This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Sunflowers are unable to fully recover from drought, new research has found, contradicting previous findings on the plant's ability to reverse drought-induced failure of water-transporting tissues and revealing new insights into how drought affects plants. As a plant dries, gas bubble blockages, or embolisms, can form in the plant's water-transporting tissues.
Previous studies concluded that sunflowers could reverse these blockages through a process called refilling but offered very little direct evidence. A study by Colorado State University, the University of Colorado Boulder and the U.S. Department of Agriculture showed that although sunflowers appear to recover remarkably well from drought, the embolisms that accumulate in stems and leaves do not reverse after watering.
Results are published in the Journal of Experimental Botany. "The strain of extracting water from dry soil can introduce air into the tissue responsible for moving water from the roots to leaves," said co-author Troy Ocheltree, a CSU associate professor in the Warner College of Natural Resources. "Once this happens, the air blockage prevents the leaves from getting the water they need to grow and photosynthesize." Past studies relied on destructive sampling of sunflower plants—a method that is likely to lead to false positives, said lead author Jared Stewart, a postdoctoral researcher at both CSU and CU.
The new research directly observed embolisms in intact sunflower plants using a microCT scanner at CSU's College of Veterinary Medicine and Biomedical Sciences. Previous work by the team found a complete reversal of embolism and full recovery in a type of wild grass within 24 hours of watering—the first evidence of refilling in intact plants. Those findings were published last year in Proceedings of the National Academy of Sciences.
Combined results from the two studies suggest that some plants can refill embolized tissue and others cannot, shedding light on how different types of plants might recover from drought. "Most researchers' opinions fall into one of two dichotomous extremes: refilling never occurs, or refilling is relatively common," Stewart said. "The combination of our two studies means almost everyone is wrong.
It also means our previous findings with barnyard grass might have enormous potential for agricultural efforts related to drought stress and resilience." Jared J Stewart et al, No evidence of xylem embolism refilling during recovery from drought stress in intact sunflowers, Journal of Experimental Botany (2026). DOI: 10.1093/jxb/erag294 Journal information: Proceedings of the National Academy of Sciences , Journal of Experimental Botany, MA in English, copy editor since 2021 with experience in higher education and health content. Dedicated to trustworthy science news.
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