New Zealand Journal of Botany
abstracts
Short
communication
Distribution of mycorrhizal fungus associated with the endangered
pink-lipped spider orchid (Arachnorchis
(syn. Caladenia)
behrii)
at Warren Conservation Park in
South Australia
Leah Feuerherdt
Primary Industries &
Resources SA
Rural Solutions
P.O. Box 822
Clare SA 5453, Australia
Sophie Petit*
School of Natural and Built
Environments
University of South Australia
Mawson Lakes SA 5095, Australia
Manfred Jusaitis
Plant Biodiversity Centre
Department for Environment and Heritage
Hackney Road, Hackney SA 5069, Australia
*Author for correspondence
sophie.petit@unisa.edu.au
Abstract Ex
situ seed baiting of a
population of Arachnorchis (syn.
Caladenia)
behrii at Warren Conservation
Park was conducted to determine the
distribution of this orchid’s mycorrhizal fungus (or fungi) and whether
it was limiting the distribution of the orchid. Forty-five samples of
topsoil and organic matter were collected systematically from within
and outside the orchid population. All samples were baited with A.
behrii seeds and incubated for 8
weeks to assess germination. Seeds
from 24 samples out of 45 (53%), from both within and outside the
orchid population, reached stage-two germination (seed coat cracked,
protocorms swelling), but a fungus later killed five samples. Seeds
from three samples (7%) reached stage-three germination (seed coat
shed, rhizomes developing). Clearing and staining of seeds revealed
that mycorrhizal fungus was present in all samples that had reached
stage-two or stage-three germination. Mycorrhizal fungus was
distributed independently of the orchids, and, thus, the distribution
of A. behrii,
which depends on mycorrhizal fungus, did not
appear to be limited by the distribution of mycorrhizal fungus. Further
research must focus on the inoculum potential and efficacy of the
fungus/fungi in situ
over a longer time period, as well as
other ecological aspects of the orchid’s natural history, to identify
the reason(s) for its rarity.
Keywords Arachnorchis
behrii; Caladenia
behrii; mycorrhizal fungus
distribution; orchid abundance; orchid
conservation
B04041; Received 18 October
2004; accepted 18 February 2005; Online
publication date 26 April 2005
New Zealand Journal of Botany,
2005, Vol. 43: 367–371
0028–825X/05/4302–0367 © The Royal Society of New Zealand 2005
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