Deconstructing crop processes and models via identities

Abstract

This paper is part review and part opinion piece; it has three parts of increasing novelty and speculation in approach. The first presents an overview of how some of the major crop simulation models approach the issue of simulating the responses of crops to changing climatic and weather variables, mainly atmospheric CO2 concentration and increased and/or varying temperatures. It illustrates an important principle in models of a single cause having alternative effects and vice versa. The second part suggests some features, mostly missing in current crop models, that need to be included in the future, focussing on extreme events such as high temperature or extreme drought. The final opinion part is speculative but novel. It describes an approach to deconstruct resource use efficiencies into their constituent identities or elements based on the Kaya-Porter identity, each of which can be examined for responses to climate and climatic change. We give no promise that the final part is 'correct', but we hope it can be a stimulation to thought, hypothesis and experiment, and perhaps a new modelling approach. This paper is important because it offers examples of how simulation models can be used to develop understanding and predict how crops respond to environmental factors. It also presents and utilises a new concept, the Kaya-Porter identity, as a means of deconstructing biological use efficiencies into component parts as a stimulus to new thinking, models and experiments in crop physiology. © 2013 John Wiley & Sons Ltd.