Quantity over quality: light intensity, but not red/far-red ratio, affects extrafloral nectar production in Senna mexicana var. chapmanii

Extrafloral nectar (EFN) mediates food-for-protection mutualisms between plants and insects and provides plants with a form of indirect defense against herbivory. Understanding sources of variation in EFN production is important because such variations affect the number and identity of insect visitors and the effectiveness of plant defense. Light represents a potentially crucial tool for regulating resource allocation to defense, as it not only contributes energy but may help plants to anticipate future conditions. Low red/far-red (R/FR) light ratios can act as a signal of the proximity of competing plants. Exposure to such light ratios has been shown to promote competitive behaviors that coincide with reduced resource allocation to direct chemical defenses. Little is known, however, about how such informational light signals might affect indirect defenses such as EFN, and the interactions that they mediate. Through controlled glasshouse experiments, we investigated the effects of light...

花外蜜（Extrafloral Nectar, EFN）介导了植物与昆虫间的食物-保护互利共生关系，为植物提供了一种对抗植食为害的间接防御手段。解析花外蜜分泌的变异来源具有重要学术意义，因为此类变异会影响昆虫访者的数量与类群组成，以及植物防御的生效效果。光照是调控防御相关资源分配的潜在关键因子：它不仅可为植物提供能量，还能帮助植物预判未来的环境条件。较低的红光/远红光（R/FR）光比值可作为邻近竞争者存在的信号。已有研究表明，暴露于该光比值环境下的植物会表现出竞争相关行为，同时其直接化学防御的资源分配水平会降低。然而，此类具有信息传递功能的光信号如何影响花外蜜这类间接防御，以及其所介导的物种间互作，目前仍知之甚少。本研究通过受控温室实验，探究了光照对……