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Ecological adaptation strategies in alien species: effects of salinity, temperature and photoperiod on Spartina alterniflora Loisel. seed germination

100%

Yuan Z., Shi F.

Polish Journal of Ecology

2009

tom 57

nr 4

677-683

Spartina alterniflora (smooth cordgrass), a perennial grass native to the coastal marshes of eastern America, is widely distributed in northern China since 1979 of its introduction. In the tidal marshlands of north China, S. alterniflora has displaced native species and is presently dominant member of the community owing to its opportunistic characteristics. In this study we investigated S. alterniflora seed germination responses to different temperatures, between 5–25ºC in one thermoperiod (16/26ºC) and in two light treatments – 10/14h (night/day) photoperiod and dark conditions. Variations of seed germination at different storage temperatures and storage duration were also examined. In addition, the effect of different salt concentrations on seed germination was evaluated. The optimal temperature for germination was 25ºC and 16/26ºC (night/day) thermo-period – germination percentage was greater than 90%. Light intensity had no influence on the percent of seed germination and germination indices when seeds were exposed to identical temperatures. At 120 d of storage and -5, 0, and 5ºC temperatures, germination percentage exceeded 75%. The optimal salinity level for seed germination was 150 mM NaCl. Germination percentages were highest (> 90%) when salinity did not exceed 450 mM NaCl. The ability of S. alterniflora seeds to germinate under a wide range of temperature and light conditions resulted in continued seedling development under high salinity.

The ecological profit in phenology and pollination of alien species Spartina alterniflora [Loisel] introduced to coastal wetlands in Northern China

80%

Shi F., Yuan Z., He K. S., Li J., Guo S.

Polish Journal of Ecology

2009

tom 57

nr 2

283-289

For the plant species, effective phenology and pollination syndromes can increase viable seeds which enhance the species to colonize new areas. So the species with a suit of advantageous characteristics inherent in its reproductive ecology is critical to its dispersion. Spartina alterniflora – a perennial grass native to coastal marshes of America was introduced to China in 1979 and now it is distributed in the Tianjin coastal wetlands of northern China. Flowering phenology was examined and indicated that in northern localities, flowering initiated in mid-August and senescence occurred by the end of October. The pollen-ovule ratio was 9875 (±2150). Abundant pollen grains compensated for a lack of pollen viability. Pollen viability was 10% approximately when pollen released 4 hours, but stigma receptivity was above 10% when stigmas exserted 7 hours. Stigmas maintained viability longer than the period of pollen release, ensuring successful pollination. Scanning electron microscopy was used to observe stigma surface characters and pollen viability. Further investigation proved stigma adaptations to increase pollen capture and exterior pollen tube growth following pollination was beneficial to fertilization. The results suggested that flowering phenology and pollination traits are vital to pollination and production of viable seed, enabling the species to spread rapidly and succeed in new habitats of northern China.

Ograniczanie wyników

2 Polish Journal of Ecology

2 Shi F.

2 Yuan Z.

1 Guo S.

1 He K. S.

1 Li J.

2 2009

Wyniki wyszukiwania

Ecological adaptation strategies in alien species: effects of salinity, temperature and photoperiod on Spartina alterniflora Loisel. seed germination

The ecological profit in phenology and pollination of alien species Spartina alterniflora [Loisel] introduced to coastal wetlands in Northern China