Modelling variability in the branching structure of strawberry inflorescences

The branching structure of inflorescences of the cultivated strawberry (Fra garia x ananassa Duch.) is very variable. This paper demonstrates that some aspects of this variability are well described by a simple stochastic mode l of branching that has two adjustable parameters. The model is shown to pr ovide a good fit to data from a set of almost 700 inflorescences of the cul tivar Elsanta, collected over two successive years. For one parameter the m aximum likelihood estimator is a moment estimator which is fully efficient even if the detailed branching structure of the inflorescences is not recor ded. This parameter provides a convenient summary of branching vigour. The maximum likelihood estimator of the second parameter must be determined ite ratively and can be quite inefficient unless the full branching structure i s recorded. The model demonstrates that branching structure is affected by the order in which inflorescences emerge on the plant.