水淹对三峡库区两种岸生植物秋华柳(Salix variegata Franch.)和野古草(Arundinella anomala Steud.)水下光合的影响

Underwater photosynthesis of the riparian plants Salix variegata Franch.and Arundinella anomala Steud.in Three Gorges reservoir region as affected by simulated flooding

为了阐明水淹对三峡库区岸生植物秋华柳(Salix variegata Franch.)和野古草(Arundinella anomala Steud.)水下光合作用的影响,模拟三峡库区消落带水淹发生情况,考察了在不同水淹处理下秋华柳和野古草的水下光合。实验设置了对照(不进行水淹,常规供水管理)和2m深度水淹(植株置于水中,植株顶部在水面下2m)2个不同的水淹深度和5、15、20、40d和60d等5个不同的水淹时间处理,采用Chlorolab-2液相氧电极(英国Hansatech公司生产)测定了在不同水淹时间和水淹深度处理下秋华柳和野古草的水下光合作用。实验结果表明:(1)水淹60d后,秋华柳和野古草的存活率均为100%,而典型的陆生植物香樟和马唐分别在水淹40d和15d后全部死亡。(2)在相同的水淹时间和水淹深度下,秋华柳和野古草的水下光合速率(放氧速率)显著高于典型的陆生植物(香樟(Cinnamomumcamphora(L.)Presl.)和马唐(Digitariasanguinalis(L.)Scop.))(3)在长期水淹的条件下,秋华柳和野古草仍具有水下光合的能力。在水淹60d后,水淹2m的秋华柳和野古草植株的水下放氧速率显著低于对照植株的水下放氧速率,但仍具有水下光合的能力,其水下光合速率分别为0.202μmol.m-.2s-1和0.139μmo.lm-.2s-1。同时,研究也表明在水淹40d和60d后,秋华柳表现出比野古草强的水下光合能力。研究表明,秋华柳和野古草在存活率和水下光合方面对长期水淹表现出良好的适应性,是可以用于三峡库区消落区植被构建的优良植物物种。

To reveal the effects of flooding on underwater photosynthesis of riparian plant species Salix variegata Franch. and Arundinella anomala Steud. in Three Gorges reservoir region, a flooding simulation experiment was conducted and the underwater photosynthesis of S. variegata and A. anomala was analyzed. Two flooding-depth levels and five flooding durations were set in the experiment. Two flooding-depth levels included ： control and submerged with 2m water depth （ top of plants 2m below water surface）. Five flooding durations included： 5 days, 15 days, 20days, 40 days and 60 days. The underwater photosynthesis was determined by Chlorolab-2 oxygen electrode produced by Hansatech Company in England. The results showed that： （ 1 ） After 60d inundation, all submerged S. variegata and A. anomala were 100% survived, but two kinds of typical terrestrial species （ Cinnamomum camphora （ L. ） Presl and Digitaria sanguinalis （ L. ） Scop. ） died of inundation after 40 d and 15 d, respectively. （2） With the same flooding durations and flooding-depth levels, the underwater photosynthetic rates （ release of oxygen） of S. variegata and A. anomala were significantly higher than those of two typical terrestrial species （ C. camphora and D. sanguinalis ）. （ 3 ） After long-term inundation, S. variegata and A. anomala could maintain photosynthetic capacity. After 40 d and 60 d inundation, the underwater photosynthesis of S. variegata and A. anomala submerged with 2 m water depth was significantly lower than that of control plants, but （ submerged plants） still had underwater photosynthetic capacity, the values of photosynthetic rate were 0.202 μmol· m^ -2· s^-1 and 0. 139 μmol· m^-2·s^-1, respectively. It was also found that after long-term inundation, the underwater photosynthetic rate of S. variegate was higher than A. anomala. Our work shows that as regards survival rate and underwater photosynthesis, S. variegata and A. anomala have high adaptation to inundation, they are promising species for revegetation of riparian area in Three Gorge reservoir region.