Temp Effects of Temperature Stress

Tubes 1 through 4 were placed one at a time in water baths at varying temperatures — 20, 45, 50, and 70 degrees Celsius. Beet samples were soaked in the water baths for a period of one minute, and were then returned to their test tubes that were then filled with 10mL of distilled water, in which they soaked for twenty minutes. All six beet samples were then examined for the depth of their color using a comparative scale. The absorbance of light of each sample after treatment was also measured and recorded.

Results

The samples that had been exposed to the highest and the lowest temperatures showed the greatest depth of color and higher rates of absorbance, suggesting that cell membranes in these samples had ruptured and released the betacyanin that gives the common beet its distinctive red shade and helped make these samples more opaque. Samples 1 and 2, which had been immersed in water baths of 70 and 55 degrees Celsius respectively, had respective color intensities of 5 and 4 and absorbance measures of .228 and .116. Sample 6, which had been exposed to below-freezing temperatures, had a color intensity of 7 and an absorbance of .472. Samples 3 and 4 had color intensities of 1 and absorbance measurements of .

016 and .020, respectively, while sample 5 had a color intensity of 0 and an absorbance of .016. The differences in these samples were not seen to be especially significant, and likely would not prove to be statistically significant given repeated experimentation.

Discussion

The results clearly support the hypothesis, though the effects of freezing temperatures were far more extreme than the effects of the highest temperatures to which the samples were exposed in this experiment. The trendline of the data suggests that higher temperatures would have led to higher color intensities and absorbance measurements, indicating higher rates of cell membrane destruction, but this is unconfirmed in the current experiment. The similarity in observed color intensity and absorbance in the samples exposed to less extreme temperatures suggests that relatively little or no damage occurs to cell membranes at room temperature or at temperatures commonly experienced, which is expected given the survival and growth of the common beet at these temperatures.

References

Bochu W, Hucheng Z, Yiyao L, Yi J, Sakanishi A. 2000. The effects of alternative stress on the cell membrane deformability of chrysanthemum callus cells. Colloids and Surfaces B: Biounterfaces 20(4):321-325.

Lund.

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