Seedlings are now, in US corn belt, growing roots from the first stem nodes. Near the root tip new primordia are initiated, from which lateral roots can grow. The number of lateral roots is affected by genetics and environment. There is a tendency for fewer if soil is exceptionally dry, resulting in more extension downwards of the secondary roots. More lateral roots have some advantage for reducing root lodging but also comes at some energy cost in that because each of the new root tips draws more energy from the leaves. On the other hand, the deeper growth of the main roots is most likely to reach deeper water reserves. More information available at www.plantphysiol.org/cgi/doi/10.1104/pp.15.00187.
I personally witnessed this phenomenon in 1980. A hybrid (A) was frequently noted as having high yields in many environments but in the very dry year of 1980 it was outstandingly higher yielding including much better than its widely used competitor hybrid (B). Demand for hybrid A skyrocketed. 1981 was a near opposite season for water. Hybrid B did very well whereas Hybrid A had decent ears but root lodged badly only shortly after pollination. The drought resistance obtained by having deeper roots but fewer lateral roots was good under dry conditions but Hybrid B, with its tendency to have more lateral roots was better when the topsoil was exceptionally wet for most of the summer, especially as minimal till placed much organic matter in those top layers.
Like most aspects of corn, we look for a balance of structures appropriate for that season’s condition and no hybrid seems to be at its best every year.
About Corn Journal
The purpose of this blog is to share perspectives of the biology of corn, its seed and diseases in a mix of technical and not so technical terms with all who are interested in this major crop. With more technical references to any of the topics easily available on the web with a search of key words, the blog will rarely cite references but will attempt to be accurate. Comments are welcome but will be screened before publishing. Comments and questions directed to the author by emails are encouraged.