Modern wheat grows deep

Modern wheat (Triticum aestivum) is the product of selectively breeding ancient wheat species such as emmer, einkorn and spelt over millennia. This gradual domestication process has resulted in high yields, and in modern times, suitability to intensive agricultural production. However, the ancient grains still have much to offer, and scientists are increasingly turning to these species in their breeding programs because of their broad genetic diversity. While much is known about the aboveground traits of modern and ancient wheats, differences in their roots have now been addressed for the first time in a field study published in the Annals of Botany.  

“This is the first field study of roots of ancient and modern wheats, where we clearly see that there are substantial differences between the root systems,” write Odone et al. “These results help to explain how past selection for yield has affected below-ground crop physiology.” 

Odone et al found that modern wheat has deeper roots than their ancestral species and can more efficiently and quickly tap deeper soils. Their roots extend beyond 1 m much earlier in plant development than their ancestral species. Odone et al suggest that these deeper roots were indirectly selected as a result of breeding for yield. The result was a root pattern that optimises resource uptake in fields that are fertilised but not irrigated, as is done in intensive wheat agriculture. 

“This enables modern wheat to access more N [nitrogen] and particularly water, which is necessary for its fast growth and high yielding ability,” write Odone et al. Facile access to nitrogen and water is critical for modern wheat to support their abundant grain yield. Deep roots are essential to this access, allowing the plants to take up water and nutrients from greater soil depths where there is less root-root competition between plants. 

To better understand the rooting differences between modern wheat and ancient species, Odone et al conducted a field trial at an experimental farm in Taastrup, Denmark using emmer (T. turgidum ssp. dicoccum), spelt, (T. aestivum ssp. spelta) einkorn (T. monococcum) and eight modern Danish wheat cultivars (‘Bright’, ‘Heerup’, ‘Kvarn’, ‘Momentum’, ‘Pondus’, ‘Rembrandt’, ‘Sheriff’ and ‘Zyatt’).  

Root growth was monitored via minirhizotron tubes made of clear PVC that were inserted into the soil at one end of each plot after sowing the seeds. Over the growing period, a camera was lowered into the tube on three separate occasions so that still photographs of roots could be taken every 5 cm along the tube length. Specialised software was then used to extract images of the roots and calculate data pertaining to root traits such as length.   

Odone et al found that modern wheat had more roots at greater depths than their ancestors at every time point during the growth process. Specifically, einkorn and spelt had lots of shallow roots but few deep roots. Emmer had fewer roots than modern wheat at all soil depths but more deep roots than einkorn and spelt.  

“The results here reveal the diversity of the below-ground physiology of ancient and modern wheats, and help to tell the story of how breeding has affected crop resource use, which may be useful when trying to improve yield stability and adapting to climate change in the future,” write Odone et al.  

Now that these differences in root patterns are better understood, they can be used in breeding programmes to help select for cultivars with robust water and nutrient uptake.

READ THE ARTICLE

Odone, A. and Thorup-Kristensen, K. (2025) “Modern wheat has deeper roots than ancient wheats, is this an adaptation to higher productivity?,” Annals of Botany. Available at: https://doi.org/10.1093/aob/mcaf065

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Cover image: Triticum aestivum in USA by Bonnie Semmling / iNaturalist CC-BY