A new SAGIT-funded project will delve into the impact different wheat varieties have on microbial gene regulators of N cycling and free-living nitrogen-fixing bacteria in soils and the influence that has on the mineralisation of nitrogen and its uptake by the crop.
CSIRO research scientist Dr Gupta Vadakattu will oversee glasshouse and field studies at Roseworthy and Karoonda during the project which will use genetic analysis to evaluate the presence of microbial groups associated with plant roots and involved in nitrogen cycling in soils.
“The project is looking at the type of microbes that are present near the roots because plant microbe associations help the plant acquire nutrients, withstand disease and withstand other abiotic stresses,” he said.
“Wheat varieties differ in their ability to grow roots and also in their ability to take up the nutrients, in this case nitrogen.
“There are certain wheat varieties that are agronomically adapted to South Australia that have been shown to have a different nitrogen use efficiency.”
Dr Vadakattu said growers would benefit from this project by learning how microbes vary in different varieties of wheat and how certain microbes help wheat plants with their nitrogen uptake.
“That will help farmers to decide which varieties are better suited for nitrogen use efficiency in their environment,” he said.
“The other way it helps farmers indirectly is through plant breeders who are developing the varieties.
“This will help them to understand which varieties have better plant microbe associations and interactions.
“That will help them develop varieties that are better utilising these associations for getting their nitrogen.”
In the first stage of the project, field trials were set up by SARDI at Roseworthy where 15 varieties were sown.
Roots and soil in the rhizosphere – the zone of soil surrounding plant roots – were sampled and processed in CSIRO laboratories at the Waite campus to measure the type of microbes present near the roots and rhizosphere.
Preliminary results have found there are significant varietal-based variations in general microbial composition and abundances of microbial groups involved in nitrogen cycling processes in different wheat varieties.
It was also found microbial biomass and activity differed between varieties and therefore can affect nitrogen availability.
These findings suggest that the selection of varieties which are more readily associated with more effective groups of nitrogen cycling microbes could be a sustainable option to increase nitrogen use efficiency in cereal crops.