Water-use strategies of two desert plants along a precipitation gradient in northwestern China
Water-use strategies of two desert plants along a precipitation gradient in northwestern China
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DOI：
10.3724/sp.j.1258.2011.00789
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发表时间：
2011-08
影响因子：
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通讯作者：
Guanghui Lin;L. Qi;Shiping Chen;Wei-Min Song;Ya-Dan Zhou
中科院分区：
文献类型：
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作者：
Guanghui Lin;L. Qi;Shiping Chen;Wei-Min Song;Ya-Dan Zhou
目的 在干旱和半干旱地区，降水是植物最重要的水源。我们的目的是研究中国西北部降水梯度上两种主要沙漠植物的水分利用策略。方法 对不同年降水量的三个研究点（内蒙古自治区杭锦旗、磴口县和甘肃省民勤县）的油蒿和白刺茎水以及潜在水源（雨水、地下水和土壤水）进行稳定氢氧同位素组成测定。然后使用 IsoSource 模型计算潜在水源对植物总吸水量的可能贡献。我们还测定了两个物种的叶碳同位素比和游离脯氨酸含量，以表明水分利用效率和渗透调节能力。重要发现 在杭锦旗地区（年降水量最高），两种物种从浅层土壤中获取的水分比例最高，而油麦则主要从 0-50 厘米土层吸收水分。但磴口、民勤等地年降水量较少，主要依靠深层土壤水或地下水。两种物种的水分利用效率都随着年降水量的增加而下降。油麦碳同位素比值与游离脯氨酸含量呈正相关。这些结果表明，沙漠植物可以根据自然降水的变化来调整其从不同水源吸收的能力和其他生理特性，但这些策略是特定于物种的。
Aims In arid and semiarid regions, precipitation is the most important water source for plants. Our objective was to investigate the water-use strategies of two dominant desert plants along a precipitation gradient in northwestern China. Methods We determined stable hydrogen and oxygen isotope compositions of the stem water from Artemisia ordosica and Nitraria tangutorum and potential water sources (rain water, groundwater and soil water) at three study sites with different annual precipitation (Hanggin Banner and Dengkou County of Inner Mongolia Autonomous Region and Minqin County of Gansu Province). The IsoSource model was then used to calculate probable contributions of potential water sources to total plant water uptake. We also determined foliar carbon isotope ratios and free proline contents of both species to indicate water use efficiency and osmotic-adjustment ability. Important findings At the Hanggin Banner site (highest annual precipitation), both species obtained the highest proportion of water from shallow soil water and A. ordosica took up water mostly from the 0–50 cm soil layer. However, they depended mainly on deep soil water or groundwater at the Dengkou and Minqin sites with lower annual precipitation. The water use efficiency of both species decreased with increasing annual precipitation. There was a positive correlation between carbon isotope ratio and free proline content in A. ordosica. These results suggest that desert plants can adjust their capabilities for up-take from different water sources and other physiological properties with variation in natural precipitation, but the strategies are species-specific.