[A rapid method for the simultaneous determination of β-amylase and protein content of barley and the heritability of these traits in an experiment with 16 varieties of malting barley].

1. A rapid method for simultaneous determination of β-amylase and protein content in malting barley was developed. 500 mg of flour are shaken up with a cysteine containing activation solution and the suspension is mixed directly with the enzyme substrate. The aldoses in the supernatent are titrated iodometrically, and the proteins dissolved in alkaline solution are Kjeldahl digested and nesslerized in the same test tube. 2. Samples of the 16 varieties used for the official Czechoslovakian State trials, grown at 4 different localities were analyzed and the results compared with the official ones. 3. By an analysis of variance the following standard errors, including analytical and trial errors, were estimated: For the official nitrogen content and β-amylase determination 3.2% and 9.7% respectively, compared with 6.5% each by rapid method determination of β-amylase and nitrogen, in terms of the measured value. The standard analytical error of the rapid determination of nitrogen and β-amylase content was 2.4% and 3.1% respectively. 4. Both analytical methods showed the locality differences to have the greatest effect on the variability of both traits; and affected each to the same extent. No varietal differences in nitrogen content could be demonstrated but considerable genetic variability of β-amylase content was found by both analytical methods. 5. In the 64 barley samples tested the heritability of β-amylase was estimated as 0.37. The sum of the locality and variety variance was taken as the population variance. Within localities the genetic variance was 41.6 and 51.5% of the total variance of β-amylase values obtained by means of the official and rapid method, respectively. 6. The rapid method supplies at least as much useful information as the official method, and can be used for the purpose of selection.