The effects of flooding on aerenchyma formation in the stem of Arundinella anomala var. depauperata Keng, a riparian plant in Three Gorges reservoir area
三峡库区河岸植物野古草(Arundinella anomala var. depauperata Keng)茎通气组织发生对水淹的响应
摘 要 ：野古草(Arundinella anomala var. depauperata Keng)在三峡库区长江及其支流江(河)岸有广泛分布，对水淹有很好的耐受能力。有研究表明许多植物在水淹时通气组织发生增强，通气组织的产生改善了植株通气状况，提高了植物对水淹的抵御能力。为了研究水淹是否会影响野古草的通气组织发生以及野古草通气组织发生对水淹的反应，考察了不同水淹深度、不同水淹时间和不同水淹方式处理时野古草茎中通气组织的发生情况。实验中共设置3个水淹深度：不进行水淹（对照）、植株地下部分淹没、植株完全淹没于水下2m深处；5个淹没时间：植株被淹没的时间长度分别为5、10、20、30d和60d；2种水淹方式：连续水淹和间歇水淹。实验结果表明：（1）在无水淹情况下野古草茎中可以产生通气组织，通气组织产生随植株的生长而增强；水淹加快了野古草通气组织发生的进程，促进了野古草通气组织的提前发生。（2）野古草茎中通气组织并不会因为水淹的时间越长而产生越多，植株通气组织的大小达到一定程度后不再因水淹时间的增长而继续增大。（3）淹没深度对通气组织发生有一定影响，总的看来，地下部分淹没野古草植株的通气组织发生要强于完全淹没植株。（4）不同水淹方式对野古草通气组织发生的影响因水淹深度不同而有差异。在完全淹没情况下，连续水淹植株的通气组织比间歇水淹植株的通气组织发达；在地下部分淹没情况下，除水淹初期外，随水淹时间的延长，连续水淹植株通气组织发生与间歇水淹植株没有差异。
Abstract:Arundinella anomala var. depauperata Keng, a graminoid species, distributes extensively at riversides of Yangtze and its tributaries in Three Gorges reservoir area, it is able to tolerate the river flooding every year and develop good plant community at the riversides. Some researchers have demonstrated that some plant species can form aerenchyma when flooding occurs, thereby ameliorating the gas transport within plant and enhancing the tolerance to flooding. To reveal whether flooding may affect the aerenchyma formation in A. anomala var. depauperata and the responses of A. anomala var. depauperata to different flooding regimes, the aerenchyma formation in the stems of A. anomala var. depauperata subjected to various water submersion depths, submersion durations, and submersion modes were investigated. In the experiment, 3 submersion depths (non-submersion control, belowground submersion, complete submersion with 2m water depth), 5 submersion durations (5, 10, 20, 30, 60days), 2 submersion modes (continuous submersion and intermittent submersion) were included. It was found in the experiment that: (1) A. anomala var. depauperata can form aerenchyma in its stem under the condition of non-flooding and the aerenchyma size increased gradually as plant grew. Flooding accelerated the formation of aerenchyma in A. anomala var. depauperata plants, and advanced the aerenchyma formation in flooded plants. (2) The aerenchyma formation in A. anomala var. depauperata plants did not continuously increase with the time of submersion, when the aerenchyma reached to a certain size, the aerenchyma formation did not increase though the plants were still flooded. (3) Submersion depth had some effects on the aerenchyma formation of A. anomala var. depauperata, in general, belowground submerged plants had larger aerenchyma than completely submerged plants. (4) The effects of submersion modes on the aerenchyma formation of A. anomala var. depauperata were dependent on submersion depth. Under the condition of complete submersion, continuously flooded plants had larger aerenchyma than intermittently flooded plants. However, as to belowground submersion, except at the initial period of flooding, continuously flooded plants did not show any difference in aerenchyma size as compared to intermittently flooded plants.