暗紫贝母的繁殖器官在海拔梯度上的变异

Reproductive organ variation in Fritillaria unibracteata along an altitudinal gradient

在青藏高原东部的一个高山坡面上,沿着海拔设置高、中、低3个海拔部位,并在高、低海拔之间进行暗紫贝母植株的对换移植实验,然后测定各部位的生态因子、暗紫贝母植株花、果实和种子的特征。结果表明,1)生态因子中积雪融化时间、气温及土壤含水量在各海拔之间有明显的差异;2)花部特征中花被片的长度和宽度,雄蕊花药和花丝的长度,花柱和柱头裂片的长度都是高海拔部位最长,低海拔部位最短;3)对花生物量来说,高海拔部位比低海拔部位大39.4%;从花与地上部分二者生物量的比率来看,高海拔部位比低海拔部位大12.3%,两个指标都是高海拔部位排名第一;4)单粒果实重以低海拔部位最重,达到1282 mg,比高海拔部位大48.3%;5)单粒果实种子数以高海拔部位最少,比低海拔部位少了38.1%;6)高海拔部位的种子百粒重达到142.3 mg,而低海拔部位种子百粒重只有94.6 mg。移植实验进一步验证了上述的测定结果,这说明暗紫贝母繁殖器官确实要受海拔的影响,而且主要跟海拔梯度上的融雪时间、气温(尤其是零下低温)、紫外线强度、访花昆虫等有关。

Three sites (high,medium and low altitude)were established in an alpine mountainous region in the eastern Tibetan Plateau.The reproductive organs of Fritillaria unibracteata at each site were measured.A transplant experiment using F .unibracteata was also carried out;plants from low altitude were transferred to the high site and plants from the high site transferred to the low altitude site.Ecological factors such as snow-melt duration,air temperature,soil water content and soil pH were measured.Reproductive organs including flower,fruit and seed of F .unibracteata were also measured.Snow-melt duration,air temperature and soil water content differed among the different altitudinal sites significantly.Snowpack at the low site melted earlier than those at the other two sites;average air temperature (in March,April and May)at the low site was higher than the other two sites;however soil water content at the low site was the lowest.The highest values for pet-al length and width,filaments,anthers,styles and style ramifications were measured at the high site and the least at the low site.Flower biomass at the high site was 39.4% heavier than that at the low site,and the ratioof flower biomass to aboveground biomass at the high site was 12.3% higher than that at the low site.Dry weight per fruit at the low site was 48.3% heavier than that at the high site,reaching 1282 mg.Seed number per fruit at the high site was the lowest,38.1% less than that at the low site.The 100-seed weight at the high site was 142.3 mg,94.6 mg at the low site.The transplant experiment verified the results described above. We concluded that the reproductive organs of F .unibracteata were significantly affected by altitude factors, particularly snow-melt duration,air temperature (especially sub-zero temperatures),ultraviolet light and in-sect pollinators.