Leafing Out of Corn
Bob Nielsen, Extension Corn Production Specialist,
Department of Agronomy, Purdue University
In addition to successful germination, successful
emergence of corn
seedlings is an important early step in successful stand establishment.
The synchronization of coleoptile development and the cessation
mesocotyl elongation usually results in the appearance of the first
from the tip of the coleoptile just as the coleoptile breaks the
surface. Occasionally, the first leaf instead emerges underground,
trapping the remainder of the young whorl below the soil surface,
causing eventual stunting or death of the affected plant.
Such leafing out underground can be caused by several factors.
factor may be physical restriction of coleoptile penetration through
soil due to dense surface soil crusting. A similar physical restriction
of coleoptile penetration can occur in response to severe seed
sidewall compaction and heavy down-pressure settings on planter
A third possible cause of underground leafing
is chilling injury to
mesocotyl or coleoptile plant tissue caused by sub-lethal cold
temperatures during the emergence process. Such chilling injury
cause deformed development of the affected plant tissue, causing
corkscrewing of mesocotyl that delays the emergence of the coleoptile
prior to usual emergence of leaves from the coleoptile.