Modelling QTL-trait-crop relationships : Past experiences and future prospects

Ecophysiological crop models have long been used to understand crop responses to environmental factors and to crop management practices, by integrating quantitative functional relationships for various physiological processes. In view of the potential added value of robust crop modelling to classical quantitative genetics, model-input parameters are increasingly considered to represent ‘genetic coeffi cients’, which are environment-independent and amenable to selection. Likewise, modern molecular genetics can enhance applications of ecophysiological modelling in breeding design by elucidating the genetic basis of model-input parameters. A number of case studies, in which the effects of quantitative trait loci (QTL) have been incorporated into existing ecophysiological models to replace modelinput parameters, have shown promise of using these QTL-based models in analysing genotype-phenotype relationships of more complex crop traits. In this chapter, we will review recent research achievements and express our opinions on perspectives for QTL-based modelling of genotype-by-environment interactions and even epistasis on complex traits at crop level.