新疆荒漠植物耳叶补血草的爆发式开花式样与传粉模式  

Mast flowering and pollination mode in a desert plant Limonium otolepis(Plumbaginaceae) from Xinjiang,northwest China

作　　者：黄云兰[1] 安秀峰[1] 师东[1] 张爱勤[1] 

机构地区：[1]新疆大学生命科学与技术学院,乌鲁木齐830046

出　　处：《生物多样性》2012年第3期368-375,共8页Biodiversity Science

基　　金：国家大学生创新性实验计划(091075516)

摘　　要：荒漠环境中干热、大风、浮尘、温度骤变等突发性天气状况,对植物的有性生殖具不利影响。耳叶补血草(Limoniumot olepis)是新疆盐生荒漠的主要建群种,对其适应荒漠恶劣环境的生殖策略仍缺乏研究。为了探讨荒漠植物适应环境的开花式样和传粉模式,作者通过野外定点观测和室内电镜扫描等方法对耳叶补血草的开花进程、花部特征、传粉媒介、结实特性等进行了研究。耳叶补血草的花期在6月上旬至7月中旬,花期较长且具明显不同步的单株开花状态。在一天中,单花表现出极为集中的开花、散粉过程:一般早上8:00开始开放,9:00达开放高峰期,11:00以后基本不再有单花开放;开放后的单花持续6-8h后闭合。每单花平均有花粉752粒,花粉表面有网状纹饰,有花蜜。传粉者主要为蜜蜂科和食蚜蝇科昆虫,访花高峰期在9:00-14:00。人工授粉实验表明耳叶补血草以异交为主,自动自花授粉率低。自然状态下结实率为36%,在花序中基部第一位上单花的结实率(45.7%)明显高于第二位上单花(3.3%)。耳叶补血草爆发式开花、在短时间内快速完成传粉过程,可能是躲避荒漠环境突发性天气条件的一种策略;而居群分散的开花时间及较长的花期在应对不稳定生境,分摊生殖风险方面具重要意义。Weather patterns in desert environments （e.g., dry heat, strong winds, dust storms, and temperature fluctuations） can be highly unpredictable and can have deleterious effects on sexual reproduction of flowering plants. The herb Limonium otolepis is a dominant species in desert areas of Xinjiang, northwest China; however, reproductive strategies in unfavorable environments remain to be explored. Overall, we addressed flowering pattern and pollination modes, flowering process, floral traits, pollinators, and fruiting characteristics ofL. otolepsis in Junggar Basin region. We employed scanning electron microscopy to examine the morphology of pistil stigmas and pollen grains. The flowering period of L. otolepis was from early June to mid-July, with extended flowering due to unsynchronized flowering phenology among individuals in the same population. During a given day, it showed a concentrated flowering and pollen release, with anthesis lasting for about 6-8 h. Petals unfolded at about 8：00 and reached the peak of flowering at about 9：00, with no more flowers opening after 11：00. One flower produced 752 pollen grains with a small amount of nectar. The pollen exine ornamentation was reticulate. Insects, including bees and hoverflies, were primary pollina- tors. Highest visiting frequencies occurred between 9：00 and 14：00. L. otolepsis was mainly outcrossing given that automatic selfing yielded a few seeds. Overall, fruit sets of open-pollinated flowers were 36.1%. Within inflorescences, fruit sets on basal flowers （45.7%） were significantly higher than those on neighboring flowers （3.3%）. Mast flowering in L. otolepis reported here may facilitate pollination in unpredictable weather conditions. The reproductive strategy may also dispense reproductive risk by maintaining flowering asynchrony to prolong overall flowering period.

关 键 词：LIMONIUM otolepis 开花式样 传粉模式 生殖对策 荒漠植物 

分 类 号：Q948[生物学—植物学]