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Salty soil is no problem for these tomatoes, thanks to some microbial helpers

There’s no better way to eat a fresh tomato than by adding a little salt. But when growing these sumptuous fruits (or vegetables, depending on your perspective), salt in the soil or salty irrigation water has been a big no-no. Until now.

Plant scientists in the Middle East have discovered that adding a desert root fungus, Piriformospora indica—first isolated in India—to the soil protects the tomato from salt’s damaging effects. They planted tomatoes in a greenhouse similar to how a commercial grower might, half in soil with fungi in it. For 4 months, they watered about half the tomatoes with and without fungus in the soil with water about one-third as salty as seawater. The tomato’s leaves from infected plants made more of an enzyme that removes harmful sodium from cells. What’s more, the plant was better able to maintain proper levels of potassium, which is necessary for growth, the team reports this month in Scientia Horticulturae.

In plants irrigated with salty water, fungal infection of the roots boosted the yield of tomatoes 65% compared with uninfected plants. Even infected tomatoes irrigated with nonsalty water did better, with a 22% increase in yield. Others had shown this fungus improved the growth of barley and rice grown in salty conditions. And another fungus had proved beneficial in low salt conditions.

These boosts are important, the plant scientists say, because by 2050, half the cultivated soil in the world will be salty. And the addition of fungi to soil may be a low-cost way of coping with that change.