ICOM1 Abstract
session 4
Chan W.K. Department of Applied Biology & Chemical Technology, Hong Kong
Polytechnic University, Hunghom, Kowloon, Hong Kong. - The seasonal
effects on VA mycorrhization in Machilus chinensis Hemsl. and Acacia
confusa Merr.
Machilus chinensis and Acacia confusa are two very important tree
species in Hong Kong. M. chinensis (Lauraceae) is a native species of
Hong Kong and South China and is one of the most dominant species in the
natural secondary forests in Hong Kong. A. confusa (Mimosaceae) is
native of Taiwan and the Philippines and grows well in Hong Kong, it has
been widely grown as road-side plants and in plantations. Both species
are evergreen and found to be infected by VA mycorrhizal fungi. One of
the studied site is a natural succession secondary forest of M.
chinensis, the other is a plantation of A. confusa; the two sites were
in close proximity. The soil conditions of both sites are typically
sandy, nutrient poor and acidic (pH3.5-4.9). The survey have been
carried out for 12 months from June 1994 to May 1995. Four trees of the
same species were sampled at each site; soil and root samples were taken
from the top 10cm of the rhizosphere at four different directions.
Various parameters including number of VA spores in soil, infection rate
of roots, hyphal length in soil, pH and relative humidity of the
rhizosphere were monitored and studied. The average number of spores
were higher in the A. confusa site through out the 12 months period,
however both the percentage of infection in roots and the hyphal length
in soil were higher in the M. chinensis site. This could perhaps
explain the phenomenon that Machilus spp. can establish successfully
only through natural succession but not in plantations using nursery
grown seedlings.