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Journal articles on the topic "Shoot tip reduction"

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Remphrey, W. R., and C. G. Davidson. "Branch architecture and its relation to shoot-tip abortion in mature Fraxinus pennsylvanica." Canadian Journal of Botany 70, no. 6 (1992): 1147–53. http://dx.doi.org/10.1139/b92-142.

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The architecture of branch complexes, 10 to 14 years old, from mature male and female green ash trees (Fraxinus pennsylvanica var. subintegerrima (Vahl) Fern.) of two crown shapes was analyzed. Shoot length (annual increment of extension growth) declined with increasing order of branching and 47% of the shoots were less than 30 mm. Although variable, shoot length also tended to decrease along an axis. There was a consistent positive correlation between lengths and numbers of daughter shoots and lengths of parent shoots, but for a given parent length the predicted values declined proportionately with increasing order. An index of apical control comparing the lengths of terminal shoots with the longest lateral shoots revealed weaker apical control with increasing branch order in the broad, rounded crown shape class compared with the narrow shape class. Elevation angles of terminal daughter shoots were highly correlated with that of the parent shoot. When a shoot tip aborted, the terminal was replaced, but a weakening of apical control resulted in the modification of branch development and the formation of forks in certain axes. There was a reduction in the angle of divergence of lateral shoots in response to shoot-tip abortion, the terminal replacements being the most acute. Key words: crown architecture, shoot-tip abortion, green ash, Fraxinus, tree form, branching pattern.
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Aguinaz, Hayat, Ahmed Qaddoury, and Mohamed Anjarne. "Control of in vitro shoot tip necrosis in Carob Ceratonia siliqua L." Israel Journal of Plant Sciences 67, no. 3-4 (2020): 212–18. http://dx.doi.org/10.1163/22238980-20201046.

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Shoot tip necrosis (STN) is a physiological abnormality whereby the apical shoot initially becomes necrotic and subsequently dies leading to considerable loss of shoots and hampering any commercial application of carob (Ceratonia siliqua L.) micropropagation. The objective of the present study is the optimization of a method to alleviate STN during in vitro multiplication of carob dealing with a range of culture media compounds. Obtained results showed that macroelement strength of the culture medium as well as cytokinin and calcium concentrations were the most important factors in controlling STN incidence in carob. In fact, Zimmerman macroelements are most efficient in terms of STN reduction (only 5% STN observed) and shoot multiplication (28.75 shoots with 26.8 leaves and 4.73 cm length). Moreover, shoots cultured on Zimmerman or Ca enriched ½MS showed higher mineral nutrient contents than those cultured on low Ca media. On the other hand, most shoots recovered from STN have produced roots in presence of 1 mg.L-1 IAA (70%) and 83% survived after transfer to ex vitro conditions. The performance of Zimmerman macroelements is most likely due to its high Ca concentration (7.3 mM) compared to the other media. This is confirmed by the steep reduction of STN intensity obtained on ½MS enriched with Ca.
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Dahniya, M. T., S. K. Hahn, and C. O. Oputa. "Effect of Shoot Removal on Shoot and Root Yields of Sweet Potato." Experimental Agriculture 21, no. 2 (1985): 183–86. http://dx.doi.org/10.1017/s0014479700012461.

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SUMMARYExperiments on harvesting sweet potato as a green vegetable and as a root crop are described. Whole shoots yielded 62% more than shoot tips. Similar total shoot yields were harvested whether tip removal was at two, three or four week intervals. Root yield was decreased by 31 to 48% by removing shoot tips, while removing whole shoots led to root yield decreases of 48 to 62%. Harvesting shoots at two week intervals gave 72% reduction in root yield, compared with 50% with four week intervals. There were fewer and smaller tubers as the frequency of shoot harvests increased. There were varietal differences in response to shoot removal For reasonable yields of both shoot tips and tuberous roots harvesting shoot tips at four week intervals is recommended.
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Pancaningtyas, Sulistyani. "Effectiveness of calcium chloride in reduction of shoot necrosis incocoa (Theobroma cacao L.) in vitro propagation." Pelita Perkebunan (a Coffee and Cocoa Research Journal) 28, no. 1 (2012): 23–31. http://dx.doi.org/10.22302/iccri.jur.pelitaperkebunan.v28i1.161.

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Various efforts have been developed for the optimization of the various stages in vitro micropropagation. The maturation stage and pre-acclimatization plantlets is an important stages that must be considered to produce vigorous plants and ready to be planted in the field. The purpose of this study was to reduced shoot tip necrosis in cocoa planlets to obtaine vigorous planlets from in vitro propagation through the addition of Calcium Chloride (CaCl2). The study used two stages of embryogenic development. The first was embryo maturation stage and the second was the shoot growth development stage. The study was arranged factorially in experiment design of Completely Randomized Design consisting of two factors i.e. concentration of CaCl2 consisted of 0, 50, 100, 150, and 200 mg/l and clones consisted of Sulawesi 1 and Sca 6. Each experiment was repeated three times, so the number of combination trials were 5x2x3=30 experimental units. The parameters observed included shoot growth percentage and vigorous planlets percentage. The results showed that the addition of CaCl2 at a concentration of 150 mg/l during maturition stage increased the embryos performance and percentage of shoot tip. However, it could not prevent the shoot tip necrosis. Whereas, the addition at a concentration of 50 mg/l during the shoot m growth development stage could reduced necrosis, suggested to increase the quality of in vitro planlets.Key words: Cocoa, necrosis, calcium chloride, somatic embryogenesis, embryos, planlets, in vitro.
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Driessche, R. Van Den, and D. Ponsford. "Nitrogen induced potassium deficiency in white spruce (Piceaglauca) and Engelmann spruce (Piceaengelmannii) seedlings." Canadian Journal of Forest Research 25, no. 9 (1995): 1445–54. http://dx.doi.org/10.1139/x95-157.

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White spruce (Piceaglauca (Moench) Voss) and Engelmann spruce (Piceaengelmannii Parry ex Engelm.) seedlings grown for 2 or more years in sandy loam nursery soils in British Columbia often show yellow and necrotic shoot-tip symptoms. Chemical analysis of a white spruce and a white × Engelmann hybrid spruce provenance showed that the symptoms were associated with low needle K concentrations. After nursery growth was complete, growth tests showed that seedlings with symptoms took longer to flush and had 43% less shoot extension than normal green seedlings. To see why K fertilizer alone did not always cure the symptoms, 1.5-year-old Engelmann spruce seedlings were transplanted and grown for a further 1.5 years in a 4 × 3 × 3 factorial experiment (K level × N source × N level). Nitrogen fertilization increased growth and symptom occurrence, with sources resulting in more symptoms in the order (NH4)2SO4 < NH4NO3 < Ca(NO3)2. Potassium fertilization decreased symptoms, although not completely, but had no effect on growth. Shoot-tip NH4+ was positively correlated with symptoms, while higher levels of soil and shoot-tip K, as well as soil and shoot-tip Mg, were associated with reduction in symptoms. It was concluded that heavy N fertilization created requirements for K, and probably Mg, above the tissue concentrations normally regarded as adequate, and that K fertilization did not always eliminate symptoms because of a Mg requirement.
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Mohammad Javad, Mahmoudi Meimand, Malekzade Khalil, Hossein Shamshiri Mohammad, Reza Dehghani Mohammad, and Dadaei Somayeh. "ROLE OF VENTILATION, CALCIUM AND BORON ON SHOOT TIP NECROSIS AND HYPERHYDRICITY REDUCTION OF IN VITRO ROORSTOOCKS OF PISTACIO ‘BADAMI’ ȘI ‘UCB1’." Fruit Growing Research 37, no. 37 (2021): 123–30. http://dx.doi.org/10.33045/fgr.v37.2021.17.

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Shoot tip necrosis (STN) is one of the main physiological disorders in the micropropagation of pistachios. In the current study, the effects of CaNO3.4H2O at 196 mg/L and 291 mg/L, H3BO3 at 196 mg/L and 291 mg/L, and CaCl2.2H2O at 2,980 mg/L on STN and hyperhydricity reduction of Pistacia vera L., ‘Badami’ and ‘UCB1’ rootstocks were assessed, compared to the MS standard medium containing 3% sucrose, 0.7% agar supplemented with benzyladenine (BA) (1.5 mg/L), indole butyric acid (IBA) (0.1 mg/L). For ventilation parameter, filter container vessels with a 50-µm microporous polypropylene membrane (Pardis®) were used. Based on the results, an increase in calcium chloride content of the MS standard medium prevented hyperhydricity in the UCB1 rootstock, whereas it increased STN, yellow leaves, decreasing the multiplication of shoots in the ‘Badami’ rootstock. The results also showed that increasing boric acid from 196 mg/L up to 291 mg/L decreased STN in the UCB1 rootstock and increased this disorder by 37% in the ‘Badami’ rootstock. Ventilation showed no significantly reducing effect on the percentage of STN in the regenerated shoots of the ‘Badami’ rootstock, whilst it decreased the STN of the ‘UCB1’ rootstock to the lowest percentage. For the ‘Badami’ rootstock, CaNO3.4H2O at 196 mg/L led to the highest proliferation rate, shoot height, shoot diameter, and leaf number, but for the ‘UCB1’ rootstock, an increase in the concentration of CaNO3.4H2O up to 291 mg/L under ventilated conditions resulted in an increase in proliferation, shoot height, and shoot diameter.
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Snir, Iona. "Influence of Paclobutrazol on in Vitro Growth of Sweet Cherry Shoots." HortScience 23, no. 2 (1988): 304–5. http://dx.doi.org/10.21273/hortsci.23.2.304.

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Abstract Shoot tips from in vitro-established shoot tip cultures of Prunus avium L. cv. Hedelfingen and cv. Starkrimson were cultured on sweet cherry propagation medium to which several concentrations of paclobutrazol (PP333) were added and gibberellic acid (GA3) omitted, in order to reduce the elongation of the shoots. A reduction in both shoot length and bud number was achieved even with the lowest concentration of paclobutrazol (0.2 mg·liter–1). Shoot tips from the inhibited cultures when replanted on regular propagation medium overcame the inhibition at the first transfer. In order to use this system for cold preservation experiments, the cultures were examined under dark and low temperature conditions (0.5° ± 0.5°C). There was a significant difference between the PP333 system and the control after certain periods of cold preservation. The survival ratio of the PP333-inhibited culture was higher than the control after removing from the cold preservation conditions and recultured. Chemical name used: β-[(4- chlorophenyl)methyl]-α-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol.
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Remphrey, William R., Grant A. Bartlett, and Campbell G. Davidson. "Shoot morphology and fate of buds in relation to crown location in young Fraxinus pennsylvanica var. subintegerrima." Canadian Journal of Botany 80, no. 12 (2002): 1274–82. http://dx.doi.org/10.1139/b02-120.

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The relationships between shoot size and morphological patterns and crown location were investigated in 6-year-old green ash (Fraxinus pennsylvanica var. subintegerrima (Vahl) Fern.). In general, shoots were shorter in the inner part of the crown compared with either the top or bottom near the periphery. The differences were related to a reduction in both metamer number and length. In some cases the lower crown location was similar to the upper; in other cases it was similar to the inside. The fate of buds along a shoot was generally dependent on shoot position in the crown. A greater proportion of buds became lateral shoots and inflorescences in the top compared with the bottom of the crown, and the fewest developed towards the inside location. As the number of metamers per shoot increased, there was an increase in the proportion of lateral shoots produced and a decrease in the proportion of inflorescences and (or) aborted buds. For shoots with the same number of metamers per shoot, those in the top produced a greater proportion of inflorescences and lateral shoots compared with the bottom or inside. In all crown locations, the highest number of buds aborted near the base, the greatest proportion of inflorescences occurred in mid-shoot regions, and the largest proportion of lateral shoots occurred near the tip. The information presented in this paper will be used as a component in developing a simulation model of crown development.Key words: architecture, shoot, bud fate, green ash, metamer.
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Yang, Yuehua, Fangkui Wang, Jialin Jiang, and Ling Jiang. "Inhibition of Citrus Huanglongbing Disease by Paenibacillus polymyx KN-03 and Analysis with Transcriptome and Microflora." Agronomy 13, no. 12 (2023): 2958. http://dx.doi.org/10.3390/agronomy13122958.

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Soil drench treatment using Paenibacillus polymyxa strain KN-03 was applied to citrus plants infected with Candidatus Liberibacter asiaticus (CLas). The infection status was assessed using PCR and a real-time quantitative PCR detection system (qPCR). The application of KN-03 resulted in a notable reduction in CLas levels in citrus plants. Specifically, by the 257th day post treatment commencement, following 24 KN-03 applications, the negative rates of CLas in the vein, root tip, and shoot tip were 50%, 0%, and 50%, respectively. After 24 cycles, KN-03 application significantly enhanced plant growth and stimulated reactive oxygen production in citrus leaves compared to control plants. Transcriptome analysis identified specific upregulated pathways. Furthermore, flora analysis revealed an increased abundance of microorganisms possessing potential utilization value, including Burkholderia-Caballeronia-Paraburkholderia, uncultured_bacterium_o_Acidobacteriales, uncultured_bacterium_f_Gemmatimonadaceae, and Rhodanobacter, in the root zone. Moreover, the BugBase analysis indicated that KN-03 treatment increased the abundance of beneficial rhizosphere bacteria associated with biofilm formation, element mobilization, and stress tolerance. These findings support the utility of Paenibacillus polymyxa KN-03 as an effective plant-growth-promoting bacterium for CLas management, with additional benefits for plant growth and soil health, specifically offering detoxification resources for shoot tip grafting.
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HICKLENTON, PETER R. "HEIGHT CONTROL OF POT CHRYSANTHEMUMS WITH PRE- AND POST-PLANT TREATMENTS OF DAMINOZIDE AND UNICONAZOLE." Canadian Journal of Plant Science 70, no. 3 (1990): 925–30. http://dx.doi.org/10.4141/cjps90-113.

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This study investigated the effects of growth retardants uniconazole [(E) - (p-chlorohenyl) -4, 4-dimethyl-2-(1,2,4-triazol-1-yl)-1-penten-3-ol] and daminozide (butanedioic acid mono 2,2-dimethylhydrazide) on three chrysanthemum (Dendranthema grandiflora Tzvelev.) cultivars. Uniconazole applied as a soil drench (0.02 mg a.i. pot−1) or foliar spray (0.014 mg a.i. pot−1) 10 d after removal of the shoot tip reduced plant height at harvest in cultivars Deep Luv, Tip and Tara. Higher doses of uniconazole resulted in further plant height reduction in Tip and Tara but not in Deep Luv. Daminozide spray (14 mg a.i. pot) and uniconazole spray (0.028 or 0.056 mg a.i. pot−1) produced plants of similar height. Pre-plant dips of both growth retardants were less effective than sprays or drenches in controlling height. Flower area and flower dry weight were reduced with uniconazole drench and spray, and daminozide spray in each cultivar. Shoot dry weight was similarly affected in Tip and Tara but not in Deep Luv. Flowering was delayed in each cultivar by post-plant treatments of uniconazole drench and spray and by daminozide spray (0.08, 0.014 and 14 mg a.i. pot−1, respectively), and by daminozide and uniconazole pre-plant dips (5.0 mg L−1 and 4000 mg L−1, respectively).Key words: Sumagic, XE-1019, B-Nine, Alar, Chrysanthemum × morifolium, Dendanthema grandiflora
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Books on the topic "Shoot tip reduction"

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Brunner, Ronald D., and Amanda H. Lynch. Adaptive Governance. Oxford University Press, 2017. http://dx.doi.org/10.1093/acrefore/9780190228620.013.601.

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Adaptive governance is defined by a focus on decentralized decision-making structures and procedurally rational policy, supported by intensive natural and social science. Decentralized decision-making structures allow a large, complex problem like global climate change to be factored into many smaller problems, each more tractable for policy and scientific purposes. Many smaller problems can be addressed separately and concurrently by smaller communities. Procedurally rational policy in each community is an adaptation to profound uncertainties, inherent in complex systems and cognitive constraints, that limit predictability. Hence planning to meet projected targets and timetables is secondary to continuing appraisal of incremental steps toward long-term goals: What has and hasn’t worked compared to a historical baseline, and why? Each step in such trial-and-error processes depends on politics to balance, if not integrate, the interests of multiple participants to advance their common interest—the point of governance in a free society. Intensive science recognizes that each community is unique because the interests, interactions, and environmental responses of its participants are multiple and coevolve. Hence, inquiry focuses on case studies of particular contexts considered comprehensively and in some detail.Varieties of adaptive governance emerged in response to the limitations of scientific management, the dominant pattern of governance in the 20th century. In scientific management, central authorities sought technically rational policies supported by predictive science to rise above politics and thereby realize policy goals more efficiently from the top down. This approach was manifest in the framing of climate change as an “irreducibly global” problem in the years around 1990. The Intergovernmental Panel on Climate Change (IPCC) was established to assess science for the Conference of the Parties (COP) to the U.N. Framework Convention on Climate Change (UNFCCC). The parties negotiated the Kyoto Protocol that attempted to prescribe legally binding targets and timetables for national reductions in greenhouse gas emissions. But progress under the protocol fell far short of realizing the ultimate objective in Article 1 of the UNFCCC, “stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference in the climate system.” As concentrations continued to increase, the COP recognized the limitations of this approach in Copenhagen in 2009 and authorized nationally determined contributions to greenhouse gas reductions in the Paris Agreement in 2015.Adaptive governance is a promising but underutilized approach to advancing common interests in response to climate impacts. The interests affected by climate, and their relative priorities, differ from one community to the next, but typically they include protecting life and limb, property and prosperity, other human artifacts, and ecosystem services, while minimizing costs. Adaptive governance is promising because some communities have made significant progress in reducing their losses and vulnerability to climate impacts in the course of advancing their common interests. In doing so, they provide field-tested models for similar communities to consider. Policies that have worked anywhere in a network tend to be diffused for possible adaptation elsewhere in that network. Policies that have worked consistently intensify and justify collective action from the bottom up to reallocate supporting resources from the top down. Researchers can help realize the potential of adaptive governance on larger scales by recognizing it as a complementary approach in climate policy—not a substitute for scientific management, the historical baseline.
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Book chapters on the topic "Shoot tip reduction"

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Zayed, Zeinab E. "Enhanced Indirect Somatic Embryogenesis from Shoot-Tip Explants of Date Palm by Gradual Reductions of 2,4-D Concentration." In Methods in Molecular Biology. Springer New York, 2017. http://dx.doi.org/10.1007/978-1-4939-7156-5_7.

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Cardona, Francesco, and Renata Rizzo. "Treatment of Psychiatric Comorbidities in Tourette Syndrome." In Tourette Syndrome, 2nd ed., edited by Eli R. Lebowitz and Bekir Artukoğlu. Oxford University Press, 2022. http://dx.doi.org/10.1093/med/9780197543214.003.0027.

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Abstract Behavioral treatment should be recommended as initial treatment for patients with Tourette syndrome (TS) or other tic disorder and attention-deficit/hyperactivity disorder (ADHD), especially if symptoms are mild or parents refuse pharmacological treatments. Although obsessive–compulsive disorder (OCD) and TS are closely related, no clinical trials have specifically evaluated the treatment of OC symptoms in TS patients. Monotherapy with serotonin reuptake inhibitors (SRIs) or selective serotonin reuptake inhibitors (SSRIs) has been proven to be efficacious in the treatment of OCD patients, both adults and children, in the short term as well as the long term. No individual drug in these classes has demonstrated a superior efficacy to the others. However, nearly half of OCD patients do not respond completely to SSI/SSRI monotherapy, and even among the responders, few become asymptomatic. Various strategies have been proposed for OCD nonresponders: increasing doses, switching to another drug, augmentation strategies, and novel treatments. OCD patients with comorbid chronic tics or TS show a lower response rate compared to those without tics, both in term of percentage of responders and in terms of symptom reduction. An increased rate of response to antipsychotic augmentation in OCD patients with comorbid tics compared to those without has been reported in only one study. Despite the high rate and the clinical relevance of other psychiatric comorbidities (non-OCD anxiety disorders, self-injurious behaviors, and disruptive behaviors) in TS patients, only a few studies have been devoted to investigating a specific therapeutic approach in these patients.
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Conference papers on the topic "Shoot tip reduction"

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Brune, T., K. M. Kraemer, C. Kontermann, M. Oechsner, M. Bellmer, and M. Schlesinger. "Atmosphere Influence on the Fatigue Crack Growth Behavior of Wrought, Cast and PBF-LB/M Processed IN718 under Different Loading Conditions at 650 °C." In AM-EPRI 2024. ASM International, 2024. http://dx.doi.org/10.31399/asm.cp.am-epri-2024p0483.

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Abstract For the safe life prediction of components under high cycle fatigue loading at high temperature, such as gas turbine blades and turbocharger components, the behavior of initial defects, which are physically short cracks below the long crack threshold ΔK is of crucial importance. The evolution of different crack closure mechanisms (such as plasticity, roughness and oxide induced crack closure) can lead to crack arrest by a reduction of the effective crack tip loading. To visualize the crack growth behavior of such cracks, cyclic crack resistance curves (cyclic R-curves) are used. The experimental determination of cyclic R-curves is challenging, especially under high temperature conditions due to a lack of optical accessibility. The formation of very short cracks in high strength materials makes it even more complicated to reliably determine these data. Within this study the crack growth behavior of physically short fatigue cracks in three different material states of the nickel alloy IN718 (wrought, cast and PBF-LB/M - processed) is experimentally determined at 650 °C. Based on a load increase procedure applied on Single Edge Notched (SEN) specimens with a compression pre-cracking procedure in advance, crack propagation of physically short cracks is measured with alternating current potential drop systems in air and under vacuum conditions. These examinations are carried out for three different load ratios (R = -1, 0 and 0.5) to investigate the amount of certain crack closure mechanisms active under different loading conditions. Moreover, the formation of a plastic wake along the crack flanks is determined by a finite element simulation. The results determined in air and under vacuum conditions are used to describe the impact of oxide induced crack closure on the behavior of physically short cracks. This allows the evaluation of the behavior of both near-surface and internal defects that are not accessible to the atmosphere.
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Rodríguez, Martín A., Ricardo M. Carranza, and Raul B. Rebak. "Crevice Corrosion of Alloy 22 at Open Circuit Potential in Chloride Solutions at 90 °C." In CORROSION 2009. NACE International, 2009. https://doi.org/10.5006/c2009-09424.

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Abstract Crevice corrosion of Alloy 22 (N06022) in hot chloride solutions at open circuit potential was studied in short term tests. Mill Annealed (MA) and thermally aged PCA (Prism Crevice Assembly) specimens were used. Thermally aged specimens were obtained by aging at 760 °C for 10 hours. Precipitation of secondary phases (TCP: Topologically Close Packed phases) at grain boundaries occurred. Electrochemical tests performed included open circuit potential monitoring for up to 48 hours, electrochemical impedance spectroscopy (EIS) and galvanic coupling with an MA Alloy 22 foil. Crevice corrosion propagation started in Alloy 22 after a few hours of immersion in pH 2, NaCl at 90 °C. Steady state open circuit potential was higher for thermally aged specimens than for MA specimens. Galvanic coupling was performed in order to asses the effect of an increasing cathodic area. Galvanic current and potential were recorded with time. A potential maximum was correlated with a current minimum, indicating the onset of crevice corrosion propagation. Crevice corrosion kinetics was limited by oxygen reduction on passive Alloy 22 surface areas. Crevice corrosion attacked area and propagation potential (ECORR) were set to balance oxygen reduction rate. Oxygen reduction on passive Alloy 22 was inhibited. Low crevice corrosion propagation rates can be expected for crevice corrosion provided that oxygen is the only oxidant and the ratio of creviced area / passive area is large.
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Cao, Teng, Tadashi Kanzaka, Liping Xu, and Tobias Brandvik. "Tip Leakage Flow Instability in a Centrifugal Compressor." In ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-90217.

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Abstract In this paper, an unsteady tip leakage flow phenomenon is identified and investigated in a centrifugal compressor with a vaneless diffuser at near-stall conditions. This phenomenon is associated with the inception of a rotating instability in the compressor. The study is based on numerical simulations which are supported by experimental measurements. The study confirms that the unstable flow is primarily driven by the Kelvin-Helmholtz instability inherent in the shear layer between the main-stream flow and the tip leakage flow. The shear layer instability induces large scale vortex shedding which propagates circumferentially, leading to pressure perturbations with short wavelength and high amplitude which rotates at about half of the blade speed. The shed vortex is also found to interact with the main blade leading edge, resulting in the reduction of the blade loading identified in the experiment. The paper also reveals that the downstream volute imposes a long wavelength circumferential non-uniform back pressure at the impeller exit, which is found to either excite or supress the vortex shedding within the blade passage depending on the relative circumferential position of the impeller and the volutes.
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Zhang, Sha, Wuli Chu, and Jibo Yang. "Effect of Axial Short Slot Casing Treatment and its Center Deviation on Stability of a Transonic Axial Flow Compressor." In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-14588.

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Abstract In order to increase the stability margin of axial compressor with low efficiency losses, this paper studies the influence of axial short slot casing treatment and its axial position on compressor performance. A transonic axial compressor rotor, NASA rotor37, is taken as the research object, and the solid wall case and three axial slot casing treatments with different axial positions are studied by numerical simulation. The results show that the configuration with a center deviation of 0 (CT _C) has the best effect, with a margin improvement of 7.6% and an efficiency reduction of 0.09%; the configuration with an upstream positioned axial slot (CT_L) is the second, with a margin improvement of 5.4% and an efficiency reduction of 0.28%; the configuration with a downstream positioned axial slot (CT_T) is the worst, with a margin improvement of 3.6% and an efficiency reduction of 0.3%. A shift of the slot in downstream direction is not effective because it only affects the extent of boundary layer separation and has little effect on the development of the tip leakage flow. The upstream positioned axial slot with unsatisfactory effect affects the tip leakage flow trajectory and weakens the radial vortex at the blade tip, but it cannot affect the subsequent development of the leakage vortex. The short slot casing treatment in the central position effectively inhibits the development of the vortex. At the same time, it affects the development of the boundary layer to some extent and ensures the lower efficiency reduction while obtaining better stability margin.
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Inoue, Masahiro, Motoo Kuroumaru, Shinichi Yoshida, Takahiro Minami, Kazutoyo Yamada, and Masato Furukawa. "Effect of Tip Clearance on Stall Evolution Process in a Low-Speed Axial Compressor Stage." In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-53354.

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Effect of the tip clearance on the transient process of rotating stall evolution has been studied experimentally in a low-speed axial compressor stage with various stator-rotor gaps. In the previous authors’ experiments for the small tip clearance, the stall evolution process of the rotor was sensitive to the gaps between the blade rows. For the large tip clearance, however, little difference is observed in the evolution processes independently of the blade row gap. In the first half process, it is characterized by gradual reduction of overall pressure-rise with flow rate decreasing, and the number of short length-scale disturbances is increasing with their amplitude increasing. In the latter half a long length-scale disturbance develops rapidly to result in deep stall. Just before the stall inception the spectral power density of the casing wall pressure reveals the existence of rotating disturbances with broadband high frequency near a quarter of the blade passing frequency. This is caused by the short length-scale disturbances occurring intermittently. A flow model is presented to explain mechanisms of the rotating short length-scale disturbance, which includes a tornado-like separation vortex and tip-leakage vortex breakdown. The model is supported by a result of a numerical unsteady flow simulation.
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Stößel, Marcel, Stefan Bindl, and Reinhard Niehuis. "Ejector Tip Injection for Active Compressor Stabilization." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-25073.

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In propulsion industry there is an ongoing need to significantly reduce SFC of jet engines resulting in cost reduction and lower emissions. Since the design of most of the engine components is at the limit of today’s technology level further gain of improvement on short term is to be achieved by implementation of new system concepts. Especially the stall safety margin in compression system design holds high potential for the optimization of the overall engine system. Once a reliable and effective stall control system becomes available an extension of present operating range is likely to be achieved by moving the steady operating line towards the stability limit and to intervene only in critical situations. At the Institute of Jet Propulsion at the University of the Federal Armed Forces in Munich, Germany a Larzac 04 twin-spool turbofan engine has already been equipped and tested with an adequate active stabilization system of the low pressure compressor for research purposes. Those investigations revealed a strong dependency of the achievable stabilization effect and the amount and momentum of the injected air mass flow. For flying applications this mass flow has to be delivered by carried on means. Therefore it always penalizes the propulsion efficiency. In the given configuration, redirected air from the last stage of the high pressure compressor is used for injection. Usage of this bleed air directly influences the propulsion efficiency of the engine. In order to optimize the mass flow needed for stabilization, the existing injection system was redesigned to utilize ejector pumps. With this configuration a comparable stabilizing effect could be realized with less redirected air mass flow. In fact the open ejector pump configuration showed an even higher performance at maximum injection rate than the closed injection before. Therefore further investigations with this system focused on the effect of additional flow ports to the engine intake as they are necessary for an ejector pump and their basic influence on the operation stability of the low pressure compressor (LPC). In combination with the already existing stall detection algorithm of the institute a very promising system for increasing the available operating range in turbo compressors could be achieved.
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Benedek, Tamás, and János Vad. "Study on the Effect of Inlet Geometry on the Noise of an Axial Fan, With Involvement of the Phased Array Microphone Technique." In ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-57772.

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The paper presents a comparative case study in which a free-inlet, free-outlet industrial ventilating fan has been equipped with various inlet geometries. The original short-tapered entry has been replaced by a standardized bellmouth entry, resulting in remarkable noise reduction. The experimentation presented herein is adaptable to industrial onsite diagnostics. The upstream-radiated broadband noise associated with rotating sources has been mapped in a spatially resolved manner, by means of a Phased Array Microphone system and a Rotating Source Identifier beamforming algorithm. The acoustic measurements have been supplemented with aerodynamic measurements on the inlet velocity profile, and with Computational Fluid Dynamics studies. The acoustic data have been processed for enabling their evaluation in association with the aerodynamic operation of the elemental rotor cascades in a two-dimensional approach, and also for their interpretation in relationship to three-dimensional flow phenomena such as tip leakage flow. For this purpose, the acoustic data have been presented in the form of circumferentially-averaged noise profiles along the blade span, as well as noise source imaging maps. The studies reveal the following acoustic benefits of reconfiguring the original short-tapered entry to the bellmouth entry. A peripheral separation zone is characteristic for the short-tapered entry, provoking double-leakage tip clearance flow, being the dominant source of noise at higher frequencies. Such a peripheral separation zone is suppressed by the bellmouth inlet, and thus, the double-leakage flow and the related noise is eliminated. Farther away from the tip, along the dominant portion of the span, the moderation of endwall blockage due to suppressing the peripheral separation zone has led to the reduction of the rotor inlet velocity, thus moderating the noise associated with the suction side boundary layer developing on the blades.
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Sun, Zonghan, Jie Tian, Grzegorz Liśkiewicz, Zhaohui Du, and Hua Ouyang. "Noise Reduction Analysis of Electronic Device Cooling Fan With Duct and Its Application Under Variable Working Conditions." In ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/gt2021-58739.

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Abstract A noise reduction method for axial flow fans using a short inlet duct is proposed. The pattern of noise reduction imposed by the short inlet duct on the axial flow cooling fan under variable working conditions was experimentally and numerically examined. A 2-cm inlet duct was found to reduce tonal noise. As the tip Mach number of the fan increased from 0.049 to 0.156, the reduction in the total average sound pressure level at 1 m from the fan increased from 0.8 dB(A) to 4.3 dB(A), and further achieved 4.8 dB(A) when a 1-cm inlet duct was used. The steady computational fluid dynamics (CFD) showed that the inlet duct has little effect on the aerodynamic performance of the fan. The results of the full passage unsteady calculation at the maximum flow rate showed that the duct has a significant influence on the suction vortexes caused by the inlet flow non-uniformity. The suction vortexes move upstream to weaken the interaction with the rotor blades, which significantly reduces the pulsating pressure on the blades. The sound pressure level (SPL) at the blade passing frequency (BPF) contributed by the thrust force was calculated to reduce by 36 dB at a 135° observer angle, reflecting the rectification effect of the duct on the non-uniform inlet flow and the improvement in characteristics of the noise source. The proper orthogonal decomposition (POD) of the static pressure field on the blades verified that the main spatial mode is more uniformly distributed due to the duct, and energy owing to the rotor-inlet interaction decreases. A speed regulation strategy for the cooling fan with short inlet duct is proposed, which provides guidance for the application of this noise reduction method.
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Miglietti, Warren, Ian Summerside, Simone Hoevel, and Zaki Zainuddin. "Repair Process Technology Development and Experience for W501F Row 1 Hot Gas Path Blades." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-22443.

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Volatile market dynamics in the electrical power generation field continues to force power companies to identify prudent material cost reductions opportunities in their Operations and Maintenance (O&M) business. Today, there is an industry-recognized need for advanced hot gas path component repair and reconditioning capability for operators of F-Class gas turbines that can be highly cost effective with short cycle times. The SGT6-5000F (W501FD) engine, an “F” class machine has been in operation for more than a decade now. Of importance to operators/users and owners of this gas turbine engine is the ability to recondition the turbine “hot-end section” components, in order to support maintenance requirements. The first 2 rows of blades are unshrouded; whereas the last 2 rows are shrouded. The row 1 blades show severe degradation and thus repair of this component has been a focus point for PSM. The technical objective is to develop repair schemes for the row 1 blades since this component (other than the Transition Piece (TP)) has the highest frequency of replacement, plus is the highest replacement cost per component. Special processes have been developed for these components repairs, including but not limited to: a) Acid stripping of the coating; b) Machining off of the original brazed tip cap plates; c) High frequency gas tungsten arc welding and vacuum diffusion braze repair of platform cracks; d) High frequency gas tungsten arc weld attachment or laser welding of new tip cap plates; e) Laser metal forming/cladding of new squealer tips; f) Rejuvenation heat treatment; g) Application of superior MCrAlY and TBC coating to that originally applied. This technical paper describes the repair process development and implementation of the different stages of the repair schemes, and shows metallurgical and mechanical characteristics of the repaired regions of the component.
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Mondin, Gabriel, William Riéra, Pierre Duquesne, and Xavier Ottavy. "Beneficial Effects of Guide Fins on Corner Separation." In ASME Turbo Expo 2023: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/gt2023-101012.

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Abstract Corner separation is a major phenomenon limiting the operability of aeronautical compressors. Passive control devices such as guide fins are envisioned to reduce its deleterious effects. In this paper, guide fins are optimized to reduce the total pressure losses downstream of a subsonic compressor cascade (M = 0.11, Re = 3.2 105, modern stator blades) at design and near-stall incidences. Guide fins shapes are defined using 15 parameters. An optimization strategy relying on the iterative refinement of surrogate model with Reynolds-Averaged Navier-Stokes (RANS) computations is carried out. A database of 1033 guide fins is obtained, a large number of which strongly reduces the near-stall losses. Three guide fins are thoroughly investigated and referred to as Short Fence (short and straight guide fin), Long Fence (long and straight guide fin) and 3D (long guide fin with a strong pyramidal aspect). Their effect on the downstream measurement plane is validated experimentally, as well as their integrated performances. Large reductions of total pressure losses at near-stall incidence are obtained (−2.4 pt to −2.9 pt, or a relative reduction of −50% to −60%) without degrading neither the nominal losses nor the stator deflection. These guide fins are used to highlight three beneficial mechanisms that alter the corner separation development within the blade passage a) Tip Vortex (energizes the passage flow) b) Fence (induces 2 passage vortices) c) Guide (induces a local favourable pressure gradient). The role of these mechanisms in the generation of total pressure losses are analyzed in depth with streamlines visualisations and with a topological analysis. Kriging surrogate models reveal that three parameters drive the guide fins performances : the axial position, height, and thickness value at hub. The performances of the investigated guide fins are robust to significant variations of these parameters, as well as small variation of the inlet boundary layer thickness.
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Reports on the topic "Shoot tip reduction"

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Raikow, David, Mark Wasser, Amanda McCutcheon, and Anne Farahi. Trends in water quality of Waikolu Stream, Kalaupapa National Historical Park, Moloka?i, Hawaii, 2007?2017. National Park Service, 2024. http://dx.doi.org/10.36967/2302153.

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Water quality was monitored in Waikolu Stream, Kalaupapa National Historical Park, Moloka?i, Hawa?i from 2007-2017. Water was collected for nutrient analyses and a sonde equipped with multiple probes was used to measure water quality parameters. The sampling regime was based on a split-panel of permanently established or ?fixed? sites sampled during each sampling effort, and ?temporary? sites of randomly assigned locations, for each sampling effort. Results included: ? NO-3 + NO-2 regularly exceeded state water quality criteria. ? TP exceeded state water quality criteria once out of three quarters evaluated. ? Other nutrient concentrations were consistent with Hawaiian streams. ? Waters were clear and well oxygenated. ? Conditions were consistent with similar pacific island streams. ? Dissolved nutrient fractions dominated base flow conditions. ? Seasonality was detected for TDN, NO-3 + NO-2, chlorophyll, pH, oxygen, and temperature. ? Several trends were detected; however, the magnitude of change was small and did not warrant concern. ? Temporal patterns did not obviously correspond to climate conditions. ? Parameters varied spatially to a limited extent, with nitrogen decreasing and temperature, specific conductance, and oxygen increasing from headwaters to the mouth. ? Temporary site conditions were highly correlated with fixed sites and did not provide additional insights. Water quality in Waikolu Stream was generally good with the exception of NO-3 + NO-2 which exceeded state standards. However, concentrations of NO-3 + NO-2 were generally consistent with many streams in Hawaii and natural causes of observed concentrations may have included older soils, steep slopes, and high precipitation. Exotic species including ungulates, which are known to occur in Waikolu Valley, could have contributed to elevated N through droppings and soil erosion in the riparian zone. Waikolu Stream TDN, TDP, chlorophyll, pH, turbidity, SpC, and oxygen were consistent with streams in other well-protected NPS watersheds on pacific islands on Maui, Guam, and American Samoa. Due to the watershed?s small size, the stream?s short length, and because variation or unique conditions were not captured by using split-panel, we recommend reducing the sampling effort. For example, our observations indicate that one easily accessible site in the lower reaches of the stream (FKALA03) displays water quality that reflects the entire stream. We also recommend adding nutrient analytes to better characterize biogeochemical cycling in this stream, including TP, TN, NH+4, and PO4. A power analysis is underway to evaluate reduction of sample sites. Such a reduction will result in large cost savings for the PACN water quality monitoring program.
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Eshel, Amram, Jonathan P. Lynch, and Kathleen M. Brown. Physiological Regulation of Root System Architecture: The Role of Ethylene and Phosphorus. United States Department of Agriculture, 2001. http://dx.doi.org/10.32747/2001.7585195.bard.

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Specific Objectives and Related Results: 1) Determine the effect of phosphorus availability on ethylene production by roots. Test the hypothesis that phosphorus availability regulates ethylene production Clear differences were found between the two plants that were studied. In beans ethylene production is affected by P nutrition, tissue type, and stage of development. There are genotypic differences in the rate of ethylene production by various root types and in the differential in ethylene production when P treatments are compared. The acceleration in ethylene production with P deficiency increases with time. These findings support the hypothesis that ethylene production may be enhanced by phosphorus deficiency, and that the degree of enhancement varies with genotype. In tomatoes the low-P level did not enhance significantly ethylene production by the roots. Wildtype cultivars and ethylene insensitive mutants behaved similarly in that respect. 2) Characterize the effects of phosphorus availability and ethylene on the architecture of whole root systems. Test the hypothesis that both ethylene and low phosphorus availability modify root architecture. In common bean, the basal roots give rise to a major fraction of the whole root system. Unlike other laterals these roots respond to gravitropic stimulation. Their growth angle determines the proportion of the root length in the shallow layers of the soil. A correlation between ethylene production and basal root angle was found in shallow rooted but not deep-rooted genotypes, indicating that acceleration of ethylene synthesis may account for the change in basal root angle in genotypes demonstrating a plastic response to P availability. Short-time gravitropic response of the tap roots of young bean seedlings was not affected by P level in the nutrient solution. Low phosphorus specifically increases root hair length and root hair density in Arabidopsis. We tested 7 different mutants in ethylene perception and response and in each case, the response to low P was lower than that of the wild-type. The extent of reduction in P response varied among the mutants, but every mutant retained some responsiveness to changes in P concentration. The increase in root hair density was due to the increase in the number of trichoblast cell files under low P and was not mediated by ethylene. Low P did not increase the number of root hairs forming from atrichoblasts. This is in contrast to ethylene treatment, which increased the number of root hairs partly by causing root hairs to form on atrichoblasts. 3) Assess the adaptive value of root architectural plasticity in response to phosphorus availability. A simulation study indicated that genetic variation for root architecture in common bean may be related to adaptation to diverse competitive environments. The fractal dimension of tomato root system was directly correlated with P level.
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Petit, Vincent. Road to a rapid transition to sustainable energy security in Europe. Schneider Electric Sustainability Research Institute, 2022. http://dx.doi.org/10.58284/se.sri.bcap9655.

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Decarbonization and energy security in Europe are two faces of the same coin. They are both related to the large dependency of the European Union economy on fossil fuels, which today represent around 70% of the total supply of energy. The bulk of these energy resources are imported, with Russia being the largest supplier, accounting for 40% of natural gas and 27% of oil imports. However, fossil fuels are also the primary root cause of greenhouse gas emissions, and the European Union is committed to reduce those by 55% by 2030 (versus 1990). This report is based on the landmark research from the Joint Research Center of the European Commission, the “Integrated Database of the European Energy Sector”, which for the first time mapped actual energy uses for each country within the European Union, across 17 sectors of activity, with data granularity at the level of each process step (or end-use) of each of these sectors. Our approach here has been to systematically review these process steps (or end-uses) and qualify the extent to which they could be electrified, effectively removing the demand for fossil fuels as a result. We have focused only on those process steps where technology was already widely available and for which we evaluated the switch to be relatively easy (or attractive). In other words, we estimated the impact of rapid electrification of “easy to abate” activities. The conclusion of this evaluation is that the share of electricity demand in the final energy mix could jump from around 20% today to 50%, which would drive a reduction in emissions at end-use of around 1,300 MtCO2 /y, as well as a drop in natural gas and oil supply of around 50%. As a result of such transformation, electricity demand would nearly double, with the bulk of that growth materializing in the building sector. Short-term, the challenge of addressing climate targets while providing for energy security is thus intimately connected to buildings. While such transition would certainly require major infrastructure upgrades, which may prove a roadblock to rapid deployment, we find that the combination of energy efficiency measures (notably digital) and distributed generation penetration (rooftop solar) could significantly tame the issue, and hence help accelerate the move away from fossil fuels, with energy spend savings as high as 80% across some building types; a major driver of change. Beyond this, further potential exists for electrification. Other measures on the demand-side will include deeper renovations of the industrial stock (notably in the automotive, machinery, paper, and petrochemical industries for which our current assessment may be underestimated) and further electrification of mobility (trucks). The transition of the power system away from coal (and ultimately natural gas) will then also play a key role, followed ultimately by feedstocks substitution in industry. Some of these transitions are already on the way and will likely bring further improvements. The key message, however, is that a significant opportunity revolves around buildings to both quickly decarbonize and reduce energy dependencies in Europe. Rapid transformation of the energy system may be more feasible than we think. We notably estimate that, by 2030, an ambitious and focused effort could help displace 15% to 25% of natural gas and oil supply and reduce emissions by around 500 MtCO2 /y (note that these savings would come on top of additional measures regarding energy efficiency and flexibility, which are not the object of this study). For this to happen, approximately 100 million buildings will need renovating, and a similar number of electric vehicles would need to hit the road.
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Sela, Hanan, Eduard Akhunov, and Brian J. Steffenson. Population genomics, linkage disequilibrium and association mapping of stripe rust resistance genes in wild emmer wheat, Triticum turgidum ssp. dicoccoides. United States Department of Agriculture, 2014. http://dx.doi.org/10.32747/2014.7598170.bard.

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The primary goals of this project were: (1) development of a genetically characterized association panel of wild emmer for high resolution analysis of the genetic basis of complex traits; (2) characterization and mapping of genes and QTL for seedling and adult plant resistance to stripe rust in wild emmer populations; (3) characterization of LD patterns along wild emmer chromosomes; (4) elucidation of the multi-locus genetic structure of wild emmer populations and its correlation with geo-climatic variables at the collection sites. Introduction In recent years, Stripe (yellow) rust (Yr) caused by Pucciniastriiformis f. sp. tritici(PST) has become a major threat to wheat crops in many parts of the world. New races have overcome most of the known resistances. It is essential, therefore, that the search for new genes will continue, followed by their mapping by molecular markers and introgression into the elite varieties by marker-assisted selection (MAS). The reservoir of genes for disease and pest resistance in wild emmer wheat (Triticumdicoccoides) is an important resource that must be made available to wheat breeders. The majority of resistance genes that were introgressed so far in cultivated wheat are resistance (R) genes. These genes, though confering near-immunity from the seedling stage, are often overcome by the pathogen in a short period after being deployed over vast production areas. On the other hand, adult-plant resistance (APR) is usually more durable since it is, in many cases, polygenic and confers partial resistance that may put less selective pressure on the pathogen. In this project, we have screened a collection of 480 wild emmer accessions originating from Israel for APR and seedling resistance to PST. Seedling resistance was tested against one Israeli and 3 North American PST isolates. APR was tested on accessions that did not have seedling resistance. The APR screen was conducted in two fields in Israel and in one field in the USA over 3 years for a total of 11 replicates. We have found about 20 accessions that have moderate stripe rust APR with infection type (IT<5), and about 20 additional accessions that have novel seedling resistance (IT<3). We have genotyped the collection using genotyping by sequencing (GBS) and the 90K SNP chip array. GBS yielded a total 341K SNP that were filtered to 150K informative SNP. The 90K assay resulted in 11K informative SNP. We have conducted a genome-wide association scan (GWAS) and found one significant locus on 6BL ( -log p >5). Two novel loci were found for seedling resistance. Further investigation of the 6BL locus and the effect of Yr36 showed that the 6BL locus and the Yr36 have additive effect and that the presence of favorable alleles of both loci results in reduction of 2 grades in the IT score. To identify alleles conferring adaption to extreme climatic conditions, we have associated the patterns of genomic variation in wild emmer with historic climate data from the accessions’ collection sites. The analysis of population stratification revealed four genetically distinct groups of wild emmer accessions coinciding with their geographic distribution. Partitioning of genomic variance showed that geographic location and climate together explain 43% of SNPs among emmer accessions with 19% of SNPs affected by climatic factors. The top three bioclimatic factors driving SNP distribution were temperature seasonality, precipitation seasonality, and isothermality. Association mapping approaches revealed 57 SNPs associated with these bio-climatic variables. Out of 21 unique genomic regions controlling heading date variation, 10 (~50%) overlapped with SNPs showing significant association with at least one of the three bioclimatic variables. This result suggests that a substantial part of the genomic variation associated with local adaptation in wild emmer is driven by selection acting on loci regulating flowering. Conclusions: Wild emmer can serve as a good source for novel APR and seedling R genes for stripe rust resistance. APR for stripe rust is a complex trait conferred by several loci that may have an additive effect. GWAS is feasible in the wild emmer population, however, its detection power is limited. A panel of wild emmer tagged with more than 150K SNP is available for further GWAS of important traits. The insights gained by the bioclimatic-gentic associations should be taken into consideration when planning conservation strategies.
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