Towards modelling the flexible timing of shoot development: simulation of maize organogenesis based on coordination within and between phytomers

Zhu, J.; Andrieu, B.; Vos, J.; Werf, W. van der; Fournier, C.; Evers, J.B.


* Background and Aims: Experimental evidence challenges the approximation, central in crop models, that developmental events followa fixed thermal time schedule, and indicates that leaf emergence events play a role in the timing of development. The objective of this studywas to build a structural development model of maize (Zeamays) based on a set of coordination rules at organ level that regulate duration of elongation, and to show how the distribution of leaf sizes emerges from this. * Methods: A model of maize developmentwas constructed based on three coordination rules between leaf emergence events and the dynamics of organ extension. The model was parameterized with data frommaize grown at a low plant population density and tested using data from maize grown at high population density. * Key Results: The model gave a good account of the timing and duration of organ extension. By using initial conditions associated with high population density, the model reproduced well the increase in blade elongation duration and the delay in sheath extension in high-density populations compared with low-density populations. Predictions of the sizes of sheaths at high densitywere accurate, whereas predictions of the dynamics of blade length were accurate up to rank 9; moderate overestimation of blade length occurred at higher ranks. * Conclusions: A set of simple rules for coordinated growth of organs is sufficient to simulate the development of maize plant structure without taking into account any regulation by assimilates. In this model, whole-plant architecture is shaped through initial conditions that feed a cascade of coordination events.