栽培石碌含笑的开花生物学与繁育特性

Flowering Biological Characteristics and Reproductive Characteristic of Cultivated Michelia shiluensis (Magnoliaceae)

摘要:

为探讨石碌含笑(Michelia shiluensis)濒危的内在原因，对花器官形态特征、开花动态、访花昆虫进行观察，并对花粉萌发率和柱头可授性、繁育系统特性进行了检测。结果表明，开花时，石碌含笑的雄蕊群和雌蕊群自然形成空间隔离，花被片横向弯曲形成球形空间，保护雄蕊群；雌蕊群柄持续伸长，将雌蕊群推出雄蕊群和花被片。圃地栽培植株的主要访花昆虫和传粉昆虫为西方蜜蜂(Apis mellifera)。花被片开放至最大直径50%时的VI和VII阶段柱头可授性最强；VI阶段花粉活性也最高，离体萌发率达(66.96±11.28)%。同株同花或同株异花授粉均不能结实，但异株授粉座果率为100%。可见，石碌含笑为严格的异株异花授粉植物，异交亲和，自交不亲和，不存在无融合生殖现象，与含笑属其他种类亦有生殖隔离。石碌含笑花被片和雌蕊群的动态变化揭示了其巧妙规避自交的生物学机制。

Abstract:

In order to understand the internal causes of endangerment of Michelia shiluensis, the morphological characteristics of flower organs, flowering dynamics and visiting insects were observed, and the pollen germination rate, stigma acceptability and breeding system characteristics were tested. The results showed that the stamen group and pistil group naturally form spatial isolation during flowering, and the perianth plate bends laterally to form a spherical space to protect the stamen group. The pistil stalk continues to extend, pushing the pistil out of the stamen and perianth. The main flower-visiting and pollinating insect of the nurseries are Apis mellifera. Stigma acceptability was strongest in stages VI and VII when the perianth was open to 50% of the maximum diameter. The pollen activity of stage VI was also the highest, and the germination rate in vitro was (66.96±11.28)%. The same flower or cross-flower pollination of the same plant could not bear fruit, but the fruit rate of cross-pollination was 100%. Therefore, Michelia shiluensis is a strictly hetero-pollinated plant, with outbreeding and self-incompatibility, and there is no apomixes, and there is also reproductive isolation with other species of Michelia. The dynamic changes in perianth and pistillation groups of M. shiluensis revealed the biological mechanism of cleverly avoiding self-mating.