Coupling estimated effects of QTLs for physiological traits to a crop growth model: predicting yield variation among recombinant inbred lines in barley

Advances in the use of molecular markers to elucidate the inheritance of qu antitative traits enable the integration of genetic information on physiolo gical traits into crop growth models. The objective of this study was to as sess the ability of a crop growth model with QTL-based estimates of physiol ogical input parameters to predict the yield of recombinant inbred lines (R ILs) of barley. The model used predicts yield as spike biomass accumulated over the post-flowering period. We describe a two-stage procedure for predi cting trait values from estimated additive and epistatic effects of QTLs. V alues of physiological traits estimated by that procedure or measured in th e field were used as input to the crop growth model. The output values (yie ld and shoot biomass) from the growth model using these two types of input values were highly correlated, indicating that QTL information can successf ully replace measured input parameters. With the current crop growth model, however, both types of input Values often resulted in large discrepancies between observed and predicted values. Improvement of performance may be ac hieved by incorporating physiological processes not yet included in the mod el. The prospects of using QTL-based predictions of model-input traits to i dentify new, high yielding barley genotypes are discussed.