Does the allelopathy of garlic have effect on the germination of radish seeds?
Some animals, plants, fungi, and bacteria produce what is called an allelopathy. This is a biological chemical that affects the growth of some plants in positive and negative ways (Wikipedia). The biochemicals that are produced are not important to the metabolism of the plants, which makes it the reason for the positive or negative effects. They are "secondary metabolites". Allelopathy has been discovered a very long ago in 300 B.C. by a man named Theophrastus. However at the time he did not know what exactly he was dealing with, he just figured out that chickpeas had the power to "exhaust" soil and destroy weeds (Cornell). In general allelopathy is considered to be a "competition chemical" which is a basically a chemical used by plants against other plants. The chemicals Secreted are growth or germination inhibitors that are used to prevent another plant from growing (Michael Allaby). The reason for such harshness is that eliminating other plants leaves more resources for the plants that survive and therefor enable them to sustain life even further.
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After the research and reading that I have done I have reason to believe that allelopathy of garlic does have an effect on the germination of radish seeds. I believe it would have a negative effect on the germination of radish seeds, preventing them from germinating.
Materials & Methods
- Round plastic see-through containers.
- Round piece of special tissue.
- Radish Seeds.
- Crushed Garlic.
- Crushed Carrot.
The way we set up the experiment was first we grabbed four see-through plastic containers that would contain most of the parts. Each container received a round piece of special tissue at the bottom in order to hold the water for the seeds. An equal amount of 20 radish seeds were placed into each container leaving room in the middle in the two out of the four containers. In one of the containers we crushed garlic and placed it into tinfoil open from the top right into the middle of the container. The other container received crushed carrot in tinfoil opened from the top straight into the middle. Two of the containers were used as a control group and were not given carrot or garlic. All of the four containers received an equally measured eight milliliters of water. The top lid on the containers was closed and tape was applied to the sides to prevent any damage or harm.
The designated observation process was two weeks. Every day except Friday, Saturday, and Sunday the containers were checked for germination activity. Exactly a week after set-up the containers were given another eight milliliters of water each, as the water had seemed to be drying up. Each day the data was recorded and documented. The information recorded was such as amount of seeds that germinated, length of the roots, leaves, and stems, as well as the color of the leaves, and roots.
The nuisance variables such as temperature, water, and light were kept constant by keeping all the containers in the same exact environment. They received the same exact amount of light due to them being right next to each other. The amount of water was the same because we measured and added the same amount to each container. Temperature was constant as well because once again they were located in the same area, where the temperature couldn't change.
Graph number one shows our first control group, consisting of just radish. As you can see almost all the seeds have germinated. The stems and leaves produced were green and were about half an inch long.
Graph number two showed very similar results to graph number one, in fact almost identical. The number of seeds germinated only varied by one, which might have been caused by seed health or position. Other variables were the same. Seeds and stems were also about half an inch long and a healthy green color.
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Graph number three shows our first and main test group, the effect is clearly visible on the graph. The seeds that were placed in the same container as garlic had a significantly less germination rate than the two control groups. Also the leaves and stems of the radish were not green and healthy. The stems and leaves looked rather dead as they were a pale white color; as well the size was half of the control group.
Graph number four shows our last test group. In this case we had put the radish in the container with crushed carrot. According to the results the carrot had similar effect on the radish just like the garlic did. The amount of seeds germinated was significantly less. The stems and leaves were smaller and showed a very faint color of green.
After the experiment had finished and the data was collected and analyzed it was clear garlic and carrot as well had a great effect on the radish seeds. The seeds that were placed in the same container as the garlic and carrot had a significantly lower germination rate and speed. The color of the stems and leaves, as well as size, that the two test groups produced was much more faint and the size was about half of the control groups.
In conclusion we can say that the experiment was a successful one on the basis of our results. We have analyzed and collected data over a two week period. The experiment was set up correctly as it had all of the following necessities such as a control group, test groups, as well as the nuisance variables being maintained the entire time of the experiment. The hypothesis that was stated in the beginning was proven to be correct as we have learned that allelopathy of garlic indeed has an effect on the germination of radish seeds. The effect that it has is negative, as it provides the biochemicals that inhibit the germination and growth of radish.
- MICHAEL ALLABY. "allelopathy." A Dictionary of Ecology. 2004. Encyclopedia.com. 1 Feb. 2010 〈http://www.encyclopedia.com〉.
- "Allelopathy -." Wikipedia, the free encyclopedia. Web. 01 Feb. 2010. 〈http://en.wikipedia.org/wiki/Allelopathy〉.
- "Allelopathy." CSIP Student Inquiry Projects - home. Web. 02 Feb. 2010. 〈http://csip.cornell.edu/Projects/CEIRP/AR/Allelopathy.htm〉.
- "[Allelopathy of garlic root exudates on different ... [Ying Yong Sheng Tai Xue Bao. 2007] - PubMed result." National Center for Biotechnology Information. Web. 02 Feb. 2010. 〈http://www.ncbi.nlm.nih.gov/pubmed/17396504〉.