Australia, known for its frequent occurrence of bushfires during the summer season, experiences significant impact on its plant life. As a result, various indigenous Australian plant species residing in fire-dependent ecosystems have developed unique reproductive mechanisms to cope with fire-related factors. These adaptations, influencing the process of germination, can be categorized as either physical, arising from the intense heat of bushfires that triggers seed germination, or chemical, resulting from a blend of diverse chemical components present in smoke that stimulates the germination process.
The objective of this laboratory experiment in the field of biology is to investigate the impact of a solution called smoke water, comprising a combination of water, charred vegetation, and hay, on the process of seed germination and subsequent growth of Eucalyptus pilularis. Eucalyptus pilularis, commonly known as gumnut or blackbutt, is an indigenous Australian plant species that predominantly thrives in forest environments subject to regular burning events.
When compared to de-ionized water, can smoke water encourage the germination and post-germination growth of Eucalyptus pilularis seeds?
The post-germination growth of the Eucalyptus pilularis seeds by the smoke water will be more successful as a result of the smoke water's ability to germinate more Eucalyptus pilularis than de-ionized water. The height of the seedling that emerges serves as a measure of effectiveness in this experiment. from the gumnut seed that has sprouted. Eucalyptus pilularis will start to emerge from its latent state if the various substances, such as phosphorous and nitrogenous compounds contained in the smoke-filled residues of organic materials, act as chemical triggers. Since de-ionized water lacks the naturally occurring phosphorus and nitrogenous chemicals found in organic debris, such as NaN03, KN03, NH4Cl, and NH4N03, smoke water is expected to germinate.
The trees used to produce the gumnut seeds were found in nearby forestry operations. It was deemed vital to test whether or not the gumnut seeds would sprout.
Number of seeds germinating = \(\frac{22}{50}\)
Percentage germination = 44%
The supply of seeds was considered viable enough to proceed with the experiment.
When compared to de-ionized water, can smoke water encourage the germination and post-germination growth of Eucalyptus pilularis seeds?
The experiment lasted fourteen days in order to provide researchers enough time to evaluate the impact of the manipulated variable, the various types of water. According to the procedure, two identically heated sand baths are put next to one another, with the assumption that they are both receiving the same quantity of light. Since all samples of the potting mix came from the same batch, it was reasonable to conclude that the ingredient ratio was the same. To enable observations to be performed through the glass without disturbing the seeds, the E. pilularis was also immersed into the potting mix at a consistent depth of 0.5 cm and closer to the edges of the Petri dish.
In order to collect data for this experiment, we counted the number of seeds from various Petri plates that successfully germinated in the control and test groups, respectively. This is accomplished by checking the Petri dish's side to see if the seed coat has broken and the seedling has emerged. The height of the seedlings of the germinated seeds after the experiment's 14 days is another technique to gather data. This height is measured from the soil's surface to the seedling tip. The t-test for seedling development and the x2 test for seed germination were used to compare smoke water and de-ionized water, respectively.
The number of seeds that clearly displayed shattering of the seed coat and the emergence of the seedling for both the smoke water and the de-ionized water test groups were counted and entered into the table below in order to calculate the number of seeds that were successfully germinated. A has a presentation of the raw data.
We can easily observe that smoke water germinates, on average, from the processed data that tells us how many seeds successfully sprouted.
X2 test
An X2 test was performed to see whether there was a discernible difference between the germination of seeds treated with smoke water and seeds treated with de-ionized water.
Null Hypothesis: Gumnut seeds do not become germinated when exposed to smoke water.
Alternative Hypothesis: Gumnut seed germination is impacted by smoke water.
Smoke water | De-ionised water | Row total | |
---|---|---|---|
Germinated | 88 | 49 | 137 |
Not germinated | 12 | 51 | 63 |
Column total | 100 | 100 | 200 |
Proportion of seed germinating \( = \frac{137}{200} = 68.5\%\)
Proportion of seeds not germinating = 100 – 68.5 = 31.5%
Expected number of smoke water treated seeds to germinate = 68.5% of 100 = 68.5
Expected number of de-ionised water treated seeds to germinate = 68.5% of 100 = 68.5
Expected number of smoke water treated seeds not to germination = 31.5% of 100 = 31.5
Expected number of de-ionised water treated seeds not to germinate = 31.5% of 100 = 31.5
Observed frequency | Expected frequency | Difference | Positive difference | |
---|---|---|---|---|
O | E | O - E | IO - EI | \(\frac{(IO\ -\ EI)^2}E\) |
88 | 68.5 | 19.5 | 19.5 | 5.55 |
49 | 68.5 | -19.5 | 19.5 | 5.55 |
12 | 31.5 | -19.5 | 19.5 | 12.07 |
51 | 31.5 | 19.5 | 19.5 | 12.07 |
X2calc | 35.25 |
Number of degrees of freedom = (rows – 1) × (columns – 1) = (2-1) × (2-1) = 1
X2calc = 3.84 for p = 0.05
We must reject the null hypothesis and accept the alternative hypothesis since the test result for X2 calc = 35.25 is significantly higher than the critical value for the null hypothesis, which is X2 crit = 3.84. If p < 0.001, the test value is significant.
Depending on the type of water it received—de-ionized or smoke water—this section of the experiment is meant to assess the gumnut seed's ability to germinate. The height of the seedling that emerged following the germination of gumnut seeds served as a gauge of effectiveness. The influence of water on germination increases with seedling height. A has the raw data.