Barley malting quality and yield interrelationships and the effect on yield distribution of selection for malting quality in the early generations

Relationships between malting quality attributes and grain yield in segregating populations can profoundly influence the intensity and sequence of trait selection. Consequently, the interrelationships between malting quality parameters predicted by near infrared transmittance (NIT) spectroscopy, grain weight, and grain yield in unselected populations of F-2, F-3, and F-4 breeding lines from 4 barley crosses were examined. The simple and partial correlations between malt extract, protein content, and diastatic power were similar to those reported in previous studies except for a positive correlation between malt extract and diastatic power in the F-2 and F-3 generations. This positive relationship should enhance selection for improved malting quality in breeding programs. There were no relationships between grain yield and malting quality attributes, which would have an adverse impact on the intensity and sequence of trait selection. The effect of F-2 and F-3 selection for malting quality on F-3 and F-4 yield distributions was estimated by comparing the F-3 and F-4 yield distributions of the entire unselected population with those for the selected populations. Individual selection and sequential independent selection in the F-2 and F-3 generation for malting quality parameters predicted by NIT spectroscopy and grain weight in 4 crosses generally did not alter the nature of the subsequent yield distributions, yet 78-90% of lines could be discarded and there still existed adequate genetic gain for grain yield in the retained population of potentially good malting quality lines. These results indicate that barley breeders could use NIT spectroscopy to efficiently select in the early generations for malting quality prior to the conduct of yield testing and obtain good genetic gain for both malting quality and grain yield.