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Title:Physiological and nutritional changes in nitrogen fixing trees associated with autumnal senescence and chilling
Author(s):Vogel, Christoph Steven
Doctoral Committee Chair(s):Dawson, Jeffrey O.
Department / Program:Biology
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Biology, Ecology
Agriculture, Forestry and Wildlife
Biology, Plant Physiology
Abstract:In the first of two studies, autumnal leaf senescence of four temperate woody deciduous plants, autumn olive (Elaeagnus umbellata Thunb.), black locust (Robinia pseudoacadia L.), American sycamore (Platanus occidentalis L.) and honey locust (Gleditsia triacanthos L.), was studied during the autumns of 1987 and 1988 on two physically and nutritionally distinct sites in central Illinois, USA. The dinitrogen fixing species, actinorhizal (Frankia-nodulated) autumn olive and leguminous black locust (Rhizobium-nodulated), resorbed proportionally more net phosphorus (P) than nitrogen (N) from leaves prior to autumnal leaf abscission than the non-fixing species, sycamore and leguminous honey locust. Site had little effect on the net change in foliar N or P. Root bark seemed to be an important storage site for P during autumn in the dinitrogen fixing species as were buds of autumn olive. Each of the species investigated showed significant increases in twig bark concentration of N, although changes in twig bark concentrations of P were variable.
In the second study, actinorhizal black alder (Alnus glutinosa (L.) Gaertn.) seedlings fertilized with 0.36 mM nitrate or 7.14 mM nitrate were exposed to 2.5 h of night-time chilling temperatures of $-$1 to 4$\sp\circ$C. Cold treatment decreased nitrogenase activity by an average of 37% and recovery occurred within seven days after chilling treatment. In constrast, in vivo nitrate reductase (NR) activities of leaves and fine roots increased immediately after chilling then decreased as nitrogenase activities recovered. Fine roots of alder seedlings exhibited NR activities proportional to the amounts of nitrate in the rooting medium. By contrast, the NR activities of leaves was independent of substrate and tissue nitrate levels and corresponded with nitrogenase activity in the root nodules. Net photosynthesis of black alder seedlings declined in response to chilling by an average of 18%. After chilling, stomatal conductance (g$\sb{\rm s}$) decreased by 39% and internal CO$\sb2$ concentration (c$\sb{\rm i}$) decreased by 5% in plants receiving the high nitrate fertilizer, whereas plants receiving the low nitrate fertilizer showed no change in g$\sb{\rm s}$ and a 13% increase in c$\sb{\rm i}$. These results are consistent with the hypothesis that chilling temperatures inhibit nitrogenase activity of black alder more than either NR activity or PS.
Issue Date:1991
Rights Information:Copyright 1991 Vogel, Christoph Steven
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9136760
OCLC Identifier:(UMI)AAI9136760

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