Evaluation of hop yield stability in Czech bitter hop varieties

Between the years 2011 and 2022, the Czech hop varieties Agnus, Rubín, Vital, Gaia and Boomerang were evaluated in terms of their hop yield. The highest hop yield was recorded in Gaia (2.99 kg/plant) and Vital (2.92 kg/plant). Boomerang had the lowest yield (2.11 kg/plant.). The lowest variability of yield was determined in Vital (19.74%) and the highest in Boomerang (33.29%) and Agnus (32.98%). Vital demonstrated the lowest decreasing trend of hop yield over a period of 12 years. Rubín showed the highest decreasing trend

Essential oils in Czech hop varieties

Czech hop varieties were evaluated as part of maintenance breeding. The evaluation was performed in a single location between 2011 and 2020. The average weight of hop essential oils (HEOs) is 0.43 to 2.28% w/w. The Saaz, Saaz Brilliant, Mimosa, Saaz Shine and Saaz Comfort hop varieties have a low amount of HEOs. Their maximum content of these compounds amounts to 1.1% w/w. The average proportion of myrcene is between 23.42 and 45.14% rel. Only the Agnus, Vital and Boomerang hop varieties have the maximum myrcene proportion above 50% rel. The average share of caryophyllene ranges between 6.19 and 13.15% rel. Saaz Late has a broad range of caryophyllene percentage – from 5.39% rel. to 15.53% rel. The average percenatge of farnesene is between 0.14 and 16.91% rel. Only the Saaz Comfort and Saaz Shine hop varieties have the maximum farnesene share above 20% rel. The average humulene content has a very broad range between 2.23 and 35.79% rel. The Vital, Mimosa, Gaia and Saaz Comfort hop varieties are in a group with a low humulene percentage, which is clearly different from other hop varieties. The average share of selinenes ranges broadly from 0.97 to 33.56% rel. Mimosa differs from the before mentioned varieties with its proportion of selinenes between 23.08 and 43.75% rel. The aim was to characterize and compare Czech hop varieties in terms of content and composition of HEOs

Evaluation of variability of the content of alpha and beta acids in Czech bittering hop varieties (Humulus lupulus L.)

Czech bitter varieties were evaluated between 2010 and 2022. Hop varieties displayed an average content of alpha acids between 10.24% w/w (Agnus) and 13.73% w/w (Gaia). Variability below 15%, proved good stability of alpha acids content in all tested bittering hops. All varieties showed a decrease in the content of alpha acids over a period of 13 years of hop cultivation. The highest content of beta acids was determined in Gaia (7.30% w/w). In contrast, the lowest content of beta acids was found in Rubín (3.73% w/w). The new bitter genotypes Uran and 5304 had an average alpha acid content of 11.56% w/w and 10.82% w/w, respectively. Uran showed an average beta acid content of 5.47% w/w and for the genotype 5304 it was 3.61% w/w. In terms of the alpha/beta acids ratio, the hop varieties can be divided into three groups. The first group included the varieties with an alpha/beta acids ratio below 2, i.e. Vital, Boomerang and Gaia. While Agnus and Uran displayed an alpha/beta ratio slightly above 2. The highest alpha/beta ratio above 3 was found in Rubín and the 5303 genotype