Heterosis and growth in a developing maize plant

Heterosis has been extensively studied for nearly a century, yet genetic and biological mechanisms underlying the phenomenon remain elusive. This study extends our understanding of heterosis in maize (Zea mays L) by examining heterosis in the language of growth and development–growth rate, duration of the linear phase, and final trait value. By utilizing a set of phenologically uniform genetic materials the confounding effect of differences in development were eliminated. Using two parental inbred lines and the F1 hybrid, heterosis was examined using logistic growth curves for a series of vegetative and reproductive traits across stages of development (V-stages). Vegetative and reproductive traits examined in this study displayed the classic sigmoidal growth curve. More im- portantly these curves were occurring at the same developmental time points in the F1 and parental inbred lines. In short, heterosis confers an advantage to the F1 that occurs early in development in terms of growth rate and while the growth rate of the F1 and parental lines eventually coalesce, that initial advantage due to heterosis is maintained throughout the lifecycle of the plant resulting in a larger final trait valu