中文摘要：

种子中营养物质的含量及其组成对种子的萌发及幼苗建植发挥着各自的作用，因此其含量的差异可能导致种子采取不同的萌发及幼苗生长对策。为了探讨植物种子中营养物质含量是否随着海拔梯度的变化而产生适应性变化，本研究以青藏高原东北缘甘肃省藏族自治州境内常见的227种植物种子为研究材料，用索式提取法、蒽酮比色法和考马斯亮蓝G一250法分别测定了种子中主要营养成分——粗脂肪、可溶性糖、淀粉和蛋白质的含量，分析了植物种子中主要营养成分含量与海拔之间的关系。结果表明：无论种内还是种间，种子中都在高海拔有较高的脂肪和可溶性糖、较低的蛋白质含量，而淀粉含量没有明显的变化规律。随着海拔的升高，温度逐渐降低，植物种子中储藏较多的脂肪和可溶性糖、较少的蛋白质，可以为种子萌发和幼苗的初始生长提供足够的能量以抵御严寒的环境。因此，这可能是植物应对高寒环境的一种适应性选择。研究结果为进一步探讨高寒草甸植物在种子水平上的适应机制及其进化适应意义提供了理论依据。

英文摘要：

The components and contents of main seed reserves are very important to seed germination and subsequent seedling establishment. The different seed germination and seedling growth strategies might be shaped by the difference in contents of seed reserves due to their different functional effects. In this study, the main reserve contents in seeds of 227 species on the northeastern Tsinghai-Tibet Plateau was analyzed, which could provide a theoretical basis for adaptability of alpine plants. The contents of crude fats were determined by Soxhlet extraction with petroleum （60-90 ℃ ） as solvent for 8 hours; the contents of soluble sugar and starch were determined by anthrone colorimetric method; protein contents were obtained by Coomassie Brilliant Blue G-250. The results showed that regardless of intraspecific and interspecific variation, the contents of crude fats and soluble sugar were higher and the protein content was lower at high altitude, and the starch content had no obvious change with increasing altitude. Due to the decreased temperature with increasing altitude, relatively higher percentages of fats and soluble sugars in seeds at higher altitude might provide enough energy for seed germination and initial growth of seedlings. Therefore, this pattern might be an adaptive selection to alpine environment.