In this section:
Clover
South-East Pastures Group
Overview
The South East Pastures Group continues in its pursuit to improve pasture species for the region. At present the team’s principal research activities involve :
• developing productive subclovers for mid-season districts.
• selecting a “low-shattering” replacement for Bolta balansa clover.
• selecting new Persian clover cultivars for the export market.
• identifying salt-tolerant legume species suited to the saline environments of the Upper South East.
• Identifying the changes that have occurred as a result of the Upper South East deep drainage scheme and developing profitable pasture systems for these environments.
Details of these activities are presented below.
1. Annual Legume Development
A number of trials are currently being conducted in order to develop new annual legume cultivars with specific beneficial attributes. These activities are being undertaken under the auspices of the Australian Pastures Alliance, a joint commercial venture between SARDI and Seedmark. Three principal activities are being progressed :
1. We are seeking to select a new mid-season subclover that provides early-season growth. This work is being undertaken in response to a series of low rainfall years and the greater emphasis being placed on “early-season” dry matter productivity.
2. We are continuing our development of balansa clover – research that has already seen the release of the cultivars Paradana, Bolta and Frontier. At present we are developing a new line with improved seed retention characteristics. This line has a maturity very similar to that of Bolta and will be well adapted to the 500-600 mm rainfall zone.
3. We are developing a number of Persian clover cultivars, with the objective being to select improved types for the overseas export market. One of the important traits under consideration is improved rust tolerance. All of the commercial “majus” cultivars are susceptible to leaf and stem rust, resulting in serious losses in herbage production and seed yield. Introducing rust tolerance into existing cultivars would greatly enhance SARDI’s product range.
2. Salt Tolerance Studies
Dryland salinity in the Upper Southeast of South Australia affects approximately 250,000 ha of farming land. Currently there is a lack of well-adapted legumes for these environments. Balansa clover, the current industry standard, displays only low levels of salt tolerance. Legumes that display moderate-high levels of salt tolerance are required to allow a higher percentage of farming land to be sown to pasture legumes, thereby providing the necessary nitrogen inputs into the system. “Successful” legumes in these areas need to be early maturing, tolerant to salt at germination and as mature age plants, and possess tolerance to soil alkalinity, waterlogging, and grazing.
Through the CRC for Plant Based Management of Dryland Salinity one new annual legume species, Melilotus siculus, was identified as potentially filling this role. Melilotus siculus is an exciting new prospect for Australian agriculture.
Melilotus siculus
In 2004, a number of Melilotus species were evaluated in a series of field and glasshouse trials with the objective of identifying a low coumarin, productive pasture cultivar for the saline environments of southern and eastern Australia. Melilotus species vary widely in their characteristics and contain variable levels of coumarins – the compounds believed to be associated with the well-know smell and taint of Melilotus indicus (King Island melilot). Of the Melilotus species evaluated, Melilotus siculus was identified as having low coumarin levels and as holding the greatest potential for success. Subsequent investigation and scrutiny indicates that this species also poses a minimal risk as an environmental weed.
In 2005, 30 accessions of M. siculus were sown in the field and assessed. The characters measured included seedling establishment, seedling vigour, hypocotyl height, plant growth habit, flowering date, dry matter production and waterlogging tolerance. Coumarin levels were also determined. The best 15 accessions were subsequently selected for further evaluation through field sowings in 2006 and 2007. A seed increase program was also implemented to support the on-going field program.
However during the evaluation process it became evident that major rhizobial problems were being encountered during the regeneration year. Widespread nodulation failure was observed in all 15 experimental lines. Thus the evaluation of the plant germplasm had to be curtailed at this point, as the plants were not growing well enough to justify continuing the program. Rather, efforts were re-directed towards the selection of a persistent and effective strain of rhizobial inoculant for M. siculus. This work is now being conducted in conjunction with the SARDI rhizobial research unit based at the Waite Campus, Adelaide and Phil Nichols in Western Australia, and is financially supported by the Future Farm Industries CRC. Once existing rhizobial constraints have been overcome, efforts will be re-directed back towards the development of the plant germplasm.
Information on other saltland pastures can be found on the Saltland Genie website
3. Upper South-East Drainage Studies
This project has been developed in response to the construction of the deep drainage scheme in the Upper South East and the desire and need to capitalise on this major investment. It seeks to obtain a comprehensive understanding of the impacts of the scheme, focusing on changes in soil characteristics and the development of profitable pasture-based systems. This research will provide conclusive evidence of the success of the drainage scheme. Importantly, this work is being supported financially by an Australian Government “Caring For Our Country” grant.
Producers are currently unaware of the extent and nature of changes to the environment since the construction of the deep drain network. This project will address this deficiency by informing producers of soil changes (primarily salinity and pH) since construction and, importantly, of the best pasture-based systems for this new environment. This information is particularly relevant given the recent drought and the potential long-term effects of climate change on the region.
This project will utilise commercial pastures species that are readily available to producers. This will ensure a fast flow-on affect, increasing landowner profitability.
Key components of the project include :
• Soil survey, seasonal analysis and profiling
An initial soil survey will be conducted on numerous field sites in proximity to deep drains (old and recently constructed) to identify the nature and magnitude of changes in soil characteristics as a result of the deep drainage scheme. Survey’s will be conducted along a number of transects to identify changes and trends in soil characteristics. This information will provide the basis for the selection of pasture species field evaluation sites.
• Pasture species evaluation trials
Pasture species evaluation trials will be established at varying distances to the deep drains in low, medium and high salinity areas. Each trial will be sown with a wide array of commercial pasture plants, including perennial and annual grasses, legumes and herbs. Species selection will be based on prior research and knowledge of the region and environment. The performance of each species will be monitored over the duration of the project.
• Pasture demonstration areas
Large-scale pasture demonstration strips will be established at key locations during the second year of the project to better reflect the performance of the most productive species. These will greatly assist in promoting the outcomes of the project. Field days will be held to increase producer awareness and promote the adoption of the identified best pasture-based systems.
Andy Craig (Phone: 08 87629193)
Amanda Bonython (Phone: 08 87629194)
