the study of allelopathy

Arevik Akhperjanyants

Introduction

Some species of plants can release allelochemicals through various ways such as volatilization, residue decomposition and other processes that can be either be harmful or beneficial on other plans and its environment; this process is referred to as allelopathy. In 300 B.C. Theophrastus wrote about allelopathy; he noted how chickpea destroys weeds by exhausting the soil. Allelochemicals can be present in many parts of a plant; the leaves stems, roots, flowers etc. Allelopathy can affect plant communities and their structure in terms of plant growth, dominance and diversity. Some plants may be harmful to certain hosts that consume it due to their production of toxic allelopathic chemicals. There are two types of allelopathy, negative and positive. Both negative and positive allelopathy enhances a plants chance of survival. Allelopathic activity can vary in certain plants according to the season, weather conditions etc. The study of allelopathy can be helpful in the agricultural processes.

Hypothesis

The volatile garlic smell and the carrot allelopathy due to decomposition will have a detrimental effect on the germination of the surrounding seeds.

Materials and Method

There were various materials use to conduct this experiment such as whatman filter paper, petri dishes, radish seeds, aluminum foil, clove of garlic, piece of carrot, and water. Whatman paper filter was placed in four petri dishes. Twenty radish seeds were placed in each petri dish. A single clove of garlic was crushed and put into a little "boat" made out of aluminum foil. The little "boat" of garlic was placed in one of the petri dishes. A piece of carrot was crushed and put into a little "boat" made out of aluminum foil. The little "boat" of carrot was placed in another petri dish. The petri dishes containing the garlic and the carrot were the experimental group and the petri dishes containing only radish seeds were the control group #1 and #2. All four petri dishes were watered and sealed with tape. The nuisance variables such as temperature, light and water were kept the same by placing all four petri dishes in the same place under the same conditions. All four petri dishes were placed by a window so they get the same amount of light; they were all kept under the same room temperature and the amount of water was monitored.

Results

The first graph compares the experimental carrot group and the control group #1. During the first two days there was no germination of radish seeds in both the experimental and the control group. The radish seeds in both the control and the experimental groups began to germinate at a slow pace on the third day; there was not much difference in stem length. After day 6 the radish seeds in the experimental group began to germinate drastically while there wasn't much change in the control group. By day 8 there radish seeds in the experimental group had germinated far past the radish seeds in the control group by as much as 60 mm.

The second graph compares the experimental garlic group and control group #2. There was no germination of the radish seeds in neither the control nor the experimental groups the first two days. The radish seeds began to slowly germinate in both the experimental and control group on day three. The germination of the radish seeds in both the experimental and control group was steady between day three and six. By day seven the radish seeds in the control group began to germinate quicker than the radish seeds in the control group. By day 8 the radish seeds in the experimental group germinated more than the control group with a difference of about 20 mm.

Discussion

&nsbp;&nsbp;&nsbp;&nsbp;&nsbp;In my hypothesis I stated that the presence of a volatile garlic smell and carrot allelopathy was going to have a detrimental effect on the germination of radish seeds. By the data that was collected my hypothesis was not correct. The carrot seemed to have no effect on the germination of the radish seeds. The seeds in the carrot experimental group when compared to the seeds in the control group actually germinated quicker and were more developed. The germinated seeds in the carrot experimental group had longer thicker stems, more developed and larger leaves they were also a deeper green color than the germinated seeds in the control group. The garlic also seemed to have no effect on the germination of the radish seeds. The radish seeds in the garlic experimental group outgrew the radish seeds in the control group they were being compared to. The radish seeds in the garlic experimental group had longer stems and larger leaves after germinating then the seeds in the control group. The conclusion that is brought out in this experiment is that neither the volatile garlic smell nor the carrot allelopathy has a negative effect on the germination of radish seeds. This experiment was conducted to determine whether or not the smell of garlic and allelopathy from a carrot has a detrimental effect on the germination of radish seeds; further experiments could be conducted to determine if the roots of certain weeds or plants release allelochemicals that effect the growth of plants around it. An experiment with alleopathic soil can also be an effective way to determine the growth of plants.

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