Vegetative development in maize (Zen mays L.) can be divided into juve
nile and adult phases, each with distinct anatomy and physiology. Vege
tative phase change occurs at the node(s) at which juvenile-vegetative
traits are replaced by adult-vegetative traits. The objective of this
study was to determine the effects of inbreeding in a sugary1 populat
ion of 'Minn11' C3 (pseudostarchy) on several phase-specific, developm
ental traits that are used as markers of the timing of vegetative phas
e change. All agronomic traits had significant, linear changes between
the S-0 and S-5 generations, including decreased leaf length, leaf wi
dth? ear height, and plant height, and later flowering time. Changes o
f this type are normally associated with inbreeding depression. In con
trast, phase-specific, developmental traits generally did not exhibit
inbreeding depression. Tiller number was the only phase-specific, deve
lopmental trail: thar showed a significant, linear response over gener
ations. Our results suggest that most phase-specific, developmental tr
aits are governed primarily by additive effects with dominance effects
occurring only for tiller number. Breeders should be able to successf
ully include most phase-specific, developmental traits in selection in
dices. In addition, studies assessing the timing of vegetative phase c
hange based on phase-specific, developmental traits should have only t
iller number confounded by different levels of inbreeding among entrie
s.