Fruit Set,Seed Dispersal And Germination Characteristics Of The Desert Relict Plant Gymnocarpos Przewalskii

In this paper,fruit set,seed dispersal and germination characteristics of the desert relict plant Gymnocarpos przewalskii were explored in field and indoor studies,and the fruit set pattern,spatial and temporal characteristics of seed dispersal and germination stratege was determined.It is expected to provide a theoretical basis for the restoration and reconstruction of the natural populations of this species.The main results are as follows:There were differences in seed morphological(length of seeds,width of seeds,thickness of seeds and mass of 100 seeds)and fruit set percentage from different populations(P<0.05),seed morphological and fruit set percentage were extremely significantly positively correlated with rainfall and altitude respectively(P<0.01),and had extremely significant negative correlations with longitude,latitude and temperature respectively(P<0.01);The full-seeds from the first terminal flowers was significantly higher than full-seeds from the lateral flowers of G.przewalskii(P<0.05),this fruit set patterns might be non-random abortion.Seeds began to dispersal in early June,and the initial dispersal time was slightly different in different years,and lasting for about 2 months.The dispersal trend is a single peak curve and presents a pattern of"mass dispersal".The peak of seed dispersal coincides with the peak of precipitation in that year.The seeds dispersal in the south and southeast have a large dispersal density and a long dispersal distance,the direction of seeds dispersal is in consistent with the direction of wind;Seeds were mainly concentrated under the parental plant crown,and as the distance from the mother plant increased,the seeds density decreased.There is a significant negative correlation between dispersal distance and dispersal density in different directions(P<0.01);The main reason for the high dispersal density of seeds of G.przewalskii under the mother plant is that its numerous branches weakened the wind in the plants.In conclusion,the seeds of G.przewalskii have non-dormancy,and fresh seeds did germinate in light and darkness over a range of temperatures.20/35? was the optimal temperature for its seed germination,5/15? could inhibited seed germination;The germination type is rapid germination,and has an"opportunism" germination strategy;The seed type was non-hotoblastic,light has no significant effect on seed germination(P>0.05);Under different temperature conditions,sepals has no significant effect on the seeds germination percentage(P>0.05),but the germination index of intact seeds was significantly lower than that of seeds from without sepal(P<0.05),the sepals could delay the initial germination time under 5/15?.The fruit set of G.przewalskii was strongly influenced by the geographical environment of the populations.The seed dispersal of G.przewalskii was related to precipitation,wind direction and its biological characteristics.Seeds dispersal before a large amount of precipitation,which is conducive to the germination of its seeds in a suitable microhabitat;The "rapid germination" strategy of G.przewalskii was benefited to achieve seed germination when a large amount of precipitation or continuous precipitation occurs.The sepals can delay the germination rate of seeds,it is better adapted to the changing desert climate.In summary,the fruit set,seed dispersal and germination characteristics were a long-term adaptation to harsh desert environmental conditions.