||We learned in the radish seed germination experiment that radishes germinate very quickly. Most of the radishes grew at least 1.5 inches taller each day we measured and collected data. The radish roots grew longer than the shoots and the roots were able to reach the bottom of the bag by the end of the seven days. The radish seeds in the control group that received tap water grew on average, 9.35cm after 7 days while the radish seeds in the experimental group grew on average to 8.1cm after seven days. The strengths from this experiment were putting the seeds close to the top of the bag, watering the seeds when the water looked low, placing them in direct sunlight, and getting the correct measurements of the seedling. The areas for improvement from the radish seed lab were making sure there is enough space for the seeds and making sure the seeds don’t fall into the water.
A seed is an embryo of a plant enclosed in a protective outer covering. A seed is also the flowering plant’s unit of reproduction, capable of developing into a new plant. Seeds are created through sexual reproduction in plants. When pollen lands on the flower’s stigma, it germinates and forms a pollen tube. It quickly grows into the plant’s ovary. Once the pollen finds an ovule, the pollen tube bursts to release sperm cells which fertilize the ovule and initiate seed formation. Inside of the seed is the embryo. One part of the embryo becomes the shoot of the plant while the other part becomes the root of the plant. The parts of the seed are endosperm (stores food), seed coat (protects the seed), and embryo (develops into the new plant).
Germination is the development of the plant from a seed. The three factors required for germination are water, oxygen, and proper temperature in order for the seed to germinate.
The Independent variable (IV) we used for this experiment was pH of the water used to grow the plants. The pH of water is the measure of how acidic or basic the water is, and we chose this independent variable because we wanted to learn how pH impacts the growth of plants.
We used the nasturtium (Tropaeolum) seeds.
Fun facts about nasturtium plants:
The flowers are one of the most recognized edible flowers and have a peppery taste to them. The seeds and leaves are also edible.
The name nasturtium means “nose twister” in Latin, referring to people’s reaction upon eating the flowers.
The flowers are a good source of vitamin c and iron.
Nasturtium seeds were used as a substitute for pepper during World War II.
In tropical countries nasturtiums are not pollinated by bees but by hummingbirds.
Nasturtiums are also a medicinal plant
Seeds of nasturtiums can retain their properties and are able to be planted even after 3-5 years of storage.
Nasturtium juice is used to treat burns
Extract of nasturtium is added into cosmetic products for wrinkle smoothing and essential oils to help fight acne.
Nasturtiums help protect gardens from pests
||Will decreasing the pH of the water used to grow seeds help them grow?
The purpose of our experiment is to determine whether or not decreasing the pH of the water used to grow nasturtium plants impacts how tall they grow.
We chose pH as our independent variable because we found out that drinking water is at a pH of 6.5-8.5, and were curious to see if changing the pH would make a difference when growing nasturtium plants.
From our last experiment using radish seeds, we deduced that decreasing the pH of the water used to grow radish seeds did not give them an advantage in terms of how long they grew to be. We conducted this experiment to find out whether these findings would stay consistent with other types of plants as well.
||If the pH of the water used to grow nasturtium seeds is decreased, then the shoots of the nasturtium plants will not grow as much as the shoots of the nasturtium plants grown in tap water over 20 days.
||The setup is in a ziplock bag vertically, with the water poured into the bottom of the bag and paper towels used to move the water from the bottom of the bag to the seeds, which are placed on staples near the top of the ziplock. We tape the bags to the window to allow for constant and equal sunlight. We measure the length of the shoot of the seedling every two days and water them every two to three days, adding 30 ml of water each time. The pH6 water is created using 150ml of tap water mixed with 10ml of acetic acid.
Control Group - pH8 water (tap water)
Experimental Group - pH6 water (using acetic acid)
Independent Variable - pH of the water
Dependent Variable - length of the shoot of the plant:
-What - length in cm
-How - using a ruler
-How Often - every 2-3 days
-How Long - 13 days
-Used a metric ruler to measure length of the shoots of the seedlings in centimeters
-Sunlight - we placed the bags containing the seedlings on the same window at the same height each day so that all seedlings would receive equal sunlight
-Water - both the control and experimental groups received water on the same days at the same time, and were given 30 ml of water each time they were watered.
Sample Size - 10 seeds
Trials - 1 trial
||This experiment went pretty well, we used nasturtium seeds to see if they would react in a similar way as the radish seeds did. This experiment we collected data a day more than the radish experiment. This time we only measured the shoot instead of the whole length of the seedling. The results of this experiment were that changing the pH of the water didn’t really have an effect on how fast the seed germinated. The average length of the shoot of the seedlings that received tap water (pH 8) was 9.8 whereas, the seedlings that received tap water with acetic acid (pH 6) only ended up with an average of 7.8 cm. We learned that doing the bag method to start germination of seeds is the easier way to go. We obtained these results because we did the same things to take care of our seedlings as we did with the radish experiment, which was successful since the seeds germinated.
The nasturtium seeds in the control group that received tap water grew on average, 9.8cm after 7 days while the nasturtium seeds in the experimental group grew on average to 7.8cm. These results support our hypothesis because decreasing the pH of the water used to grow nasturtium seeds did not result in longer plants. Since both the radish seed experiment and nasturtium seed experiment deduced that pH6 water is not better for the growth of the plants, we learned that using more acidic water is not the best way to grow plants. One possible reason for the outcome is that pH6 water is unnatural for radish and nasturtium plants.
One of our strengths were our constants. The constants we had in our experiment were amount of sunlight, amount of water, and a metric ruler used to measure. The reason these constants were one of our strengths is because we took extra measures to make sure everything was much more consistent than during the radish experiment. For example, in this experiment, we made sure to put the bags in the exact same place on the window each day to ensure that the sunlight stays constant. Another one of our strengths was that we fixed our mistakes from the last experiment. One of the mistakes from our previous experiment was that all of the staples were not perfectly horizontal, causing one of the seeds to fall into the water and therefore not grow properly. This time, when setting up the nasturtium experiment, we made sure to put all of the staples side by side horizontally so that no seed could fall off the staple and into the water at the bottom of the bag.
One of our weaknesses in this experiment was the spacing. Even though we updated the spacing from the radish experiment, the nasturtium seeds are much larger than the radish seeds, so there still wasn’t enough space for the seeds. We believe this is the reason that two of the seeds didn’t germinate and why one of the seeds barely grew despite germinating. Next time, it would be better to either use a larger ziplock or a smaller sample size to ensure that each seed has enough space to grow. Another area of improvement for our experiment would be to water the plants more consistently. One day during the experiment, we decided not to water the plants because both bags still had some water in them. By the next watering day, the paper towels had become entirely dry. It would be better to water the plants consistently, even if it seems like it isn’t necessary.
||High School Students (Grades 9,10,11,12)
||Adlai E. Stevenson High School