MATERIALS AND METHODS:
Materials:
(original):
- 6 green bean sprout seeds of the same variety
- 6 containers of the same type and size
- Soil from backyard (50g for each container)
- Water (10mL for each plant each day)
- Hygrometer (to measure humidity)
- Balance (to weigh soil)
- Ruler (to measure height of plants)
- Dessertspoon that holds 10mL
- Plastic wrap
- Natural light
(added)
- 3 larger plastic containers
- 3 plastic covers
- Teaspoon that holds 5mL
Procedure:
- I obtained over 50 potential green bean sprout seeds for growth, but only chose the best six. (best = appears healthiest)
- I dug up soil from the same area of my backyard. Then, I equally divided the soil into six portions (50g for each container).
- I obtained six containers, each with a diameter of 10cm and height of 15cm. Next, I placed the divided portions of soil into each of the containers.
- I labeled the containers with a permanent marker. Container labels were: A, B, C, D, E, F. Containers A, B, C were placed in the containers enclosed with plastic wrap (high humidity) and D, E, F being the ones exposed (low humidity).
- I watered the plants (10mL for each plant) during each observation. I decreased the amount of the water (from 10mL to 5mL) for the plants in the wrapped containers after two days because the soil continued to be very moist.
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I observed the growth of the six plants each day at 6pm. (June 1st to June 11th) Data was collected from measuring plant growth with a ruler and counting the beads of water exuded. Any necessary photographs were taken.
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Note – This was not part of the original procedure but it was necessary in order to continue the experiment: After Day 5, the plants in containers A, B, C were already coming into contact with the plastic wrap; therefore, I had to remove the plastic wrap from containers A, B, and C in order to allow space for them to grow. I substituted the plastic wrap with a plastic container (please refer to figure 1.)
The control of variables:
Controlling the following variables is necessary to acquire the most accurate results (these are listed in no particular order as each one is important):
- same type (found in the same location)
- same quantity (50g for each container)
Reason: Differences in the soil may alter plant growth; the amount of soil may speed up or slow down the rate of growth as well
- same amount (10mL for each plant)
- same source (taken from the same location – kitchen tap)
- same temperature (5°C)
Reason: As a result of receiving more or less water, plants may grow rapidly or slowly. To ensure that plants receive the same treatment, the same amount, source, and temperature of water should be noted
- same amount
- same intensity
There is the assumption that the amount of intensity of light is kept constant because the plants are placed within the same area the light should therefore be distributed evenly to each plant.
Reason: The even distribution of light is important as light is a major factor of plant growth and should therefore be controlled.
- observed at the same time and for the same duration
- watered at relatively the same time
Reason: Watering the plants at different times of the day may cause plants to grow at different rates because some plants may absorb more or less water throughout different time periods of the day. Observing the plants at the same time is a fair way to obtain data because plant conditions may change as often as every minute.
Reason: Containers made of different materials may alter plant growth because a plant’s surrounding environment (in this case, the container in which it grows in) is extremely important to its growth – the environment should be controlled. In addition, different sizes of containers may allow for more or less light to make contact with the plant and thus result in unwanted inaccuracies.
- Same type or variety
- Very similar in size
Reason: As we know, different plants grow very differently. Some may sprout on the day it is planted while others may take several days to germinate.
* Each variable above has the ability to alter the development and growth of a plant; therefore, in order to ensure a fair test of the process of guttation in the plants, each plant must receive the same treatment.
Methods of collecting sufficient relevant data:
- The experiment is ongoing for 11 days, which should allow for the collection of enough relevant data
- Multiple trials should be able to verify that results are consistent and precise
- Repeating the experiment several times should ensure that the outcome is not a coincidence or accident
- By using six plants (three for each category), there is a higher probability that the results will be reliable
- Observing more than one plant will allow for dependability of data
- Using more than one plant is a good idea as there is always the possibility that some plants may die midway through the experiment
RESULTS – DATA COLLECTION:
Quantitative Data (collected from observations):
Table 1. The differences of temperature and humidity between the green bean sprouts placed in enclosed containers versus those placed in exposed containers.
NOTE:
Plants A, B, and C are the ones placed in the enclosed containers and plants D, E, and F are the ones placed in exposed containers.
Day 1 (31 May 2007):
- Seeds placed into containers; no growth has taken place yet
Day 2 (1 June 2007):
- Watered plant at 6pm; no growth has been observed in any of the 6 plants
Day 3 (2 June 2007):
- Watered plant at 6pm; no growth has been observed in any of the 6 plants
Day 4 (3 June 2007):
Day 5 (4 June 2007):
Day 6 (5 June 2007):
Day 7 (6 June 2007):
Day 8 (7 June 2007):
Day 9 (8 June 2007):
Day 10 (9 June 2007):
Day 11 (10 June 2007):
Day 12 (3 June 2007):
Day 13 (11 June 2007):
Qualitative Data (collected from observations):
NOTE: Not all the photographs taken during the observations are shown. Only the most necessary and important ones appear below:
Figure 1. Figure 2. Figure 3.
Day 6 of plant A in its Day 8 of plant B in its Day 13 of plant C in its
enclosed container enclosed container enclosed container
(two layers of saran wrap). (plastic container with lid). (plastic container with a
separate detachable cover).
Figure 4. Figure 5. Figure 6.
Day 6 of plant D in its Day 8 of plant E in its Day 13 of plant F in its
exposed container. exposed container. exposed container.
Figure 7. Figure 8. Figure 9. Figure 10.
The process of A bead of water is The plastic This is one of the
guttation is shown seen at the leaf’s container enclosing green bean sprouts
here. There are four hydathodes (tips). the plant is covered in an exposed
beads of water in moisture as a container. There are
exuded from the result of the high no beads of water
hydathodes and humidity within the exuded from this
remain on the leaf’s container. plant’s leaves.
surface.
DATA PROCESSING AND PRESENTATION:
Figure 11.
The growth of green bean sprouts in enclosed containers A, B, and C is shown in this graph. We are able to see that none of these plants demonstrate any outstanding irregularities because their growth continues in a smooth inclination. The green bean sprouts emerged from beneath the soil on Day 4, one day before those grown in the exposed containers (shown in Figure 12 below).
Figure 12.
The growth of green bean sprouts in exposed containers D, E, and F is shown in this graph. Once again, we are able to see that there are no exceptional anomalies illustrated although these numbers have a slightly larger range as compared to those in Figure 11. For example, this graph shows that on Day 10, the heights of plants E and F have the greatest variation out of any other cases. Nevertheless, there is an ongoing smooth trend. The green bean sprouts here emerged from beneath the soil on Day 5, one day later than those grown in the enclosed containers.
Figure 13.
As this graph displays, none of the green bean sprouts grown in the exposed containers exuded any beads of water on any day. In contrast, the green bean sprouts grown in the enclosed containers exuded beads of water everyday, but the numbers only range from one bead to four beads. There seems to be no regular pattern taking place. The only abnormality seen here is perhaps on Day 13 where the green bean sprout grown in container B exudes only one bead of water (the only time it occurs throughout the 13 days of observations).
DISCUSSION:
Did the results apply to the hypothesis?
My hypothesis was that if plants usually perform the process of guttation under conditions of high humidity and low transpiration, then the leaves of the green bean sprouts grown inside the enclosed containers should exude more water than the ones grown in the exposed containers. From the data collected throughout the thirteen days of observation, the results supported the hypothesis because the green bean sprouts grown in the enclosed containers indeed performed the process of guttation while the green bean sprouts grown in the exposed containers did not. My original goal of the experiment was to examine only the process of guttation; however, I ended up also observing the plant’s growth as the difference in height of the green bean sprouts grown in the enclosed versus exposed containers were significantly noticeable from the very beginning of the experiment (Day 4). Although the results produced generally supported my hypothesis, there were some errors and uncertainties which must be considered and they are mentioned in the following section.
Errors and Uncertainties:
In this self-directed study, there may have been some errors which occurred. First of all, the issue of using accurate devices cannot be absolute. The use of the hygrometer to measure the humidity on the exterior and interior of the containers may not have been exact. Especially since I used the household type of hygrometer (mechanical) instead of the professional type (electronic), the measurements may have been slightly erroneous. A mechanical hygrometer should be calibrated in order to assure more precise results. Calibrating the hygrometer means to test its accuracy by comparing it with an independent standard. After calibrating, the hygrometer should read around 75%, which is the standard reading. However, I did not calibrate my hygrometer as I assumed that it would be relatively accurate already.
Since the green bean sprouts grown inside the enclosed containers grew much quicker than I had expected, I needed to transfer the plants twice—once from the plastic wrap container into the plastic container, and another time from the plastic container into the container with the detachable lid. This may have altered the initial results because the plant had undergone environmental changes although they may have been very subtle. By adjusting the plants environment, growth may have been interrupted. Perhaps an improvement for future experiments is to try and establish an environment for the organism and refrain from changing it as the change may have a harmful impact on the organism’s growth or behaviour.
Improvements or recommendations:
For future experiments involving the use of a hygrometer or any other mechanical devices, I should standardize the apparatus before use in order to ensure a greater accuracy when measuring. This is important because numerical data is often a vital part of any scientific study.
Perhaps an improvement for future experiments involving living organisms is to try and establish an environment for the organism and refrain from changing it as the change may have a harmful impact on the organism’s growth or behaviour.
I may want to further investigate on this topic and perhaps observe the green bean sprouts more than once a day so that I can examine whether the growth and behaviour of the plants may vary throughout the day. By examining the plant possibly three times a day will allow for a greater understanding of the processes in which the plants undergo. Under the topic of guttation, I may observe whether the hydathodes exude water at a different rate during different times of the day and whether the water exuded is always of the same content (level of salts, sucrose, etc).
CONCLUSION:
In conclusion, the changes in the level of humidity and transpiration in fact caused the green bean sprouts to display the process of guttation. From this experiment, one can see that abiotic factors (atmospheric conditions) such as humidity are extremely prominent to plant growth.
