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  • 1
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Weed research 29 (1989), S. 0 
    ISSN: 1365-3180
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Twenty inbred maize lines, raised in a growth chamber, were treated with 0 or 1 ng g−1 of chlorsulfuron which caused a variable reduction in root-length. In a second experiment, all crosses (reciprocals included) among two tolerant lines (T: Va85 and Mes44) and two susceptible lines (S: B73 and B79) were raised in a growth chamber together with the parental lines and exposed to 0,0×5 or 1 ng g−1, The interaction of reciprocal effects x rates was not significant for all traits, The T × S hybrids showed an intermediate response between the T × T and S × S responses for root-length and dry weight. Interaction (hybrids vs. parental lines) × rates was not significant for all traits. These results indicate that susceptibility to chlorsulfuron is not controlled by extra-nuclear factors and that additive gene actions prevail. Four crosses (one T × T, two T × S and one S × S) were further investigated at nine rates from 0 to 1 ng g−1. The responses confirmed the intermediate behaviour of T×S hybrids, resulting in a GR20 of 0×07, 0×55 and 0×94 ng g−1 for S × S, T × S and T × T, respectively. In a third experiment, the four crosses previously considered were grown in the field with parental lines and treated at five rates from 0 to 1·12 g a.i. ha−1. Effects on shoot height and dry weight were consistent with root effects found in growth chamber experiments.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 101 (1988), S. 0 
    ISSN: 1439-0523
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: In order to investigate the direct and correlated responses to selection for heading date in barley, two F2 populations were subjected to four cycles of divergent selection. For each cross, eight populations selected for earliness (from 1E to 4E) and for lateness, (from 1L to 4L) and four unselected populations (1, 2, 3 and 4 SSD) were obtained and than compared together with parental lines. Selection caused a change greater than one day/cycle in Doth directions, and the cumulative responses were -5.4 and -5,9 days in the direction of earliness, 7.7 and 7,1 days in the opposite direction. Such results suggest that in the two base populations the heading, date is under the control of a polygenic system with prevailing additive effects and a slight directional dominance toward earliness.Early populations showed a reduction of ear moisture and an increase of plant height, ear extrusion, kernel weight and harvest index, whereas late populations showed the opposite changes. Grain yield was linearly reduced by selection for lateness, whereas no substantial change was evidenced in the opposite direction, so that 4E significantly out-yielded 4L in both crosses.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    ISSN: 1438-1168
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Beschreibung / Inhaltsverzeichnis: Zusammenfassung Eine chemische und mineralogische Untersuchung der magmatischen Einschlüsse in den sauren Gesteinen des Tolfa-Ceriti-Manziana Sektors (Toskanische Provinz, Zentralitalien) zeigt, daß sie nach dem Grad der Alkalinitdt unterteilt werden können. Wir unterscheiden TCM latite (TCML) mit einer Alkali-Kalium Affinität; Ceriti Latite (CL) mit einer kalkalkalischen Affinität und Manziana Shoshonite und Latite (MS-ML) mit einer Affinität die zwischen alkalisch und subalkalisch liegt. Die Letztgenannten sind Mischgesteine, die durch die Mischung zweier Magmen mit verschiedenen geochemischen Affinitäten entstanden sind. Diese Magmen, die genetisch nicht mit den Wirtsgesteinen in Beziehung stehen, dürften Schmelzen repräsentieren, die auf teilweise Aufschmelzung eines heterogenen Mantels, der durch eine krustale Quelle metasomatisiert wurde, zurückgehen. Die am meisten alkalischen Magmen (TCML) sind mit dem höchsten Grad der Metasomatose assoziiert, der wiederum, wenn noch stärker entwickelt, zur Entstehung der kalireichen Magmen der römischen Provinz führen könnte.
    Notizen: Summary A chemical and mineralogical study of magmatic inclusions in the silica-rich rocks of the Tolfa-Ceriti-Manziana sector (Tuscan Province, Central Italy) shows that they can be grouped according to their degree of alkalinity. We distinguish: TCM latites (TCML) with an alkaline-potassic affinity; Ceriti latites (CL) with calc-alkaline affinity; and Manziana shoshonites and latites (MS-ML) with an affinity intermediate between alkaline and subalkaline. The latter are hybrid rocks originating from the mixing of two magmas with slightly different geochemical affinities. These magmas may represent liquids derived by partial melting of a heterogeneous mantle, metasomatized by a crustal source. The most alkaline magmas (TCML) are associated with the largest degree of metasomatism which, if more pronounced, could lead to the production of the potassic magmas of the Roman Province.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Bulletin of volcanology 62 (2000), S. 294-300 
    ISSN: 1432-0819
    Schlagwort(e): Stromboli Persistent strombolian activity Tephrostratigraphy 14C datings
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Abstract. Stromboli, known worldwide as the "Lighthouse of the Mediterranean", is commonly believed to have been in a state of persistent activity for the past 2000–2500 years. However, historical sources older than 1000 A.D. are not accurate enough to assess if the activity of the volcano was exactly the same as we see at present. In order to attempt to identify the onset of the present eruptive regime, and assess if it has been maintained with the same characteristics through time, stratigraphic and radiometric studies of the recent tephra deposits were undertaken. Up to 4-m-deep stratigraphic trenches, dug at a height of approximately 500 m on the NE flank of the volcano, exposed a conformable tephra pile containing charcoal fragments. One of the most interesting finds was the discovery of a 7-cm-thick weathered bed rich in organic matter (thin palaeosol) approximately 3 m below the surface. The sequence underneath the palaeosol consists of decimetre-thick lapilli fallout beds alternating with ash deposits bearing small charcoals with calibrated ages of between the fourth century B.C. and the first century A.D. The sequence above the palaeosol is charcoal free and consists of coarse-ash deposits with discrete, centimetre-thick lapilli fallout beds composed of crystal-poor golden pumice and subordinate crystal-rich black scoriae similar to scoria/pumice pairs emitted during the more energetic explosions of the present-day activity. The data collected indicate that between the third and seventh centuries A.D., after a period of quiescence, the activity resumed with an eruptive style identical to the present one. We conclude that the "Lighthouse of the Mediterranean" actually began its activity in a period much later than previously thought.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Sexual plant reproduction 2 (1989), S. 65-69 
    ISSN: 1432-2145
    Schlagwort(e): Herbicide tolerance ; Pollen selection ; Sulfonylurea ; Chlorsulfuron
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Maize pollen was exposed to the herbicide Chlorsulfuron (CS), and segregation for tolerance was observed. The resulting plant generation exhibited significantly greater tolerance to CS than other (control) progeny. Since the increase in tolerance occurred after only one generation of pollen exposure, this result demonstrates that pollen selection can be used to develop herbicide-resistant crop species, even when the species are not amenable to cell culture. It also suggests a possible mechanism for the rapid evolution of herbicide tolerance in weeds.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Contributions to mineralogy and petrology 135 (1999), S. 179-197 
    ISSN: 1432-0967
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Abstract Products of the Pomici di Base plinian eruption of Somma-Vesuvius consist of pumice and scoria fall deposits overlain by lithic-rich phreatomagmatic deposits. The plinian fall, which represents most of the magma volume involved in the eruption, ranges in composition from trachyte (SiO2 = 62.5 wt%) to latite (SiO2 ≈ 58 wt%) in the lower one-third of the deposit, whereas the upper two-thirds of the total thickness consists of latitic scoriae with fairly uniform composition (SiO2 ≈ 55–56 wt%). All the products have very low content of phenocrysts (from 4 wt% in trachyte pumice to 1 wt% in the latite scoriae), most of which are not in equilibrium with the host rock. Minerals not in equilibrium, both in trachytic and latitic rocks, consist of discrete crystals of sanidine and plagioclase wetted by trachytic glass and felsic aggregates with interstital trachytic glass. Trends of major and trace elements are consistent with crystal-liquid fractionation processes and rule out syn-eruptive mixing processes between latitic and trachytic magmas. We suggest that discrete crystals and crystal aggregates not in equilibrium with the host rock represent fragments of the crystallising boundary layer at the upper walls of the magma chamber, which were wrenched and admixed into the magma during the ascent. This process diversifies the mineral assemblage and increases the crystal content of the rocks. We propose that diffusive crystallization processes operating at the wall of the chamber allowed the formation of a two-fold layered reservoir with a more mafic, homogeneous lower body and a more evolved, compositionally graded upper body. Around one-quarter of crystals adhering to the upper part of the magma chamber were admixed into the magma during the eruption. The absence of significant syn-eruptive mixing processes and the major role played by diffusive crystallization are consistent with a low aspect ratio magma chamber (width/height 〈1).
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    ISSN: 1432-0819
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Abstract Subsurface geothermal exploration has considerably added to our knowledge of the Latera volcanic complex. A syenitic body is located about 2 km below the present-day surface; K-Ar data point a 0.9 Ma age. The primary magma was a silica-saturated trachyte; undersaturated, hauyne-bearing products are found near the carbonatic wall-rocks and have been interpreted as reaction products. Subsurface data from deep drilling and geophysical surveys suggest that the Latera caldera resulted from three main successive collapse phases: (i) formation of an old caldera, now buried, related to the eruption of ignimbrites from the syenitic magma chamber; (ii) sinking of the eastern sector as a consequence of the formation of the nearby Bolsena caldera (∼0.3 Ma); (iii) multistage formation of the present Latera caldera (∼0.16 Ma).
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 88 (1994), S. 812-817 
    ISSN: 1432-2242
    Schlagwort(e): Zea mays L. ; Pollen assay ; Gametophytic selection ; Alachlor ; Herbicide tolerance
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In order to assess the efficiency of male gametophytic selection (MGS) for crop improvement, pollen selection for tolerance to herbicide was applied in maize. The experiment was designed to test the parallel reactivity to Alachlor of pollen and plants grown in controlled conditions or in the field, the response to pollen selection in the sporophytic progeny, the response to a second cycle of MGS, and the transmission of the selected trait to the following generations. The results demonstrated that pollen assay can be used to predict Alachlor tolerance under field conditions and to monitor the response to selection. A positive response to selection applied to pollen in the sporophytic progeny was obtained in diverse genetic backgrounds, indicating that the technique can be generally included in standard breeding programs; the analysis of the data produced in a second selection cycle indicated that the selected trait is maintained in the next generation.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 88 (1994), S. 780-784 
    ISSN: 1432-2242
    Schlagwort(e): Acetochlor tolerance ; Gene expression Pollen selection ; Zea mays
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The objectives of this research were to determine if genes controlling the reaction to the herbicide acetochlor in maize (Zea mays L.) are active during both the haploid and the diploid phases of the life cycle and if pollen selection can be utilized for improving sporophytic resistance. Pollen of eight inbred lines, previously characterized through sporophytic analysis for the level of tolerance to acetochlor, showed a differential reaction to the herbicide forin vitro tube length; moreover, such pollen reactions proved to be significantly correlated (r =0.786*,df=6) with those of the sporophytes producing the pollen. Pollen analysis of two inbred lines (i.e. Mo17, tolerant, and B79, susceptible) and their single cross showed that thein vitro pollen-tube length reaction of the hybrid was intermediate between those of two parents. An experiment on pollen selection was then performed by growing tassels of Mo17xB79 in the presence of the herbicide. Pollen obtained from treated tassels showed a greater tolerance to acetochlor, assessed asin vitro tube length reaction, than pollen obtained from control tassels. Moreover, the backcross [B79 (Mo17xB79)] sporophytic population obtained using pollen from the treated tassels was more tolerant (as indicated by the fresh weight of plants grown in the presence of the herbicide) than was the control backcross population. The two populations did not differ when grown without the herbicide. These findings indicate that genes controlling the reaction to acetochlor in maize have haplodiploid expression; consequently, pollen selection can be applied for improving plant tolerance.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    ISSN: 1432-2242
    Schlagwort(e): Key words Abscisic acid (ABA) ; Drought stress ; Quantitative trait loci (QTLs) ; Maize (Zea mays L.) ; RFLPs
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  Abscisic acid (ABA) concentration in leaves of drought-stressed plants is a quantitatively inherited trait. In order to identify quantitative trait loci (QTLs) controlling leaf ABA concentration (L-ABA) in maize, leaf samples were collected from 80 F3:4 families of the cross Os420 (high L-ABA)×IABO78 (low L-ABA) tested under drought conditions in field trials conducted over 2 years. In each year, leaf samples were collected at stem elongation and near anthesis. The genetic map obtained with 106 restriction fragment length polymorphism (RFLP) loci covered 1370 cM, which represented approximately 85% of the UMC maize map. Sixteen different QTLs with a LOD〉2.0 were revealed in at least one sampling. Across samplings, only four QTLs significantly influenced L-ABA, accounting for 66% of the phenotypic variation and 76% of the genetic variation among families. At these QTLs, the alleles which increased L-ABA were contributed by Os420. The two most important QTLs were mapped on chromosome 2 near csu133 and csu109a. The effects associated with the QTL near csu133 were more pronounced near anthesis. The support intervals of the four primary QTLs for L-ABA did not overlap the presumed map position of mutants impaired in ABA biosynthesis.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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