Visser E J W, Bögemann G M, VAN DE Steeg H M, Pierik R, Blom C W P M
1 Department of Experimental Plant Ecology, University of Nijmegen, 6525 ED Nijmegen, The Netherlands.
New Phytol. 2000 Oct;148(1):93-103. doi: 10.1046/j.1469-8137.2000.00742.x.
The flooding tolerance of Carex species was studied in relation to their field distribution and their capacity to form root aerenchyma under controlled conditions. In an alpine meadow, six Carex species were selected which were distributed in a clear zonation correlating with water content of the soil. Carex sempervirens and C. ferruginea were only found on nonflooded soil, the latter species preferring moister conditions. Carex davalliana and C. nigra were both associated with water-saturated soil, whereas C. limosa and C. rostrata preferred partially submerged conditions. Carex davalliana and C. limosa were bound to flooded soils with a relatively high redox potential and horizontally flowing groundwater. Carex rostrata and C. nigra grew in stagnant soil-flooded conditions with low soil redox potentials. The amount of aerenchyma in the roots of all species increased when grown in oxygen-deficient stagnant agar. This increase in root porosity, combined with increased root diameter, presumably improved internal aeration of the roots. Although all species survived experimental soil flooding, partial submergence was lethal to C. sempervirens and, surprisingly, also to the wetland species C. davalliana. Carex ferruginea showed a reduced growth rate during partial submergence. The three other species, all wetland plants, reached highest biomass production under soil-flooded and partially submerged conditions, with slower growth on free-draining soil. It is concluded that aerenchyma is not constitutive in the Carex species under study, and is best developed in Carex species from wetlands. Species with less aerenchyma perform poorly when soil-flooded, but conditions of partial submergence could even affect species with a considerable amount of root aerenchyma.
研究了苔草属物种的耐淹性与其野外分布以及在受控条件下形成根通气组织的能力之间的关系。在一个高山草甸中，选择了六种苔草属物种，它们的分布呈现出与土壤含水量相关的明显带状分布。常绿苔草和锈苔草仅在非淹水土壤中发现，后者更喜欢较湿润的条件。Davalliana苔草和黑苔草都与水饱和土壤相关，而沼苔草和喙苔草更喜欢部分淹没的条件。Davalliana苔草和沼苔草生长在氧化还原电位相对较高且有水平流动地下水的淹水土壤中。喙苔草和黑苔草生长在土壤氧化还原电位较低的积水淹水条件下。当所有物种在缺氧的静止琼脂中生长时，其根中通气组织的数量都会增加。根孔隙率的这种增加，再加上根直径的增加，可能改善了根的内部通气。尽管所有物种都在实验性土壤淹水条件下存活了下来，但部分淹没对常绿苔草是致命的，令人惊讶的是，对湿地物种Davalliana苔草也是如此。锈苔草在部分淹没期间生长速率降低。其他三种物种，都是湿地植物，在土壤淹水和部分淹没条件下生物量产量最高，在排水良好的土壤上生长较慢。得出的结论是，在所研究的苔草属物种中，通气组织并非固有存在，在湿地苔草属物种中发育最好。通气组织较少的物种在土壤淹水时表现不佳，但部分淹没条件甚至可能影响具有大量根通气组织的物种。
