Identification of PEG 6000 concentrations for assessing drought resistance in millet genotypes during the seed germination phase

Background. Using LD50 concentrations of the osmotic PEG 6000 to select millet genotypes during seed germination for drought resistance breeding is the best way of millet genotype differentiation according to the studied trait.Materials and methods. The millet cultivars ‘Omriyane’, ‘Kharkovskoe 57’, ‘Konstantinovskoe’, ‘Slobozhanskoe’, and the accession IR 5 were selected as the test material. Water stress was applied through five concentrations of PEG (6000 MW): 11.5%, 15.3%, 19.6%, 23.5%, 28.9%, and 0.0% (control). On the sixth day of incubation, millet seed germination was measured. The regression method for assessing LD50 (half-lethal dose) by V. B. Prozorovskii was used to theoretically substantiate the selection of an optimal osmotic concentration, which would be most accurate in identifying the level of drought tolerance in millet genotypes during seed germination.Results and conclusions: The 15.3% to 28.9% concentrations of PEG 6000 solutions had a negative effect on seed germination of millet genotypes. A strongly suppressed seed germination rate was observed at the PEG concentration of 23.5%: germination percentage in all cultivars (except for IR 5, with 56.0%) fell below 50%. Calculations according to the Verhulst logistic curve and the probit analysis by V. B. Prozorovskii’s technique showed that the mean LD50 concentration of PEG 6000 solutions for all studied genotypes was 23.03%. Thus, as a result of the analysis of our experimental data and their statistical processing, we recommended the 23.0% concentration of PEG 6000 solution as the most differentiating in terms of drought resistance in the millet seed germination phase.

Concentration effect of polyethylene glycol in evaluation of grain legumes for drought tolerance

The article covers selection of differentiating concentrations of PEG-6000 for assessing genetic resource collections of pea, chickpea and lentil. The germinability of 4 accessions of each crop in 5, 10, 15, 20 and 25% PEG-6000 solutions was evaluated. The results showed that 25% PEG-6000 completely inhibited growth processes in all the crops; 5 and 10% PEG-6000 did not affect the germinability of lentil seeds; and the maximum differentiation was observed at an osmotic concentration of 20%. In chickpea, there were no seedlings even in 20% PEG-6000. In 15% PEG-6000, seeds of drought-tolerant accessions UD0500022 and Dnіprovskyi Vysokoroslyi only sprouted; and 5 and 10% solutions had the maximum differentiating effect. Pea germination in PEG-6000 solutions of different concentrations demonstrated that only one accession could germinate in 20 and 15% solutions. Two accessions gave seedlings in 10% PEG-6000, and 5% solution had almost no effect on the germinability of pea seeds.

Pilot Scale Osmotic Concentration Process for Reducing Wastewater Volumes from Gas Processing Facilities in Qatar

Over the past 10-15 years, there has been increasing attention in the development of forward osmosis (FO) technology as a low-energy technical solution to wastewater treatment through the exploitation of the natural osmosis phenomenon across semi-permeable membrane. The significant energy benefit arises in applications where direct recovery of the permeate product from the draw solution (DS) is obviated such as in osmotic concentration (OC) process. In the current research, an OC FO-based pilot-scale unit was applied for wastewater volume reduction from oil and gas processing facilities in Qatar. The pilot unit uses seawater of 40 g/L salinity as a DS and wastewater generated during oil and gas operations as a feed. This feed water is of comparatively low conductivity (2 g/L salinity), making it unusually suited to treatment by OC. Based on FO technology principles, the feed gets concentrated at lower volume with the water permeation through the membrane, meanwhile the water transfer to DS side dilutes it. The diluted DS could be directly discharged into the ocean; so the energy intensive step of DS recovery is entirely eliminated. Two FO membranes (Toyobo and NTU) of hollow fiber configuration were tested to assess their performance and fouling propensity on both synthetic and real wastewaters. Results demonstrated that the membrane-based process can achieve feed water recoveries up to 90% without any scaling issues. Achieved water flux ranges between 1.5 to 12 LMH for feed recoveries between 60 and 90% using a constant dilution rate of the draw solution. Above all, the pilot unit maintained stable water flux of 1.62 and 6 LMH using at 75% feed recovery for over 48 hours of continuous operation Toyobo and NTU membranes respectively.

Comparative impact of different iso-osmotic solutions on osmotic adjustment in Gossypium barbadense

<p>To discriminate the specific response of ion toxicity versus osmotic stress on altering leaf solute contents, contributing of organic and/or inorganic components in osmotic adjustment and its reflection on plant performances under ionic and osmotic stresses, two cotton (Gossypium barbadense L.) cultivars, Giza 90 and Giza 83, were subjected to iso-osmotic concentration (–0.57 and –1.05 MPa) created by; NaCl, KCl and polyethylene glycol-6000. The three used osmotica altered seedling length, chlorophyll, leaf dry weight, relative water content, organic and inorganic solutes and proline. Contribution of organic solutes to osmotic adjustment tittered among the two cultivars, it was higher in PEG˃ KCl˃ NaCl in Giza 83, suggesting that the character of osmotic adjustment via salt attuned to high yield with moderate ion toxicity is effectively achieved by KCl than NaCl. At high-stress intensities, regardless to cultivar, the salt stress-induced nutritional imbalance, leaf chlorosis than osmotic stress that could be attributed to specific ion toxicity, not to osmotic stress of salt. In salt sensible cultivar only NaCl, among different osmotica, reduced leaf K+ content implying that avoidance of Na-induced K+ deficiency in leaf might stimulate salt tolerance in cotton. In our study, the capacity of plants to regulate their metabolic and physiological functions had superiority in water stress tolerance rather than osmotic adjustment.</p>