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  • 11
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 228 (1970), S. 1225-1225 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] The seed of A. ludoviciana is a caryopsis surrounded by hard hulls or pales. Normally the spikelet comprises two such seeds and it does not disarticulate at maturity. This feature in contrast to A. fatua, the spring wild oat, makes it possible to compare directly seeds from the same spikelet. Such ...
    Materialart: Digitale Medien
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  • 12
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 233 (1971), S. 347-350 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] Radicles and hypocotyls of most seedlings are strongly orthogeotropic2'3. Synthetic growth regulators with physiological action like that of IAA (p indol-3-yl acetic acid) affect root and shoot growth, sometimes making these organs grow in an unexpected direction. Antitropistic effects can also be ...
    Materialart: Digitale Medien
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  • 13
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature 198 (1963), S. 805-806 
    ISSN: 1476-4687
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik
    Notizen: [Auszug] The following observations were made on a population in a pond about 1 mile west of Burghfield, near Reading, Berkshire. The snails are present in large numbers on the submerged aquatic vegetation at the edge of the pond and four samples were collected with a pond net during the summer of 1962, at ...
    Materialart: Digitale Medien
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  • 14
    Digitale Medien
    Digitale Medien
    Springer
    Planta 124 (1975), S. 169-175 
    ISSN: 1432-2048
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Whole plant senescence was studied in peas (Pisum sativum L.) by defruiting, defoliating, and grafting. Fruit removal delays senescence. The delay in senescence is associated with the initiation of bud expansion at nodes near those producing pods. The apical meristem dies regardless of defruiting though later than normal phants. Graft unions are only made if the stock is defruited The pattern of senescence of unions indicates a non polar movement of senescence factors from fruits. Leaves seem not to be involved in whole plant senescence.
    Materialart: Digitale Medien
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  • 15
    ISSN: 1432-2048
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Abscisic acid (ABA) has been unequivocally identified as an endogenous component of seeds of Grand Rapids lettuce. Both “free” and “bound” ABA levels were followed during imbibition at various temperatures but no clear role for ABA in the imposition of thermodormancy emerged. Furthermore it was apparent that different seed batches showed different ratios of “free” to “bound” ABA and patterns of changes. An unsuccessful attempt was made to identify “bound” ABA, presumed to be the glucosyl ester.
    Materialart: Digitale Medien
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  • 16
    ISSN: 1573-5036
    Schlagwort(e): Alnus rubra ; Alnus glutinosa ; Fatty acids ; Frankia ; Nitrogen fixation
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary Alnus species are used widely in Britain for land reclamation, forestry and other purposes. Rapid juvenile growth of the AmericanAlnus rubra makes it an attractive species for planting on N-deficient soils, particularly those of low organic content. In small plot trials, this species is nodulated by indigenous soil frankiae as effectively asAlnus glutinosa. Over a three year period both species return similar amounts of N to the ecosystem, estimated at up to 10–12 kg N ha−1. Several strains ofFrankia have been isolated from local (Lennox Forest)A. rubra nodules. These differ morphologically and in their growth on different culture media, both from each other and fromA. glutinosa nodule isolates. AllAlnus isolates, however, have a total cellular fatty acid composition qualitatively similar to some other Group B frankiae. Glasshouse tests in N free culture suggest thatA. rubra nodules formed after inoculation of seedlings with American spore (−) isolates are three times more effective in N fixation than those inoculated with LennoxA. rubra spore (+) nodule homogenates. By contrast, the early growth of seedlings inoculated with spore (−)Frankia strains suggests at best a 35% improvement in N fixing activity over seedlings inoculated with LennoxA. rubra nodule isolates. Nevertheless, this improvement in activity, together with the better performance of seedlings inoculated with isolates compared with those treated with crushed nodule preparations, suggest that it would be worthwhile commercially to inoculate nursery stock with a spore (−)Frankia strain.
    Materialart: Digitale Medien
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  • 17
    Digitale Medien
    Digitale Medien
    Springer
    Hydrobiologia 210 (1991), S. 183-189 
    ISSN: 1573-5117
    Schlagwort(e): water temperature ; rivers ; regression ; climate change
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The water temperatures of four English chalk streams which have a large groundwater component in their discharge were studied. Simple linear regression models were used to described mean monthly water temperature as a function of mean monthly air temperature. There were no significant between-year differences within rivers, in the case of the Lambourn, Winterbourne and Tadnoll. For the Frome, only one year out of the eight studied was significantly different from the others. Further analysis revealed that there were no significant differences between the Tadnoll, Winterbourne and Lambourn, and that the relationship between maximum monthly water temperature and air temperature was best described by the equation y = 4.29 + 0.55x. Using this pooled equation to predict river temperatures for the three rivers studied gave mean deviations of less than 1 °C from the observed temperatures. It was concluded that linear regressions of the type presented are sufficiently accurate to predict the thermal regimes of rivers for a variety of limnological purposes. They can also be used to predict the temperature response of chalk streams to increased air temperatures that may be produced by climate change. The results predict that chalk streams would show less increase in temperature than other running waters under these circumstances.
    Materialart: Digitale Medien
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  • 18
    Digitale Medien
    Digitale Medien
    Springer
    Hydrobiologia 248 (1992), S. 3-9 
    ISSN: 1573-5117
    Schlagwort(e): chalk stream ; chalk hydrology ; stream flow ; water temperature ; water chemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Chalk is a very pure and porous form of limestone. Water percolates down through the rock to form aquifers which overflow as springs forming chalk streams which receive little surface runoff. Passage through the rock is relatively slow and smooths out irregularities in rainfall and stabilises the water temperature. As a result the streams tend to have a regular annual hydrograph with a relatively small difference between winter and summer flows and with no spate conditions; and the temperature range in the streams remains closer to the annual mean than in rivers receiving more surface runoff. The water is calcareous with a pH of 7.4–8.0 and an ample supply of plant nutrients. The streams support diverse and productive communities of plants and animals and the restricted temperature range is particularly suitable for the growth of brown trout.
    Materialart: Digitale Medien
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  • 19
    Digitale Medien
    Digitale Medien
    Springer
    Hydrobiologia 248 (1992), S. 1-2 
    ISSN: 1573-5117
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Materialart: Digitale Medien
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