Scleroderma, a genus of ectomycorrhizal (ECM) fungi, is often associated with
trees in disturbed habitats and is therefore considered to be suitable for use in
plantation forestry. This study investigated aspects of Scleroderma and its
mycorrhizas with the view to its future use in plantation forestry in south China.
Spores were chosen as inoculum as they are preferred by nursery managers in south
China, due to the lack of on-site fermentation and storage facilities.
To determine the need for inoculation, Eucalyptus plantations in south China
were sampled for sporocarps and mycorrhizas over two years. This study revealed a
low diversity of ECM fungi consisting of 15 taxa fruiting beneath Eucalyptus
plantations. The most common genera were Scleroderma and Pisolithus, but they
were infrequent and the extent of root colonization was poor. Bioassay trials with E.
urophylla as a bait host, using soils collected from 8 eucalypt plantations, confirmed
low levels of inoculum in field soil. It was concluded that introduction of suitable
ECM symbionts into eucalypt nurseries in south China is desirable in the future.
As the Scleroderma genus has not been well studied in Australasia or SE Asia,
over 140 collections gathered mainly from eucalypt plantations in south China and
south-western Australia were described using sporocarp and spore morphology.
Twelve Scleroderma taxa were recognized from collections made from under
eucalypt plantations in south-western Australia and 6 of these were collected from
under eucalypt plantations in south China. In conjunction with classical taxonomy,
30 collections, including those used in inoculation trials, were further characterized
by phylogenetic analyses of ITS or LSU rDNA sequences. These studies supported classical delineation of some Scleroderma species but not all. Although a limited
number of collections were amplified, phylogenetic results showed that most
collections in this study were distinct from the European and Malaysian taxa
extracted from GenBank (89% bootstrap support for both LSU and ITS regions).
In order to optimise spore germination and root colonization, two glasshouse
trials were established to examine suitable spore density and spore storage conditions
on E. globulus and E. urophylla. A spore density of 105 spores seedling-1 was
identified as a suitable dose for promoting root colonization. Spores stored for 5
years at low temperate (4 0C) were almost as effective as freshly collected spores in
forming mycorrhizas.
As the compatibility of Scleroderma fungi with plantation trees is unknown, a
glasshouse experiment examined the ability of 15 collections of Scleroderma to form
mycorrhizas with seedlings of six plantation trees (Acacia mangium, A. mearnsii, E.
globulus, E. urophylla, Pinus elliottii and P. radiata) in a nursery potting mix. Most
collections were able to aggressively colonize eucalypts and pines, while roots of
acacias were poorly colonized. As the Australian collections were more effective in
colonizing short roots on eucalypts than the Chinese collections, it was concluded
Scleroderma should be sourced from outside China for inoculating eucalypts in
Chinese nurseries.
To optimize nursery practices to meet the demand for high quality seedlings and
clonal lines of E. urophylla and hybrids, for outplanting in south China, effects of
rooting medium and inoculation with 6 Scleroderma collections on the growth of E.
urophylla were examined in a nursery in south China. Four types of soil taken from
eucalypt plantations in south China were compared to a potting mix composed of
vermiculite, peat and sand. The inoculant Scleroderma fungi were able to out-compete indigenous mycorrhizal fungi in the rooting media. However, the
potting mix was superior to soils both for plant growth and ECM development under
nursery conditions.
This research should facilitate the use of Scleroderma spores in eucalypt
nurseries in south China. Spore orchards could be set up in China using Australian
Scleroderma spp. from under eucalypts. Spores could be stored dry at 4 0C until they
are required for inoculation in potting mixes in containerized nurseries. However,
before commercial application, further work on persistence of Scleroderma in the
nursery and field, and responses of trees in the field to inoculation, needs to be
undertaken.
| Identifer | oai:union.ndltd.org:ADTP/221732 |
| Date | January 2006 |
| Creators | Yinglongchen@hotmail.com, Yinglong Chen |
| Publisher | Murdoch University |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | http://www.murdoch.edu.au/goto/CopyrightNotice, Copyright Yinglong Chen |
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