Honeybees (Apis mellifera L.) are the most used pollinators for onion (Allium cepa L.) seed production. Two types of onion varieties are mainly grown worldwide: hybrids and open pollination (OP) cultivars. Although hybrids offer advantages to bulb growers, seed yields of hybrids are lower than OP cultivars. Since honeybees play a major role in onion pollination, understanding the contribution of the floral rewards to bee visitation is crucial to improve seed yield. The goal of this study is to establish the best moment for the introduction of honeybee hives into onion fields to increase seed yields. To reach this goal, the correlation between sugar compounds in nectar throughout the flowering period and honeybee foraging activity was determined. The sugar profile and bee visits were highly correlated, and fructose concentration was strongly linked to bee frequency of foraging on the onion umbels. The highest number of bee visits was recorded at 70% of flowering. Based on these results, beehives should be introduced once 40–50% of flowering is reached.

中文翻译：

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洋葱 (Allium cepa L.) 杂交种子生产：开花期糖含量变化

蜜蜂 ( Apis mellifera L.) 是洋葱 ( Allium cepa ) 最常用的传粉媒介L.) 种子生产。世界范围内主要种植两种洋葱品种：杂交品种和开放授粉 (OP) 栽培品种。尽管杂种为球茎种植者提供优势，但杂种的种子产量低于 OP 栽培品种。由于蜜蜂在洋葱授粉中发挥重要作用，因此了解花卉奖励对蜜蜂访问的贡献对于提高种子产量至关重要。本研究的目标是确定将蜜蜂蜂箱引入洋葱田以提高种子产量的最佳时机。为了实现这一目标，确定了整个开花期花蜜中的糖化合物与蜜蜂觅食活动之间的相关性。糖谱和蜜蜂访问高度相关，果糖浓度与蜜蜂在洋葱伞形花序上觅食的频率密切相关。在 70% 的开花期记录了蜜蜂访问的最高数量。根据这些结果，一旦达到 40-50% 的开花，就应该引入蜂箱。