Tomatoes are some of the most widely-produced and consumed crops worldwide. They’re also vulnerable to increasing soil salinity. But now researchers say they may have a solution—and it comes in the form of a refreshing spritz for developing tomato plants.
Using their new spray, they’ve dramatically increased plant weight, photosynthetic capabilities, and crop resilience, compared to untreated tomatoes that have been exposed to the same level of salt stress.
Salinity affects 3.2 million square miles of global cropland, an area about the size of Australia. Finding solutions is a priority for future farming—especially for tomatoes, which have been the subject of many salt-fighting studies. Tomatoes are “known to be fairly salt-sensitive,” said Hamidreza Sharifan, an assistant professor of environmental chemistry at Florida Atlantic University, and the study’s lead author. “If it works well in tomatoes, that’s a strong signal it could be adapted to other salt-sensitive crops.”
Sharifan and team tested their spray in a series of greenhouse experiments on two main batches of tomato plants, each exposed to medium and high salt stress in the soil. They sprayed one group, while the other went untreated. Their concoction combines two ingredients: manganese oxide nanoparticles and chitosan, an ingredient found in crustacean shells of which there is also an abundant supply from seafood waste streams.
In the untreated tomatoes, the highly saline soils reduced their biomass and the quantity of photosynthesizing pigments like chlorophyll and carotenoids. The plants also showed more signs of oxidative stress, which ultimately leads to cell damage.
The spritzed tomatoes, on the other hand, fared strikingly well: their roots doubled in weight, increasing by 55% compared to the unsprayed controls. Photosynthesizing pigments also increased in these plants by between 25 and 91%. Signs of cellular damage declined, and the responsiveness of key antioxidants in plant tissues increased by between 100 and 300% compared to the controls, suggesting that these tomatoes were overall much more resilient plants.
The benefits come down to the spray’s carefully-selected ingredients, Sharifan explained to Anthropocene. “The manganese nanoparticles help activate the plant’s own antioxidant enzymes, which neutralize oxidative damage. Chitosan acts more like a protective coating, it helps the plant hold onto water, stabilizes cell membranes, and supports the plant’s internal salt-water balance,” he said. “Together, they work synergistically better than either one alone.”
Spraying the leaves helps the plants absorb the beneficial tonic quickly, instead of a root treatment which would first have to bypass the large quantity of salt in the surrounding soil, Sharifan added.
The results are striking, but the researcher cautioned that so far they’ve only been demonstrated under relatively controlled, greenhouse conditions. The next step will be to test their spray out in the field to find out if it can sustain tomatoes against salt in other growing conditions.
“This isn’t about fighting the salt directly, it’s about giving the plant the tools to protect itself. That’s a shift in philosophy from a lot of traditional approaches, and it’s why the treatment works at such a low dose,” Sharifan said.
That might also make it more cost-effective for struggling farmers, he said. “It points to a practical, affordable tool that could help farmers keep growing food on land that’s becoming too salty to farm, which is a fast-growing problem worldwide.”
Sharifan et. al. “Synergistic alleviation of salinity stress in tomato: unraveling the physiological, biochemical, and antioxidant mechanisms modulated by manganese nanoparticles and chitosan.” International Journal of Phytoremediation. 2026.
Image: Based on Foodie-girl/Freerange Stock
