LONG TERM, SUSTAINABLE MANAGEMENT OF PARTHENIUM WEED (PARTHENIUM HYSTEROPHORUS L.) USING SUPPRESSIVE PASTURE PLANTS

Naeem Khan (2011). LONG TERM, SUSTAINABLE MANAGEMENT OF PARTHENIUM WEED (PARTHENIUM HYSTEROPHORUS L.) USING SUPPRESSIVE PASTURE PLANTS PhD Thesis, School of Agriculture and Food Sciences, The University of Queensland.

       
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Author Naeem Khan
Thesis Title LONG TERM, SUSTAINABLE MANAGEMENT OF PARTHENIUM WEED (PARTHENIUM HYSTEROPHORUS L.) USING SUPPRESSIVE PASTURE PLANTS
School, Centre or Institute School of Agriculture and Food Sciences
Institution The University of Queensland
Publication date 2011
Thesis type PhD Thesis
Supervisor Professor Steve Adkins
Dr. Doug George
Total pages 211
Total colour pages 11
Total black and white pages 200
Subjects 07 Agricultural and Veterinary Sciences
Abstract/Summary Parthenium weed (Parthenium hysterophorus L.) is a broad leaf herbaceous invasive Asteraceae weed of tropical and sub-tropical regions of the world. This weed is imposing severe losses in pasture and crop production systems, and affects livestock and reduces plant biodiversity. The weed also puts human and animal health at risk as it causes various diseases such as allergies, hay fever, rhinitis and other respiratory complications in both people and livestock. To address one of the major issues due to this weed in southern Queensland, that of ‘pasture production losses’ it was thought necessary to develop a new sustainable management approach using suppressive plants. Such an approach would provide quality fodder, reduce the growth of parthenium weed and hopefully reduce the presently existing great seed bank in the soil. Glasshouse trials were undertaken to investigate the suppressive ability of 20 test species upon parthenium weed growth. Five species from this present glasshouse study, five from earlier glasshouse studies and one species on the basis of its suspected high biomass production and suppressive ability were selected and then retested under field conditions in Australia at two locations. In addition, three species, selected from the field trials undertaken in central and southern Queensland and two more species selected on the basis of their performance in Pakistan and in other countries were tested in Pakistan at two further locations. Six out of the seven tested species at one location in Australia, were then also tested in a simulated grazing trial. Lastly, the suppressive ability of a selection of suppressive species was studied under an elevated CO2 concentration (550 ppmv) in a controlled growth facility. All of these studies were designed to help develop an improved management approach for parthenium weed that could help minimize the pasture losses and to reduce the weeds spread in the present, as well as under future climates. Out of the 20 native and introduced test species, 10 were shown to be suppressive to the growth of parthenium weed under a glasshouse conditions. Test species, such as purple pigeon grass, guinea grass, and buffel grass were all ranked as strongly suppressive and produced suppressive index (SI) values of > 1.5. Other test species, such as bull Mitchell grass, Indian bluegrass, Kangaroo grass, hoop Mitchell grass, pitted bluegrass and lablab gave moderate SI values of ≥ 1.0. Silky brown top, red leg grass, centurion, curly Mitchell grass, cotton panic grass, forest bluegrass, weeping grass, desert bluegrass, Wallaby grass and black spear grass were all less suppressive than parthenium weed and gave low SI values of < 1.0. The suppressive species were also those that gave greater and rapid height attainment, had rapid growth and a greater tillering or branching capacity, and to have a large root mass. Eleven test species selected from the glasshouse screen, showed differing degrees of suppression upon the growth of parthenium weed under field conditions and at two locations in central and southern Queensland. Purple pigeon grass, buffel grass, Rhodes grass, creeping bluegrass and butterfly pea (all introduced species) and bull Mitchell grass, Kangaroo grass and Queensland bluegrass (all native species) were all shown to be suppressive and significantly reducing the shoot biomass of parthenium weed by > 50 %. It was interesting to note that all of these suppressive species also produced greater shoot biomass for fodder purposes. Under field conditions in Pakistan, Rhodes grass, Rhodesia sorghum and rice bean (all introduced) while buffel grass (native to Pakistan), all showed significant suppressive ability upon the growth of parthenium weed. In addition, some of these selected species also demonstrated a similar suppressive ability against parthenium weed growth in two locations of Pakistan. The same suppressive species were also those that produced greater shoot biomass for fodder purposes. Following on from the field studies, six test species were then studied for their suppressive ability over the growth of parthenium weed under four simulated grazing pressures: no (0 %), low (25 %), moderate (50 %) or heavy (75 %) grazing pressures at Injune southern Queensland. Parthenium weed growth was suppressed by > 50 % under the low and moderate simulated grazing pressures by purple pigeon grass and buffel grass. These two species were also shown to produce high amounts of fodder under these two grazing pressures. Kangaroo grass, bull Mitchell grass and butterfly pea all suppressed parthenium weed growth by > 50 % under the low simulated grazing pressure. In addition, Kangaroo grass and butterfly pea have also produced high amounts of palatable fodder under this simulated grazing pressure, while bull Mitchell grass yielded comparatively less fodder. Butterfly pea and bull Mitchell grass were less suppressive of the growth of the weed and produced comparatively less fodder under all simulated grazing pressures. The best species for suppression the growth of parthenium weed and for the production of fodder was purple pigeon grass. Its strong suppressive and highly productive performance was probably due to its rapid shoot biomass production and rapid and greater attainment of height. The SI values of the test species operating a C4 photosynthetic mechanism (purple pigeon grass and bull Mitchell grass) were reduced when these plants were grown under an elevated CO2 condition (550 ppmv) and in competition with parthenium weed. Additionally, the growth of parthenium weed was found to increase under these conditions, both when grown alone as well as when grown with the C4 grass species, while that of the C4 species remained unchanged when grown alone. The SI values of the test species operating a C3 photosynthetic mechanism (e.g. butterfly pea) greatly increased under an elevated CO2 condition (550 ppmv) and in competition with parthenium weed. The growth of both plant species (i.e. butterfly pea and parthenium weed) was found to increase under these conditions; however the growth of butterfly pea, being a C3 broadleaf legume, was increased more than that of parthenium weed and hence promoted its suppressive ability over parthenium weed by producing higher total biomass. The significance of these findings is that parthenium weed could be managed sustainably by using a suppressive plants approach in the infested pastural lands of central and southern Queensland and could be useful in other locations within Australia. In addition, these findings could also useful to be considered as a sustainable management approach of parthenium weed in other countries such as Pakistan.
Keyword climate change
glasshouse conditions
field conditions
parthenium weed
Queensland
sustainable management
suppressive beneficial plants
simulated grazing
Additional Notes colour pages= 5-6,53,77-78,90,92,94,96,129,136 A3 pages= 40,47,54-55,56-60,66-68,89,91,93,95,109,114,116,117,132-135 Landscape pages= 45,63,82,98

 
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Created: Mon, 19 Sep 2011, 17:59:31 EST by Mr Naeem Khan on behalf of Library - Information Access Service