天山天池二倍体棱叶蒜的开花动态及交配系统

以分布于新疆天山天池的二倍体棱叶蒜(Allium caeruleum)为研究对象,观察记录了开花进程,测定其花粉活力和柱头可授性,并采用去雄、套袋、人工授粉等方法对其交配系统进行检测。结果表明:(1)伞形花序平均直径为(29.07±1.17)mm,花被片天蓝色,花期6—8月;两性花,平均小花数205.67±19.88个,密集,无株芽;小花开放历经弹头、张口、吐药、展开、抱合和萎蔫等过程,历时5~7 d;小花开放进程中花药和柱头间存在空间隔离,从第1枚花药伸出至6枚花药全部脱落以及柱头伸长至萎蔫各需要2~3 d;阴天比晴天分别延长散粉以及延迟柱头萎蔫0.5~1 d。棱叶蒜具有雄蕊先熟、雌雄异熟、雌雄异位以及吸引昆虫避免自交的花部特征。(2)花药开裂散粉4 h时花粉活力最强(79.23%±1.97%的花粉具有活力),36 h后降至很低,属于短寿命花粉。(3)联苯胺—过氧化氢和MTT法检测柱头可授性;花丝、花柱等长期部分柱头开始具有可授性,花丝、花柱合拢期至花丝萎蔫期柱头可授性最强。同一朵花雄蕊和雌蕊的可育期存在部分时间重叠,防止了杂交失败。(4)单花花粉量为31 275±3 651,胚珠数6,P/O值为5 212±608;杂交指数OCI为5;无自发的自花传粉现象,不存在风媒传粉和无融合生殖;倾向于异交为主、自交可育,具备兼性异交并需要传粉媒介的混合交配系统的特征。天山天池二倍体棱叶蒜还以种子休眠、鳞芽无性繁殖的生殖补偿方式保证特殊地理环境下的种群繁衍。

Floral Dynamic and Mating System of Diploid Allium caeruleum from Tianchi,Tianshan Mountains

The diploid of Allium caeruleum，distributed in Tianchi，Tianshan Mountains，was observed as the research materials. The flowering process，the pollen viability and the stigma receptivity of A. caeruleum were recorded and detected，and the mating system was estimated by using emasculation，bagging and artificial pollination methods. The results showed that（1）the average diameter of umbel was（29.07 ± 1.17）mm；tepals were sky blue and flowering period was from June to August；bisexual florets was intensive and without bulbils，and the average quantity of florets was 205.67 ± 19.88；the floret experienced morphological changes of bullet，open mouth，spit anther，unfold，cohesion and wilting，which lasted 5–7 d；the anthers and the stigma existed spatial isolation in the process of floret opening and there were 12 dynamic changes that was from the first anther extending to all of six anthers shedding and from stigma elongation to wilting was needed 2–3 d，respectively；Under cloudy weather the anthers dehiscence were increased and the stigma wilting was delayed 0.5–1 d，respectively. The floral syndrome of A. caeruleum was protandry，dichogamy and herkogamy to prevent self-pollination.（2）The pollen viability was 79.23% ± 1.97% after the anther dehiscence 4 h. The pollen viability was within 36 h. A. caeruleum belonged to the short life pollen.（3）The stigma receptivity was detected by both the MTT and the benzidine hydrogen peroxide methods；when filaments equaled to the style the stigma receptivity was to be detected partially，and when filaments over passed the style the stigma receptivity was to be detected totally. The partial overlap of the stamens and pistils could prevent the failure of cross hybridization.（4）The single flower of A. caeruleum had 31 275 ± 3 651 pollens and six ovules；the ratio of pollen to ovule（P/O）was 5 212 ± 608 and the out-crossing index（OCI）was 5. The detection results of mating system showed that A. caeruleum has no spontaneous self-pollinating phenomenon and there was no wind pollination and apomixes. It tends to be outcrossing and selfing fertility. It has outcrossing and mixed mating system features and needs floral visits. The diploid A. caeruleum from Tianchi also take the seed dormancy and asexual propagation compensation strategies to ensure the population reproduction successfully.