The diseases of one Another


Allelopathy derives from the Greek, meaning "diseases of one another". "It is the harmful effect of one higher plant upon another by reproducing of chemical compounds that escape into the environment"[1] In order for an organism to survive or reproduce is by competing both with their own and other species. One-way, plants compete is by producing chemicals that protects them from predators or from other plants. In addition, plants compete for space, light and nutrition.

In this case, we are going to study the alleopathy of famous plant, garlic. "When garlic is crushed its cloves release a strong characteristic smell. The smell is produced by volatile, a chemical that evaporates into the air"[2] Even though smell of garlic can either help the seeds grow faster, slows them down or not grows at all. "Some of the factors that may affect seed germination are: and adequate supply of water and oxygen, an optimum temperature, presence or absence of light. It is worth mentioning that some seeds can even germinate when they are submerged in water, whereas others can't because of lack of oxygen"[3] In order to determine the effect of the garlic on the lettuce seeds we conducted two sets of experiments from control group and experimental group. Our prediction concluded that the seeds without the garlic will grow faster than the ones that had garlic on it. The Hypothesis for this experiment is the volatile from the garlic will stunt the germination of the lettuce seeds.



  • 2 Petri Dishes (9cm diameter)
  • 2 pieces of Whatman filter paper
  • Distilled Water (3ml per setup)
  • Masking tape
  • Tinfoil or 35*10 Falcon tissue culture dishes
  • Garlic press
  • Triple beam balance


Firstly, we take two Petri dishes and place a filter paper at the bottom. Then, we take 50 radish seeds and place 25 seeds on each Petri dish. Next, we crushed garlic with hand press. Weighed 1.0 sample on a triple beam balance and transfer the material samples to a tinfoil boat. Our control group will have seeds while the experimental group will have garlic in addition. After that, we placed the crushed plant material on a Petri dish and then add 3ml of water on each setup. Finally, we sealed the dishes with masking tape, and incubated them for two weeks under classroom conditions. We recorded data after we conducted the experiment.



All of the seeds in the control group germinated and grew faster than the experimental group. In addition, The stems of the seeds from control group were longer, 6.5cm being the longest than stems of the seeds from the experimental group 2.5cm. As we mentioned before, "the process of germinating involves three main factor: moisture, a plant medium and warmth. If any of these goes wrong than seed may fail to germinate"[4] Ten out of twenty-five seeds mold on them. On the other hand, control group most of the sprouts were green, and a week later we observed white mold on some sprouts. Eleven of the sprouts had leaves on them, and sprouts begin the process of drying out.

The garlic gives off allelochemicals, which "assist plants by reducing competition from neighboring plants and provide protection from predators or pathogens." Often these chemicals inhibit seed's germination and growth of young neighboring plants with less effect on plants"[5]We noticed that control group went on growing faster than the experimental. The longest stem on the control group was 3.5cm and shortest was 0.9cm, whereas on the experimental group was 1.5 cm longest and shortest was 0.5cm. At the beginning of the experiment, our group's hypothesis stated that the volatile from the garlic would stunt the germination of the radish seed; our statement was proven that it is true by the dates we gathered in two weeks.


According to the dates that we can say that aromatic substance of garlic, inhibit the growth and development of the radish seeds. Results from the experiment proved our hypothesis and it became a theory. The garlic had big impact on the growth and development of the on radish seed's germination. The radish seeds with crushed garlic did not grow as well as the radish seeds without crushed garlic. The experiment could have been done much better if there were at least one extra more groups control and experimental.


  1. Stone,Doris.The Lives of Plants.Published by:Charles Scribner`s Sons,New York.(1983)146-47.
  2. Rice, E.L. Allelopathy. 2nd. Edition. Orlando, FL:Acedemi Press, Inc. (1984)
  3. Dittmer, Howard J. "Modern Plant Biology" > Published By : Van Nostrand Reinhold Company, New York (1972):217-18
  4. Bewley J. Derek. Plant Sciences. ED. Richard Robinson. Vol. 2. New York: Macmillan Reference USA, 2001. p174-76
  5. Salisbury, F.B. &s; Ross, C.W.. Plant Physiology, 3rd Edition. Belmont, CA:Wadsworth publishing(1985)
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