The Murder Plot That Failed, Part Two

When we decided that the radishes looked full-grown, we pulled them out of the hydroponic apparatus. We weighed the entire plants, then cut off the leaves and weighed the roots only. We put them in cups of water and left them in the refrigerator for several days because Mr. Mazzella said they would taste better if we did that.

Three radish samples in our taste test

The Taste-Tests

One of our dependent variables in this experiment was how the radishes tasted. We convinced Ms. Nick and Mrs. Cottingham to taste the radishes and see what they thought. We gave them each three radish slices labeled A, B, and C so they would not know which radishes they were tasting. Here are the results:

Ms. Nick Mrs. Cottingham

Nothing: more evenly spicy, a little softer bland

Normal: even more bland, no kick crunchy, little peppery, spicy

Double: kind of bland, little kick spicier than Nothing, but less spicy than Normal

From these strange results, we concluded:

Taste-testing is a subjective measurement; opinions of taste may vary from person to person.
Taste-testing is not always reliable. For example, Ms. Nick made two different taste observations of the same radish. This may be due to bias on Ms. Nick's part; it also may show that different sections of the same radish can taste different.
All radishes grown in the same nutrient solution do not taste alike. For example, Mrs. Cottingham thought that the biggest radish with the Nothing treatment tasted like the radish from the Normal treatment. She also thought the weird radish from the Normal treatment (the only one that floated in water) tasted like the radish from the Double treatment.
We could not pick which radishes tasted the best because the two opinions we gathered were inconsistent. We really should have gotten more people to taste the radishes, but we were running out of time as well as radishes.

Experimental Data

We did not make any quantitative observations during the experiment (we only took pictures), but we did measure the weight of the radish plants and the weight of their roots at the end of the experiment in order to compare how the different nutrient solutions had affected them. The results turned out very interesting:

Average Growth of Radishes in Different Nutrient Solutions

Total weight (g) Edible root only
Nothing 16.14 4.21
Normal 5.09 1.02
Double 10.05 3.28

Average Growth of Radishes in Different Nutrient Solutions

Maximum Growth of Radishes in Different Nutrient Solutions

Total weight (g) Edible root only
Nothing 40.38 13.86
Normal 16.90 4.30
Double 28.00 9.65

Maximum Growth of Radishes in Different Nutrient Solutions

Becky made the following observations of the radish plants at the end of the experiment:

Nothing:

Four plants: two healthy, two underdeveloped. They have large, thick stems, long root systems, and branched leaves.

Normal:

Eight plants, medium and underdeveloped. They are large and tall with relatively thick stems, many long leaves, and long root systems. The tallest radish has a very underdeveloped root system, but it has tall, branched stems and leaves and a tiny (1 cm) flower at the top with buds forming in eight locations.

Double:

Five plants: one healthy, three medium, one underdeveloped. They have thick stems with relatively tall and branched leaves. They have long root systems, though not as long as the Nothing and Normal radishes. The medium radishes have a fleshy, fushia-colored, spherical bulb and are very healthy looking. Some of the plants have a faint yellow and red edge on their leaves. Some also have slightly curled leaves.

Conclusion

The Nothing radishes seemed to grow larger than the Double and Normal radishes. From this we can conclude that an oversupply of magnesium is indeed harmful to radish plants. The radish plants with the most magnesium even had some visible signs that they were unhealthy.

We cannot really draw conclusions about the radishes with no magnesium because when we made their nutrient solution with tap water, they got magnesium and grew normally. However, this addition of magnesium to the Nothing radishes gave them a magnesium level closer to normal. Similarly, the addition of magnesium to the Normal radishes gave them a magnesium level above normal, and the addition of magnesium to the Double radishes gave them a magnesium level that was higher still. This supports our conclusion that radishes with too much magnesium, which in this experiment included the Normal radishes, are not as healthy as radishes with some magnesium but not as much.

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