"The Story of the Seed" Lab Report: Broccoli Romanesco
Does watering broccoli romanesco with different pH levels slow their growth?
Introduction:In our lab we tested solutions of different pH levels to find out if they would slow or stop the broccoli romanesco's growth. The plants will be watered with their appropriate solutions of acids, bases, and the control (water). They would be placed under the fume hood for two weeks, watered every other day (except for the weekend), and their height would be recorded frequently.
Hypothesis:
If watering plants with liquids of different pH levels affects their growth, then the less neutral the solution is, the less the plant will grow, the longer it will take to germinate, and less seeds will germinate.
Control: two cups of three seeds watered with tap water
Variable: two cups of three seeds watered with a basic solution of tap water and sodium hydroxide (pH level of 10), and two sets of three seeds watered with an acidic solution of tap water and lemon juice (pH level of 4)
Purpose:
We chose this as our hypothesis because if it is correct it would lessen the need creating of future hypotheses such as "If watering a plant with orange juice changes the growth rate of plants, then watering a plant with orange juice will make it grow faster" because we would already know that it would most likely not work since it is an acid. We also wanted to know if there would be any desirable affects of watering a plant with an acid or base instead of water, such as a different color in the plant.
Materials:
We chose this as our hypothesis because if it is correct it would lessen the need creating of future hypotheses such as "If watering a plant with orange juice changes the growth rate of plants, then watering a plant with orange juice will make it grow faster" because we would already know that it would most likely not work since it is an acid. We also wanted to know if there would be any desirable affects of watering a plant with an acid or base instead of water, such as a different color in the plant.
Materials:
Lemon juice (40mL total)
Sodium hydroxide (approximately 8mL or 160 drops total)
Tap water (approximately 3552 mL total)
18 broccoli romanesco seeds
Soil
Metric ruler
Beaker (one that can hold at least 150mL)
Graduated cylinder
Pipette/dropper
Stirring rod
Paper towels
Safety glasses
6 plastic cups
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| Lemon juice |
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| Sodium hydroxide |
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| Broccoli romanesco seeds |
How to create the acidic/basic solutions:
- Acidic solution: mix 10 mL of lemon juice with 300mL of tap water
- Basic solution: mix approximately 40 drops or 2mL of sodium hydroxide (use pH strips to see when it is at 10) with 300mL of tap water
1. Fill all of the cups with soil
2. Poke holes in the bottom of the cups so the water can drain
3. Label 2 of the pots for each group of plants (acid, base, and water/control)
4. 3 seeds will be placed approximately 0.3 cm (1/8 inch) in each pot
5. The plants will be watered with 150 mL of their appropriate solutions every other day (except for the weekends)
6. The plant's height and other observations about it will be measured every other day (except for the weekend)
7. Steps 5 and 6 will be repeated for 2 weeks
8. Analyze the data and create graphs to represent them
Data and Observations:
Check 1:
No change in the seeds was observed, for we had just planted and watered the seeds with their solutions.
Check 2:
None of the seeds in any of the groups at this point have sprouted. The soil of the cups remained moist and the height of it decreased by about 1.2 cm. The soil of the acid group turned yellowish possibly because of the lemon juice while the base and control group's soil were dark brown.
Check 3:
Today is the first day that the seeds have started to sprout. The first cup of the acid group had one plant sprout and reach 2.8 cm while the second cup remained the same as the last check. None of the seeds in the base group have begun to grow. However, the control group had 3 plants grow, the first in the first cup being the tallest at 3.5 cm, the second in the first cup being a bit shorter at 3 cm, and the third in the second cup being 3.2 cm tall. Also, the control group's plants were a darker shade of green, a little thicker, and overall healthier looking than the acid group's plant.
Check 4:
Surprisingly, the plants have nearly tripled in size! The acidic plant grew 4.2 cm and reached 7 cm, the first control group plant grew 5.3 cm to a total of 8.8 cm, the second grew 4.5 cm to 7.5 cm, and the one in the second control group cup grew 4.3 cm to the height of 7.5 cm. One new plant has also begun to sprout in the second control group, it is 1.5 cm tall. In addition, the acidic plant has become much more noticeably flimsy than before in the previous check; however, the plants in the control group are flimsy enough to bend over the sides, except for the newly sprouted ones that are able to stand straight up.
Check 5:
This is the last time that the plants will be checked and no new seeds have sprouted. In the acid group, its only plant grew 1 cm to reach 8 cm. In the first cup of the control group, both plants grew about 2 cm and stretched to 11 and 9 cm. In the second cup of the control group, the first plant grew to 10 cm (a 2.5 cm growth) while the second plant grew to 5 cm (a 3.5 cm growth). The control group's plants have become more firm and less bendable while the acidic plant became so thin and unhealthy that one of its leaves broke off and became detached while we delicately measured it.
A picture of all the plants in day 5. The control group is in the back, the acid group is in the middle, and the base group is in the front.
A closer view of the day 5 plants with the control group in the back and the acid group in the front.
Result and Data Analysis:
Data of Seed Height and Germination
This chart was made to show exactly what the data was so that any calculations about our experiment could be precisely made.
This graph shows the average final height of the plants in each group.
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This graph was made to illustrate how long it took for each seed group to germinate.
This graph was created to help show the amount of seeds that germinated in each group.
We put our data (the height of the plants, the amount of days it took for the seeds to germinate, and how many of the seeds germinated) into graphs through Google Spreadsheet to help show the different aspects of how the different plants grew and to help answer the three statements in our hypothesis. The chart was created so that we could easily create precise percentages or other results by having all of the data lined up in organized rows. Through these graphs, we were able to conclude that watering plants with acids causes them to grow slower and smaller than the plants in the control group. However, it takes the same amount of time for them to germinate, but not as many of them do. The plants watered with bases never grew. Some results that we were unable to graph due to it being qualitative data is that the plant in the acid group had a lighter green color, was much thinner, and more flimsy and fragile than the plants in the control group.
Conclusion:
In our results, it was concluded that watering plants with different pH levels worsens their growth, with acids simply slowing the growth and bases stopping growth. We believe that the base group did not grow because the sodium hydroxide solution was too powerful to the point where it burns human skin. From our general knowledge we believe that these types of liquids are not suitable to be consumed or produce life, even if the test subject is a plant.
Unfortunately, there were several factors that flawed our test data. First of all, the plants were sometimes measured before being watered, making them seem shorter since the soil did not go down because of the liquids. The placement of the plants under the fume hood also could have had an affect on the plant's growth as well as the fact that the pH levels of the solutions were not exactly the same each time the plants were watered. In addition, we had a very small test group of only 6 seeds per test group due to the fact that we had a limited amount of time and resources. Furthermore, we only had one plant sprout in the acid group, which is where we got all of our data for the acid group, so we do not know if the plant was smaller by chance or if it was because it was watered an acidic solution. While these slight mishaps may have only slightly changed our results, it is important to stay consistent to maintain the integrity of the experiment.
We can create much better replicas of this experiment by fixing the previously mentioned problems. We can also create new future experiments such as testing other acids and bases to see if they have the same affect. However, based on the information that we received from our lab, we can create an experiment testing if bases kill seeds or if they simply fail to germinate them. Due to our very vague results, planning based of future experiments based on our data should be kept to a minimum until further tests are executed.
In conclusion, our experiment was a success and was able to test our hypothesis of "If watering plants with liquids of different pH levels affects their growth, then the less neutral the solution is, the less the plant will grow, the longer it will take to germinate, and less seeds will germinate" and answer our question.
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