华山新麦草开花物候期观测和自然种群基因流的间接估测

华山新麦草（Psathyrostachys huashanica keng)为我国特有种，仅分布在陕西华山。通过对自然种群传粉物候期观测发现，华山新麦草的传粉高峰期与海拔有一定关系。海拔每升高200m，传粉物候期就推迟2－3d；海拔差异超过500m的亚种群，传粉物候期就不会出现重叠。同时应用等位酶分析技术和E－统计分析间接估测华山新麦草自然种群的基因流（Nm），其值较一般风媒传粉植物低。通过华山新麦草资源状况、生长环境的调查以及移栽试验的观察，认为该物种稀的主要原因之一 可能是其生存竞争能力弱，最终被迫生长在其它物种所不能生存的环境。

POLLINATION PHENOLOGY AND AN INDIRECT ESTIMATE OF GENE FLOW IN NATURALPOPULATIONS OF PSATHYROSTACHYS HUASHANICA

Psathyrostachys huashanica Keng. is a Chinese endemic species whose distribution is restricted to Hua mountain in Shaanxi Province. Flowering phenology studies showed that the timing of peak pollination was related to altitude: flowering was delayed 2 to 3 days for every two hundred meters of elevation. Phenological periods did not overlap with differences between subpopulations of greater than 500 m. The Nm values estimated by E statistics are lower than those reported for other anemophytes. Judging from the results of this survey in combination with observations of the habitat of P. huashanica and transplant experiments, poor competitive ability may be one of the main causes in restricting the distribution of this species.