The Effect Of Flooding On The Reproduction Of Arundinella Anomala Steud.

It is important to understand the reproduction of flood-tolerant plants, the answer can give us the reference to whether the flood-tolerant plant can occupy habitats for long time and expansion of the critical habitat in water-fluctuation zone.Arundinella anomala Steud., which widespread in the natural flooding zone of Changjiang River and adapt to the habitat, was observed flood-tolerant and considered very promising for vegetation rehabilitation in water-fluctuation zone in Three -Gorges reservoir region. To evaluate the reproductive mode of A. anomala on flooding, common garden and flooding with different time or duration experiments were conducted in the ecological garden.In common garden, The A. anomala, which 5-10 cm long and originated three different elevation sites in Jialing River's bank in May 2004, be planted for two years and measures the morphological characters in May 2006. Tiller length, stem length, florescence length, internode length and number of internodes in stems of longest sexual tiller in genet were measured, lamina length and sheath length of longest asexual tiller in genet also be measured. In duration flooding experiments, control (no flooding and conventional water supply management) and five flooding durations (A. anomala was submerged in the 2.5m deep water) were set in the experiment. Five flooding durations included: 20days, 40days, 60days, 80days and 100days. Survival rate, the percentage of flowering, genet biomass, sexual tiller number, sexual tiller biomass, asexual tiller number, asexual tiller biomass and reproduction allocation of A. anomala were determined after the treatments. In different flooding timing experiment, except control, four simulating flooding treatments (2m water depth) with different periods and the same duration (28days) were set in the flooding season of the year 2006: July 12-August 9, August 11-Spetember 8, September 12- October 8 and October 10-November 7. Absolute and relative resources allocation to asexual reproduction and sexual reproduction were investigated and compared with the corresponding non-flooding plants.The common garden experiment was shown that the longest sexual tiller in genet which originated in the low elevation site of bank has longer length of tiller, florescence, internode, and great length ratio of florescence to tiller, fewer number of internodes in stems, although the length of the stem has no significant difference; as for the longest asexual tiller in genet which originated in the low elevation site of bank has longer length of lamina, sheath, and fewer length ratio of lamina to sheath. The flooding experiment was shown that the lower zone of the bank, the stronger tolerance to submergence for A. anomala.The duration flooding experiments showed that: With the increase in the duration of flooding, the survival rate, the percentage of flowering, number of tillers in genet, number of sexual tillers, number ratio of sexual tillers to total genet tillers, biomass of genet, biomass of sexual tillers and distribution to sexual reproduction were decreased; With the increase in the duration of flooding, the number ratio of asexual tillers to total genet tillers and the biomass ratio of asexual tillers to total genet were raised; for the A. anomala which flooding duration 40 days, biomass of asexual tillers in genet is more and the biomass of other treatments were no significant difference.The different flooding timing experiment was found that early flooding led to fewer number and less biomass of sexual tillers, smaller number ratio of sexual tillers to total genet tillers and smaller biomass ratio of inflorescence to the whole genet than those of corresponding control plants. The total biomass of asexual tillers, number ratio of asexual tillers to sexual tillers and biomass ratio of total asexual tillers to total genet were greater than the control plants, although no significant difference is found for the number of asexual tillers in the flooding treatments and the control. This increased allocation to asexual reproduction become less significant with the postponed flood timing.In general, this paper: (1)A. anomala, which distribute in different elevation sites on the bank of Jialing River, have ecological differentiation and the tolerance of the A. anomala which originated low elevation on the bank of the River is stronger;(2)with the increase in the duration of flooding, the sexual and asexual reproduction of A. anomala were decreased; sexual reproduction has more sensitivity than asexual reproduction to submergence, the importance of asexual reproduction is raised with the increase of duration flooding, A. anomala can only asexual reproduction and sexual reproduction of was A. anomala completely inhibited when flooding duration 100days;(3)sexual reproduction was more effected by flood-timing than asexual reproduction and earlier flooding leads to more resources allocation to asexual reproduction less to sexual reproduction.