Green galenia is a South African woody prostrate perennial that was first
recorded in Australia in the early 1900s and has since become a serious
threat to indigenous temperate grasslands and surrounding agricultural
areas. Laboratory and field based experiments were conducted to examine the
effect of environmental factors on the germination and viability of green
galenia seed. It was shown that green galenia was able to germinate over a
broad range of temperatures, but short bursts (5 min) of high temperatures
(80 C to 120 C replicating possible exposures to a fire) reduced seed
germination. Seed germination was positively favored by light, declined
rapidly in darkness, and decreased by > 80% at a depth of only 0.5 cm in
soil. Water stress greatly reduced seed germination (45% germination at
osmotic potentials below −0.2 MPa). Germination was completely inhibited at
water potentials of −0.4 to −1.0 MPa. This species is moderately tolerant to
salinity, with over 50% of seeds germinating at low levels of salinity (60
mM NaCl), and moderate germination (49%) occurring at 120 mM NaCl, it can
germinate well in both alkaline (pH 10–83%) and acidic (pH 4–80%)
conditions. The results of this study have contributed to our understanding
of the germination and emergence of green galenia, and this will assist in
developing tools and strategies for the long term management of this noxious
weed in Victoria and other parts of Australia.