and beta carotene were measured. Results showed that interaction of salt and cultivars was significant for all studied traits except of beta-carotene. At this experiment, gluten content changed very little with salinity levels. Cultivar 71135 at all salinity levels had the highest gluten content. With increasing of salt severity, the content of protein and carbohydrate decreased and content of phosphorous increased compared with control. In 60 mM salinity, cultivars 61130 and 71135, in 120 mM, 71135 and KDM and in control, 61130 and PGS respectively, had the highest and lowest content of protein. Cultivars 71135 and 61130 had the highest and PGS had the lowest phosphorous content in control. At 60 mM, cultivars 71135 and PGS respectively, had the highest and lowest phosphorous content. At 120mM, 71135 and Haurani respectively, had the highest and lowest phosphorous content. In three salt levels, cultivar 71135 was determined as the most tolerant cultivar according to content of grain reserve composition results.
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Exposure to environmental stress due to salinity has been reported to result in adverse effects on the growth of plants. Studies have shown that the use of plant growth regulators (PGRs) has an ameliorative effect on plants grown under saline conditions. In the present investigation, effect of gibberellic acid (GA 3), 6-furfuryladenine (Kinetin) and benzyl adenine (BA) on Spinacia oleracea L. var. All Green, cultivated under saline conditions has been studied. After a pre-soaking treatment of six hours in 20 mg L -1 solutions of GA 3, Kinetin and BA, the seeds were allowed to germinate and grow for forty-five days under saline conditions. On the analysis of mature leaves, it was observed that both chlorophyll a and b, and total chlorophyll showed an increase in PGR-treated plants compared to the untreated set. With the pretreatment, the reducing and non-reducing sugar content, as well as protein content of the leaves showed an increase in accumulation compared to the untreated plants. The accumulation of the stress metabolite proline, which increases under saline conditions, showed a significant decrease in the plants pretreated with PGRs.
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С использованием базы данных AtGenExpress проводили биоинформационный и корреляционный анализы экспрессии генов белков теплового шока (БТШ) и PR-белков в корнях, стеблях и культуре клеток арабидопсиса. Биоинформационный анализ показал эффект подавления БТШ при синтезе PR-белков в корнях, стеблях и культуре клеток арабидопсиса. С помощью корреляционного анализа выявлена обратная корреляционная зависимость между экспрессией генов БТШ и PR-белков только в культуре клеток, на корнях и стеблях арабидопсиса зависимости не наблюдалось.
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The present study was conducted with the aim to identify the response of antioxidant enzyme activities in seedlings of different sorghum cultivars under mannitol stress. Seven-day old seedlings were subjected to 100-500 mM mannitol stress which resulted in the decreases in shoot/root length and relative water content thus indicating the primary response to these tissues at phenotypic level. The level of lipid peroxidation as well as the specific activity of antioxidant enzymes such as peroxidase, catalase and superoxide dismutase increased at higher conc. except at 200 mM conditions. The level of catalase and peroxidase decreased at 500 mM conc. In the two different cultivars whereas the activity of superoxide dismutase consistently increased in response to the mannitol stress. Our data demonstrate that drought responsiveness tolerance in sorghum cultivars during germination is associated with enhanced activity of antioxidant enzymes.
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Heavy metals are important environmental pollutants and their toxicity is a problem of increasing significance for ecological, evolutionary and environmental reasons. The interference of germination related proteins by heavy metals has not been well documented at the proteomic and genomic level. In the current study, molecular responses of germinating groundnut seeds were investigated under Zinc stress. The SDS-PAGE showed the preliminary changes in the polypeptides patterns under Zinc stress. Restriction digestion banding pattern of EcoRI and Hind III enzymes showed distinct banding pattern in the treated plants.
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Изучали влияние температуры, глубины посева и гранулометрического состава почвы на скорость прорастания, лабораторную и полевую всхожесть семян редьки масличной. Было установлено, что период посев-всходы определяется, как температурой, так и гранулометрическим составом почвы. Наибольшую полевую всхожесть отмечали семян редьки масличной на супеси при глубине посева семян - 3 см и температуре 20° С.
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To evaluate the freezing resistance and genetic diversity in barley physiological traits, molecular markers and their relationship in 20 barley genotypes were assessed in field and greenhouse condition. The analysis of variance showed a significant difference among studied genotypes. The effect of acclimation temperature on prolin content, quantum efficiency of photosystem II, chlorophyll and soluble sugars content were studied as physiological traits. Freezing treatments were -4, -7, -10, -13 and -16 °C temperatures that applied in a 3 replicated randomized complete block design. Then their lethal temperature at which 50% of plant were died (LT 50) was determined. To estimate FSI (Field Survival Index) index, the 20 genotypes were cultured in a separate experiment on field with 3 replications. The results showed negative significant correlation (-0.601) between field survival index and LT 50. Cluster analysis using physiological traits, genotypes of F-A1-1, F-A1-2, F-A2-11, F-GRB-85-5, Sahra, Sahand, Dasht and Makouei were categorized in a distinct group and had a high FSI and low LT 50. Makouei cultivar having LT 50=-17.66 °C and the highest percentage of winter survival in the field, was the most resistant genotype. 10 ISSR markers from 35 primers sequences were selected and used. These 9 ISSR primers produced 50 polymorphic bands. PIC and MI average index for all primers were 0.37 and 1.72 respectively. Cluster analysis of molecular data using Jaccard similarity coefficient categorized the genotypes to four distinct groups. Associations between molecular markers and traits were assessed by multiple regression analysis. Some informative markers related to FSI and also LT 50 was determined. So it may be possible to use these markers for selection of resistant lines or genotypes in breeding programs.
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A key issue in salt adaptation is the osmotic adjustment, therefore, during ear emergence the effect of exogenous application of kinetin and spermine on osmotic pressure (OP) and solutes allocation (total soluble sugars, total soluble nitrogen, proline, organic acids and inorganic ions (Na +, K +, Ca 2+, Mg 2+ and Cl -) were quantified in flag leaf of wheat plants irrigated by seawater at 25%. Seawater salinity induced significant increase in osmotic pressure. Furthermore, seawater stress induced marked increase in total soluble sugars, total soluble nitrogen, proline, organic acids, as well as Na +, K +, Ca ++, Mg ++, Cl - and P +++ in wheat flag leaf. On the other hand, seawater decreased SPR, SAR and PAR in flag leaves of wheat plants. Grain priming with kinetin, spermine or their interaction appeared to mitigate the ill effect of seawater on wheat plants by increasing its own capability to be more tolerant against seawater salinity by inducing additional increase in osmotic pressure and the osmolytes concentrations in flag leaf during ear emergence. Moreover, the effect was more pronounced with the interaction of kinetin and spermine treatment.
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One of the most important limiting factors in spread of apricot in Iran is late spring frost, which damages flower bud and decrease total yield of crop. It has been found that ascorbic acid (AA) plays a beneficial role during plant response to chilling and freezing stresses. To evaluate the effects of AA on alleviating of cold stress, the flower buds of Prunus armeniaca L. cv. Shahroudi were sprayed at pink cluster stage with AS at 4 levels (0, 100, 200 and 300 mg. L -1) and were then exposed to artificial cold stress (4 h at – 4 °C) or without cold stress (+ 25°C). Experimental attributes including electrolyte leakage (EL) of flower buds and percentage of damage of pistil, anthers and petals to temperature treatments were determined. The results showed that at - 4°C the lowest and highest percentage of damage and EL of flower buds were observed in application of 200 and 0 mg.L -1 AA, respectively. The highest and lowest percentage of damage of flower organs and EL were obtained in application of 300 and 200 mg. L -1 AA, respectively at + 25 °C. Based on the results of this experiment, AA alleviates the negative effect of cold stress on EL and flower organ damages in apricot cv. Shahroudi, depending on the concentrations of AA used.
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An assessment was undertaken to study the efficacy of bacterial consortia isolated from different sources viz. rhizosphere of rice plant, oil spill sites of a petrol pump and from the sludge of a pharmaceutical waste water drain against the impact of fluoride. The experiments were conducted with two crops. In this mung bean experiment Vigna radiata was selected as a test crop. The seeds were sown in the field with bacterial consortia, compost and reduced dose (25% less nitrogen than recommended dose) of chemical fertilizer. After 30days of seed sowing (DAS), plants were collected from the field and dipped into the sodium fluoride solution with different concentrations for 48 hours. Thereafter, the impact of fluoride on chlorophyll, sugar, proline and relative water content (%) were evaluated. Scanning electron microscopy (SEM) of the stem section was performed. SEM studies revealed that anatomical structure deformed with 1.5 mg/l sodium fluoride solution. It was observed that such treatment combination during the sowing of crops leads to combat the impact of lower doses of sodium fluoride (0.2 mg/l). Another experiment was also conducted within plastic pots with and without bacterial consortia isolated from rhizosphere of rice plant and oil spilled soil of petrol pump with the same field soil. Each pot was filled with 5 kg of soil + 2lt of water (on the basis of soil saturation). Oryza sativa seedlings were transplanted with different strength of sodium fluoride solution (25 mgNaF/kg, 50 mgNaF/kg, 100 mgNaF/kg and 500mgNaF/kg) within the above pots. In second experiment, rice plants dried in all pots after 500 mgNaF/kg concentration of sodium fluoride. In this pot experiment bacterial strain are capable of reducing fluoride content in soil as noted by measuring fluoride in the pot soil after the experiment.
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Plants respond to the environmental cues in various ways, recent knowledge of RNA interference in conferring stress tolerance had become a new hope of developing tolerant varieties. Here we attempt to unfold the molecular mechanism of stress tolerance through miRNA profiling and expression analysis in Finger millet (Eleusine coracona) under salt and drought stress conditions. The expression analysis of 12 stress specific conserved miRNAs was studied using semi-quantitative real time PCR and Northern blot assay. Our studies revealed that, although most of the miRNAs responded to the stresses, the expression of particular miRNA differed with the nature of stress and the tissue. The expression analysis was correlated with the existing data of their target genes. Abiotic stress up-regulated miRNAs are expected to target negative regulators of stress responses or positive regulators of processes that are inhibited by stresses. On the other hand, stress down-regulated miRNAs may repress the expression of positive regulators and/or stress up-regulated genes. Thus the current study of miRNAs and their targets under abiotic stress conditions displays miRNAs may be good candidates to attribute the stress tolerance in plants by transgenic technology.
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The study was focused on the varieties of macrocarpous semi-culture apple-trees, which are promising for growing in Southern Predbaikal’ye. Most of varieties studied were shown to be characterized by low winter-resistance in the case of low trunk grafting. Tree skeleton grafting demonstrated an increase of winter-resistance of macrocarpous semi-culture apple-trees.
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This investigation was conducted to study the tolerance strategy of maize, broad bean and pea plants to salinity stress with exogenous applications of proline or phenylalanine on seed germination and seedlings growth. From the results obtained, it can be observed that osmotic stress affected adversely the rate of germination in maize, broad bean and pea plants. The excessive inhibition was more prominent at higher concentration of NaCl. The seeds and grains tested were exhibited some differential responses to salinity, in a manner that the inhibitory effect of salinity on seed germination ran in the order, maize higher than broad bean and the later was higher than pea plant. Treatment with proline or phenylalanine (100 ppm) significantly increased these seed germination and seedlings growth characteristics even at lowest salinity level tested.
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Influence of short-term hardening osmotic exposure (immersion in 1 M sucrose solution with subsequent transferring to distilled water for 20 min) on the hydrogen peroxide generation and superoxide dismutase activity in wheat ( Triticum aestivum L., cv. Elegiya) seedlings and their tolerance to osmotic shock were investigated. During the initial 30 min after osmotic exposure, the increasing of hydrogen peroxide amount in roots and shoots (to a lesser extent) was observed, but the resistance of the seedlings and superoxide dismutase (SOD) activity decreased. Sometime later the decrease in hydrogen peroxide amount and the increase of seedlings tolerance to osmotic shock took place. SOD activity increased in 10 min after hardening osmotic exposure. Transient accumulation of hydrogen peroxide induced in this way was suppressed by the treatment of seedlings with sodium diethyldithiocarbamate (DDC), SOD inhibitor. DDC and hydrogen peroxide scavenger dimethylthiourea decreased positive hardening effect of osmotic exposure on the development of seedlings tolerance. It was concluded that SOD providing the generation of signal hydrogen peroxide pool took part in the induction of seedlings tolerance to osmotic shock development caused by preliminary hardening effect.
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Drought stress is one of the major abiotic constraint limiting plant growth and productivity world wide. The current study was undertaken with the aim to investigate the effect of water deficit imposed by PEG-6000, on chlorophyll metabolism in maize leaves to work out the mechanistic details. Leaf segments prepared from primary leaves of etiolated maize seedlings were treated with varying concentrations of polyethylene glycol-6000 (PEG-6000; w/v- 5%, 10%, 20%, 30%) in continuous light of intensity 40 Wm -2 at 26±2 °C for 24 h in light chamber. The results demonstrate a concentration dependent decline in chlorophyll content with increasing concentration of polyethylene glycol-6000 (PEG-6000). Reduction in chlorophyll ‘a’ level was to a greater extent than the chlorophyll ‘b’. The RNA content decreased in a concentration dependent manner with PEG, however, proline content increased significantly. Relative water content decreased significantly with the supply of 30% PEG only. A substantial decrease in chlorophyll synthesis due to significant reduction in ALA content and ALAD activity, with no change in chlorophyllase activity with the supply of PEG suggests that water deficit affects chlorophyll formation rather than its degradation.
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Environmental cues, such as temperature, play important roles in the regulation of physiology and behavior in small mammals. The aim of the present study was to test the hypothesis that ambient temperature was a cue to induce adjustments in body mass and thermogenic capacity in Apodemus chevrieri . It showed that A. chevrieri increased resting metabolic rate (RMR), nonshivering thermogenesis (NST) and energy intake and decreased body mass and body temperature when exposed to the cold while showed a significant increase in body mass and body temperature after rewarming. The decrease of body temperature can reduce the difference in temperature in environment, save energy consumption. The increase in body mass after rewarming was associated with the higher energy intake. Together, these data supported our hypothesis that ambient temperature was a cue to induce changes in body mass and metabolism in A. chevrieri.
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A pot experiment was carried out in the botanical garden of Faculty of Education, Ain Shams University, with the aim of studying the effect of salinity levels (4, 8 and 16% of diluted seawater) and foliar application of aspartic acid and/or glutathione on the growth and chemical constituents of tomatoes (lycopersicon esculentum Mill) plants. The most important results can be summarized as: 1). Treatments of high salinity levels reduced all growth parameters and chemical constituents of plants. 2) Both aspartic acid and glutathione significantly increased plant growth, the contents of anthocyanin, α-tocopherol, ascorbic acid and enzymatic activities. In addition, the content of endogenous amino acids was increased which in turn led to positive changes in the picture of protein electrophoresis, theses changes were accompanied by appearance and disappearance of some protein bands and caused obvious changes in the anatomical features of the stems. 3) The effect of aspartic acid was superior to that of glutathione on increasing plant growth and chemical constituents. 4) Under low saline conditions, the maximum plant growth for all the recorded growth parameters was obtained from plants treated with aspartic acid and grown under 8% of seawater, followed by 4%. However, glutathione had inhibitor effect on plant growth and chemical constituents of plants grown at 16% seawater. The data revealed that the different antioxidants could partially alleviate the harmful effects of salinity stress that reflected on growth and some physiological changes of tomato plant.
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Plant scientists are investigating the potential of previously unexploited legume species where environmental and biological stresses constrain the use of more conventional forage crops or where these species are better suited to the needs of sustainable agriculture. Trifolium isthmocarpum Brot., Moroccan clover, occurs as a weed in different habitats in Morocco. It grows in moderately saline areas, where traditional forage legumes cannot be cultivated; however, it has not been widely studied despite its good palatability. The salt tolerance was studied between natural field conditions and glasshouse. The extensive field studies have recorded the species in many different habitats ranging from healthy agricultural lands to abandoned saline areas. The plants maintained high nodulation capacity (ranging between 60% and 97%) and nitrogenase activities (average 2.04 µmol C 2H 4 plant -1 h -1) in different habitats. Shoot systems of plants collected from salt-affected soils exhibited higher concentrations of Na + and Cl - than those collected from healthy soils. Greenhouse experiments showed that germination percentage and vigor value of the studied species was not significantly (P > 0.05) affected at 160 mM NaCl, and that 25% of the germination ability was maintained when growing on substrats containing 240 mM NaCl. The growth rate of seedlings was not signicantly affected by 160 mM NaCl but was reduced by 38% under 240 mM NaCl. Leaf succulence and indices of leaf water status did not differ among the salt treatments, whereas relative water content was reduced by only 8% and water content at saturation increased by about 12% at high salt concentrations in the growing medium. This study suggest recommending the cultivation of T. isthmocarpum in salt-affected soils, which are widespread and pose a problem for the farmers of Morocco and other countries in the world’s arid belt.
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Leaf photosynthesis, a major determinant for yield sustainability in rice, is greatly conditioned by high temperature stress during growth. The effect of short-term high temperatures on leaf photosynthesis, stomatal conductance, Fv/Fm, SPAD readings and yield characteristics was studied in two Colombian rice cultivars. Two genotypes, cv. Fedearroz 50 (F50) and cv. Fedearroz 733 (F733) were used in pot experiments with heat stress treatment (Plants were exposed to 40°C for two and half hours for five consecutive days) and natural temperature (control) treatment. Heat treatments were carried out at the initiation of panicle primordial (IP) or grain-filling (GF) phases. The results showed that short-term high temperature stress produced a reduction on the photosynthesis rate in both cultivars either IP or GF phases. Similar trends were found on stomatal conductance in all cases due to high temperatures. Although Fv/Fm and SPAD readings were not affected by high temperatures, these variables diminished significantly among phenological phases. 'F733' rice plants showed higher number spikelet sterility due to heat stress treatments. These results seem to indicate that heat-tolerant cultivars of rice is associated with high levels of photosynthesis rate in leaves.
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Впервые была изучена активность гваякол-зависимых пероксидаз при разных значениях рН в листовых пластинках Plantago major L.
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The Institute of Forest Genetics and Tree Breeding, Coimbatore, India has a long term systematic tree improvement programme for Eucalyptus species aimed at enhancing productivity and breeding for trait specific clones. In the process, thirty high yielding clones of Eucalyptus camaldulensis Dehnh . were identified. Carbondioxide enrichment studies in special chambers help in understanding the changes at individual level, and also at physiological, biochemical and genetic level. It also provides valuable information for establishing plantations at different geographic locations. Considerable variations were observed when the selected 30 clones of E. camaldulensis were subjected to physiological studies under elevated CO 2 conditions (600 mol mol -1). Ten clones exhibited superior growth coupled with favourable physiological characteristics including high photosynthetic rate, carboxylation and water use efficiency under elevated carbon di oxide levels. Clones with minimal variation in physiological characteristics under elevated levels of CO 2 suggest their ability to overcome physiological stresses and adapt to varying climatic conditions.
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Enzyme activity is influenced by a large number of factors. Environmental conditions such as pH, temperature, salt concentration, substrate concentration, activators, and inhibitors may change the three dimensional shape of an enzyme, altering its rate of activity and/or its ability to bind substrate. The effects of such environmental factors were evaluated. The optimum pH and temperature of the purified urease were 7.2 and 48 0C, respectively, using urea as substrate. The optimum substrate (urea) concentration for urease was 25 mM. The enzyme showed the highest activity when incubated for 30 min at 48 0C. EDTA, a metal chelator, decreased the enzyme activity significantly. This may be due to the removal of metal ions located on or near the active site. Divalent cations like Ba 2+ and Mg 2+ slightly stimulated the enzyme at a concentration of 1-3 mM whereas Na + and K + produced little or no effect on the activity. Ca 2+ enhanced urease activity by 120.47%, while Pb 2+, Cu 2+, Zn 2+ and Hg 2+ almost completely inhibited the urease activity.
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An experiment was carried out using saline water (6.57 dS.m -1) and subsurface drip irrigation (SDI) on two tomato cultivars ( Solanum lycopersicum , cv. Rio Grande and Heinz-2274) in a silty clay soil. The former is a salinity tolerant and the latter a sensitive cultivar. Exogenous application of proline was done by foliar spray at two concentrations: 10 and 20 mg.L -1, with a control (saline water without proline), during the flowering stage. As a result of the proline applied, significant effects were observed on both cultivars of tomato, particularly with low concentration of proline (10 mg.L -1). It led to increase of leaf area, growth length and fruit yield. Regarding mineral nutrition, Ca 2+ was higher in different organs while low accumulation of Na + occurred. However, Cl - was very low significantly in all tissues of plants of Rio Grande at the higher concentration of proline applied.
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Salt (NaCl) induced changes of morphological and biochemical parameters were investigated in Aegiceras corniculatum L. Blanco supplemented with an increasing concentration of NaCl (0 mM, 100 mM, 150 mM, 200 mM, 250 mM and 300 mM). The plant height, stem diameter, dry weight, number of leaves and number of branches per plant were studied and found to be maximum in plants grown in 250 mM concentration of NaCl comparable to others. Biochemical test like total protein, total sugar, chlorophyll and carotenoid contents from leaf samples were performed. No significant changes were observed in total chlorophyll content among 0 and 30 days of NaCl treatment, however an increment was noticed in all the salt treated samples than that of control. The total soluble protein and sugar content were decreased under salinity condition even in both the 30 and 60 days of supplementation. From this experiment it may be concluded that the mangrove plant Aegiceras corniculatum can be sustained and propagated in optimum (250 mM) salinity under green house condition.
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Abiotic stresses, such as temperature, drought and salinity are serious threats to agriculture. Temperature stress is the primary cause of crop loss worldwide, reducing average yields for most major crop plants. In present study role of 24-epibrassinolide in three Brassica species ( B. carinata, B. juncea and B. napus ) on lipid peroxidation and proline under temperature stress was investigated. Seeds were given temperature treatments (4, 14, 24, 34 and 44°C) for 5 hours alone or in combination with EBR (10 -11, 10 -9 and 10 -7 M). Temperature stress whether low and high causes stress in terms of lipid peroxidation. High temperature causes more stress as compared with low temperature stress, as level of temperature stress rises increase in the membrane damage was observed. However the seeds treated with the EBR shows positive effect as there is decrease in the lipid peroxidation in terms of MDA content. Accumulation of proline was also observed in all temperature stress in all three Brassica species. Application of EBR at all concentrations causes significant increase in the proline content as compared with control and untreated.
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A pot experiment was conducted to study the effects of silicon (Si) and/or potassium (K) on plant growth, nitrogen uptake and N 2-fixation in water stressed (FC1) and well watered (FC2) chickpea plants using 15N and 13C isotopes. Three fertilizer rates of Si (Si 50, Si 100 and Si 200) and one fertilizer rate of K were used. For most of the growth parameters, it was found that Si either alone or in combination with K was more effective to alleviate water stress than K alone. Increasing soil water level from FC1 to FC2 often had a positive impact on values of almost all studied parameters. The Si 100K + (FC1) and Si 50K + (FC2) treatments gave high enough amounts of N 2-fixation, higher dry matter production and greater nitrogen yield. The percent increments of total N 2-fixed in the above mentioned treatments were 51 and 47% over their controls, respectively. On the other hand, increasing leave’s dry matter in response to the solely added Si (Si 50K - and Si 100K -) is associated with lower Δ 13C under both watering regimes. This may indicate that Si fertilization had a beneficial effect on water use efficiency (WUE). Hence, Δ 13C could be an adequate indicator of WUE in response to the exogenous supply of silicon to chickpea plants. Our results highlight that Si is not only involved in amelioration of growth and in maintaining of water status but it can be also considered an important element for the symbiotic performance of chickpea plants. It can be concluded that the synergistic effect of silicon and potassium fertilization with adequate irrigation improves growth and nitrogen fixation in chickpea plants.