Modeling germination and seedling elongation of common lambsquarters (Chenopodium album)

The ability ro predict time of weed seedling emergence relative to the crop is an important component of a mechanistic model describing weed and crop competition. In this paper, we hypothesized that the process of germination could be described by the interaction of temperature and water potential a nd that the rate of seedling shoot and radicle elongation vary as a functio n of temperature. To test these hypotheses, incubator studies were conducte d using seeds and seedlings of common lambsquarters. Probit analysis was us ed to account for variation in cardinal temperatures and base water potenti als and to develop parameters for a new mathematical model that. describes seed germination and shoot and radicle elongation in terms of hydrothermal time and temperature, respectively. This hydrothermal time model describes the phenology of seed germination using a single curve, generated from the relationship of temperature and water potential.