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Relationship Between Malting Quality Traits and Hordeins as Affected by Timing of Nitrogen Fertilizer Application

The application of nitrogen (N) fertilizer in malting barley is necessary to obtain good yield, but it also influences kernel protein content, which affects malting quality. The negative correlation between kernel protein content and malting extract is due to the hordein proteins. The aim of this study was to determine the effect of N application timing on hordein fractions and how this influences malt quality. Reversed-phase high-performance liquid chromatography (RP-HPLC) was used to determine the hordein fractions in the two- and six-row barley parents and their doubled-haploid progeny, for two seasons for one location, and two locations in the second season. There were no changes in hordein level in response to timing of N application over years and locations. The two-row parent had the lowest hordein level and the six-row progeny had the highest. Total hordein content of the two-row progeny and six-row parent were similar. The supply of additional N in the form of fertilizer rather than the timing of all N applications influenced the production of all hordein fractions. There were significant correlations between hordein fractions and malting quality that also were reported in other studies. Kernel plumpness showed significant negative correlations with D, C, and B hordeins and total hordein content when half of the fertilizer was applied at planting and the other half at the six-leaf stage. Absorption showed significant positive correlation with C hordeins and a negative correlation with the B-to-C ratio, also when the second half of the N was given at the six-leaf stage.