Agronomic and chemical evaluation of hop cultivars grown under Mediterranean conditions

Aim of study: Evaluation of the agronomic performance and chemical profile of four hop cultivars grown under Mediterranean conditions. Area of study: The study was undertaken in Braganca, north-eastern Portugal. Material and methods: The newly introduced cultivars ('Columbus', 'Cascade' and 'Comet') were compared with the well-stablished 'Nugget'. The field experiment was carried out between 2017 and 2019. Dry matter (DM) yield (plant and cones), tissue elemental composition and bitter acid and nitrate (NO3-) concentrations in the cones were assessed. Main results: 'Comet' was the most productive cultivar with the highest total DM yield (1,624 to 1,634 g plant(-1)), cone yield (572 to 633 g plant(-1)), and dry weight of individual cones (0.28 to 0.79 g cone(-1)). 'Cascade' showed the lowest average total DM yield (723 to 1,045 g plant(-1)). The year affected the average values of DM yield and the concentration of bitter acids in the cones, with 'Cascade' showing the highest sensitivity between cultivars. The concentrations of a and beta-acids in the cones were within or close to the normal ranges internationally accepted for all cultivars. 'Columbus' exhibited the highest levels of a-acids, ranging between 12.04 % and 12.23%, followed by 'Nugget' (10.17-11.90%), 'Comet' (9.32-10.69%) and 'Cascade' (4.46-8.72%). The nutrient accumulation criteria in cone and leaf tissues seem to be a differentiating factor between cultivars with influence on bitter acid biosynthesis and biomass production. Research highlights: All cultivars showed notable performance in terms of DM yield and bitter acid concentration in the cones when compared to international standards.