We studied the floral dynamics, pollen viability, stigma receptivity, floral visitors and their behaviors,pollen ovule rate (P/O),outcrossing index (OCI) of Apocynum venetum L. in the field of the middle reaches of Heihe River. The main results were as follows:the flowering of A. venetum L. was 4～6 days,the community flowering season is June to August. Pollen viability achieved the maximum at 3 hours later in flowering. After 4 days,the pollen viability reduce to 0. Stigma receptivity achieved the maximum at 2 days later in flowering. Stigma receptivity can last for 4 days. More than 10 species of insects were observed to visit the flowering of A. venetum L. The most common floral visitors were arranged in Hymenoptera, of which Ophion luteus (Linnaeus) ,Megachile bicolor kagiana Cockerell,Megachile spissula Cockerell,Apis mellifera Linnaeus,Episyrphus balteatus , Pieris rapae (Linnaeus), Aphidencyrtus sp. were the effective pollinators. The pollen ovule rate (P/O) was 36.2 and the outcrossing index (OCI) was 2,fruit set rate of the first and second group were (2. 79 ± 0.99) ％ and (3.41 ± 1.05) ％, respectively. The results indicated that facultative autogamy is the main form in breeding system of A. venetum L., the fruit set rate is low and the floral visiting insects just have partly impact on the process of pollination.%对黑河流域中游罗布麻的开花动态、花粉活力、柱头可授性、访花昆虫种类、访花频率、花粉与胚珠比(P/O)、杂交指数(OCI)及自然条件下的座果率进行观测,结果显示:罗布麻的单花花期为4～6 d,群体花期为6～8月,花朵开裂3.5 h后,花粉活力达到最大,4 d后花粉活力下降为0,柱头可授性在开花后第2天达到最大,柱头可授性可持续4 d.访花昆虫有10余种,以膜翅目昆虫为主,姬蜂、卡切叶蜂、达戈切叶蜂、意大利蜂、黑带食蚜蝇、菜粉蝶、蚜虫为主要传粉昆虫,花粉与胚珠比(P/O)为36.2,OCI为2,实验组和对照组的座果率分别为(2.79±0.99)%和(3.41±1.05)%.实验结果表明,罗布麻为兼性自交的繁育系统,座果率偏低,虫媒在传粉过程中只是起到一定辅助作用.
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