Different Concentrations Of Polyethylene Glycol Research Articles

Effect of PEG Induced Drought Stress on Seed Germination and Seedling Growth of Greengram Genotypes

Greengram (Vigna radiata L. Wilczek) is the third most important pulse crop and drought is the most severe constraint to greengram growth and productivity. The present study was conducted to identify the drought tolerant greengram genotypes. Four greengram varieties used for standarization of drought stress using Polyethyleneglycol (PEG) 6000. The effect of water stress caused by different concentration of PEG 6000 are control (0 MPa), -0.4MPa, -0.5 MPa, -0.6MPa and -0.7 MPa. Increasing PEG concentration decrease the germination percentage, root length, shoot length, fresh weigh and dry weight of seedlings. At -0.5 MPa shows 50% seedling mortality , So control and -0.5 MPa level of drought stress was used for screening the greengram genotypes. Under PEG induced drought situations, parameters such as germination percentage, growth indices and proline content were recorded in all greengram genotypes. Compared to control, PEG induced drought stress (-0.5MPa) decrease all these parameters studied, where as drought has increased the proline content in all greengram genotypes screened. Among the greengram genotypes VGG17019 and VGG17004 posses higher germination percentage, GSI and proline content indicates high level of tolerance to drought stress.

Synthesis, characterization and biodegradation of bioplastic films produced from Parthenium hysterophorus by incorporating a plasticizer (PEG600)

The alarming use of fossil fuel based plastics causing hazardous environmental impact has drawn attention towards alternative sources. Therefore, the present study aims to utilize Parthenium hysterophorus for the production of bioplastic films and illustrates its biodegradability. A rapid biodegradable bioplastic films were synthesized using cellulose acetate (CA) prepared from Parthenium hysterophorus weed by incorporating different concentrations of polyethylene glycol 600 (PEG600) ranging from 0 to 50% w/v (BP00, BP10, BP20, BP30, BP40 and BP50) as plasticizer. The films were evaluated based on their physicochemical and mechanical properties. The highest tensile strength and Young's modulus of 11.5 ± 0.23 MPa and 170 ± 0.89 MPa, respectively have been observed for the BP10. The highest elongation at break of 9.13 ± 0.12% was exhibited by BP40. The functional groups of the plasticized and unplasticized films were characterized using Fourier transform infrared spectroscopy (FTIR). The bioplastic film BP50 exhibits highest relative crystallinity of 21.27% determined by X-ray diffraction analysis (XRD). All the bioplastic films exhibit a good thermal stability and shows three degradation stages in Thermogravimetric analysis (TGA). The bioplastic films are 69.29% biodegradable in natural conditions in 45 days, while 70.29% and 83.57% degradation are observed under composting and laboratory condition, respectively. Hence, the bioplastic films prepared from Parthenium hysterophorus by incorporating PEG600 can be a potential substitute for petroleum based plastics.

Effect of substrate stiffness on human intestinal enteroids’ infectivity by enteroaggregative Escherichia coli

Human intestinal enteroids (HIE) models have contributed significantly to our understanding of diarrheal diseases and other intestinal infections, but their routine culture conditions fail to mimic the mechanical environment of the native intestinal wall. Because the mechanical characteristics of the intestine significantly alter how pathogens interact with the intestinal epithelium, we used different concentrations of polyethylene glycol (PEG) to generate soft (~2 kPa), medium (~10 kPa), and stiff (~100 kPa) hydrogel biomaterial scaffolds. The height of HIEs cultured in monolayers atop these hydrogels was 18 µm whereas HIEs grown on rigid tissue culture surfaces (with stiffness in the GPa range) were 10 µm. Substrate stiffness also influenced the amount of enteroaggregative E. coli (EAEC strain 042) adhered to the HIEs. We quantified a striking difference in adherence pattern; on the medium and soft gels, the bacteria formed clusters of > 100 and even > 1000 on both duodenal and jejunal HIEs (such as would be found in biofilms), but did not on glass slides and stiff hydrogels. All hydrogel cultured HIEs showed significant enrichment for gene and signaling pathways related to epithelial differentiation, cell junctions and adhesions, extracellular matrix, mucins, and cell signaling compared to the HIEs cultured on rigid tissue culture surfaces. Collectively, these results indicate that the HIE monolayers cultured on the hydrogels are primed for a robust engagement with their mechanical environment, and that the soft hydrogels promote the formation of larger EAEC aggregates, likely through an indirect differential effect on mucus. Statement of significanceEnteroids are a form of in vitro experimental mini-guts created from intestinal stem cells. Enteroids are usually cultured in 3D within Matrigel atop rigid glass or plastic substrates, which fail to mimic the native intestinal mechanical environment. Because intestinal mechanics significantly alter how pathogens interact with the intestinal epithelium, we grew human intestinal enteroids in 2D atop polyethylene glycol (PEG) hydrogel scaffolds that were soft, medium, or stiff. Compared with enteroids grown in 2D atop glass or plastic, the enteroids grown on hydrogels were taller and more enriched in mechanobiology-related gene signaling pathways. Additionally, enteroids on the softest hydrogels supported adhesion of large aggregates of enteroaggregative E. coli. Thus, this platform offers a more biomimetic model for studying enteric diseases.

In vitro effect of polyethylene glycol and sorbitol on two banana varieties viz. Grand naine and Nalla bontha to study drought stress

Water stress is one of the foremost categories of stress damaging plants’ overall growth and development. The aim of the present study was to explore and demonstrate stress-induced drought to calibrate changes in stress parameters of two banana plant varieties viz. Grand naine (G9) and Nalla bontha were cultured in Murashige and Skoog medium (MS) media supplemented with stress inducers -Poly ethylene glycol (PEG) and sorbitol. The different concentrations of inducers were used to induce drought stress in two varieties of banana with contrasting characters for drought condition. The study indicated that PEG contrived mild to moderate osmotic stress and so does the alditol i.e. sorbitol on in vitro banana plants. The different concentrations of PEG and sorbitol produced significant effects on various parameters. The maximum decrease in shoot length was prominent in G9(52%) as compared to Nalla bontha (11%). When treated with 3% w/v sorbitol, even average root length showed the same level of damage with G9(59%) while in case of Nalla bontha there was a 17% decrease. The banana plantlet produced in vitro was estimated at one and two weeks after inoculation, respectively. Proline content tended to increase as the concentration of osmotic inducers increased (-44 % in G9 at 3% w/v sorbitol), whereas RWC (8.9% in G9 at 3% w/v Peg) showed an opposite effect. It was concluded that quantitative and qualitative changes in physiological (shoot and root length) and biochemical (Proline and relative water content, RWC) parameters played an important role in plants under drought stress conditions. This pattern varied from species to species. This work has been attempted for the first time in banana, especially Grand naine varieties with contrasting characters under induced drought stress.

Effect of water stress induced by polyethylene glycol 6000 on the somatic embryos conversion into whole plantlets in cocoa (Theobroma cacao L.)

Rainfall scarcity due to climate change is a major constraint that limits cocoa productivity in Côte d'Ivoire. This work aims to regenerate cocoa plants tolerant to water stress using in vitro methods. Staminode and petal explants of the genotypes C1, C9, C14, C15, C16, C18 and C20 were used to produce somatic embryos through two methods. Firstly, somatic embryos were induced under stressfull conditions on media containing different concentrations of polyethylene glycol (PEG) 6000 (0; 25; 50; 75; 100 and 125 g/l) and secondly; under non-stressed conditions. Somatic embryos were placed on a conversion medium in the same stress condition. The number of regenerants decreased with the increase in the concentration of PEG with all genotypes. Only genotypes C1 and C15 regenerated plantlets under water stress conditions. The sensitive genotypes C9, C14, C16, C18 and C20 have not developed plantlets on media containing PEG. The plantlets produced under water deficit conditions exhibited a reduction in stem length and leaves number and an increase in length or offset of the high number of roots. The survival rate of regenerants during acclimatization was higher on the sandsubstrate. The selected genotypes could be used in an improvement program of cocoa production.Keywords: Climate change; plant regeneration; genotype; tolerance; drought; in vitro

In Vitro Screening of Sugarcane Cultivars (Saccharum spp. Hybrids) for Tolerance to Polyethylene Glycol-Induced Water Stress

Water stress caused by drought affects the productivity of the sugarcane crop. A breeding alternative is the selection of drought-tolerant sugarcane cultivars. The objective of this study was the in vitro screening of cultivars tolerant to water stress using polyethylene glycol (PEG) as a stressing agent. Cultivars (cv) Mex 69-290, CP 72-2086, Mex 79-431 and MOTZMex 92-207 were subjected to different concentrations of PEG 6000 (0, 3, 6 and 9% w/v) using Murashige and Skoog semi-solid culture medium. At 30 days of culture, different developmental variables and dry matter (DM), total protein (TP), proline (Pr) and glycine-betaine (GB) contents were evaluated. The results showed reduced development in cv CP 72-2086, Mex 79-431 and MOTZMex 92-207 with increasing PEG concentration. The cv Mex 69-290 showed tolerance to osmotic stress of −0.45 MPa using 3% PEG. Overall, TP content decreased with increasing PEG concentration, while DM, Pr and GB contents rose with increasing PEG concentration in all evaluated cultivars. Our results suggest that cv Mex 69-290 has a slight tolerance to water stress and could be used for rainfed cultivation with low rainfall or reduced irrigation for better water use efficiency. In conclusion, the in vitro screening technique of cultivars tolerant to PEG-induced water stress is an alternative for early determination of drought stress in sugarcane.

Quantification of salinity stress and drought effects on fourteen ecotypes of black caraway (Nigella sativa L.) medicinal plant

Introduction Environmental stresses, especially drought and salinity stresses are considered as inhibitors of plant growth and development. The salinity stress cause delay in germination, decrease in the rate and percentage of germination and delay in the emergence of roots and stems in the germination stage. It seems that if seed could pass through the germination stage under stress conditions, the seedling will have more opportunity to grow and develop, and will have the higher ability to tolerate and overcome adverse environmental conditions. This greatly depends on the biochemical and physiological structures of the seedlings. The response is also species and genotypes dependent and depends on the length and severity of the salinity, the age, and stage of development. Differences in the salt tolerance have variation among species within a genus, and of genotypes within a species. black caraway (Nigella sativa L.) is an annual plant with valuable medicinal properties belong to Ranunculaceae family. Because Black caraway growth is slow at the beginning of the season, and on the other hand, salinity and drought are some limiting and effective factors on germination and other stages of plant growth, the aim of this study was to evaluate different N. sativa ecotypes in terms of tolerance to salinity and drought. Materials and methods In order to investigate the effects of salinity and drought stress on seed germination factors of fourteen black caraway, two separate experiments were carried out in a completely randomized design in the Seed Technology Laboratory of the University of Tehran in 2018. The treatments consisted of fourteen black caraway ecotypes (Ashkzar, Arak, Isfahan, Eqlid, Bejestan, Khaf, Khomeini Shahr, Razan, Zabol 1, Zabol 2, Sarayan, Semirum, Gardmiran, Hamedan), six salinity stress levels (0 , 40, 80, 120, 160 and 200 mM) and four levels of drought stress (0, 0.3, -0.6 and -0.9 MPa) with four replicates in each level. Salinity stress levels were due to different concentrations of sodium chloride and levels of drought stress were due to different concentrations of polyethylene glycol 6000. Distilled water was used to create a zero stress level (control treatment) in both experiments. To conduct the experiments, 50 seeds were placed on filter paper in 8 cm diameter Petri dishes containing 7 mL of each solution. Petri dishes were kept in the growth chamber at a constant temperature of 20°C. The number of seeds germinated was recorded daily until no germination was observed for two consecutive days. The Germin program was used to calculate germination percentage and rate of germination. In addition, to illustrate the germination response to drought stress, the hydrotime model was used. Results and discussion salinity experiment; The highest Ymax (germination percentage) was found in Razan, Arak, and Ashkzar ecotypes (99.5, 99.33 and 99.16% respectively) and the lowest in Khomeini-e-Shahr ecotype (85.83%). The highest salinity tolerance threshold (X0) was detected in Semirum ecotype (37.17 mM). Arak ecotype had the highest rate of germination (0.013 per hour) in salinity conditions. Thus, Semirom ecotype was the most tolerance ecotype due to the higher salinity tolerance threshold. Drought experiment; The minimum hydrotime constant (θH= 284.040 MPa h) was related to the Bejestan ecotype, and the lowest water potential (Ψb(50)= -0.563 MP ) was observed in the Isfahan ecotype. Since there is a positive correlation between the less water potential )Ψb(50) ( and the emergence percentage and rate of seedling emergence, the Isfahan ecotype was the most tolerant among biotypes that were studied. Conclusion In general, the results of these experiments showed that salinity and drought stresses reduced the percentage and rate of germination. Germination percentage response shape and germination rate were different between various ecotypes. Hydrotime model and salinity regression have high ability in separating ecotypes for germination components. The Bejestan and the Isfahan ecotypes are recommended for cultivation in drought conditions. In salt stress conditions, the Semirom ecotype was the most tolerant ecotype among ecotypes.

Cell Suspension Culture and In Vitro Screening for Drought Tolerance in Soybean Using Poly-Ethylene Glycol.

Soybean (Glycine max (L) Merrill) is used in India mostly as a substantial fund of protein and oil, which makes the crop significantly important. Somaclonal variation has been researched as a base of additional variability for drought in soybean. In the present experiment calli/cell clumps/embryoids rose from immature and mature embryonic axis and cotyledons explants were exposed to different concentrations of polyethylene glycol (PEG6000). A discontinuous method proved to be superior as it permitted the calli/embryoids/cell clumps to regain their regeneration competence. A total of 64 (12.21%) plantlets of genotype JS335 and 78 (13.13%) of genotype JS93-05 were regenerated after four consequent subcultures on the selection medium with an effective lethal concentration of 20% PEG6000, and proliferated calli/embryoids/cell clumps were further subcultured on Murashige and Skoog regeneration medium supplemented with 0.5 mgL−1 each of α-napthalene acetic acid (NAA), 6-benzyladenine (BA) and Kinetin (Kn), 20.0 gL−1 sucrose and 7.5 gL−1 agar. Putative drought-tolerant plantlets were acquired from genotype JS93-05 (38) in more numbers compared to genotype JS335 (26). Random decamer primers confirmed the presence of variability between mother plants and regenerated plants from both the genotypes. Since these plantlets recovered from tolerant calli/embryoids/cell clumps selected from the medium supplemented with PEG6000, the possibility exists that these plants may prove to be tolerant against drought stress.

THE EFFECT OF POLYETHYLENE GLYCOL (PEG) ON CALLUSES OF SWEET BASIL (OCIMUM BASILICUM L.)

Ocimum basilicum L. sweet basil is native to India and Iran, an aromatic herb and perennial belong to the Lamiaceae family. This study was done at the Genetic Engineering and Biotechnology Laboratory, Faculty of Agriculture, Damanhour University, Egypt from 2019 to 2020. Developing stress tolerant plants using in vitro selection is an effective method; therefore, the purpose of this study was to detect the best concentration of phytohormones to produce embryogenic callus of Ocimum basilicum L. and study the effect of poly ethylene glycol (PEG) on embryogenic callus of basil.Leaf specimens of basil were cultured on MS medium (Murashige and Skoog) with concentration of auxin and cytokinin. A1 (2, 4-D at 0.5 mg/l), A2 (2, 4-D at 1.0 mg/l) and A3 (2, 4-D and BAP at 1.0 mg/l and 0.2 mg/l). Embryogenic callus of basil was sub cultured under normal and drought stress media containing different concentration of polyethylene glycol (PEG; M.W 4000) at 2, 5 and 10%. Results showed that medium A3 was the best medium of embryogenic callus induction. Also, the concentration of PEG at 5% was shown maximized callus survivability compared with the other PEG concentrations with no significant effect. This study adds new information on the effect of 5% PEG which showed the highest (positive) survivability of callus. The morphogenic of calluses on 5% PEG were yellowish, friable while the morphogenic of calluses on 10% PEG turned into brown.

Root system architecture, physiological analysis and dynamic transcriptomics unravel the drought-responsive traits in rice genotypes

Drought is the major abiotic factors that limit crop productivity worldwide. To withstand stress conditions, plants alter numerous mechanisms for adaption and tolerance. Therefore, in the present study, 106 rice varieties were screened for drought tolerance phenotype via exposing different concentrations of polyethylene glycol 6000 (PEG) in the hydroponic nutrient medium at the time interval of 1, 3, and 7 days to evaluate the changes in their root system architecture. Further, based on root phenotype obtained after PEG-induced drought, two contrasting varieties drought-tolerant Heena and -sensitive Kiran were selected to study transcriptional and physiological alterations at the same stress durations. Physiological parameters (photosynthesis rate, stomatal conductance, transpiration), and non-enzymatic antioxidants (carotenoids, anthocyanins, total phenol content) production indicated better performance of Heena than Kiran. Comparatively higher accumulation of carotenoid and anthocyanin content and the increased photosynthetic rate was also observed in Heena. Root morphology (length, numbers of root hairs, seminal roots and adventitious roots) and anatomical data (lignin deposition, xylem area) enable tolerant variety Heena to better maintain membrane integrity and relative water content, which also contribute to comparatively higher biomass accumulation in Heena under drought. In transcriptome profiling, significant drought stress-associated differentially expressed genes (DEGs) were identified in both the varieties. A total of 1033 and 936 uniquely upregulated DEGs were found in Heena and Kiran respectively. The significant modulation of DEGs that were mainly associated with phytohormone signaling, stress-responsive genes (LEA, DREB), transcription factors (TFs) (AP2/ERF, MYB, WRKY, bHLH), and genes involved in photosynthesis and antioxidative mechanisms indicate better adaptive nature of Heena in stress tolerance. Additionally, the QTL-mapping analysis showed a very high number of DEGs associated with drought stress at AQHP069 QTL in Heena in comparison to Kiran which further distinguishes the drought-responsive traits at the chromosomal level in both the contrasting varieties. Overall, results support the higher capability of Heena over Kiran variety to induce numerous genes along with the development of better root architecture to endure drought stress.

Stomatal features and desiccation responses of Persian walnut leaf as caused by in vitro stimuli aimed at stomatal closure

Functional stomata can be generated by in vitro ABA applications. This mitigates the desiccation responses of Persian walnut leaves in their early stage of ex vitro exposure. This finding paves the way for discovering a solution for the uncontrollable water loss problem of in vitro-generated walnut plantlets. Most in vitro-generated plants are susceptible to wilting when they are transferred to an ex vitro environment, which is characterized by a higher evaporative nature. In this study, two stomatal closing stimuli [abscisic acid (ABA) and polyethylene glycol (PEG)] were added to in vitro culture medium of Persian walnut (Juglans regia L.) to evaluate their leaf ability to control water loss during exposure to an ex vitro environment. Different concentrations of PEG (0, 3 and 5%) and ABA (0, 1 and 10 µM) were tested, and their effects were evaluated in two separate experiments. In the first experiment, the proline concentration decreased in the leaves grown on media containing PEG. In contrast, glycine betaine (GB) increased only in leaves grown on a culture medium with 5% PEG. Leaf osmotic potential (ψs) increased parallel to the increase in PEG concentration. Adding PEG to the culture medium caused a decrease in stomatal aperture, and, as a result, the water conservation capacity of the in vitro-grown leaves was increased during detached leaf ex vitro desiccation. However, PEG-induced osmotic stress caused a negative influence on the morpho-physiologic characteristics and chlorophyll content of in vitro-grown nodal segments. In the second experiment, ABA was tested in the culture medium with the eventual aim of making in vitro leaves lose less water when they were transferred to an ex vitro environment. ABA (especially 10 µM) improved the leaf water conservation capacity during ex vitro desiccation of detached leaves. Small stomata having narrow apertures were increased in number by supplementing the cultures with ABA, although the length of shoots decreased with its use; no serious side effect was observed on morpho-physiologic parameters. Our findings are significant because they can ultimately be useful for preventing the uncontrollable water loss problem of in vitro-generated walnut plantlets.

AtSK11 and AtSK12 Mediate the Mild Osmotic Stress-Induced Root Growth Response in Arabidopsis.

Although most osmotic stresses are harmful to plant growth and development, certain drought- or polyethylene glycol (PEG)-induced mild osmotic stresses promote plant root growth. The underlying regulatory mechanisms of this response remain elusive. Here, we report that the GLYCOGEN SYNTHASE KINASE 3 (GSK3) genes ARABIDOPSIS THALIANA SHAGGY-RELATED KINASE 11 (AtSK11) (AT5G26751) and AtSK12 (AT3G05840) are involved in the mild osmotic stress (−0.4 MPa) response in Arabidopsis thaliana. When grown on plant medium infused with different concentrations of PEG to mimic osmotic stress, both wild-type (WT) and atsk11atsk12 plants showed stimulated root growth under mild osmotic stress (−0.4 MPa) but repressed root growth under relatively strong osmotic stress (−0.5, −0.6, −0.7 MPa) as compared to the mock condition (−0.25 MPa). The root growth stimulation of atsk11atsk12 was more sensitive to −0.4 MPa treatment than was that of WT, indicating that AtSK11 and AtSK12 inhibit the mild stress-induced root growth response. RNA-seq analysis of WT and atsk11atsk12 plants under three water potentials (−0.25 MPa, −0.4 MPa, −0.6 MPa) revealed 10 differentially expressed candidate genes mainly involved in cell wall homeostasis, which were regulated by AtSK11 and AtSK12 to regulate root growth in response to the mild stress condition (−0.4 MPa). Promoter motif and transcription factor binding analyses suggested that the basic helix-loop-helix (bHLH) transcription factor bHLH69/LJRHL1-LIKE 2 (LRL2) may directly regulate the expression of most −0.4 MPa-responsive genes. These findings indicate that mild osmotic stress (−0.4 MPa) promotes plant growth and that the GSK3 family kinase genes AtSK11 and AtSK12 play a negative role in the induction of root growth in response to mild osmotic stress.

Screening of Mungbean Genotypes under Polyethylene Glycol (PEG) Induced Drought Stress Condition

Sixteen advance genotypes of mungbeans under 5 different concentrations of Polyethylene Glycol (PEG) were studied to find out the better cultivar against drought stress condition. The experiment results revealed that germination, seedling production and water-related behavior of mungbean genotypes differed significantly under different PEG (drought inducer) concentrations. The mungbean genotype BINA Mung-6 (V8) is proved as highly tolerant against drought stress condition among all other tested genotypes. The results of the investigation revealed that BINA Mung-6 (V8) genotype consistently scored the highest value for all parameters except for the root shoot ratio and water retention capacity that was statistically comparable to genotypes BARI Mung-4 (V2) and BINA Mung-5 (V7). Consistently poor performance were recorded from IPM-02-03 (V16) genotype which is statistically similar as genotypes BMXK1-09015-2 (V13) and BMXK1-09015-6 (V10). The maximum percentage of germination (98.12%), shoot length (139.40 mm), root length (99.07 mm), shoot dry weight (22.32 mg), root dry weight (6.88 mg), relative water content (94.78), water retention capacity (24.98), germination co-efficient (22.27) and vigor index (233.90) were reported from BINA Mung-6 (V8) at a concentration of 0 percent PEG. The minimum percentage of germination (28.22 percent), shoot length (31.17 mm), root length (16.50 mm), shoot dry weight (2.21 mg), root dry weight (0.97 mg), relative water content (25.55), water retention capacity (3.08), germination co-efficient (6.06) and vigor index (13.45) were reported from IPM-02-03 (V16) mungbean advance lines at 0 percent PEG. Maximum (0.92) root shoot ratio was recorded from both BARI Mung-8 (V6) and BMX-08011-2 (V11) mungbean genotypes at 20 percent PEG concentration and minimum (0.22) at 0 percent PEG concentration from BARI Mung-5 (V3) genotype. Maximum water retention capacity (74.45) was recorded at 20 per cent PEG concentration from IPM-02-03 (V16) genotype and minimum (5.22) was at 0 per cent PEG concentration from BINA Mung-6 (V8) genotype.

PEG-Induced Drought Stress During Germination: Effects on Soybean Germplasm

Soybean is the one of the most important oilseed and protein sources worldwide. Among environmental stresses negatively affecting soybean, drought is considered as the most limiting factor in terms of yield losses encountered. In view of the need for improving drought tolerance, this study aimed at determining the seed germination and seedling growth potential under drought conditions as an approach to identify tolerant genotypes at early growth stages. The genetic material consisted of a set of commercial and pre-commercial varieties (Adonai, Neoplanta, Celina, Zora, PR92M22, P21T45, PR92M35, PR92B63, PR91M10). Drought stress was induced by different concentrations of polyethylene glycol (0, 5, 10 and 20 % PEG-6000). Genotype performance was assessed on the basis of Germination Percentage (GP), seed Water Uptake (WU), seedling Water Content (WC), root and shoot length and number of seedlings with abnormal phenotype. Stress substantially affected all traits associated to germination and seedling growth, with its effects though differing significantly among genotypes. Overall findings point to the superiority of varieties Neoplanta, Adonai, PR92M22 and Celina. Further, it was evidenced that GP as well as root and shoot length form suitable criteria for drought tolerance, while WU and WC did not allow the classification of genotypes in terms of drought tolerance. Our findings provide conclusive evidence that traits associated to germination and growth potential may be employed for revealing genetic variability related to drought tolerance, thus enabling their exploitation as screening criteria for drought tolerance. Upon confirmation of its validity, such short-cut selection approach may considerably upgrade the efficiency of breeding procedures targeted at the improvement of drought tolerance in soybean.

Differences in response to drought stress among highbush blueberry plants propagated conventionally and by tissue culture

The effects of drought stress on the morphological and physiological features of highbush blueberry Brigitta Blue plants were investigated. The plants were propagated conventionally by stem cutting (SC) and tissue culture (TC). Micropropagated plants originating from axillary (TC-Ax) and adventitious (TC-Ad) shoots were separated. An additional group consisted of plants propagated several times by stem cuttings, derived from TC mother plants (TC/SC). Different concentrations of polyethylene glycol (PEG) (3% and 7%) were applied to induce drought stress. Parameters such as dry and fresh weight, water content, shoot elongation as well as chlorophyll fluorescence and content were measured. The effect of PEG treatment varied in plants of different origin. Shoot elongation was mainly inhibited in SC plants, whereas TC/SC plants exhibited a stronger reduction of photosystem II efficiency. Fm and Fv differences between TC plants propagated by axillary or adventitious shoots were also observed under control conditions. These epigenotypes also differed in shoot elongation under 7% PEG treatment. The obtained results confirmed the influence of the propagation method of highbush blueberry plants not only on morphological traits, but also on the physiological status.

Effect of hydropriming on Trigonella foenum callus growth, biochemical traits and phytochemical components under PEG treatment

The induction of secondary metabolites under osmotic stress is well documented. However, cell death is probably due to osmotic stress. This work tries to study the synergetic effect of hydropriming and polyethylene glycol (PEG) on enhancing the secondary metabolites production in fenugreek callus cultures without facing cell death. PEG initiates the stress and the hydropriming increase the plant cell response against the stress. Fenugreek calli were initiated from hypocotyl of two groups of seeds, the first was hydroprimed overnight before germination, the second remained dry. Three months old calli of the two groups were subcultured on media containing two different concentration of PEG (5, 10%). The calli growth, biochemical analysis, secondary metabolism keys, and secondary metabolites were determined after 4 weeks. PE induced oxidative stress, which increased the membrane lipid peroxidation and decreased cell viability and growth. Hydropriming enhanced the activity of antioxidant enzymes, regulating the reactive oxygen species level, accumulating the osmolytes and secondary products. Therefore the primed callus can tolerate the osmotic stress initiated with PEG. Consequently, cell biomass increased and not affected by PEG treatment. On the other hand, the calli from non-primed seeds have a significant decrease in fresh weight, and dry weight under the higher PEG treatment. The hydropriming protected the growth of the cells under PEG treatment with a high content of secondary metabolites and high antioxidant machinery. The synergetic effect of hydropriming and PEG can be used as a simple and low-cost way to produce valuable compounds in commercial industrial bioreactors. The synergetic effect of hydropriming and PEG enhances the secondary metabolites production in fenugreek callus. PEG initiates the stress and the hydropriming improves the plant cell response against the stress.

Effect of polyethylene glycol on corrosion of fresh macroporous silicon in 1.0 M NaOH and application in determination of porosity and thickness by gravimetric measurement

This work presents on improvement in gravimetric measurement for determining the porosity and thickness of microporous silicon. Herein, the corrosion of fresh macroporous silicon (f-MPSi) in 1.0 M NaOH with different concentrations of polyethylene glycol (PEG 200/400/600) was studied by weight loss measurement and scanning electron microscopy (SEM). The results showed that the corrosion rate decreased with increasing polyethylene glycol concentration, and increased with an increase in temperature. Polyethylene glycol can inhibit the corrosion of f-MPSi in NaOH solution. Moreover, 1.0 M NaOH/PEG 600 (10%) can be used as the optimized solution to remove f-MPSi for measuring its porosity and thickness by gravimetric measurement.

Response of Albizia lebbeck to Moisture Stress on Seed Germination and Moisture Gradient on Seedling Growth

The polyethylene glycol (PEG 6000) was used under laboratory conditions. The studied parameters viz., germination percentage, mean daily germination, peak value, germination value and hypocotyls length was significantly reduced with increase in moisture stress. The control treatment T1 had highest Germination percentage, mean daily germination, peak value, and germination value and hypocotyls length. There were decreases in the values of all the studied germination parameters with increase in moisture stress created by use of different concentration of polyethylene glycol (PEG 6000). The different irrigation interval (days) followed for seedling production in nursery exhibited that different moisture gradients in nursery soil effected significantly seedling growth parameters viz., seedling height, collar diameter, number of leaves, leaf area, number, fresh shoot weight, fresh root weight, chlorophyll a content, chlorophyll b content, nutrient uptake in leafs (N,P,K) and root: shoot ratio were significant. There was decrease in all the studied growth parameters (except root shoot ratio) recorded with increase in moisture stress caused by irrigation interval studied. Out of the three container size of hyco-trays studied, the container size T3 (300 cc) had significantly the highest seedling height, collar diameter, number of leaves, leaf area, fresh shoot weight, fresh root weight, total chlorophyll, nitrogen content in leaf, phosphorus content in leaf, potassium content in leaf and root; shoot ratio as compared to container size T1 (93 cc) and T2 (150 cc).There were increase in all the studied growth parameters (except root shoot ratio) studied with increase in size of root containers, which could be attributed to more growing media and nutrients, and higher water holding capacity in large sized containers.

Morphological, antioxidant enzyme activity and secondary metabolites accumulation in response of polyethylene glycol-induced osmotic stress in embryo-derived plantlets and callus cultures of Salvia leriifolia

In this study, different levels of polyethylene glycol (PEG) 6000 (5, 7.5 and 10% w/v) were applied to induce drought stress in the embryo and callus culture of Salvia leriifolia Benth, an Iranian medicinal plant. The results related to the embryo culture showed that the germination percentage, stem length, root and stem diameter and total chlorophyll content of plantlets decreased by increasing the PEG concentration, while the highest root length was obtained at the lower PEG concentration (5%). The short-term callus culturing on the media containing different concentrations of PEG resulted in an insignificant difference in the fresh weight, dry weight, and browning intensity of calli between the PEG-free and 5% PEG medium. The proline, hydrogen peroxide, and malondialdehyde contents as indicators of oxidative stress significantly increased in the plantlets and calli at all PEG concentrations. The activity of antioxidant enzymes including catalase and guaiacol peroxidase also increased while superoxide dismutase activity decreased. The rosmarinic acid, caffeic acid, and salvianolic acid B contents increased significantly in all the plantlets and calli culture media containing the PEG. However, the highest contents of these secondary metabolites in plantlets and callus cultures were observed in the medium with 5% PEG. Totally, the results showed that, the short-term reduction in the osmotic potential of culture medium by low concentration of PEG elicitor can effectively improve the content of rosmarinic acid, caffeic acid, and salvianolic acid B in S. leriifolia, especially in callus cultures. Polyethylene glycol elicitor as a drought stress inducer can be effectively improved the content of rosmarinic acid, caffeic acid, and salvianolic acid B in plantlet and callus culture of Salvia leriifolia benth.

Effect of PEG as a plasticizer on the electrical and optical properties of polymer blend electrolyte MC-CH-LiBF4 based films

Plasticized polymer blend electrolyte films based on methylcellulose (MC), chitosan (CH), lithium tetrafluoroborate (LiBF4), and polyethylene glycol (PEG) as a plasticizer were prepared and investigated. The effect of different concentrations of PEG was studied using AC impedance spectroscopy, and UV–Visible spectroscopy. The electrical and optical properties of polymer electrolytes have been improved upon addition of PEG. The DC conductivity was evaluated from the bulk resistance achieved from Nyquist impedance plots. Results from temperature studies reveal that all samples comply with the Arrhenius formula in the investigated temperature range. The sample with 10 wt% of PEG exhibits the highest ionic conductivity of 2.12×10-5S/cm with the minimum activation energy of 0.528eV at ambient temperature. The lowest relaxation time for highest ion conductive sample indicates the faster ion dynamics. The frequency-dependence AC conductivity was found to follows the Jonscher’s power law at various temperatures, and the conduction mechanism for this system followed the overlapping large polaron tunneling (OLPT) model. The increase in absorption and a decrease in optical band-gap in the UV region was confined by UV–Visible spectroscopy.