Purpling in Corn

Purpling of corn plant tissue results from the formation of a reddish-purple anthocyanin pigment that occurs in the form of a water-soluble cyanidin glucoside. A hybrid's genetic makeup greatly determines whether corn plants are able to produce anthocyanin. A hybrid may have none, one, or many genes that can trigger production of anthocyanin. Purpling can also appear in the silks, anthers and even coleoptile tip of a corn plant.

Well, you may say, that's fine but what triggers the production of the anthocyanin in young corn at this time of year? The answer is not clearly understood, but most agree that these pigments develop in young plants in direct response to a number of stresses. These stresses include cool temperatures, high solar radiation levels, and water stress (both waterlogged and droughty conditions).

Does the leaf purpling lead to yield losses later on? The cause of leaf purpling, not the purpling itself, will determine whether yield loss will occur by harvest time. If the cause of the stress is temporary (e.g., cool soils), then yield loss will be negligible. If the cause of the stress lingers for some time (e.g., effects of soil compaction), then yield loss is possible.

--Bob Nielsen, Department of Agronomy, Purdue University