向日葵列当是向日葵专性寄生植物,其种子必须在向日葵根系分泌物的诱导下才能萌发,其最早出土期基本上是在向日葵的现蕾期,大量出土是在向日葵普遍开花期,而在向日葵幼苗期未见出土。为探索向日葵列当萌发机理,找出其未能在向日葵幼苗期萌发的原因。以幼苗期和现蕾期向日葵为供试材料,采用水培收集法收集向日葵幼苗期和现蕾期植株根系分泌物,以向日葵列当种子萌发生测试验来指导萌发刺激物的分离、纯化,最终利用气相色谱—质谱(GC-MS)分析、鉴定出向日葵列当种子萌发刺激物种类及结构。实验结果表明:向日葵根系分泌物中含有去氢木香内酯,该物质能够诱导向日葵列当种子萌发,且向日葵在幼苗期和现蕾期均能分泌去氢木香内酯。在向日葵根际周围的去氢木香内酯浓度及土壤温、湿度等环境条件适宜的情况下,向日葵列当在向日葵的整个生育期内都可以萌发。 Helianthus annuus is a sunflower obligate parasitic plants, the seeds must germinate under the guidance of sunflower root secretions, the earliest period of its germination is basically in the sunflower budding period, a large number of unearthed in the sunflower general flowering period, and in the sunflower No seedling emergence. In order to explore the germination mechanism of sunflower column, find out why it failed to germinate in sunflower seedling stage. Taking the sunflower as seedling stage and budding stage as test materials, the root exudates of sunflower seedling and budding stage were collected by hydroponic culture method, the germination test of sunflower seed was conducted to guide the separation, purification, Finally, the species and structure of sunflower seed germination stimulator were identified by gas chromatography-mass spectrometry (GC-MS). The experimental results show that the root exudates of sunflower contain dehydrovarigallone, which can induce the germination of sunflower seeds, and the sunflower can secrete dehumidyllactone at seedling stage and budding stage. In the sunflower rhizosphere around dehydrolactone concentration and soil temperature, humidity and other environmental conditions suitable circumstances, the sunflower column can be germinated in the sunflower throughout the growth period.