Comparison Of Life-history Strategies Between Eremurus Anisopterus And Eremurus Inderiensis On The Basis Of The Reproductive Ecology Traits

Reproductive ecology characteristics of Eremurus anisopterus and Eremurus inderiensis, two ephemeroid plants, which growed in Gurbantunggut desert in Xinjiang, China, was carefully studied for two years. The results were shown as following.E. anisopterus and E. inderiensis are hermaphroditic flower plant, and belong to Liliaceae family Eremurus general. Flowering of E. anisopterus took place from late April to middle May,while the flowering of E. inderiensis took place from middle May to early June. The two results for two years shown that the flowering of two Eremurus species only have one~two days are overlapped, it is may be the adaption of insector-competition for the limit of insector in desert. The tepal of E. anisopterus is pink, and there is yellowish spot on the base of the tepal. When E. anisopterus are flowering, the six tepals are outspread thoroughly, the six anthers are bare, the anther is yellow. The tepal of E. inderiensis is green-purple, the coronal just like the canister, and there have nectar secreted in the base of the ovary on the late time of pollen-dispersion(the six anthers are all matured). While the six tepals of E. inderiensis are not outspread, and the six anthers come out the tepal one by one, the anther is orange. The two Eremurus species anthesis of a single flower lasted for 1d. If the highest air temperature was under 20℃, however, the anthesis of a single flower prolonged to 2d. Although duration of pollen dispersion for each anther was about only 40 min, pollen-dispersion period of single flower could last for 4 to 5h as a whole by heterotypical maturation of stamina, which significantly prolonged the pollen-dispersion period of a single flower, it was a kind of effective adaptation to the habitat of E. anisopterus in the desert where the pollinators were not reliable. The timing of blossom of the ephemeroid plant was closely correlated to the wind velocity, the habit and characteristics of the pollinators in the desert.Pollens of the two plants might spread over 70m by wind, although about 60% of the pollens was clumped within 20m away from the plant. Insects were very important pollination medium. The main pollinators of E. anisopterus are belongs to Apidae,Megachilidae,Halictidae,Syrphidae and Sarcrophagidae. 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 tepal. 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 and energy trade-off of the plant to its sandy desert habitat. The main insects of E. inderiensis are belongs to Apidae, Syrphidae, Bombyliidae, Therevidae and Halictidae. The insects are easy to bring the pollen, because they usually landed at the bare stamens and chapiters. Higher visiting frequency was reached between 10:30 and 13:30. The timing of flower-open, the daily variation of wind speed in the desert and visitor's activity were significantly correlated. If bad weather (the date highest temperature < 20℃) was coming, visitors of E. anisopterus were reduced obviously. The difference of the flower form and attractant of the two species bring on the different kinds of insects, it may be the results of niche-polarization due to the lack of insects.The patterns of the paternal function(pollen number, size; attractant and so on) and maternal function(ovule, pollen) of the two Eremurus species have a great difference, which is the results of tradeoff of the limited resource in order to ensure the normal survival and reproduction of the two species in the dicky desert surroundings. The results of the scanning electron microscope and fluorescent microscope of the two species chapiter in different time after pollinating shown that only in the late time of pollen-dispersion the two Eremurus species have the pollen on the chapiter, but there have not the pollen tube. So the pollen sprouting of the two species is delayed, it may be the strategy to avoid the interference of female and male function and make good use of the paternal and maternal resources.The P/O of E.anisopterus was equal to 6164, while the P/O of E.inderiensis was equal to 20153. It suggested that the two plants inclined to cross pollination, according to Cruden's criterion. But artificial isolation experiment showed that E. anisopterus was self-compatible. There was no seed set in bagged emasculated flowers indicated that there was no apomixes occur. Seed weight and germination capacity of two desert ephemeral plants E.anisopterus and E.inderiensis from different breeding systems were tested. The results showed that self-pollination not only led to decrease of seed germination vigor and seed germination capacity but also prolonged the phase of seed germination; on the other hand, self-pollination could result in increase of seed weight, which may be an effective compensatory mechanism of inbreeding depression that might improve survival potential of the seedlings.