中文摘要：

选取磴口、民勤唐古特白刺,敦煌东湖附近洪积扇中部、底部生长的泡泡刺为研究对象,通过叶片扫描与Image-Pro Plus6.0图像处理软件分析获得叶片形态参数（长、宽、周长和面积）,应用同位素分析获得叶片δ13C值。结果表明：随着水分有效性的增加,白刺叶片面积具有增加趋势,叶片面积在增加过程中,叶片长、宽增幅具有非同步性;相同叶片宽度,生长于水分条件较好地区的唐古特白刺和泡泡刺叶片更长。虽然磴口、民勤及敦煌东湖附近洪积扇中部、底部水分环境存在较大的差异,但生长于这些区域的唐古特白刺及泡泡刺叶片δ13C值的差异不显著（P〉0.05）。叶片周长/面积比是连接叶片形态变化与植物水分生理的重要因子;白刺叶面积增加过程中,叶片长度的优先增加有利于减缓周长/面积比的下降速率,从而使白刺保持较高的水分利用效率。

英文摘要：

Leaf shapes are not only useful indicators in plant taxonomy, but also important factors affecting energy and material exchange in leaves. In this paper, we collected and scanned the leaves of Nitraria tangutorum in Dengkou and Minqin and N. sphaerocarpa in Dunhuang, and then analyzed leaf shape parameters with Image - Pro Plus6.0 image processing software and leaf 8-3C values in the isotope laboratory of the Chinese Academy of Forestry. The result showed that： 1 ） as leaf area increased with increasing water availability the increases in the leaf length and width were asynehronously. 2） with the same leaf width, the leaves of N. tangutorum and N. sphaerocarpa were significantly longer in high water available conditions. 3 ） although there were significantly differences in water availability between Dengkou and Minqin, as well as between the bottom and middle of the alluvial fan near the East Lake in Dunhuang, the leaf 8t3C values of N. tangutorum or N. sphaerocarpa were similar in different water conditions （P 〉 0.05）. Our results suggested that the ratio of leaf perimeter to area would be an important factor which linked leaf shape to plant water physiology. During growing procedure of leaf area, leaf length increase was prior to its width to alleviate the reduction in ratio of perimeter to area and maintain water use efficiency of the plant.