Based on the growth observed in the sunflowers, and the declining conductivity levels in the perchlorate hydroponic system, I have supported my hypothesis that the plant can constantly absorb
perchlorate from a solution. The sunflowers flourished, implying that the perchlorate metabolized or that it didn't interfere with plant functions. Over the period of a week, perchlorate was actively absorbed, and one plant lowered the solution's strength by 1500 ppm. 
However, due to limited time and lack of equipment, there are some holes I would like to fill. I don't know if perchlorate affects flower and seed production, or if it is completely removed from plant tissue. With access to a mass spectrometer and a few more months, I would have more well-rounded results.

    Another question I would like to research is the real-world context of cleanup using sunflowers. There are limits to phytoremediation:

  •    Weather 
  •    Depth of contaminated groundwater that is underground
  •    Presence of a solution more concentrated than 0.05%
  •    Time
    Observing the hardiness of the sunflower, these problems should be minuscule in the state of California. Weather here is mild enough for year-long growth of these plants. Although it would take a long amount of time to absorb large levels of this chemical, they can be planted in high risk areas to prevent future contamination of groundwater. Considering the low cost and easiness to grow, a major amount of money and effort can be saved. For other areas, hardy generations of sunflowers can be created using selective breeding.

    I'd like to do more research using a larger experimental population, as it is impossible to find a direct correlation using only one specimen. I can only infer using the results from my experiment. Sunflower B had weaker foliage then the control group, but it did not limit the uses of the sunflower or the overall result of the experiment. It most likely occurred because of the lack of nitrogen in the system, which foliage feeding could only partially substitute.

    Even past the deadline, I plan on continuing both hydroponic systems to fill the gaps in my experiment. I will grow both specimens to maturity to see if they maintain proper growth. I also plan on germinating Generation 2 to see if genetic heredity is affected by perchlorate. Finally, I want to conduct a full analysis of the tissue to see any change in elemental composition. Even if the perchlorate remains, the sunflowers accumulate the chemical and make cleanup easier.

    I believe plants are making a comeback with their uses in the lives of humans. My research is only a small part in the grander scheme of things, but it is a start. However unorthodox, some of the best biological discoveries are ones that have been found in the natural world. It is up to scientists and communities to utilize these discoveries. It's not just sunflowers: there are hundreds of plants that can make our lives healthier and easier if used correctly. 

    Final thought: The next time you see a field of yellow sunflowers, think beyond the beautiful sea of gold. Those plants could just be saving your life.