Phragmites Australis Seed Germination Strategy

Phragmites australis capable of both sexual and asexual reproduction widely distributes along the tidal flat gradient in the Dongtan coastal salt marsh wetlands of Chongming. To examine whether P. australis display cross-generational adaptation seeds from different tidal flat habitats were collected and stored under various temperature. Subsequently the effects of soil properties in the original habitats seed storage temperature and salinity conditions on seed germination strategies were explored. When the salinity up to 15‰ the germination rate of P. australis seeds was 1.3% - 7.7%. Low seed-storage temperatures (4 C) significantly enhanced germination rates and potentials compared to those stored at room temperature (20 C). Soil salinity and water content were major factors influenced germination rates after storing seeds at 4 C. However germination rates and potentials were positively correlated with the soil P content. Meanwhile the seed germination indexes and speeds were more significantly affected by the room temperature. Both seed storage temperatures and the tidal flats had a positive direct impact on the germination parameters of seeds. However soil N/P had a positive indirect effect on the seed germination parameters only at the lower seed-storage temperature. The results indicated that vernalization (low-temperature seed storage) differentially promoted the germination of P. australis seeds collected from the tidal flat gradient in a subtropical marine monsoon climate salt marsh area and demonstrated cross-generational adaptation. Consequently using seeds collected from P. australis populations along the tidal flat gradient to restore the original population could be considered an effective and economical method.