Quantitative evaluation of the hop (Humulus lupulus L.) root system based on wall profile method

: Hop cones are an indispensable raw material used for beer brewing. Since the hop plant is a minor crop, expansion habit of the hop root system has not been well investigated. In this study, we observed and analyzed the root systems of two major hop cultivars in Hokkaido, Little Star and Furano Special, using the wall profile method and root depth index. The results suggest differences in expansion habit of the hop root between the two hop cultivars, which has not been reported previously. The results also indicate that the different responses in cone yield to precipitation between the two hop cultivars may be derived from their differences in root expansion habit. The results of this preliminary study support the view that a better understanding of the hop root system could lead to improved productivity of hops via the development of agronomical techniques or genotypes.