<h1>Experiments in Duck Weed Growth</h1>
<h2>Introduction</h2>
<p> These experiments were conducted in order to determine the optimum growing conditions for Duck Weed so that the growth
and cultivation of duck weed could be automated. Duck weed was chosen for three factors which make it ideal for automated
growing; 1) it is edible, 2) it is the smallest angiosperm and so many independent cultures of it can be grown in a very
small space and 3) it is an aquatic plant and so it is very easy to grow hydroponically. All of these factors make growing a
large number of experiments in parallel simple and inexpensive.</p>
<h2>Experiment One</h2>
<p>The first experiment will focus on optimizing the creation of sterile samples. Duck weed is most easily grown in sterile
sealed containers. It prefers stagnant water and so if the containers are not sterile and sealed then the water will become
fouled with algae, bacteria and fungi which will attack the plants and contaminate them, reducing their productivity and
making them inedible.</p>
<h3>Method and Materials</h3>
<p>A sample of duck weed was collected from the wild in a 125 ml mason jar.</p>
<p>One dozen 125 ml mason jars, lids and canning rings placed in a large canning pot filled with water. A pair of pincers
and a ladle were kept in a separate pot of water. A solution of fertilizer was prepared by dissolving 1/8 tea spoon of
ground GreenEarth Tomato & vegetable food pellets (4.6.8) and 1/8 tea spoon of ground CIL Rhododendron, Azalea and Camellia
fertilizer pellets (4.12.8) in 750 ml of water in a third pot. All three pots of water were boiled for one hour.</p>
<p>Each mason jar was removed from the canning pot in turn and the following steps were taken: The ladle was used to place
approximately 60 ml of boiling fertilizer solution into the mason jar, the ladle was returned to its pot, pincers were used
to remove a canning lid from the canning pot and place it on the mason jar, the pincers were used to remove a canning ring
from the canning pot and place it on the mason jar, the pincers were returned to their pot, oven gloves were then used to
tighten the hot canning ring onto the mason jar.</p>
<p>Once all of the mason jars were filled and sealed they were set aside to cool for 72 hours. At the end of the 72 hours
they were examined visually (without opening them) for bacterial or algae growth. A series of containers were filled with
solutions of bleach in water at the following concentrations, 1:10, 1:5, 1:3, and 1:2. A loop and handle was formed from a
single piece of 16 guage steal wire with a loop diameter of approximately 5 mm and a handle length of 10 cm. The wire was
heated to red hot in a flame to sterilize it and then allowed to cool for approximately five minutes. The loop was used to
transfer subsamples of one to about one dozen duck weed plants from the sample jar to the bleach solutions. Each subsample
was placed in just one of the solutions for a period of 15, 30 or 60 seconds. One of the mason jars containing the sterile
fertilizer solution was opened and the loop was used to transfer the sub sample into the mason jar which was immediately
closed and labelled with a label indicating the time and concentration of bleach solution used for that sample. Each
combination of the 3 time periods and 4 bleach concentrations was used exactly once to inoculate a mason jar producing 12
mason jars with the 12 different labels {1/2 15, 1/2 30, 1/2 60, 1/3 15, 1/3 30, 1/3 60, 1/5 15, 1/5 30, 1/5 60, 1/10 15,
1/10 30, 1/10 60}.</p>
<p>The twelve mason jars were placed on their sides in a cardboard box and a LED grow light panel was placed directly on top
of them. The grow light was plugged into a timer which was set to provide power to the grow light for one 14 hour period per
day. The timer was plugged into a standard 120 V wall receptacle. This apparatus was allowed to cycle for several weeks and
was observed.</p>
<h3>Results</h3>
<p>The LED grow light was observed daily to ensure that it was lighting. It failed to light on only one day (due to a loose
wire).</p>
<p>The mason jars were examined daily for the first week for signs that the duck weed died due to exposure to the bleach or
that bacterial growth had commenced on the surface of the water. During the first week there was no sign of bacterial growth
in any of the jars. However three duck weed subsamples died presumably due to too much exposure to bleach in the
sterilization process. They were the subsamples labelled 1/2 30, 1/2 60 and 1/3 15. Individual duck weed plants in most
other samples died also. However, only the completely dead samples were discarded.</p>
<p> After several weeks the plants jars were examined again. The plants were counted and checked visually for bacteria and
algae. Table 1 shows the results</p>
<h4>Table 1: Number of Duck Weed plants observed in each sample jar after several weeks</h4>
<table border="1">
<tr><th>Time (s) exposed to bleach:</th><th>15</th><th>30</th><th>60</th></tr>
<tr><th>Bleach Concentration</th></tr>
<tr><th>1:10</th><td>4</td><td>12</td><td>4</td></tr>
<tr><th>1:5</th><td>11 + algae</td><td>6 + algae</td><td>7 + algae</td></tr>
<tr><th>1:3</th><td>[discarded]</td><td>21 + algae</td><td>8 + algae + bacteria</td></tr>
<tr><th>1:2</th><td>5</td><td>[discarded]</td><td>[discarded]</td></tr>
</table>
<h3>Discussion</h3>
<p>It was noted that the positioning of the bottles under the LED grow light may have affected the algae growth. The 1/10
and 1/2 bottles were at the end of the box and therefore the edge of the panel and so may have gotten less light, causing
both less duck week growth and less algae growth. The bottles were rotated and will be continued to be observed in order to
determine if algae growth will be observed in all bottles.</p>
<p>The grow light panel has LED's in three colours, white, red and blue. They are not distributed evenly over the panel and
so different mason jars may have been getting different concentrations of the light. This could be improved upon in two
ways, The box could be lined with mirrors. This would redistribute the various colours of light around the box more evenly.
The bottles could be rotated regularly (daily) in order to ensure that all bottles got the same amount of light.</p>
<p>The fertilizer used was not perfectly soluble. It was observed that the algae in many samples was growing on the solid
residue of the crushed fertilizer pellets. Repetition with a more soluble liquid fertilizer rather than ground pellets of
fertilizer may produce better results.</p>
<p>The fact that almost all samples of duck weed exhibited algae growth is of concern. Evidently the bleach is ineffective at
killing the algae without also killing the duck weed. A further experiment in which the duck weed is removed from the the
sterile fertilizer solution after various periods of growth, re-sterilized in a bleach solution and placed in a new sterile
fertilizer solution may help to separate the duck weed from the algae more effectively.</p>