紫背天葵花部特征与繁育系统的研究

 通过对濒危植物紫背天葵（Begonia fimbristipula Hance）野外定点观测和引种栽培，运用杂交指数、花粉活力及柱头可授性、花粉-胚珠比、人工授粉和套袋试验等方法，对其花部特征、开花动态及繁育系统进行研究。结果表明：紫背天葵单株花期25 ~ 30 d，群体花期45 ~ 55 d，花单性，雌雄同株同花序、异熟，雄蕊先熟。花药与柱头相距约2.0 cm，花开放式样为雄花-雌花-雄花的开放顺序，雌花开放一般滞后雄花2 ~ 3 d，杂交指数OCI ≥ 4，P/O 值为96.56，结合去雄、人工套袋和自然授粉坐果率判断，紫背天葵繁育系统为自交亲和为主，与异交并存的混合交配型系统。对生存环境的专一性依赖及其小居群长期自交的方式可能是导致该物种濒危的原因之一，“球茎”是其生殖补偿的有效途径。

A Study on Floral Syndrome and Breeding System of Begonia fimbristipula Hance

By investigating on the specific field observation and breeding cultivation of endangeredplant（Begonia fimbristipula Hance），its outcrossing index，pollen vitality and stigma receptivity，the ratioof pollen and ovule，artificial pollination and bagging experiments were performed for understanding theflower feature，blossom dynamic and breeding system. Results showed：The single plant florescence of B.fimbristipula is 25–30 d，while group plants florescence last to 45–55 d. The flowers，setting on thesame inflorescence，are monoecism. Male and female flowers mature at different time，the stamens matureearlier than pistils，and the distance between anther and stigma is about 2.0 cm. The blooming patternfollows male-female-male；Female flowers lag 2–3 days than male ones. The out cross index（OCI）is ≥4，pollen-ovule ratio（P/O）is 96.56. Taking the results of the emasculated，bagged and artificial pollinationexperiment together ， it indicates that B. fimbristipula flower is a mixed-crossing system usingself-compatibility as the main breeding form and concomitance out-crossing. The specific dependence onits living environment and the long term of small gregarious self-compatibility might be one of the reasonscausing this species in endangered，“bulb”is an effective way to its reproductive compensation.