New Delhi: Crops grown during drought may have lower nutritional value due to the iron absorption rates of the plants, states a new study published in the Cell journal. An experiment conducted on rice, tomato and canola crops showed that during drought, the water-stressed plants send out signals that reduce their iron uptake, and other immune defences, leading to lesser nutrition in the plant as a whole.
The study, ‘Protecting plant nutrition from the effects of climate change’, has been authored by researchers from Canada and the US. It was published on 28 May.
“Drought doesn’t just stress plants. It fundamentally rewires how they manage nutrients and interact with the microbial world around them,” said Connor Fitzpatrick, professor at the University of Calgary and lead author on the study, in a press release.
The researchers wanted to explore how plants changed microbial interactions during droughts. According to the paper, the scientists wanted to understand whether plants sent out ‘distress signals’ during drought to attract certain bacteria in their roots.
The initial idea for the paper came from observing increased ‘Streptomyces’ bacteria production near the roots of plants during droughts. The scientists wanted to understand what this bacteria does, and whether it helps the plant survive droughts. They thought that because of the lack of water during droughts, plants might send a ‘cry for help’ hormonal signal through their roots, and attract beneficial bacteria to help them overcome the water stress.
However, as they began observing plant activity by simulating drought-like conditions, they realised that in reality, plants do much more than increase streptomyces activity in droughts. Plants actually rework their nutrient absorption and reduce iron uptake in case of a drought, as well as reduce overall immune defences by allowing more bacteria to grow around their roots.
Moreover, the streptomyces bacteria are not entirely beneficial; essentially, the study found that there are more than 600 types of streptomyces bacteria, of which some are good, and some are bad. During droughts, when plants lose their immune systems, these bacteria gather around the roots and are able to ‘colonise’ the plant easily. This does not necessarily help the plant overcome a drought, and in some cases, it even leads to plant death.
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‘Droughts also reduce the nutritional quality’
The scientists first conducted the study on the Arabidopsis thaliana plant, which is a ‘model’ plant that is not edible and often used in experimental setups. Then, the experiment moved on to other plants, including rice, canola or rapeseed, and even tomatoes, and they found similar results throughout.
The study reveals challenges for global food security, especially since iron deficiency is one of the largest health issues in the world — over two billion people suffer from it. Large sections of populations across the world depend on food such as legumes and cereals for iron consumption, and the new study shows how drought might affect that.
“It means drought may not only reduce crop yield, but also reduce the nutritional quality of crops by limiting iron in edible tissues,” said Fitzpatrick in the press release.
According to a study by the Organization for Economic Cooperation and Development (OECD) published in 2025, climate change is making the world more vulnerable to droughts and increasing the surface area where droughts might occur.
While the connection between droughts and ensuing food insecurity was well-established in terms of lower crop yields, the new study sheds light on a more complex, nutritional impact of drought.
(Edited by Saptak Datta)