Aspect 3
Materials
- Continuous supply of household rain water
- 1 × Medium-sized trowel
- 1 × 1000mL measuring cup ± 25 mL
- 1 × The Green Gardener Potting Mix bag (25L)
- 25 × Grower’s Pride Dwarf Bean Tender Green seeds
- 50 × D.T Brown Sunflower seeds
- 25 × REKO 6006 100mm STD Black plastic Pots
- 1 × Plastic box (L600mm × W400mm ×D200mm)
- 1 × 300mm plastic ruler ± 1 mm
- 1 × Red permanent marker
- 1 × Papermate Kilometrico Med Point pen
- 1 × Kitchen towel
- 1 × Pair of hand gloves
- 1 × Camera
Method
Planting seeds
- Wear on gloves
- Measure 15mm starting from the head of the lid of the ball point pen, then draw a line all around the pencil at the 15mm point (refer to IV.Appendix to see how the pen was marked).
- Using a red permanent marker, label 5 pots –
0; 1; 2; 3; 4; respectively. This refers to how many sunflower seeds are planted inside the pot
eg: There will be 5 pots labelled “0”, 5 pots labelled “1”, 5 pots labelled “2”, 5 pots labelled “3” and 5 pots labelled “4”
- Using the kitchen towel, thoroughly wipe clean the inside, outside and the edges of all pots and plastic box
- Cut up the Green Gardener Potting Mix bag, and pour all the soil into the big plastic box
- Using the trowel, mix and break the clumps in the soil into fine soil
- Using the trowel, completely fill the pots up with soil. Do not pat or push down the soil into the pot – shake the pots to allow an even distribution of soil inside the pot. Use the trowel to spread out the soil to create a even and flat surface of soil
- Pick out seeds with the same or similar shape and size. Pick out twenty-five bean seeds and fifty sunflower seeds
- For pots labelled “0”, “2”, “3” and “4”, place one bean seed in the middle of the pots. According to the number on the pots, place that many number of sunflower seeds inside the pot surrounding the bean seed. Evenly place the sunflower seed around the bean seed and 20mm apart from the bean seed. For pots labelled “1”, evenly place one bean seed and one sunflower seed in the middle of the pot. The bean seed and sunflower seed must be placed 20mm from each other
eg; The pot labelled “3”, should have one bean seed and three sunflower seed place inside the pot
(refer to IV.Appendix to see how the seeds were places inside the pot).
- Using the head of the pen, push the seeds down into the soil until the 15cm line on the pen is just under the soil surface (refer to IV.Appendix to see how the pen was used)
- Use your hands to flatten out the soil and cover up the holes where the seeds were pushed into
- Fill up the measuring cup with 500mL of rainwater and water the soil, working in a circular motion from the edges of the pot towards the middle of the pot
- Place the pots at an undisturbed area where there is presence full sunlight in the day
Daily care
- Every day at 4:00pm, use the measuring cup to water each pot with 500mL of rain water. Work in a circular motion starting from the edge of the pot to the middle of the pot
- Check the surrounding conditions of the pot and plants. Any bugs or pest present must be removed immediately
Collecting data
- Wear on gloves
- Record the number of leaves on each plant
- Record the colour of leaves
- Use a 300mm ruler to record the height of the plant
- Take photos of the plants for record
DATA COLLECTION AND PROCESSING
Aspect 1
Recording Raw Data
Table 2.0: This table shows the height in millimetres of the control bean plant, bean plant planted with one sunflower, bean plant planted with two sunflowers, bean plant planted with three sunflowers and the height of the bean plant planted with four sunflowers. This table shows the height data of all five repeated tests for each independent variable of the experiment. The number of days since the experiment started and date of which the height of the bean plants was recorded are also included in this table. The uncertainty value of the measurement of data is also shown.
Table 2.1: Tables shows observations made on both the bean plant and sunflower plant during the duration of the experiment. Qualitative observations were recorded of plants as a general group and not of individual plants. Data such as day of germination, size of leaves, number of leaves, colour of leaves, plant’s direction of growth and health condition of plants were noted. This table also shows the day number that the observations were made.
Aspect 2
Processing Raw Data
Table 2.2: This table shows the average height of all five repeated set of plants for each independent variable of this experiment. This table shows the average height of the bean plant on day 12, 18, 34, 40 and 45. The overall average height of the bean plants at the end of the experiment is also included in this table. The uncertainty value of the measurement of data is also shown.
Note – The uncertainity of measurements is ±1mm but value figures are given to one decimal places due to the calculations of averages in between
Worked calculations:
Calculating the average height of the five repeated tests of the Control bean plant on day number 12
[6]
Data points: 33 34 37 33 32 * refer to Table 2.0
→ M = 33 + 34 + 37 + 33 + 32
5
= 33.8
Table 2.3: This table shows the standard deviation of the five repeated set of plants for each independent variable – the five repeated tests for Control, bean plant with 1 sunflower, bean plant with 2 sunflowers, bean plant with 3 sunflowers and bean plant with 4 sunflowers. The standard deviation of the five repeated tests was calculated for day number 12, 18 34, 40 and 45 for these were the days of raw data collection for this experiment.
Worked calculations:
Calculating the standard deviation of the five repeated tests of the Control bean plant on day number 12
[6]
Data points: 33 34 37 33 32 * refer to Table 2.0
Mean of data points: 33.8 * refer to Table 2.2
S2 = [ (33 – 33.8)2 + (34 – 33.8)2 + (37 – 33.8)2 + (33 – 33.8)2 + (32 – 33.8)2 ]
5 – 1
= 0.64 + 0.04 + 10.24 + 0.64 + 3.24
5 – 1
S2 = 14.8
S = √ 14.8
Standard deviation = 1.92
Table 2.4:
Worked calculations:
Calculating the t-value of the Control bean plant versus the height of the bean plant grown with 1 sunflower
[7]
t = 4.6
√ (113.288 + 86.528)
t = 4.6
14.136
t-value = 0.326
Worked calculations:
Determining if the data of the control bean plant and the bean plant with 1 sunflower accepts of rejects the Null Hypothesis.
The t-test is a data analysis used to compare two sets of data and determine if the two sets of data are significantly and statistically the same of different.
‘P’ denotes Probability and the critical probability for this experiment is 0.05 or the equivalent, 5%.
If P > t-value then the two sets are the same (i.e. accept the null hypothesis)
If P < t-value then the two sets are different (i.e. reject the null hypothesis) [8]
Degree of freedom for the two sets of data = 8 * refer to Table 2.4
T-value = 0.326
Table:2.5: Table of critical values for the t-test [11]
2.31 > 0.326
Therefore the data of the control bean plant and the data of the bean plant grown with 1 sunflower plant are the same. This results in the null hypothesis being accepted.
Aspect 3
Graph 2.0:
Note – The uncertainity of measurements is ±1mm (uncertainty of ruler)
Refer to Table 2.0 for data values
Graph 2.1:
Note – The uncertainity of measurement is ±1mm (uncertainty of ruler)
Refer to Table 2.0 for data values
Graph 2.2:
Note – The uncertainity of measurement is ±1mm (uncertainty of ruler)
Refer to Table 2.0 for data values
Graph 2.3:
Note – The uncertainity of measurement is ±1mm (uncertainty of ruler)
Refer to Table 2.0 for data values
Graph 2.4:
Note – The uncertainity of measurement is ±1mm (uncertainty of ruler)
Refer to Table 2.0 for data values
Graph 2.5:
Note – The uncertainity of measurement is ±1mm (uncertainty of ruler)
Refer to Table 2.0 for data values
- CONCLUSION AND EVALUATION
Aspect 1
Conclusion
Figures in Table 2.4 illustrates that there is no statistical difference between the height of the control bean plant and the height of the bean plant growing with one sunflower plant, bean plant growing with two sunflower plants sand bean plant growing with three sunflower plants. The Null Hypothesis (H0) was accepted for the control bean plant versus height of bean plant with one/two/three sunflower plants, when the statistics such as the standard deviation and t-value was calculated and processed. Although the Null Hypothesis was accepted for three variables, the Null Hypothesis was rejected for the last tested variable of this experiment, the control bean plant versus the bean plant grown with four sunflower plants. As a result of the two sets of data (control and bean plant with four sunflowers) rejected the H0, this means that the height of the control bean plant and the bean plant grown with four sunflower plants are statistically different.
A possible reason why the Null Hypothesis was rejected for the last variable of four sunflower plants is that the height of the control bean plant and the height of the bean plant grown with four sunflower plants were immensely different. Data from Table 2.0 shows that the two set of values for the control and the variable were the extremes of two ends – the height of the bean plant being the greatest and the height of the bean plant with four sunflower plants being the lowest.
When all data was processed, the degrees of freedom was calculated to be 8. The critical value for this experiment was 0.05/5%. The probability value of these two numbers (8 and 0.05) was 2.31.
The t-values calculated in this experiment are as follows
-
Control versus 1 sunflower 0.326 → < 2.31
-
Control versus 2 sunflowers 1.370 → < 2.31
-
Control versus 3 sunflowers 1.840 → < 2.31
-
Control versus 4 sunflower 2.330 → > 2.31
Even though, statistically there are no differences between the control bean plant and three variables of this experiment, the overall average height value of the plants at the end of the experiment were very different to one another. The control bean plant possessed the greatest height of 61.3mm and as hypothesised the plant that had the lowest height was the bean plant that grew with four sunflower plants. The average height of the bean plant grown with four sunflower plants was 35.2mm.
In Graph 2.0 the height differences between the control bean plant and the variable 1 sunflower were not immense. However in Graph 2.1 there was an increase in difference between the height of the control and the variable of 2 sunflowers. Graph 2.2 displays a larger difference between the control and the 3 sunflowers variable and Graph 2.3 shows the greatest difference between the height of the control plant and the variable of four sunflower plants. The four graphs demonstrate a clear correlation between the number of sunflower plants and the height of the bean plant. In reference to the experiment’s hypothesis, the plant height decreases as the number of sunflower plant grown with the bean plant increases.
Sunflower plants are classified as an allelopathic plant which means that it excretes chemical compounds that can inhibit the growth of its nearby competitors. In this experiment, the bean plant was the competitor of the sunflower plant for both plants were growing at the same location and are in taking the same nutrients. [2] Other evidence of allelopathic activities on plant was the number of days it took for the bean seeds to germinate. Table 2.1 shows that the sunflower plants germinated before the sunflower plants and in addition, the control bean plant germinated before the other bean plants that were growing with sunflower plants. The more sunflower plants there were in the pot the longer it too the bean plant to germinate. The control bean plant took 2 days to germinate whereas the bean plant planted with 4 sunflower plants germinated after 4 days. Allelopathic chemicals are strong enough to be used as herbicides and the chemical compounds when broken down as strong and complex enough to use for some pharmacological processes. [10]
The graphs presented in this report had errors bars but the errors bars in the graphs were not substantial figures. Therefore, it can be stated that the data values of height recorded for the experiment were close in values and did not vary significantly. The error values are listed in Table 2.3 and figures were all below 7.
In Table 2.1, observations on the number of leaves the plant has colour of leaves, size of leaves and the direction of the plant’s growth was qualitatively recorded. The observations in Table 2.1 confirm the allelopathic activities of the sunflower plants. An overall observation was that the sunflower plants’ heights were greater than the bean plants at every stage of the experiment. The height on the control bean plant was approximately the same height as the sunflower plants. Differences between the control bean plant and its variables were obvious at the later stages of the experiment. A pattern developed when referring to observations made on day 40 and day 45. The control plant was growing vertically whereas the stem of the bean plant growing with 4 sunflower plants started to bend to the side. Furthermore, there were increasing numbers of dead leaves on the bean plant as the number of sunflower plants increased. The dead leaves are signs of the sunflower plant inhibiting the growth of the bean plant and trying to eliminate its competitors. [10]
Also, the colour of the bean started to change as the days elapsed and towards the end-duration of the experiment. The leaves turned into an old-yellow colour, pale green and dark and lustreless coloured leaves. These are all signs of nutrients deficiency, in particularly, nitrogen and phosphorous deficiency. Plants intakes nutrients such as nitrogen and phosphorous from the soil, but due the activities of the allelopathic sunflower plants, the sunflower plant has out-competed the bean plants for these necessary and essential nutrients that plants need to grow. [9]
In addition, the control bean plant grew the largest sized leaves in comparison to the other bean plants. These patterns of bean growth agreed with the experiment’s hypothesis – the general health of the bean plant will deteriorate with increasing number of sunflower plants.
Although the apparent observations and values were recorded during this experiment and the data illustrates that by increasing the number of sunflower plants planted alongside the bean plant, the height of the bean plant will decrease and in addition the health of the plant (size and colour of leaves, direction of growth, number of leaves) will deteriorate several significant factors may have affected the data. Factors that may have affected the allelopathic activities or the growth of plants are
- After the first session of watering the plants, the soil compressed and compacted therefore the amount of soil in each pot slightly varied
- The amount of soil in the pot will affect the escaping of water through the hole at the bottom of the pots
-
Because the sunflower plants were taller than the bean plant, the sunflower plant may have blocked the sunlight getting to the bean plant and this may affected the process of plant photosynthesis
Although, the amount of soil was being kept controlled, after the first watering session the soil compressed and compacted inside the pot. The lower the surface level of the soil in comparison to the pot the faster water is able to escape out of the holes at the bottom of the pot. Water clumped the soil together inside the pot. Water inside the pot is able to escape from the soil and out into the environment. The amount of water escaping from the pot could not be kept controlled. Furthermore, the rate at which the water escapes from the holes of the pot could not be calculated. Plants need water for photosynthesis and to grow. Lack of water will affect the efficiency of photosynthesis process. Therefore, the more water that escaped from the pot, the less efficient and optimal the process of photosynthesis will be.
All plants were watered at the same time of day and on the same day however the actions of watering each plant were not done simultaneously. A time lag occurs between watering one pot and water another pot. The time lag occurs because of measuring amount of water and the method of watering the plants (circular motion). This time lag may affect the data values recorded due to while the time lag occurs evaporation of water had already begun. Evaporation is loss of water and again, this will affect the process of photosynthesis. The rate of evaporation cannot be calculated and recorded, and depending on the sunlight that will also affect rate of evaporation. In addition to the issue of sunlight, even though the plants were watered at the same time of day on the same day, the sunlight intensity can change during the watering session. Sunlight energy is the primary energy for all living things, therefore the varying of light energy amount and intensity will affect photosynthesis and evaporation. [8]
Statistics shows that under these experimental conditions there is no difference between the height of the control bean plant and the three variable of 1, 2 and 3 sunflower plants however the spectrum and scope of data must be noted. Figures showed that the height of the control bean plant and the variables 1, 2 and 3 were different but the difference was not great enough for the Null Hypothesis. a are rejected. The testing between two variables that rejected the Null Hypothesis was the data set of the control bean plant and the data set of the bean plant growing with 4 sunflower plants. The two set of data was significant enough for the Null Hypothesis to be rejected – this means that statistically there was a difference between the two sets of data. It must be kept in mind that although in most cases of this experiment, the N0 was accepted, there are evidence of allelopathic activities and observations made during this experiment also confirms that the allelopathic sunflower plant did inhibit and affect the growth of the non-allelopathic bean plant. [1]
Aspect 2 and Aspect 3
Evaluating Procedure and Improving the Investigation