模拟及河道实验浮床水芹根系生长及生物量分配对比研究

为了对比研究浮床植物水芹菜在模拟及野外河道实验中根系生长及生物量分配的差异性,探索水芹浮床模拟实验与实际应用中的差异性,我们在实验河道边放置水箱,通过抽取河水到水箱中设置水芹浮床水箱模拟实验,并且与河道中水芹浮床实验作对比。结果发现:河道和水箱中植物根系指标除了平均根直径外其他指标随着水芹的生长以指数方式增长,平均根直径随着水芹的生长以指数方式下降;在根系总长度、根系总表面积、根系分叉数、根系交叠数方面,水箱中的水芹显著大于河道中的水芹(p0.05);水箱浮床水芹根系指标的增长速度大于地上部分的增长速度,河道中水芹地上部分增长速度要大于地下部分;水芹冠根比随时间的变化呈现出先下降后上升趋势,水箱中水芹冠根比的变化速率更小。水箱中的水芹受到了营养条件的限制,用模拟水芹浮床来研究其净化效率时,在一定程度上(与实际应用相比)高估了河道水芹浮床根系部分的作用。

COMPARISON OF ROOT SYSTEM GROWTH AND BIOMASS ALLOCATION BETWEEN WATER TANK AND RIVER EXPERIMENT FOR WATERCRESS (OENANTHE JAVANICA (BLUME) DC) FLOATING BED

We conducted comparative experiment for watercress floating bed between water tank and river to investigate the difference in root growth and biomass distribution. The water in tank was pumped from the river. We aimed to explore the difference in plant growth between controlled experiment and practical application of watercress floating bed. The results showed that:Most root parameters of watercress showed an exponential increase trend in river and water tank while average root diameter showed decreases trend with time. Total root length, total root surface area, number of root branch, and number of root overlaps were all significantly higher in tanks than in river (p<0.05). The root mass of watercress in tanks showed a faster growth speed than the above water biomass which is contrary to the growth speed between above and under water biomass in river. The crown-root ratio showed a downward and then upward trend with time. But the rate of change in tanks is smaller than that in river. The above founding indicates that watercress in the tanks may be faced with nutrient limitations, which can result in overestimation of nutrient removal of watercress floating bed root system in river.