Abstract A multi-year field study was conducted in Oregon and Washington to evaluate the influence of nitrogen fertilization rate and timing on cone quality and nitrate accumulation in cones. The impact of nitrogen rate on cone yield, levels of hop acids, total oil content, color, and nitrate level were year dependent. However, when data were aggregated over years and analyzed using a mixed effect model, α-acids, β-acids, and total oil volume decreased linearly with increasing nitrogen rate; while cone color, expressed as the degree of greenness of cones, and nitrate content of cones increased linearly with nitrogen rate. Yield was not improved with the highest nitrogen rate. In one of four studies, panelists used triangle tests to evaluate hop aroma of ground hop cones and detected a difference among treatments. The α- and β-acids decreased and nitrate concentration increased when nitrogen was applied after bloom. One harvest showed that fertilizer timing led to differences in the aroma of the hop cones although this difference was within the standard aroma variation for the variety. Overall, this research indicates that applying the lowest feasible nitrogen rate and ceasing nitrogen applications before or at bloom may optimize certain cone quality factors while minimizing nitrate accumulation.

中文翻译：

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氮肥育措施对啤酒花球果质量的影响

摘要 在俄勒冈州和华盛顿进行了一项为期多年的实地研究，以评估施氮率和施氮时间对锥体质量和锥体中硝酸盐积累的影响。氮肥率对锥体产量、啤酒花酸水平、总含油量、颜色和硝酸盐水平的影响与年份有关。然而，当数据多年来汇总并使用混合效应模型进行分析时，α-酸、β-酸和总油量随着氮肥率的增加而线性下降；而锥体颜色，表示为锥体的绿色程度，锥体的硝酸盐含量随氮率线性增加。最高的氮肥率并未提高产量。在四项研究中的一项中，小组成员使用三角形测试来评估地面啤酒花锥体的啤酒花香气，并检测处理之间的差异。开花后施氮时，α-和β-酸减少，硝酸盐浓度增加。一次收获表明施肥时间导致啤酒花球果香气的差异，尽管这种差异在该品种的标准香气变化范围内。总体而言，这项研究表明，在开花前或开花时应用最低可行的施氮量并停止施氮可以优化某些锥体质量因素，同时最大限度地减少硝酸盐积累。