VARIETAL DIFFERENCES IN BARLEYS AND MALTS: I. NITROGEN DISTRIBUTION AMONG PROTEIN FRACTIONS OF BARLEY

Abstract

Determinations of total nitrogen and nitrogen fractions were made on 144 samples of barley representing 12 varieties grown at each of 12 widely separated experimental stations in Canada.A highly significant positive correlation between alcohol-soluble protein nitrogen and total nitrogen was found both within and between varieties. No correlation between total nitrogen and other nitrogen fractions was found between varieties; but significant positive correlations were found within varieties, that for insoluble protein nitrogen being considerably higher than those for total salt-soluble nitrogen, salt-soluble protein nitrogen, and non-protein nitrogen. With increasing total nitrogen, the proportion in salt-soluble form decreases, that in alcohol-soluble form increases, and that in insoluble form remains relatively constant. The results thus offer further support for Bishop's "Protein regularity principle".Mean varietal differences were found with respect to each nitrogen fraction, but elucidation of differences in nitrogen distribution patterns was complicated by the effect of varietal differences in total nitrogen content. Statistical analyses demonstrated the validity of eliminating this effect by adjusting varietal means for fractions to values corresponding to equal total nitrogen contents. When this was done it was found: that the three two-rowed varieties (Charlottetown 80, Hannchen, and Victory) were higher in alcohol-soluble protein nitrogen and lower in insoluble protein nitrogen than any of the six-rowed varieties; and that the four smooth-awned six-rowed varieties (Nobarb, Regal, Velvet, and Wisconsin 38) were lower in total salt-soluble nitrogen and higher in insoluble nitrogen than any of the rough-awned six-rowed varieties (O.A.C. 21, Mensury, Ott. 60, Olli, Peatland, and Pontiac). Owing to the variation between varieties within classes, and the small number of varieties studied, the average differences between the three classes are not statistically significant. Nevertheless, since by comparison with the rough-awned six-rowed varieties, the two-rowed varieties yield higher malt extracts, and the four smooth-awned varieties yield lower malt extracts and are lower in enzymatic activity, the indications of a possible relation between nitrogen distribution and malting quality are interesting.