Synchrotron technology sheds light on root paths

GRDC in partnership with the University of SA and the University of Qld, is supporting a unique collaboration project between scientists Casey Doolette, Helen Hou an Han Weng to better understand factors that limit root growth within soil.

The group have been given access to the Australian synchrotron, a piece of the country's most significant scientific infrastructure.

Located in Melbourne, the synchrotron allows researchers to examine the molecular and atomic details of a wide range of materials through powerful beams of light that are a million times brighter than the sun.

These electron beams travel just under the speed of light - about 299,792 kilometres a second.

The intense light they produce is filtered and adjusted to travel into an experimental workstation, where light reveals the innermost, sub-macroscopic secrets of a multitude of materials, including plants.

From a research perspective, synchrotron light offers several advantages ahead of conventional techniques in terms of accuracy, quality, robustness and the level of detail that can be seen and collected.

The process is also much faster than traditional methods.

The researchers have been using the imaging and medical beamline (IMBL) to produce high quality, 3D imagery of roots growing directly into large, undisturbed soil cores.

University of SA's Helen Hou said the high quality of the IMBL imagery had been invaluable, providing extremely high-intensity X-rays that allowed the team to examine how the roots were growing.

"This technology has provided more realistic and informative analysis," she said.

"Understanding soil factors that limit root growth is a critical aspect of improving crop yield and profitability across the Australian farming industry."

GRDC agronomy, soils, nutrition and farming systems acting senior manager Kaara Klepper said understanding root distribution was the key to improving cropping yields, especially in constrained soils, as it influenced a plant's water regulation and nutrient uptake.

"Roots have often been referred to as the 'hidden half' of cropping because they're concealed in the soil," she said.

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"That's why having access to technology like the IMBL is so important - these scientists are developing methodology which can be used to understand root dynamics.

"It allows researchers to thoroughly examine undisturbed root distribution, giving them insight into the interaction between soil, organic matter and root growth."

Dr Klepper said partnerships that supported a cohort of next generation researchers were important to continuing to advance the grains industry.

"The GRDC continues to nurture early career researchers and facilitate access to the scientific infrastructure needed to do world leading work," she said.

CASEY Doolette says studies into crop yields and fertiliser efficacy aims to ultimately will save farmers money in inputs.

"I am working on the gel-based diffusive gradients in thin-film devices (DGT) side of things, which is the passive sampler that we deploy in soil to be able to visualise where the nutrients are in the soil," she said.

"We have developed a technique to deploy quite large DGT on quite large field cores and usually DGT's are about two or three centimetres square but we have developed ones which are about 15 by 10 CM that we deploy on a soil core.

"We are refining that technique a bit more to see more nutrients, compared to what we can see at the moment, which is zinc and manganese, but would also like to see phosphorous so we are just working on the DGT to improve it to see those addition nutrients too.

"The overall idea is to overlay the information of where the nutrients are in the soil with where the roots are in the soil."

Dr Doolette says colleague Helen Hou is looking at the root architecture and the root distribution through scanning the soil cores.

"We can overlay that with the nutrient distribution," she said.

"Ultimately for the farmer, that will tell them how the root architecture relates to where the nutrients are and that will enable more efficient placement of fertiliser."