The Study Of The Reproductive Ecoogy Of The Major Legume Pasture In Songnen Grassland And Australia

The reproductive biology of flowering plants is important for determining barriers to seed and fruit set, for conservation, and for understanding pollination and breeding systems that regulate the genetic structure of populations. Legumes offer an interesting opportunity to evaluate the interaction between self-compatibility, out-crossing rate and inbreeding depression, as many annual members of the group reproduce through a combination of selfing and outcrossing. We conducted the experiments in breeding system, pollination system, floral morphology, seed germination, and reproductive allocation on Lathyrus quinquenervius, Australian native Cullen australasicum and some other pasture legume. We got the conclusions as follows:(1) This paper examines the floral structure, pollination system and the breeding system in a population of L. quinquenervius, a perennial pasture legume. The pistil and the androecia aren’t separate in space. A single florescence and the whole florescence are 3~4 days and 40 days, respectively. The stigma receptivity is almost synchronizing with the pollen viability and providing the opptunity for selfing pollination. Pollination system comprises anemophily and insect vector, and the bees were the main pollinator. According the Dafni and Cruden’criterion, the breeding system is self-compatibility and need pollinator. Seed set following spontaneous pollination was low, following hand self-pollination and cross-pollination were not significantly lower than the contrast. There were not significant differents on the pollen tube growth between hand self-pollination and cross-pollination; it means no self-incompatibility on the stigma. Hermaphroditic homogamous L. quinquenervius is a self-compatibility species, sometimes requires floral visitors such as honeybees to bring about pollination and exhibits a mixed mating system.(2) The study on breeding system on the five accession of Cullen australasicum (syn. Psoralea australasica) in the glasshouse indicated that four of the accessions showed the need for an external tripping agent to bring about pollination and that hand-tripping was the most efficient method. A scanning electron microscopy study revealed there are two types of stigmas in this species. Stigma receptivity was significantly lower at the early bud stage before anther dehiscence. The pink flowers have more attraction on the small insects such as bees than the bule ones. The results show that C. australasicum is a self-compatible species comprising accessions with a wide range of outcrossing potential, need trip on the stigma to rupture the stigmatic surface and pollination occurred. (3)Percentage of the reproductive allocation changing not too much under the different aere and stage, Lathyrus quinquenervius have developed rhizome and depend on them to survive. The percentage of investment on asexual reproduction was more than sexual reproduction. The percentage of reproductive allocation was not significant changing a lot under different fertilization, but after fertilizated during the grand anthesis, the plant height, the numbers of the leaves and so on were significantly more than the contrast.(4)The drought resistance of Melilotoides ruthenica (L.) Sojak, Medicago falcata L. and eleven varieties of Medicago sativa L. at seeds germination stage with seven osmotic potential treatments of PEG were studied. We measured the day when germination began, the germination rate, the length of the seedlings, the number of the lateral root, and the length and the width of the cotyledon. The results indicated that the biologic index of the tested samples under the different osmotic potential treatments were different, the drought resistance of Melilotoides ruthenica (L.) Sojak was lower than Medicago falcata L. and they were lower than the other varieties of Medicago sativa L. The above parameters could be the drought resistance index of the pasture legume.