Agriculture around the world needs new solutions for food and water sustainability. With frequent climate extremes, increased food demand, growing populations, and global crop threats, environmental engineers are searching for solutions to manage food production for the future, starting at the lowest level.
With current practices, up to 95 percent of applied micronutrients and 99.9 percent of applied pesticides do not reach their target places and are just wasted. They accumulate in the soil or they run off into the groundwater and they cause environmental damage, degrade the soil and waste the water and the energy used in their application and production.
If they could apply something to the leaf that could travel directly to the root, it could be a game changer for delivering antibiotics, nutrients, and pesticide in nearly 100 percent efficient way. Civil and Environmental Engineering Professor Greg Lowry, post-doctoral researcher Astrid Avellan, and a team of researchers have discovered a way to apply nanoparticles to plant leaves so that they travel through the plant and all the way to the root.
"The results from our paper really have the potential to transform the way we deliver agrochemicals to plants," said Lowry.
This is the first time that anyone has studied how nanoparticles move through the leaf in a systematic way, into the plant, to the root and into the soil. The research team sprayed gold nanoparticles with a polymer coating onto the leaves of wheat plants. Plants do not need gold, but since gold does not exist anywhere in the plant, they were able to identify where it traveled easily. They used wheat plants because they are an important crop in different countries, especially in the United States and are susceptible to nutrient deficiencies.
Once the nanoparticles are sprayed onto the leaf, the move through the cuticle, which is the waxy outer layer covering the leaf. Then, it crosses the epidermis. The cuticle and epidermis are layers that protect the leaf from harm, they prevent water loss, and allow a gas exchange for the plant to breathe.
The nanoparticle then makes its way into the inner leaf tissue or mesophyll. It then moves into the vasculature of the plant, or the veins of the plant. From there it can travel all the way down the stem and into the root, or up to higher leaves.
The researchers demonstrated that once reaching the roots, nanoparticles can be exuded into the soil, adhering to the microenvironment that sticks to the roots called the rhizosphere. It is where the plant interacts with the soil, takes in nutrients, releases small acids, carbon dioxide, and proteins and where bacteria and fungi can enter the plant. The only methods that are available to treat an unhealthy rhizosphere are mixing agrochemicals in the soil or applying water with the chemicals.
In the experiment, both cases a large amount of chemicals were lost. What the researchers have demonstrated is 100 percent efficient delivery that can decrease the amount of chemicals needed, lower the cost and limit the environmental contamination.
The tiny particles could be the important key to feeding the 10 billion people that are projected to be on Earth by 20150. Farmers could also deliver antibiotics to the plant. Once the plant gets bacteria into its veins, there's little that can be done to save it. But if antibiotic nanoparticles could be delivered through the leaves to get into the veins, they could prevent or treat systemic bacterial diseases.
