Overall Conclusion

Though the Western blot did not yield results that could be adequately used to determine phytochrome expression, the phenotypic results derived from week one allowed from some conclusions about the effect blue light has on plants to be drawn.  As was shown from the results displayed in week 2, the plant with the highest percent average growth was the non purple plant, this plant also had the smallest average leaf area.  Plants have anthocyanin pigments which are often red, purple or blue.  These pigments have been found to help protect a plant against light stress, specifically blue and UV lights (Azari, 2009).  Since this plant lacked the purple pigment, it most likely does not protect the plant against stress due to blue light, thus allowing this plant to absorb blue light and have its photoreceptors activated by it, inducing plant growth.  Since this plant is obtaining an adequate source of light, it does not have to invest energy into making its leaves larger to try and accumulate more light, which is most likely why this plant had the smallest average leaf area.  The purple plant however, showed an inverse relationship to the nonpurple plant in terms of its average percent grwoth and average leaf area.  The purple plant had the lowest overall average growth and the largest average leaf area.  Since this plant contains the purple pigment, it is protected against blue light and therefore, mainly reflects blue light as opposed to absorbing it and having its photoreceptors highly activated, which would stimulate higher percent average growth.  Since this plant was not able to utilize the most intense light source, blue, in this situation, the plant invested energy into increasing its average leaf area to try and obtain other light sources to power its growth mechanisms.  Due to photoreceptors, such as phototropins, which are blue light and UV light receptors that mediate light driven movement that causes photomorphogenetic responses including inhibition of stem elongation, stimulation of leaf expansion and opening of the stomata in addition to pigments that caused the plants to differentially absorb blue light, the pigmented and the nonpigmented plants grew differently due to differences in absorption of the blue light (Lin, 2003).  In conclusion, blue light seems to have a positive effect on the growth of all types of Wisconsin Fast Plants since none withered or died and all grew to some extent, however, due to the presence of pigments, different plants are able to utilize blue light, where others, such as purple pigmented plants are not.  These results confirmed the hypothesis being investigated in this experiment.  Additionally, if the Western Blot had been conclusive, because blue light is suspected to increase phytochrome expression, phytochrome expression would have most likely been higher in the non purple plant than the purple plant, since the purple plant reflected the blue ligth, while the non-purple plant absorbed the blue light and utilized it.  Potential sources of error include the potential contaminations of plants and all chemicals use as well as other factors such as uknown fluctuations in temperature that could have also altered how the plants grew phenotypically.