关键词: 线粒体COI基因, 遗传结构, 生活史, 海蜇, 遗传特征

Abstract: The establishment and maintenance of artificial ecological barriers in arid areas require drip irrigation to replenish water to plants on artificial shelterbelt. However, continuous drip irrigation leads to the accumulation of salt in the surface soil, which would threaten the growth and ecological function of artificial shelterbelts. To examine the effects of drip irrigation on leaf nutrient characteristics and water use strategies of desert plants in arid regions, we measured leaf nutrient content, water use efficiency, stable hydrogen isotope (δD) and stable oxygen isotope (δ¹⁸O) values of stem water and assessed potential water sources (soil water and groundwater) of Tamarix ramosissima growing in the shelterbelt and natural communities on the southern margin of the Taklimakan Desert. The results showed that the utilization rate for middle-layer soil water (40-100 cm) in T. ramosissima of the shelterbelt community was higher than that in the natural community, while groundwater was the main water source, indicating that root system of drip irrigated T. ramosissima could reach the groundwater layer. Foliar N and P concentrations of T. ramosissima in the shelterbelt community were significantly higher than those in the natural community, indicating that water supply affected the absorption and transfer of key nutrients. The long-term water use efficiency of T. ramosissima in the shelterbelt community was significantly higher than that in the natural community, which may be related to salt stress caused by irrigation or higher foliar N and P concentrations. The drip irrigation associated salt stress had not caused toxicity to T. ramosissima. After the successful establishment of shelterbelt plants, irrigation can be reduced or stopped, which would facilitate to water conservation and the maintenance of shelterbelt stability.

Key words: Rhopilema esculentum, COI gene, genetic characterization, life-cycle., genetic structure