北江荛花繁殖特性及传粉生物学研究

Study on the Reproductive Characteristics and Pollination Biology of Wiktroemia monnula

为了揭示北江荛花自然结实率低的原因,本研究对花部特征、花粉活力、柱头可授性、繁育系统与传粉生物学等方面进行观测,同时采用扫描电镜进行花粉及柱头形态特征观察。结果表明,北江荛花为两性花,花朵开口小,花萼筒细长,柱头深埋于花萼筒内部,上下两轮雄蕊排列于花萼筒中上部;扫描电镜观察发现,北江荛花花粉与柱头形态正常,不存在发育缺陷。花粉活力与柱头可授性动态观测表明,北江荛花雌雄同熟,开花后6~24 h为有效授粉期(EPP),此时期内花粉活力较高,柱头可授性较强,可正常授粉。传粉生物学观测发现,风传粉对北江荛花生殖贡献大,因其花萼筒细长,动物传粉存在困难,仅有虱、蓟马等小型昆虫可能是其潜在传粉者。结合花粉胚珠比(P/O)、杂交指数(OCI)值和传粉生物学观测情况推断,北江荛花繁育系统以异交为主、自交亲和,有时需要传粉者。研究表明,北江荛花的筒状花结构使其较难进行异花授粉,可能是导致其自然结实率低的主要原因。

In order to explain the low seed setting rate of Wiktroemia monnula,the characteristics of flower,pollen viability,stigma accessibility,breeding system and pollination biology were investigated.The results showed that the Wiktroemia monnula wasbisexual,with small flower opening and long calyx tube.The stigmaswere buried deep inside the calyx tube,and the stamens were arranged in the middle and upper part of the calyx tube.The pollen and stigma morphology of Wiktroemia monnula were normal and there were no developmental defects.The dynamic observation of pollen activity and stigma receptivity of Wiktroemia monnula showed that 6-24 hourSafter flowering wasthe effective pollination stage(EPP),with higher pollen activity and stronger stigma receptivity.Pollination biology observationSshowed that wind pollination contributed a lot to the reproduction of Wiktroemia monnula.Due to the long calyx tube,animal pollination wasdifficult,and only small insectSsuch aslouse and thripSwere possible potential pollinators.Combined with the pollen ovular ratio(P/O),hybridization index(OCI)and pollination biology observations,it wasconcluded that the breeding system of Wiktroemia monnula wasmainly outcrossed,self-compatible,and sometimeSneeded pollinators.These results indicated that the tubular flower structure of Wiktroemia monnula made cross-pollination difficult,which could be the main reason for the low natural seed setting rate of Wiktroemia monnula.