A review of dipterocarps - Center for International Forestry Research

Root Symbiosis and Nutrition
species of Amanita, Boletus and Russula with members
of the Russulaceae being most numerous. Other
researchers have also reported species of Amanita,
Russulaceae, Boletaceae and Sclerodermataceae as
mycorrhizal associates of dipterocarps in Malaysia
(Becker 1983, Lee 1992). Species of Amanita, Russula,
Boletus and Scleroderma were reported as dominant
ectomycorrhizal fungi of dipterocarps in Indonesia (Hadi
and Santoso 1988, Ogawa, 1992a, Smits 1994). Similar
associations have also been reported from Sri Lanka (de
Alwis and Abeynayake 1980). Over a six year observation
period in Kalimantan, Indonesia, 172 fungi species from
36 genera were found associated with 23 dipterocarp
species with species of Amanita, Boletus and Russula
being the dominant fungi (Yasman 1993). In the
Philippines 32 species of ectomycorrhizal fungi from
11 families were found associated with dipterocarps,
with species of Russula and Lactarius predominating
(Zarate et al. 1993). In Thailand, Aniwat (1987) reported
species of Russula, Lactarius, Boletus, Amanita,
Pisolithus, Tricholoma and Lepiota as the most common
genera of ectomycorrhizal fungi in dry deciduous
dipterocarp forest and semi-evergreen dipterocarp
forest. Such information on the identity and diversity of
the mycorrhizal fungi would assist in the development
of a base for understanding the relationship between
mycorrhizal fungi and forest function.
It is an established fact that several different fungi
can form morphologically different mycorrhizas on the
root system of a single plant. Although some
ectomycorrhizal fungi show some host specificity at the
host genus level (Chilvers 1973), most ectomycorrhizal
fungi generally have broad host ranges. In a recent
experiment Yazid et al. (1994) showed that a strain of
Pisolithus tinctorius isolated from under eucalypts in
Brazil could form perfectly functional ectomycorrhizas
with two species of Malaysian dipterocarps, Hopea
helferi and H. odorata. Various studies with dipterocarps
have shown that several different ectomycorrhizas may
be associated with the roots of any one plant and very
often the same mycorrhiza may be associated with
different host species and even genera (Becker 1983,
Yusuf Muda 1985, Berriman 1986, Lim 1986, Julich
1988, Hadi et al. 1991, Lee 1988, 1992, Smits 1994,
Lee et al. in press).
Until the late 1980s there were only two published
reports of successful isolation of indigenous
ectomycorrhizal fungi associated with dipterocarps into
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pure culture (Bakshi 1974, de Alwis and Abeynayake
1980). However, recently successful isolations of
several indigenous dipterocarp ectomycorrhizal fungi
species were obtained in Indonesia, Malaysia, the
Philippines and Thailand, from various dipterocarp hosts
(FRIM unpublished data, Sangwanit 1993, Supriyanto et
al. 1993a, Zarate et al. 1993).
Inoculation and other Studies
In most studies of the effects of mycorrhizal inoculation
on dipterocarps reported thus far, seedlings have been
inoculated with soil inoculum, chopped dipterocarp root
inoculum or chopped fruit bodies. Such uncontrolled
inoculation studies are self-limiting and non-repeatable.
Controlled inoculation experiments with identified and
definite fungal strains or species, in particular indigenous
ones, are needed so that we can better understand
dipterocarp mycorrhizal physiology and explore their
potential for application in forestry. Spore inoculum in
the form of capsules, tablets or powder of
ectomycorrhizal fungi collected from the wild have also
been used for inoculation of dipterocarps (Fakuara and
Wilarso 1992, Ogawa 1992b, Sangwanit 1993,
Supriyanto et al. 1993b), but these remain on a small
scale and are dependent on fungi which fruit frequently
and produce spores in abundance. Some progress has also
been made in the development of controlled inoculation
techniques for dipterocarps using mycelial pure cultures
(Sangwanit 1993, Lee et al. 1995) but much fundamental
research needs to be carried out before the development
of appropriate delivery systems is explored.
The few reports of controlled dipterocarp
mycorrhizal inoculation and synthesis have been
conducted with exotic fungi, mainly Pisolithus tinctorius
(Smits 1987, Sangwanit and Sangthien 1991, 1992, Hadi
et al. 1991, Lapeyrie et al. 1993, Yazid et al. 1994), and
Cenococcum (Sangwanit and Sangthien 1991, 1992). In
Indonesia, successful mycorrhizal synthesis has been
reported between a local isolate of Scleroderma
columnare and seedlings of Shorea stenoptera, S.
palembanica, S. selanica, S. leprosula, Hopea
mengerawan and H. odorata (Santoso 1989).
Successful synthesis with Astraeus hygrometricus on
Dipterocarpus alatus in Thailand (Sangwanit and
Sangthien 1991, 1992) and unnamed species of Russula,
Scleroderma and Boletus on five dipterocarp species in
Indonesia (Hadi and Santoso 1988) has been implied on
the basis of a growth response in inoculated seedlings.