香根草光合特性对水淹-干旱交替胁迫的响应

三峡水库消落带因水位的周期性变化,使其土壤含水量呈干湿交替变化,而大多数原有植物难以适应新的生境,导致生态系统严重破坏。利用盆栽法模拟其水淹条件,以30,60,90和120d为周期进行水淹—干旱交替处理,研究了香根草当年实生幼苗在水淹与干旱交替胁迫下的光合特性及生理生态适应机制。结果表明,不同胁迫周期的水淹—干旱交替胁迫均显著影响香根草幼苗的生长及其光合生理特性。各组幼苗的株高、净光合速率、气孔导度及叶绿素含量等生理生态学指标均随时间变化呈不同幅度的升降变化。而不同组间的各项指标值均随交替周期的增大而减小。但无论何种变化,各处理组最终又都能逐渐恢复或趋于稳定状态,保持较高的存活率。因此,香根草对水淹和干旱均具有良好的耐受力和适应性,可作为三峡库区消落带植被恢复建设的重要植物种类。

Respones of Physiological Adaptability of Vetiveria Zizanioides on Alternating Flooding-Drought Stress

Due to the periodical water level change of the hydro-fluctuation belt in Three Gorges reservoir area, soil of the hydro-fluctuation belt repeatedly experienced the process of flooding-drought. Thus, most of the original plants were difficult to adapt to the new habitat and that lead to seriously damage of the original ecosystems in the hydro-fluctuation belt. This research imitated the regular pattern of soil moisture condition of the hydro-fluctuation belt in Three Gorges reservoir area and investigated the photosynthetic physiological characteristics and ecological adaptation mechanism of Vetiveria zizanioides under alternating flooding-drought stress with four treatments in 30, 60, 90, and 120 d as cycles. Results showed that different alternating flooding-drought stress significantly affected growth and photosynthetic physiological characteristics of Vetiveria zizanioides seedlings. Plant height, net photosynthetic rate, stomatal conductance, and chlorophyll content physiological variables of each group showed different trends with time. Meanwhile, the alternating cycle was greater, the variation was greater. Whatever, each group eventually can gradually restore or stabilize the state, to maintain a high survival rate. Therefore, Vetiveria zizanioides have a good tolerance and adaptability to flooding and drought. It can be chosen as a plant species for ecological construction in Three Gorges reservoir area.