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Published on November 17, 2023
Harvard Study Challenges Prevailing Beliefs, Identifying Soil Dryness as Crucial to Plant Drought-Defense, Not Air AriditySource: Unsplash/ Mike Erskine

A study published in Nature Water reveals that the prevalent driver of plants' defense against drought is not the aridity of the air but dry soil. The research, led by assistant professor Kaighin McColl from Harvard's Department of Earth and Planetary Sciences and the John A. Paulson School of Engineering and Applied Sciences, challenges previous beliefs and presents potential avenues to ensure continued plant survival as reported by the Harvard Gazette.

The accepted narrative thus far held that plants in the presence of dry air would close their stomata, tiny leaf openings aiding in water preservation. Yet, through examining data from Utah and Nevada salt flats, McColl and colleagues spotted a pattern suggesting a plant's reaction to environmental stress strongly correlates with soil aridity. In light of these findings, past studies may have overemphasized the role of humidity; instead, McColl's team suggests that plants might conserve more water when facing dehydrating soil.

Such a discovery carries significant weight for those aiming to comprehend the effects of global warming on plant species' survival and evolution. "The problem with this argument is that correlation does not imply causation; when plants close their stomata, that could actually be causing the air to get drier, rather than the other way around," explained McColl on the news report.

A postdoctoral researcher at Harvard, Lucas Vargas Zeppetello, the lead author of the study, underlined the potential impact of this research on future water conservation efforts. Zeppetello stated in the same news that "our findings put emphasis on projections for water in the future. People talk about consensus on climate change, but that really has to do with global temperatures. There's much less of a consensus on what regional changes to the water cycle are going to look like."

While it is widely accepted that global warming equals ascending temperatures, there is less consensus about the changes' impacts on vital elements such as soil moisture. Armed with this newly found correlation between soil aridity and plant's drought-defense mechanisms, experts are now more equipped to devise comprehensive strategies for preserving our flora in a progressively hotter world.

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