Improving discrimination for malting quality in barley breeding programmes

In breeding programmes for malting barley, a great number of lines have to be tested for their malting quality in a short time. Such evaluation should also be reliable and consistent over years and locations. For this purpose, we considered varieties with contrasting (malting versus feeding) malting quality and used discriminant analysis to find out the combination of parameters that gave the best capability to discriminate between the two groups. In a pre-calibration step, we measured 15 quality parameters on varieties of the two quality groups in two contrasting locations for 2 years (2000 and 2001). A discriminant function combining HWE, wort viscosity and acrospire growth was nearly able to discriminate malting quality as all the measured parameters together. Then, the coefficients of the discriminant function were calibrated and validated on extended sets (12 genotypes from 15 locations, harvests 2001 and 2002). Finally, the discriminant function was used to evaluate advanced lines. This function provides a combined quality score for each genotype which is more stable in respect of the environment than each single parameter. It can be used as a basic selection criterion for malting quality and also to identify the genotypes of highest ranking in quality. We conclude that this score, based on a minimal core of parameters, provides an objective scale to rank genotypes for malting quality. Hence, it represents an optimised method to improve the efficiency of quality selection in breeding programmes for malting barley.