Pollination Biology Of Eleven Alpine Dominant Plants At The Source Area Of Urumqi River

Alpine life zone is a important constituent of global terrestrial ecosystem, the condition of alpine area is very harsh, the foreseeablility of ecological factors is uncertainty, the plant breeding system can accommodate its charictaristics strongly to environment, so the syudy of adaptability and evolutional mechanism of the breeding system of alpine plants under this unique environmental condition is of significance. Self-pollination that ensure seeds production and provide reproductive assurance when pollinators are scarce is thought to be an efficient reproductive strategy. In this paper, we have studied pollination biology of elenen alpine subnival blooming plants at the source area of Urumqi river. We have preliminarily studied the pollinating pattens and structure of stigma of eleven plants, and have a systematic study to plant characteristics, pollination biology, seed set and seed germination of Saxifraga hirculus L. The result are:1. Under high and cold condition, the eleven alpine subnival dominant plants at the source area of Urumqi river are capable of autonomous self pollination, and this autonomous self pollination can be concluded in some pattens as following:filament move, ovary or style growth, anther encircle, filament elongation, pollen flow, and cleistogamy, this different pollination pattens indicate that the plants can take autonomous self-pollination without pollination agents, and can provide insight for the reproductive strategy of plants in the extreme environmental condition.2. According to the observation of stigma surface ultrastructure of seven alpine subnival dominant plants, we found that stigma of the spiece which possesses different pollination pattern has different structure which accommodates to its own self-pollination:filter-shape stigma in spieces which pollination take on filament move patten; plat roof-shaped or erect trifurcation-shaped stigma in spieces which pollination take on ovary or style growth patten;because of close encircle of anthers at the pollinating period the papillate cells show a irregular array in spieces which pollination take on, anther encircle and filament protration patten; furrow-shape stigma in spieces which pollination take on pollen flow patten, the accommodation of structure of stigma to pollination process can provide important theoretical foundation to understand that the environmental factors can drive adaptive evolution of charactaristics of flower.3. Saxifraga hirculus L. is an alpine subnival plant and has a wide circumpolar distribution。The present study aimed to investigated the mating system of an endemic plant experiencing extreme ecological conditions. The plants are 6.64±0.73 cm (n=40) tall and slender, with a main stem 6.33±0.86 cm (n=40) long and 0.10±0.01 cm (n=40) wide. At our study sites, Saxifraga hirculus L. flowered from July to August. The blooming period at sites with only 3800m altitude is about 10 days longer than that at the sites with 3500m. Deep concave of stigmas with a lot of columned papillar and oily pollenkitt make more and more pollen contact with stigmas. We also study the breeding system of this species, the results show that autonomous selfing providing reproductive assurance in rough weather condition and no pollen limitation in quantity. There is significantly difference between hand self pollination and hand out pollination in seed production indicates that the quality of self pollen is lower than outcross pollen and self pollination can result in inbreeding depression. No effective pollinators were found. This charactatistics of S. hirculus L. indicate that as a glacial relict, S. hirculus L. has developed well capacity for delayed autonomous selfing though this species retains parts of characteristics of outcrossing from its ancestor.ALL in all, this sduties indicated that in the high arctic and alpine area, because of harsh weather condition and scrace of pollination-inserts, the plants can take autonomous self-pollinatin to achieve reproductive success, and this pollinating mode is of most importance to accommodate to high cold envirement for plant, to further studies in the pollination biology of subapine plants are theoretical basic to reveal the evolution of self-pollination of alpine subnival plants.