Seed Dormancy Characteristics In The Alpine Meadow On The Eastern Qinghai-Tibet Plateau

In this experiment, the effects of seed mass, temperature, phylogenetic development, altitude and habitat on seed dormancy were investigated. The effects on dormancy levels of 680 plants (32families) occurring in a Alpine Meadow on the eastern Qinghai-Tibet plateau, were studied. Results indicate that:1. Phylogenetic development is a crucial factor in determining seed dormancy and germination. Family can explain 28.9% of total dormancy percentage variation. The mean dormancy percentage varied significantly among families. The highest dormancy rate occurred in Leguminosae and Cyperaceae. The mean dormancy percentage of Gramineae was the lowest.2. Alternating temperature had a significant effect on the dormancy response. High dormancy percentage occurred at 5/20℃, compared with 5/15℃and 10/25℃. The rate of the dormant species at 10/25℃was strongly lower than 5/15℃and 5/20℃. High dormancy percentage occurred at 5/20℃in Compositae, Gentianaceae, Cyperaceae and Labiatae. As alternating temperature changed to 5/15℃, Seeds of Gramineae, Leguminosae, Ranunculaceae and Liliaceae showed a higher dormancy percentage. There was no obvious change on seed dormancy percentage of Polygonaceae among the three temperature sets.3. We also found a significant positive relationship between seed mass and dormancy percentage. The mean seed mass of dormant species (2.28mg) was slightly heavier than the mean seed mass of non-dormant species (1.72mg). The distributions of seed masses of species with dormant and non-dormant seeds were powerful overlapping.4. The altitude had a marked effect on total dormancy percentage. The seeds from high altitude (>4000m) displayed higher dormancy percentage than those from low altitude. Seed collected from higher altitude had the high dormancy percentage in Ranunculaceae, Gentianaceae and Umbelliferae. The high dormancy percentage in Cyperaceae and Polygonaceae occurred at lower altitude.5. Results indicate that there was significant relationship between habitats and seed germination.Generally speaking, highdormancy percentage occurred at the sunny hillside. Seeds collected from different habitats had the same dormancy tendency.6. The effects that temperature had on seed germination relied on phylogenetic development, but not on seed size. Temperature and families, altitude and family, temperature and habitat, seed size and altitude, temperature and altitude had interactions on seed dormancy, but no interaction was found between temperature and seed size.