The use of nanoparticles may boost nutrient content and growth of tomato plants, and in turn soften the strain on natural resources as human populations continue to rise. In a recent study, researchers from Washington University in St. Louis apply their work on efficient solar cells to make this possible 

"When a plant grows, it signals the soil that it needs nutrients," Pratim Biswas, one of the researchers, said in a news release. "The nutrient it needs is not in a form that the plant can take right away, so it secretes enzymes, which react with the soil and trigger bacterial microbes to turn the nutrients into a form that the plant can use. We're trying to aid this pathway by adding nanoparticles."

For their study, researchers explored the use of zinc oxide and titanium dioxide nanoparticles, which they found could increase a tomato plant's ability to absorb light and minerals. In the long run this would give the fruit a higher antioxidant content, researchers noted in their study. 

This study may help researchers better prepare for the future. That is, the world population is expected to reach nine billion by 2050. This population increase puts a higher demand on food resources, so researchers need a way to meet these needs without draining natural resources, such as water and energy. This initiative is known as the food-water-energy nexus.

"In 100 years, there will be more cities and less farmland, but we will need more food," Ramesh Raliya, a postdoctoral researcher and one of the study's co-authors, explained. "At the same time, water will be limited because of climate change. We need an efficient methodology and a controlled environment in which plants can grow."

So why did researchers turn to zinc and titanium? Zinc is common ingredient of fertilizers since it is an essential nutrient for plants and helps other enzymes function properly. On the other hand, titanium is not an essential nutrient for plants, but as researchers were creating solar cells they discovered they could boost light absorption by increasing chlorophyll content in the leaves and promote photosynthesis. In order to give tomato plants a boost, researchers deposited the nanoparticles on the leaves of plants using a fine spray. 

"We found that our aerosol technique resulted in much greater uptake of nutrients by the plant in comparison to application of the nanoparticles to soil," Raliya said. "A plant can only uptake about 20 percent of the nutrients applied through soil, with the remainder either forming stable complexes with soil constituents or being washed away with water, causing runoff. In both of the latter cases, the nutrients are unavailable to plants."

Instead, the aerosol techniques yielded 82 percent (by weight) more fruit than untreated plants. The treated plants also contained higher levels of an antioxidant known as lycopene, which is linked to reducing the risk of cancer, heart disease and age-related eye disorders. 

"These tomatoes will help address malnutrition," Raliya added, "because they allow people to get more nutrients from tomatoes than those conventionally grown." Their findings were recently published in the journal Metallomics. 

Further research is required to determine the best concentration of nanoparticles to use for maximum benefit. 

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