Study On The Invasion And Diffusion Capacity Of Solidago Canadensis L.

Solidago canadensis L. is one of the most serious invasive perannual plants in China. It produces offsprings both by seed production and clonal sprouting. The large amount of seed number it produced is the one major reasons that caused quick spread of the weed across China. In order to understand the ability of seedlings and sprouts grown in the heterogeneous habitats, the biological traits including leaf number, leaf length, stem width and plant height were measured. The seed germination traits under different pressure of p H, soil moisture, soil salinity and herbicide treatments were also processsed.Results showed that the seedlings height, stem diameter, leaf number and leaf length of sprouts were significantly higher than seedlings, and varied significantly among time(P<0.01). The average sprouts produced 33282.95±8499.47 seeds per ramet, which is siginificantly higher than seeds produced by seedlings(119.30%, P <0.01). However, the seed germination rate of both ramets and seedlings were above 60%, and no significant difference existed between ramets and seedlings. The seed germination rate under combined treatment of p H=8, soil moisture content of 40% and(0 ~ 0.02)mol / L salinity was highest(69.75%). Under the herbicide treatments, the germination rate was higher under the treatment of fluroxypyr, followed by the treatment of 2-propylamine. No seed germinated under the treatment of chipton.The average number of S. canadensis capitulum per ramet was 3199.50±459.64, and inflorescence central tubiform floret number is 3.57±0.86, margin ligulate flower number was 9.30±2.14. The flowering time of population was from October to November, of which the average flowering period of a single inflorescence was(10.90±2.93) d. The average pollen viability of an individual inflorescence tubiform floret was(93.56±8.99) %, and did not decreas with the increasing of flowering time. The outcrossing index of S. canadensis is 4 which indicated thatit belongs to the cross-pollinate plants and need pollinators during pollination. The pollen-ovule ratio was approximately 952.38±361.62, indicated that S. canadensisbreeding system is facultative xenogamy. The most common floral visitors were bee species.The seed abscission of Solidago canadensis L. is a non-random process, and is influenced by factors such as wind speed, turbulence, humidity and seed maturity, ect. Under the horizontal airflow condition, the seed release threshold was 5.1m/s. However, the seed release threshold under vertical airflow condition is remarkably smaller. Compared with the laminar flow condition, turbulence greatly increased the seed release rate by more than 300% on average. Under the turbulent conditions, the turbulence intensity alone does not significantly influence the seed releasing proportion. The high humidity decreased the seed releasing rate from inflorescences. In addition, falling seeds tended to have more pappus numbers and flat angles comparing to attached seeds.The germination rate, the characteristics of pappus, including pappus number, length, angle, barb number, and achene length, achene diameter, seeds single grain weight were examed in related with the terminal velocity and the inflorescence developmental stages. Result showed that plants had a large number of undeveloped seed in the late stage of inflorescence development, and the germination rate was 2.02±2.73%. However, the germination rate was as high as 25.34±16.54% in the early stage and was 57.32±15.05% in the full opening stage of inflorescence development, respectively. Results have shown a highly significant positive correlation betweem the termial velocity and the single weight and achenes diameter, and a negative correlation with pappus length and angle. No significant relationship existed between the achenes length and papus number. The fastest termial velocity was 0.26±0.08m/s in the late developmental stage of different inflorescence development. The terminal velocity of the dry seed was 0.25m/s and 1.21m/s to the wet seeds. It suggested that the rainfall will effectively surpress the time of seeds aloft in the air and therefore limited the dispersal distance in the field.This study relies on the research of Solidago canadensis L. seeds, the growth cycle and potential invasion and diffusion capacity of S. canadensis were cleared and the mechanism of its population rapid diffusion theory and spread invasion pathways were clarified. Furthermore, it has provided a scientific basis to development of early warning and control measures, it has offered a reference of the diffusion mechanism and invasion process in other invasive weeds seeds.