The modelling, allocation and redistribution of biomass

In their new paper published in in silico Plants, Brown and coauthors provide a detailed description and comprehensive evaluation of the general applicability of the generic biomass partitioning approaches implemented in the Agricultural Production system Simulator (APSIM) Plant Modelling Framework (PMF). The PMF is a collection of generic software classes that can be assembled and parameterised in different ways to create different plant models.

The PMF uses a generic biomass partitioning model named the ‘Organ Arbitrator’ which determines the supply of nitrogen and dry mass from each organ then dictates the partitioning of this to different organs based on their demands for structural, metabolic and storage biomass.

To ensure that their arbitration approach would capture outcomes in different crops and growth situations, the authors evaluated the models’ ability to simulate low-level processes that control biomass partitioning in two globally important crops, maize and wheat, grown in a range of water and nitrogen supply conditions that influence carbon and nitrogen assimilation.

The growth and yield of plants are limited by the amount of nitrogen and biomass they can assimilate and the way they partition and reallocate this to roots, stem, leaves and grain or fruits, says Brown, scientist at the New Zealand Institute for Plant and Food Research. “This ultimately controls the influence a plant has on its surrounding environment and its productivity. While models all partition biomass in some way, their approaches are often not well documented or tested. We hope this paper, along with another recent paper on the model development and testing process, will raise expectations for the transparency and scrutiny of widely used simulation models.”

Following parameterization of biomass supplies and demands based on a large test dataset, the model was able to give accurate predictions of the temporal patterns of partitioning and reallocation of biomass components to each organ for the two crops under different stress conditions. The authors conclude that the theory and implementation of the arbitration approach in the PMF is sound.