Nanotechnology for managing plant stress is an emerging field of research that could pay dividends for Australia's cotton growers.
Climate change and the increasing intensity of extreme weather events, such as drought, are a key challenge for the industry.
Drought stress impairs plant growth by affecting physiological and metabolic processes such as photosynthesis, damaging cell membranes and reducing nutrient and water uptake, causing nutrient deficiencies and lower yields.
Drought stress is responsible for an estimated 67 per cent of yield losses in cotton lint, but research that had its origins in human cancer treatment is now showing promise in cotton plants.
Research scientist Dr Cong Vu completed his PhD in nanomedicine at the University of New South Wales where he was part of a team that discovered how to use nanoparticles to precisely deliver anti-cancer drugs only to cancerous cells.
While working in the lab, Dr Vu had the idea that the technology could also be applied to agricultural crops, such as cotton.
"It's urgent because of climate change and heatwaves challenging agriculture which it's hard for farmers to adapt to," he said.
"If we can use the nanotechnology for agriculture it could be significant for agriculture in Australia and in many other countries as well.
"We designed a nanoparticle that can help cotton deal with drought stress so the farmer can reduce water use to help them manage the water but still maintain or increase productivity."
Dr Vu said he chose to start with cotton because it preferred warmer climates and irrigation water was a significant expense for growers.
As well as aiming to alleviate drought stress and reduce water use by crops, he was keen to find a way to use nanoparticles to target the delivery of agrochemicals that would make them more effective, reduce how much was needed, and minimise environmental impacts.
Dr Vu has adapted a silica nanoparticle that releases the chemical orthosilicic acid when it dissolves in plants, helping them cope with drought stress by reducing evaporation from the leaves.
Glasshouse trials at Western Sydney University, supported by Professor Brajesh Singh, last year showed the nanoparticles could reduce water use by 5pc without compromising plant health. This year's trials will test how much further that can be taken ahead of field trials planned for 2024-25 at WSU.
Earlier this year, Dr Vu was a winner at the ABARES Science and Innovation Awards and received a grant from the Cotton Research and Development Corporation (CRDC) to continue his novel research.
Now that the concept has been proven, Dr Vu said he had two major concerns: how to make the nanoparticles cost-effective and minimising how much toxic waste was generated in the manufacturing process.
In 2021, Dr Vu founded the startup NanoSoils Bio, with the support of UNSW Professor Justin Gooding, to commercialise the use of nanoparticles as carriers for farm chemicals.
Negotiations were underway with a major agrochemical company, which he declined to name, that had shown interest in a nanoinsecticide.
Dr Vu said he was particularly interested in developing nanoparticles that could be used with systemic neonicotinoids such as thiamethoxam, which is used as a seed treatment to control thrips, wireworms and aphids.
"But thiamethoxam is very toxic to bees and we need to protect the bees at the same time as we need insecticide to protect the crop," he said.
"We can use the nanoparticle to control the insecticides loaded inside it to get into the plant and minimise the risk to the environment. This is a win-win solution. It protects the plant from insect pests, and it minimises the effects on bees and other beneficial insects."
Dr Vu said the size and shape of nanoparticles could be tweaked to control where they released their payload inside a plant. This meant they could be prepared in liquid or powder form and used as seed coatings, foliar sprays or added to fertiliser.
"I went to Narrabri last year and we talked to farmers, and they are very keen on the technology as well," he said.
"Drought stress will be the first priority because it's very urgent ... and the nanotechnology can be used for other crops so the next ones we'll be looking at are barley, wheat and rice."
Cotton Australia chairman Nigel Burnett, who operates a mixed farm with his wife Beth north-east of Emerald, Queensland, said he was keen to see the outcomes of Dr Vu's research.
"If it can reduce our water usage and reduce our reliance on pesticides and impacts on riparian areas and the environment, that's a good thing for the industry," he said.
"In terms of sustainability and greenhouse gas emissions, if we can lower insecticide and fertiliser use that is a positive for the environment, but it's also a positive for our bottom line, for the sustainability of our farming system, but also our business."
CRDC innovation broker Susan Maas said the technology offered exciting potential benefits.
"It's early days," she said.
"It needs to be proven up so that industry can have confidence it will deliver, but potentially, it opens the door for new innovations as well as better ways of delivering existing crop protection products and growth promotants."
Ms Maas said using nanoparticles to deliver growth-promoting microbes was another option for helping drought proof cotton plants.
Their benefits had been demonstrated in research laboratories, but often failed when they were applied in the field because they weren't protected against challenges such as competing bacteria and hostile soil conditions.
"Getting them into the plant and getting them where you want them in the plant in a cost effective way - that's a challenge we're trying to overcome," she said.
"Silica nanoparticles as a carrier are providing a delivery system that overcomes some of the challenges of broadscale release and also prevents losses to other pathways."
Ms Maas said Australian agriculture was under immense pressure to reduce pesticide use and respond to climate change, and adopting innovations from other fields, such as medicine, was one way of meeting those challenges.
"The really exciting thing is it's potentially got broad application," she said.
"Because it's a delivery system, if it works for one thing, the hope is that it works across a number of different challenges we're facing."
