Flooding‐induced adventitious rooting in Rumex: morphology and development in an ecological perspective
Flooding‐induced adventitious rooting in Rumex: morphology and development in an ecological perspective
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DOI：
10.1111/j.1438-8677.1996.tb00492.x
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发表时间：
1996-03
期刊：
影响因子：
3.9
通讯作者：
E. Visser;C. Blom;L. Voesenek
中科院分区：
文献类型：
--
作者：
E. Visser;C. Blom;L. Voesenek
通气不定根的形成是许多湿地植物对土壤淹水的形态适应。这些根中有很大的空气空间，有利于气体在茎和根之间的扩散。本文研究了一种属植物的不定根形成，并将其与自然生境的差异联系起来。在近缘种之间，不定根的数量和形态都有很大的差异。在几乎永久浸水的土壤中，不定根生长缓慢，但这些根非常多孔，非常厚。水淹频繁但不持久的古蕨发育出大量不定根，且通气组织含量高。另一方面，在干旱和很少被水淹的生境中生长的thyrsiflorus和R. acetosa的不定根很差，其不定根所含的空气空间很少。在定期淹水草原上生长的一组物种（crispus R.，砾石蒿R., obtusifolius）对土壤淹水表现出中等响应。两种对照品种palustris和R. thyrsiflorus在涝渍发生后2天内出现不定根。尽管这两种植物不定根的发生时间相似，但与植株年龄无关，palustris的初生侧根在1周内完全被不定根所取代。而淹水1周后的三叶草不定根生物量从未超过初生侧根生物量的1 / 3。结果表明，植物在水淹土壤条件下形成不定根的能力及其根系的适应特征与其自然生境中发生水淹的频率密切相关。不同种间不定根的差异主要表现在根的数量、生长速度、形态和解剖结构上，而不表现在出芽时间上。
SUMMARY The formation of aerenchymatous adventitious roots is a morphological acclimation to soil flooding in many wetland plants. The large air spaces in these roots facilitate the diffusion of gases between shoot and root. This study investigated adventitious root formation in species of the genus Rumex, and related the differences between species to the natural habitat of the species. Large differences in both the number and the morphology of the adventitious roots were found between closely related species. R. hydrolapathum, a species of almost permanently waterlogged soils, showed only a slow growth of adventitious roots, but these roots were extremely porous and very thick. R. palustris, which is flooded very frequently but not permanently, developed a large number of adventitious roots with a high content of aerenchyma. On the other hand, adventitious rooting in R. thyrsiflorus and R. acetosa, which are species of dry and seldom flooded habitats, was rather poor and the adventitious roots contained only very little air space. A group of species occurring in regularly flooded grasslands (R. crispus, R. conglomeratus and R. obtusifolius) showed an intermediate response to soil flooding. Two contrasting species, R. palustris and R. thyrsiflorus, showed emergence of adventitious roots within 2 days after the onset of waterlogging. Although the time of onset of adventitious rooting was similar in these two species, the primary lateral root system of R. palustris was completely replaced by adventitious roots in 1 week, independently of the age of the plants. In contrast, the biomass of adventitious roots in R. thyrsiflorus after 1 week of flooding was never more than one-third of the biomass of the primary lateral root system. We concluded that the ability of species to form adventitious roots during flooded soil conditions and the adaptive characteristics of these roots were very closely related to the flooding frequency of these species in their natural habitat. Differences in adventitious rooting between species mainly occurred in the number, growth rate, morphology and anatomy of the roots, and not in the timing of emergence.