切除顶技对加拿大伊乐藻生长的影响

切除5cm顶枝使加拿大伊乐藻生物量立即下降28%,净光合作用速率(Pn)和植株光合作用产量(PhP)与对照相比立即下降50%以上,去顶也对各种生长指标造成不同程度的即时损伤。经过随后28d的生长试验后,处理组与对照相比,生物量和总枝长(主枝+侧枝)增长率分别下降45%和53%,主枝伸长几乎停止;侧枝(分枝)数增长略有下降;水分含量明显增加;试验期间Pn平均下降了40%,PhP平均下降了51%.表明去顶对生物量增长、主枝伸长和冠层的发育有明显的抑制,对分枝数没有明显的影响。光合产量较生物量增长幅度的下降明显要大,其恢复去顶前水平的时间也比后者要长一倍。根据结果,讨论了去顶对沉水植物生长的影响机制、沉水植物的恢复能力并和其它收获试验进行了比较。  

EFFECTS OF APEX CUTTING ON GROWTH OF ELODEA CANADENSIS ST. JOHN

The 5cm cut of apex of Elodea canadensis St.John caused a decrease ofbiomass by 28% synchronically. Both net photosynthetic rate (Pn) and photosyntheticproduction (PhP) of the shoot decreased by more than 50% when compared with thecontrol. The immediate decrease of biomass, length, Pn and chlorophyll a after cuttingwere observed to be different in percentage. During the 28 days of growth experimentafter cutting, when compared with the control, the growth of biomass and total shootslength (main shoot lateal shoots) decreased by 45% and 53% respectively. Theelongation of the main shoot was nearly terminated, segmentation of shoots reducedslightly and water content increased significantly. Pn and PhP decreased in average by31% and 51% respectively. Growth of PhP reduced more in Percentage than that ofbiomass. It tOOk 21 days for PhP and 10 days for biomass to reach their preharvestlevels, 2 times longer for PhP than for biomass to recover. It is indicated that afterthe immediate decrease of the growth indices, growth of E. Canadensis decreasedconsequently. The increase of biomass, elongation of the main shoots and thedevelopment of the canopy were inhibited significantly by the cut of the apex,Nevertheless, no marked effects were found on segmentations of shoots. Themechanism of cutting on growth and recovery of submersed macrophytes wasdiscussed based on the current results and in comparison with literature.