尖瓣海莲幼苗对模拟潮汐淹浸时间的适应性研究

Study on the Adaptability of Bruguiera sexangula var.rhynchopetala Seedlings to Simulated Tidal Inundation

室内模拟不同潮汐淹浸时间对红树植物尖瓣海莲幼苗生长的影响，测定植物生理指标（包括叶绿素、超氧化物歧化酶、游离脯氨酸、丙二醛、硝酸还原酶、电导率、根活力等）、生长量和生物量。半年的试验结果表明：叶绿素、根活力和硝酸还原酶随淹浸时间的延长先升后降，而游离脯氨酸、丙二醛和相对电导率随淹浸时间的延长先降后升，并在12h·d^-1处出现骤变分界点；淹浸时间超过16h·d^-1后，尖瓣海莲胚轴发芽率下降，超过14h·d^-1后尖瓣海莲幼苗部分死亡，淹浸24h·d^-1苗木全部死亡；淹浸逆境对幼苗叶片影响最大，叶片数月均增长最大者（淹浸4h·d^-1）比月均增长最小者（淹浸24h·d^-1）增加了450％；总生物量、茎及主根的生物量均在淹浸6h·d^-1处理下最大，当淹浸超过12h·d^-1后，尖瓣海莲幼苗总生物量骤降。结合适应度分析得出：尖瓣海莲的最适淹浸时间为6～8h·d^-1，临界淹浸时间为12h·d^-1。

A greenhouse experiment on the influence of simulated tidal inundation on the growth of Bruguiera sexangula var. rhynchopetala seedlings was conducted and some physiological and growth indexes of the seedlings, including chlorophyll, superoxide dismutase, proline, malondialdehyde, nitrate reductase, electrical conductivity, root activity, were measured. The half-year-experimental results showed that the chlorophyll, root activity and nitrate reductase rose at first and fell later while proline, praline, malondialdehyde and electrical conductivity fell at first and rose later during the period of the tidal inundation, and a sudden change occurred at 12 h ·d^-1 of the inundation. The germination percentage of hypocoty would decrease at more than 16 h · d^ -1 of the tidal inundation. Part of the seedling would die at more than 14 h ·d^-1 of the inundation, and the whole plant died at 24 hr of the tidal inundation per day. The leaves were affected most severely under waterlogging adverse circumstance, for example, the mean of leaves number per month at 4 h · d^-1 of tidal inundation was 450% more than that at 24 h ·d^-1 of tidal inundation. The maximum values of the total biomass, dry biomass of stem and dry biomass of taproot were got at 6 hours of tidal inundation per day, while the total biomass dropped suddenly when the tidal inundation was prolonged to12 h ·d^-1. It concluded that 6-8 h ·d^-1 of tidal inundation is most suitable to the growth ofB. Sexangula var. rhynchopetala seedlings, and 12 h ·d^-1 was a critical tidal inundation time when the plant responded to be obviously inadaptable.