Technical highlights - Department of Primary Industries ...

4. Weed seed dynamics
Project dates
August 2007 – June 2020
Project leader
Dr Faiz Bebawi
Tropical Weeds Research Centre
Tel: (07) 4761 5716
Email: faiz.bebawi@deedi.qld.gov.au
Other staff in 2010–11
Chris Crowley
Objectives
• Determine the seed longevity of
several priority weeds found in
central and northern Queensland for
which data is currently limited.
• Develop germination and viability
testing techniques for the
abovementioned weeds if none
are available.
• Disseminate the results and
implications of the research through
scientific publications, media
stories and presentations to relevant
stakeholder groups.
Rationale
Currently there are many declared weeds
for which we know very little about
seed ecology, particularly germination
requirements and longevity. Such
information is important in control
programs as it allows land managers
to plan activities based on the length
of time that will be required to deplete
seed banks in the absence of any
replenishment. This project will provide
this information for priority species in
central and northern Queensland.
Methods
A long-term experiment designed to
determine the seed longevity of up to
12 priority weed species is conducted on
the grounds of TWRC. The experiment
uses a 2 × 2 × 4 × 12 factorial design,
with factor A comprising two soil types
(alluvial and clay), factor B two levels of
grass cover (nil or full cover), factor C
four burial depths (0, 2.5, 10 and 20 cm)
and factor D ten sampling periods
(0, 3 and 6 months; 1, 2, 4, 6, 8, 10 and
13 years). Each treatment is replicated
four times.
Species buried so far include nine Class 2
or Class 3 declared weeds—calotrope
(Calotropis procera), yellow-flowering
and peach-flowering Captain Cook
tree (Cascabela thevetia), chinee apple
(Ziziphus mauritiana), gamba grass
(Andropogon gayanus), orange-flowering
and pink-flowering lantana (Lantana
camara), mesquite (Prosopis pallida),
parthenium (Parthenium hysterophorus),
prickly acacia (Acacia nilotica ssp.
indica) and yellow bells (Tecoma stans),
along with two other species—leucaena
(Leucaena leucocephala ssp. glabrata)
and neem (Azadirachta indica).
Progress in 2010–11
Preliminary results suggest that chinee
apple, Captain Cook tree, calotrope,
neem and yellow bells have short-lived
seed banks, with no viable seed recorded
after 24 months burial. To confirm this
finding, we buried a fresh batch of seeds
of chinee apple and the peach-flowering
variety of Captain Cook tree in October
2010 to expose them to another set of
environmental conditions. Fresh viable
seed of calotrope are currently sourced
for a repeat burial.
Mesquite has also demonstrated a
rapid loss of viable seed from the seed
bank following burial (< 1% viability
after 24 months burial). In contrast,
prickly acacia, leucaena, lantana and
parthenium are showing a greater level
of persistence.
Gamba grass from the Cape York region
was added to the trial in June 2010.
Funding in 2010–11
• Land Protection Fund ($47 000)
• Queensland Government
Collaborators
• Bob J. Mayer, Senior Biometrician
(DEEDI, Oonoonba)
• Carole Wright, Biometrician (DEEDI,
Oonoonba)
More information
For further information on this
research project, visit the invasive
plant and animal science pages on the
Biosecurity Queensland website at
www.biosecurity.qld.gov.au
Part 1 Integrated weed management 11