Model analysis for growth response of corn

The expanded growth model was developed to describe accumulation of dry matter and plant nutrients with time for annual and perennial crops. It incorporates an environmental driving function and an intrinsic growth function. Previous analysis has shown that the model applies to the annual corn (Zea mays L.) and the warm-season perennial bermudagrass (Cynodon dactylon L. Pers.). In this article the model is used to describe accumulation of dry matter and plant nutrients [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg)] by corn. The model describes dry matter accumulation by the vegetative component of the plant followed by accumulation of dry matter and plant nutrients with time by ears. The time lag between planting and full vegetative growth is 14 - 9.3 = 4.7 wk, followed by a lag of 20 - 14 = 6 wk between vegetative and ear growth. After 20 wk there is a rapid decline in plant N in the vegetative component of the plant. During ear formation plant N, P, and Mg concentrations remained essentially constant, while plant K and Ca showed a hyperbolic linkage to dry matter accumulation. Several model parameters were the same for vegetative and ear components.