Exploring beneficial GxExM interactions for crop yield and nutrient availability: effects on soil health

Summary

Plant traits that affect below-ground processes are seldom considered within breeding programs.. Decades of research show that plants do affect soils, and that there is great variation in how plant phenotypes respond to the soil environment and management. However, our lack of knowledge in this field is limiting the potential genetic gains from wheat breeding. Enhanced soil attributes include increased ability to supply nutrients, increased ability to store carbon and increased ability to store water. The effects of plants on physical, chemical and biological properties of soil are most apparent in the root zone (i.e. in the rhizosphere), where release of plant exudates and plant-fungal-bacterial interactions can result in major differences in local environments and microbial communities. These effects include changes to the species composition of microbial populations that enhance the availability of key nutrients for plants, changes in soil carbon content, and flow-on changes in structure that may influence storage of water. The research program will quantify variation in soil processes and properties in the root zone of a range of wheat genotypes (G), relating these to changes in the Environment (E - fertilizer, temperature, water supply) and Management (M – tillage, crop rotation strategy). Standard agronomic treatments (fertilizer, legumes) used on the Liverpool Plain will be employed as benchmarks, and we will use the resulting GxExM analysis to identify traits that through commercial breeding programmes are most likely to result in net economic benefits to farmers (yield, grain quality, soil carbon, water use efficiency), and also contribute to environmental management goals.

Supervisor(s)

Dr Feike Dijkstra, Associate Professor Michael Kertesz

Research Location

Agriculture and Environment

Program Type

PHD

Synopsis

The Ph.D. project will focus on the effects of plant genotype variation on nutrient transformations in the root zone, especially changes in the availability of carbon, nitrogen and phosphorus, and the cycling of carbon in the root zone. Stable isotopes will be used to examine how C, N and P cycling changes with variation in environment and management, and how this is affected by root architecture and the structure of the root-associated soil. The GxExM effects on processes such as rhizosphere priming and availability of soil N and P will be studied, in order to evaluate how they affect utilization or sequestration of carbon and mineral nutrients in the soil. The project will focus in particular on determining the resilience of below-ground plant traits relating to microbial populations to stresses relating to drought and temperature. Microcosm  experiments that apply defined and controlled drought and temperature stress conditions will be complemented by full scale field trials, to ensure that laboratory data is directly relevant to agronomic practice. The research will integrate contributions of microbial, chemical/biochemical and physical processes, which will be quantified over time using both direct and indirect (e.g. modelling) approaches. The key aim is to identify beneficial genetic (G) traits for commercial breeding programmes and to identify those management (M) regimes likely to best deliver those genetic gains while at the same time improving yield and environmental outcomes.

Additional Information

The program is supported by the Grains Research & Development Corporation (GRDC), which will provide a Ph.D. scholarship and consumables funding for the research project. Laboratory and greenhouse experiments will be carried out at the ATP campus and at the CCWF in Camden, while field trials will be based at the Narrabri campus.

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Keywords

Soil health, wheat, legumes, plant breeding, fertilizer, microbial ecology, isotopes, nutrient cycling, Soil carbon, water use efficiency, soil

Opportunity ID

The opportunity ID for this research opportunity is: 1774

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