Plant regrowth capacity and soil protection were investigated using three flooding-tolerant Yangtze River riverside species (Arundinella anomala, Hemartria compressa and Cynodon dactylon). The root and leaf surface growth, the plant regrowth capacity and the mitigation of soil runoff were analyzed using potted plants that were covered with 5, 10 and 18 cm new sediments, respectively. A. anomala reacted most slowly to the recovery from new sediments, while H. compressa had the highest recovery rates. The latter could produce 24 times the initial root length and 41 times its original leaf surface during the growth period of 12 weeks. C. dactylon showed no significant change in growth in relation to the rising sediment thickness, which means that even 18 cm of new sediments were tolerated by C. dactylon. Erosion tests showed that all three plant species can reduce the soil runoff by more than 63%. Compared to other species, A. anomala was less capable of stabilizing new sediments. The soil protecting abilities of H. compressa decreased after more than 10 cm of new sediments. C. dactylon showed the best soil retention compared to the other species examined, since it could reduce the soil runoff up to 87%. Consequently, C. dactylon was found to be significantly better for soil-protection plant species than A. anomala and H. compressa given the conditions at the Three Gorges Reservoir.
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。
