关键词: 红树植物, δ¹³C值, 水分利用效率

Abstract:

We determined the δ¹³C values of leaf samples collected from plants belonging to 6 genera in the Rhizophoraceae family grown in four locations in China, including three coastal areas (Dongzhaigang of Hainan Province, Xiamen of Fujian Province, Beihai of Guangxi Zhuang Autonomous Region), and one inland area (Xishuangbanna of Yunan Province) in May and September, 2002. The nine plant species included Carallia brachiata, C. diphopetala, Pellacalyx yunnanensis, Rhizophora apiculata, R. stylosa, Bruguiera sexangula, B. gymnorhiza, Kandelia candel, and Ceriops tagal. The results indicated that leaf δ¹³C values, corresponding to integrated wateruse efficiency (WUE) (ratio of CO₂ assimilation rate to leaf transpiration), ranged from -32‰ to -26‰, but did not vary significantly between May and September in most of those plant species. However, there were significant differences in leafδ¹³C values among growing environments with lower foliar δ¹³C values for the plants grown in the inland than those in the coastal areas on two sampling dates, indicating a higher intercellular CO₂ concentration and thus a lower water use efficiency for the plants grown in the inland. In addition, among those plants living in the coastal areas, the leaves of plants grown in the Beihai had the highest δ¹³C values indicating the lowest intercellular CO₂ concentration and thus highest WUE, which may be caused by the high salt content in the seawater or high water stress in Beihai. Our results suggest that the foliar δ¹³C values of the plants in the Rhizophoraceae family could be highly affected by intermittent environmental factors, although their genetic characteristics may play a significant role in determining their foliar δ¹³C values.

Key words: Rhizophoraceae, δ¹³C values, Water use efficiency