类短命植物异翅独尾草的传粉特性

POLLINATION CHARACTERISTICS OF EPHEMEROID PLANT EREMURUS ANISOPTERUS

该文对生长于新疆古尔班通古特沙漠的类短命植物异翅独尾草（Eremurus anisopterus）的传粉习性做了观察研究,结果如下：异翅独尾草的花期从4月下旬至5月中旬,单花花期一般为1 d,而当遭遇最高温度不足20 ℃的阴雨天气时,单花花期可延长至2 d.单花的开花时间一般为每天10∶30～15∶00,大约4～5 h,单个花药的散粉时间约为40 min,但其6枚花药的开裂与散粉具有明显的不同步性,显著地延长了单花的散粉时间,这是对干热多风的沙漠生境中传粉者不确定性高度适应的结果.异翅独尾草花粉借风传播的距离可达70 m,但其中约60%花粉的散布距离集中在20 m以内;昆虫是异翅独尾草的重要传粉媒介,蜜蜂、食蚜蝇、麻蝇、切叶蜂、隧蜂等是主要的传粉者.蜜蜂和食蚜蝇访花时,都是先飞落到花基部黄绿色斑点处,然后沿着花被片的紫色脉纹进入到花内,黄绿色斑点是对花蜜的拟态,是异翅独尾草对高温多风沙环境高度适应的结果.昆虫的访花行为最活跃的时间在10∶30～13∶30之间.一天当中单花的开放时间与沙漠中风速的日变化及访花昆虫的活动习性之间呈现出显著的相关性.异翅独尾草的花粉与胚珠比（P/O）等于6 164,为适合于异花传粉的类型.人工套袋试验结果表明自交是可育的,这可能是对占据了不稳定的、先锋生境的异翅独尾草缺乏远交机会的有效补偿.不存在无融合生殖现象.

Background and Aims This study was conducted to examine the pollination characteristics of Eremurus anisopterus, an ephememid plant in Gurbantunggut Desert in Xinjiang, China. Methords An integratve approach combining investigation in field with analysis in lab was adopted. Pollen traps were used to measure air-borne pollen loads, and artificial isolation experiments were applied to test the potentiality of cross-pollination or apomixes. Key Results Duration of flowering of Eremurus anisopterus varied from late April to middle May. Anthesis of a single flower often lasted for I d. However, if the daily maximum air temperature was under 20 ℃, the anthesis of a single flower could be prolonged to 2 d. Pollen-dispersion period of single flower could last for 4 to 5 h from 10：30 to 15：00 local time with the duration of pollen dispersion for single anther approximately 40 min. The hetemtypical maturation of stamina could significantly prolonged the pollen-dispersion period of a single flower, suggesting an adaptation to the habitat of E. anisopterus in the desert where the pollinators were not reliable. The timing of blossom of the ephememid plant showed close correlations with wind velocity, habit and characteristics of the pollinators in the desert. Pollens of the plant might spread over 70 m by wind with approximately 60% of the pollens fallen within 20 m away from the plant. Insects, especially bee, hover fly, flesh fly, mason bee and Halictus sp. were very important pollination medium. Visitors, such as bee and hover fly, usually landed at the yellowish green spot on the tepal, and then entered the flower along the purple vein on the pink tepals. The yellowish green spot might be a mimetic structure to nectar that could attract insects to visit, which was also the result of the long-period adaptation of the plant to its sandy desert habitat. Higher visiting frequency was reached between 10：30 and 13：30. The P/O of E. anisopterus （6 164） suggested the species was of cross-pollination characteristic according to Cruden＇ s criterion. However, artificial isolation experiment showed that E. anisopterus was self-compatible, which might act as a compensation mechanism for the inadequate outbreeding chances in the desert habitat. The fact that there was no seed set in bagged emasculated flowers indicated that there was no apomixes occur. Conclusions This study suggests that E. anisopterus might adapt the not-reliable pollinator habitat by selfcompatible and lengthening pollen-dispersion period of single flower.