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Copyright
© 2001, CAB International |
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BA: |
19950704834
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ET: |
Fire-followers
in chaparral: nitrogenous compounds trigger seed germination. |
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AU: |
Thanos,
C. A.; Rundel, P. W. |
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AA: |
Labaratory
of Biomedical and Environmental Sciences and Department of Biology,
University of California Los Angeles, Los Angeles, CA 90024, USA.
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SO: |
Journal
of Ecology (Oxford), 1995, Vol.83, No.2, pp.207-216, 49 ref. |
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AB: |
Application
of nitrates (optimal concentration c .10 mM) in laboratory
experiments promoted seed germination in the fire annuals Emmenanthe
penduliflora and Phacelia grandiflora and to a lesser extent in
the fire-adapted shrub Salvia mellifera . Ammonium ions, although
virtually inactive in E. penduliflora , were as effective as
nitrate in both P. grandiflora and S. mellifera . Diurnal
illuminations and a chilling pretreatment, though of little effect by
themselves, significantly enhanced the nitrate-mediated promotion of
germination in the two fire annuals. Nitrate was the principal factor
inducing germination in E. penduliflora (nitrate or ammonium in
P. grandiflora ) whereas in S. mellifera light was the
principal agent. It was also shown in E. penduliflora that nitrates
are not required during chilling, i.e. seed sensitisation by chilling and
nitrate-mediated induction of germination are entirely different
mechanisms. In the three species tested, the effect on seed germination
caused by nitrogenous substances was nearly identical to that produced by
an extract of charred wood, although chemical analysis of the extract
showed that the combined concentrations of nitrates, ammonium ions and
free amino acids could not account for the promotive action of charate.
However, the nitrate and ammonium concentrations required to induce
germination were very close to the increased values encountered after a
fire in the otherwise nitrogen-poor chaparral soil. Therefore, in addition
to the possible effect of charred wood, the postfire germination flush
observed in chaparral may be induced by the increased levels of available
nitrogen as well. |
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DE: |
ammonium;
nitrate; nitrogenous compounds; seed germination; chaparral; germination;
mineral nutrition; light |
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ID: |
Phacelia
grandiflora; Emmenanthe penduliflora; Salvia mellifera |
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IS: |
0022-0477
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CC: |
PP720; |
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RY: |
14798-03-9;
14797-55-8 |
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LA: |
English
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DT: |
Journal
article |
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SC: |
Seed
Abstracts |