Water becomes an essential influence on corn pollination. Silk elongation is a process of cell growth dependent upon osmotic pressure to expand the cells as they develop. Drought-stressed plants tend not to extend silks far enough to be exposed to pollen or if they do make it that far it may be delayed beyond the time that viable pollen is available. Although silk emergence is dependent upon moisture available for cell elongation, male flower development tends to continue at the normal timing. If the drought is accompanied with high temperatures, not only is the release of the pollen enhanced but also pollen viability is reduced. Water in the plant is dependent upon roots characters such as structure and depth. Plant density, variety genetics, soil type and fertilizers all influence the emergence of the silks under all circumstances.
On the other hand, slightly excessive water, perhaps along with cooler than normal weather, can cause some varieties to push silks out from the husk covers before pollen is released. This exposes the silks to unintended pollen from other fields and to pathogen such as those that cause common corn smut, Diplodia, Aspergillus and Fusarium (to be discussed in future blogs)
Pollen adheres to the silk hairs (trichomes) and quickly hydrates as it absorbs water from the silk cells. This hydration is needed for the initial growth of the pollen tube as well as activation of the enzymes allowing the penetration of the silk. Moist silk and the invasion of the pollen tube allows provision of the nutrition and hormones that guide the growth of the pollen tube towards the ovule. As that tube progresses toward the ovule that silk quickly dries behind it. This helps prevent further invasion of the silk by potential pathogens.
Visit us at the ASTA in Chicago, Dec 9-12 (booth G207)
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.