Question
The aim of this experiment is to investigate whether water availability prior germination affects Acacia rubida and Swainsona formosa seed germination. We will control the water availability by pre-soaking time.
Hypotheses
Null hypotheses
• Seed germination speed will not differ between long and short soaking time.
• Change in soaking time will have same effect on A. rubida and S. formosa seeds.
Alternative hypotheses
• Seed germination speed with long soaking time will differ from the speed with short soaking time.
• Change in soaking time will have different effect on A. rubida and S. formosa seeds.
Predictions
High water availability will stimulate germination process, so seeds will germinate faster in respond to long soaking time. Since A. rubida is distributed in elevated areas with high precipitation (Maslin and Pedley, 1988), its seeds should be sensitive to high water availability. S. formosa might be more sensitive to water availability since it grows in sandy or on stony ground in dry areas (Tapingkae, Taji and Kristiansen, 2007) so it is crucial for S. formosa to seize the rare opportunity of rain. Therefore S. Formosa seeds might germinate faster with longer pre-soaking time. Methods In order to investigate the effect of water availability prior germination on A. rubida and S. formosa seeds, the seeds were soaked in water to simulate water availability, e.g. raining. A. rubida and S. formosa seeds were put into 4 petri plates, two petri plates per species. Boiling water was then added into the 4 plates. After 1 minute, one plate of each species were emptied onto tissue paper to separate seeds from water. The other 2 plates were emptied after 20 minutes of soaking. For each soaking time of each species, 9 healthy-looking seeds were placed onto an agar plate with equal space between seeds (to eliminate the effect of density on seed germination). In this way, 4 plates of seeds were planted and this is one block. The rest of seeds were plated for 3 more blocks with the same procedure. The four plates of each block were put into a tray. The four trays were then randomly distributed in the greenhouse. In the following 14 days, cumulative number of germinated seeds was recorded for each plate. A radical with length greater than 1mm was counted as germination. On the 14th day, all the seeds were cut open and number of viable seeds was recorded. Lag time, mean germination time, 50% germination time and percentage germination on day 14 were calculated from raw data to evaluate germination speed. Two-way ANOVA was carried out on these data to test the statistical significance of the differences. Results All the plates had germination after 14 days. Some had fungi growth and the affected seeds were counted as unviable. Percentage germination of A. rubida seeds shows the same trend under short and long pre-soaking time and it is higher than the percentage germination of S. formosa seeds (figure 1). Longer soaking time appears to increase the germination speed for S. formosa seeds (figure 1). Figure 1 Percentage germination of A. rubida and S. formosa over 14 days. “A. rubida 1min” means A. rubida seeds with 10 minutes soaking time, etc. Sample calculation is shown in appendix. Two-way ANOVA was done to test the effect of soaking time and species on lag time, mean germination time, 50% germination time and percentage germination on day 14. Percentage germination data was normalised using archsine function before undergoing ANOVA test. As the …show more content…
Hence the effect was not significant with the large deviation of data, if there was any effect of soaking. A larger sample size and longer growing time are required to make statistically significant conclusions.
The choice of soaking times might need to change as well. Maybe 20 minutes was not long enough for seeds to react differently from 1 minute soaking. Tapingkae, Taji and Kristiansen (2007) soaked the S. formosa seeds overnight and reported almost 100% germination within 48 hours.
It can be concluded from this experiment that soaking time does not affect germination of A. rubida and S. formosa seeds, and change in soaking time will have no different effect on A. rubida and S. formosa