He J B, Bögemann G M, van de Steeg H M, Rijnders J G, Voesenek L A, Blom C W
Department of Ecology, University of Nijmegen, Toernooiveld 1, 6525 ED Nijmegen, The Netherlands e-mail:
Oecologia. 1999 Jan;118(1):1-8. doi: 10.1007/s004420050696.
The flooding resistance of four Ranunculus species was studied under controlled conditions and related to the tactics used by these species to survive in their natural habitat in river floodplains. R. bulbosus, a species from seldom-flooded river levées, was relatively intolerant of both waterlogging and complete submergence, due to a constitutively low level of aerenchyma in the root system. This lack of gas spaces resulted in high mortality rates during flooding treatments and an inability to use photosynthetically derived oxygen for root respiration during complete submergence. The pioneer R. sceleratus, predominantly abundant in low lying mudflats, was very resistant to waterlogging and shallow floods. Due to its constitutively high root porosity and its ability to greatly increase the elongation rate of petioles under water this species can ameliorate flooding stress. However, when leaf blades of R. sceleratus were unable to reach the water surface, this species died as quickly as the flooding-intolerant R. bulbosus. This indicates that fast elongation of petioles under water competes for energy and respirable reserves with maintenance processes. R. repens, a species from lower, frequently inundated floodplains, was very tolerant of prolonged waterlogging and submergence. Its high resistance to complete submergence under continuous darkness indicates that this species tolerates hypoxic and/or anoxic tissue conditions via metabolic adjustments. Lysigenous aerenchyma was also induced in the primary root system and in newly developed laterals, and it was able to use oxygen generated by underwater photosynthesis, for root respiration. R. acris, a species from less frequently flooded areas, was as resistant to waterlogging and submergence in the light as R. repens. However, it has a lower resistance than R. repens to complete submergence in the dark. A submergence pre-treatment increased the maximum net underwater photosynthetic rate in R. bulbosus, whereas a significant decrease of light compensation points was observed in R. repens when it had previously been submerged. This study shows that Ranunculus species exhibit various strategies to cope with different flooding conditions. R. repens responds to flooding by its tolerance mechanism and R. sceleratus by avoidance. R. acris ameliorates submergence and R. bulbosus was not able to adapt high water tables.
在可控条件下研究了四种毛茛属植物的抗涝性，并将其与这些物种在河漫滩自然栖息地的生存策略相关联。球根毛茛是一种来自很少被洪水淹没的河岸阶地的物种，由于其根系中通气组织的组成水平较低，对涝渍和完全淹没都相对不耐受。这种气体空间的缺乏导致在淹水处理期间死亡率很高，并且在完全淹没期间无法利用光合作用产生的氧气进行根系呼吸。先锋植物石龙芮主要生长在低洼的泥滩中，对涝渍和浅洪水具有很强的抗性。由于其根系具有较高的孔隙率，并且能够在水下极大地提高叶柄的伸长率，该物种可以缓解淹水胁迫。然而，当石龙芮的叶片无法到达水面时，该物种死亡的速度与不耐淹的球根毛茛一样快。这表明叶柄在水下的快速伸长与维持过程争夺能量和可呼吸储备。匍匐毛茛是一种来自较低的、经常被淹没的河漫滩的物种，对长期涝渍和淹没具有很强的耐受性。它在连续黑暗条件下对完全淹没的高抗性表明，该物种通过代谢调节来耐受缺氧和/或无氧的组织条件。溶生性通气组织也在初生根系统和新发育的侧根中被诱导产生，并且能够利用水下光合作用产生的氧气进行根系呼吸。锐齿毛茛是一种来自较少被洪水淹没地区的物种，在光照条件下对涝渍和淹没的抗性与匍匐毛茛相同。然而，在黑暗中它对完全淹没的抗性低于匍匐毛茛。淹水预处理提高了球根毛茛的最大净水下光合速率，而当匍匐毛茛先前被淹没时，其光补偿点显著降低。这项研究表明，毛茛属植物表现出各种应对不同淹水条件的策略。匍匐毛茛通过其耐受机制对淹水做出反应，石龙芮通过回避反应。锐齿毛茛缓解淹没，而球根毛茛无法适应高水位。
