Ausplow consultant and former CSIRO scientist and microbiologist Dr Margaret Roper is part of a research team involved in world-leading research into the potential of soil-borne suppression of crown rot in wheat.

Ausplow consultant and former CSIRO scientist and microbiologist Dr Margaret Roper is part of a research team involved in world-leading research into the potential of soil-borne suppression of crown rot in wheat.

WA scientists are involved in world-leading research investigating the potential of soil-borne suppression of crown rot in wheat.
And it could lead to identifying other positive attributes of soil biota associated with disease suppression of plants, such as sclerotinia in canola, and root diseases including rhizoctonia, take-all and pythium root rot in cereals.
Involved with a research team, which released a paper last year on the subject, was Ausplow consultant and former CSIRO scientist and microbiologist Dr Margaret Roper.
According to Dr Roper the soil contains a huge variety and number of soil biota, “capable of many positive functions in the soil”.
In the paper’s conclusion, it said the screening of 53 isolates from a collection of endophytic Actinobacteria revealed several promising isolates.
“Two in particular, strongly suppressed growth of the (crown rot) fungus in plate cultures, and resulted in increases in grain yield compared to diseased controls in glasshouse experiments,” Dr Roper said.
She added that further studies were needed to verify the efficacy of the treatments at the field scale and to determine the mode of action and underlying genetics of biocontrol activity.
According to Dr Roper, management strategies to control crown rot are somewhat limited.
“Fungicide seed dressings are available, but they are often inactivated over time by environmental conditions,” Dr Roper said.
“Research has shown (anti-fungal) protection is usually best in the early stages of the plant growth cycle.
“Plant breeding has produced some more resistant varieties but none of these show robust and durable disease resistance in the field.
“An additional problem for crown rot control is that the fungal pathogens that cause the disease (F. pseudograminearum and F. culmorum) survive and continue to grow in the stubble left after harvest, increasing the risk of infection in the following crop.
“This can happen regardless of the level of resistance/tolerance of the wheat variety in the living phase of the crop.”
Dr Roper said studies from various locations throughout the world have shown that micro-organisms (bacteria and fungi), that produce secondary metabolites, play a significant role in the formation of disease suppressive soils.
Such work suggests that there remains considerable unexplored potential within soil microbial populations for further novel biocontrol products.
“One group of bacteria (actinobacteria) are very common in soils, survive well in our extreme WA soil environments and produce various bioactive agents including antibiotics, enzymes, and vitamins,” Dr Roper said.
“Actinobacteria can reside within a plant where they are protected from adverse environmental conditions and other microbial competitors.
“There are also other soil microbes which can colonize plants as endophytes and these are likely to be the most successful in suppressing plant pathogens.”
The research work, which Dr Roper has been involved with for more than 30 years, is an exciting development as Ausplow promotes its hypothesis of the near-row BioFurrow™ system of crop establishment.
Dr Roper said in the past inter-row sowing had been used to decrease disease risk, but trials in South Australia by Dr VVSR Gupta (CSIRO) have shown that the expression of root diseases such as rhizoctonia was less under near-row seeding, as distinct from inter-row sowing.
Dr Roper listed the following benefits of near-row seeding relative to inter-row sowing as:
1. Larger and more diverse microbial communities.
2. More water available to a new crop (in water-repellent soils).
3. Improved crop establishment.
4. Repellency declines during the season.
5. Improved yields in some years.
6. Fewer weeds.
7. Greater disease risk, BUT less disease incidence and severity.
Dr Roper’s research has shown that plant roots, preserved by no-till, behave as pathways for water infiltration, particularly in water repellent soils, to create an environment which can include the above benefits.
She said the combination of near-row sowing with the DBS sowing system creates the BioFurrow™ system of crop establishment, and this can provide significant benefits for a developing seedling.
“Firstly, the provision of liquid nutrients directly below the seed provides a source of water vapour for seed germination,” Dr Roper said.
“The ‘precision seed bed’, created by the DBS closing tool to provide a firm and aerated base for the seed, contains fine capillaries through which water vapour (from the liquid nutrients) can rise to the seed and promote germination.
“Scientific research also has presented evidence that water vapour is the primary source of water for seed germination in unsaturated soils.”
(This arguably, could be part of an explanation for why DBS owners report quicker germinations in dry sowing compared with other tillage systems.
The main conversation over the past nearly 30 years in regard to dry sowing, is that the DBS penetrates hard pans and promotes water capillarity, from subsoil moisture, to wet up the seed bed).
Ausplow will continue to support and promote Dr Roper’s research in field trials at Quairading.

category: 
Publish Date: 
Tuesday, January 11, 2022