Thesis
The role of temperate grasses and biostimulants in mitigating the effects of pasture dieback
Southern Cross University
Masters by Thesis, Southern Cross University
2024
DOI:
https://doi.org/10.25918/thesis.488
Metrics
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Abstract
Pasture dieback is a widespread and poorly understood condition that has severely impacted the productivity of grazing systems in Queensland, with recent reports confirming its spread into the North Coast region of New South Wales (NSW). This condition primarily affects tropical and subtropical perennial grass species, leading to significant declines in pasture health, livestock feed availability, and overall pasture resilience. The symptoms typically begin with foliage discolouration and reduced growth, progressing to eventual plant death. Despite previous studies in Queensland, limited information exists on the potential of alternative pasture species or recovery treatments in newly affected regions like northern NSW.
This thesis aimed to evaluate two potential management strategies for mitigating the effects of pasture dieback: (1) the introduction of temperate perennial grass species, and (2) the application of biostimulants. Field trials were established to assess the performance and persistence of temperate grasses—cocksfoot (cv. Lazuly) and tall fescue with and without endophytes (cvv. Quantica MaxP and Finesse-Q) in dieback-affected sites, as well as to examine the effectiveness of different biostimulant products, including humic acids, sea minerals, and a commercial growth promotant (RC3), on the recovery and productivity of dieback-affected tropical grasses.
The results demonstrated that temperate perennial grasses were highly tolerant to pasture dieback, exhibiting no visible symptoms even when tropical grasses in the same paddocks were severely affected. These species produced substantial quantities of high-quality forage during summer and autumn, with biomass yields reaching up to 9.5 t DM/ha. Crude protein content ranged from 11% to 23%, and neutral detergent fibre from 45% to 61%, indicating their suitability as a nutritious feed source. Persistence of temperate species varied across sites and seasons, with declines observed in areas dominated by regenerating tropical species or experiencing moisture stress. Fertiliser application significantly improved the growth of temperate grasses, with biomass increases of up to 111% compared to unfertilised plots.
In contrast, the biostimulant treatments had no significant effect on the recovery or productivity of tropical grasses impacted by dieback. Yield responses were negligible at both trial sites, and pasture quality indicators showed no improvement.
These findings suggest that while biostimulants may not offer a reliable solution, introducing dieback-tolerant temperate grasses represents a promising strategy to sustain pasture productivity. The success of this approach will depend on site-specific environmental conditions and management. This research contributes practical knowledge for developing adaptive strategies to address pasture dieback in subtropical grazing systems.
Details
- Title
- The role of temperate grasses and biostimulants in mitigating the effects of pasture dieback
- Creators
- Eric Mark
- Contributors
- Terry J Rose (Supervisor) - Southern Cross UniversityAbe Gibson (Supervisor) - Southern Cross UniversitySuzanne P. Boschma (Supervisor) - New South Wales Department of Primary Industries
- Awarding Institution
- Southern Cross University; Masters by Thesis
- Theses
- Masters by Thesis, Southern Cross University
- Publisher
- Southern Cross University
- Number of pages
- xi, 98
- Identifiers
- 991013288955402368
- Copyright
- © Eric N Mark 2024
- Academic Unit
- Faculty of Science and Engineering; Southern Cross Plant Science
- Resource Type
- Thesis