|MadSci Network: Botany|
What you have is an example of hydroponics, the growth of plants without soil. Plants roots do not actually require soil. Roots only require the water, oxygen, about 14 mineral nitrients, and anchorage that the soil provides. If you anchor or support the plant in another way, plant roots can get oxygen, water and mineral nutrients from a nutrient solution. If you are using just tap water, the potato must rely on its stored mineral nutrients and what few there may be in your tap water. Plant growth in hydroponics is often better when air is bubbled through the solution to increase the oxygen level. Scientists often use hydroponics, also called solution culture, in research. For example, it is a good way to study mineral nutrient deficiencies. Hydroponics has a fascinating history (Hershey 1994) and will probably be used to grow plants in outer space. There are many online companies that sell hydroponic systems and supplies. References Hershey, D.R. 1995. Plant Biology Science Projects. New York: Wiley. Hershey, D.R. 1994. Solution culture hydroponics: History and inexpensive equipment. American Biology Teacher 56:111-118. Hershey, D.R. 1990. Pardon me but your roots are showing. Science Teacher 57 (2):42-45. Hydroponics Potato Science Projects Color Pictures of Mineral Deficiencies in Potato
Try the links in the MadSci Library for more information on Botany.