The distribution of four Caragana species is related to their differential responses to drought stress
The distribution of four Caragana species is related to their differential responses to drought stress
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四种锦鸡儿属物种的分布与其对干旱胁迫的不同反应有关
DOI：
10.1007/s11258-013-0285-8
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发表时间：
2014-01-01
期刊：
影响因子：
1.7
通讯作者：
Li, Feng-Min
中科院分区：
文献类型：
--
作者：
Fang, Xiang-Wen;Turner, Neil C.;Li, Feng-Min
锦鸡儿在中国西北地区分布广泛。然而，内蒙古半干旱地区的物种经历夏季和秋季降雨，而新疆省干旱地区形态相似的近亲经历春季湿润，夏季炎热干燥。我们假设不同物种对土壤干旱的反应差异有助于解释它们的分布。通过对内蒙古半干旱种的中叶卷木和小叶卷木与新疆干旱种的毛叶卷木和棘叶卷木进行盆栽试验，探讨其对水分亏缺的响应是否与生境环境有关。两种半干旱树种的气孔导度对黎明前叶片水势（i -叶）的降低相对不敏感，即使i -叶降低到-6.0 MPa以下，叶片也没有脱落或死亡，而两种干旱树种的幼苗气孔在较高的i -叶处关闭，当i -叶降低到-3.0 MPa左右时，叶片逐渐脱落。与干旱树种相比，半干旱树种主脉密度、次脉密度和小脉管壁厚/管腔宽的立方比[(t/b)(3)]平均分别增加了60%、150%和220%。结果表明，半干旱树种具有典型的各向异性，干旱树种具有典型的等水性。我们认为，该属植物水分利用策略的差异可能与脉结构的变化有关，并可能在确定这些物种在中国西北不同环境中的分布中发挥重要作用。
Caragana species are widespread in northwest China. However, species in semiarid areas of Inner Mongolia experience summer and autumn rainfall, whereas morphologically similar close relatives in arid areas in Xinjiang Province experience wet springs, but hot dry summers. We hypothesize that the differences among species in response to soil drought help to explain their distributions. A comparison of the closely related species C. intermedia and C. microphylla from Inner Mongolia (semiarid species) and C. pruinosa and C. spinosa from Xinjiang (arid species) was conducted to examine whether responses to a water deficit in a pot experiment were associated with the environments of their habitat. In the two semiarid species, the stomatal conductance was relatively insensitive to the decrease in predawn leaf water potential (I-leaf), and leaves did not abscise or die even when the I-leaf decreased below -6.0 MPa, while in seedlings of the two arid species the stomata closed at a relatively high I-leaf, and the leaves abscised gradually when I-leaf fell below about -3.0 MPa. Furthermore, major vein density, minor vein density and the cubed ratio of the conduit wall thickness to the conduit lumen breadth [(t/b)(3)] of minor veins increased by an average of 60, 150 and 220 %, respectively, in the semiarid species compared with the arid species. The results indicated that semiarid species have typical anisohydric properties, while arid species have typical isohydric properties. We suggest that the divergence in water-use strategies in the genus may be associated with variation in vein architecture, and may possibly play an important role in determining the distribution of these species in the different environments of northwest China.