Hydroponics Lab Report
Introduction & Hypothesis
Hydroponics is a gardening method that is becoming increasingly popular due to several benefits. When grown hydroponically, plants do not require soil – a commodity often unavailable in urban communities. In addition, growers do not experience problems with pests as the system is almost always enclosed. Despite the unique method of growing, plants grown hydroponically still need the same macro and micronutrients typically found in soil. To measure the effects of each nutrient on plant growth, each lab group prepared a solution and omitted one necessary nutrient. We hypothesized that omitting KH2PO4 would result in eventual plant death due to the beneficial properties of KH2PO4.
Materials & Methods
To test the hypothesis, four tomato seedlings were grown through the static solution culture method. Each seedling was randomly selected. Their roots were rinsed to remove all soil before being placed in a beaker through a Styrofoam lid that allowed the roots to reach the nutrients inside the beaker. The beaker was filled with a nutrient solution with the following compounds and concentrations:
5ml of 1M CaNO3
5 ml of 1M KNO3
2ml of 1M MgSO4
2ml of 1M KH2PO4 (omitted in our experiment)
1ml of FeNaEDTA
1ml of microelements
985ml of dH2O
The beaker containing the seedlings as well as the flask with additional solution was covered with aluminum foil to prevent the growth of algae. The seedlings were placed under fluorescent lighting and the growth of each plant was recorded every other day for three weeks. A control was also prepared by our lab technician, Alex Brooks. Two tomato plants were set aside as the negative control with a H2O solution while two other plants were
given the complete nutrient solution. They were also placed under fluorescent lighting with the same environmental conditions.
Results
Although the growth of the plants lacking KH2PO4remained consistent over the first 2 weeks of the 3 week trial period, they began a steady decline shortly thereafter. The roots began to rot although care was taken to prevent submersing the entire root system in the solution. The leaves of each tomato plant showed signs of browning after the two week mark. New shoots appeared deformed and failed to reach normal size. Meanwhile, the positive control flourished with the complete nutrient solution. The leaves of the plants serving as the positive control were large and healthy. Their root systems were well-developed indicating a healthy plant overall. The two tomato plants belonging to the negative control with just water suffered from stunted growth from the beginning of the experimental period of three weeks.
Discussion & Analysis
The data showed that without KH2PO4, the plants were prevented from growing healthy. Both potassium and phosphate are essential macronutrients in plant growth. According to the University of Minnesota website, potassium “stimulates early growth, improves the efficiency of water use, and is vital for stand persistence, longevity, and winter hardiness of alfalfa.” Our experiment clearly showed that while all other essential nutrients were provided, omitting KH2PO4 had a significant negative impact on the growth rate and health of tomato plants. Further comparisons to the control reinforced our hypothesis that all macro and micronutrients must be present in the solution for successful plant growth.
References
Rehm, G., & Schmitt, M. (n.d.). Potassium for Crop Production. University of Minnesota Extension. Retrieved May 5, 2012 from http://www.extension.umn.edu/distribution/cropsystems/dc6794.html.
Richardson, Eden. "Hydroponically Grown Tomato Plants." 2009. JPG file.
Hydroponics is a gardening method that is becoming increasingly popular due to several benefits. When grown hydroponically, plants do not require soil – a commodity often unavailable in urban communities. In addition, growers do not experience problems with pests as the system is almost always enclosed. Despite the unique method of growing, plants grown hydroponically still need the same macro and micronutrients typically found in soil. To measure the effects of each nutrient on plant growth, each lab group prepared a solution and omitted one necessary nutrient. We hypothesized that omitting KH2PO4 would result in eventual plant death due to the beneficial properties of KH2PO4.
Materials & Methods
To test the hypothesis, four tomato seedlings were grown through the static solution culture method. Each seedling was randomly selected. Their roots were rinsed to remove all soil before being placed in a beaker through a Styrofoam lid that allowed the roots to reach the nutrients inside the beaker. The beaker was filled with a nutrient solution with the following compounds and concentrations:
5ml of 1M CaNO3
5 ml of 1M KNO3
2ml of 1M MgSO4
2ml of 1M KH2PO4 (omitted in our experiment)
1ml of FeNaEDTA
1ml of microelements
985ml of dH2O
The beaker containing the seedlings as well as the flask with additional solution was covered with aluminum foil to prevent the growth of algae. The seedlings were placed under fluorescent lighting and the growth of each plant was recorded every other day for three weeks. A control was also prepared by our lab technician, Alex Brooks. Two tomato plants were set aside as the negative control with a H2O solution while two other plants were
given the complete nutrient solution. They were also placed under fluorescent lighting with the same environmental conditions.
Results
Although the growth of the plants lacking KH2PO4remained consistent over the first 2 weeks of the 3 week trial period, they began a steady decline shortly thereafter. The roots began to rot although care was taken to prevent submersing the entire root system in the solution. The leaves of each tomato plant showed signs of browning after the two week mark. New shoots appeared deformed and failed to reach normal size. Meanwhile, the positive control flourished with the complete nutrient solution. The leaves of the plants serving as the positive control were large and healthy. Their root systems were well-developed indicating a healthy plant overall. The two tomato plants belonging to the negative control with just water suffered from stunted growth from the beginning of the experimental period of three weeks.
Discussion & Analysis
The data showed that without KH2PO4, the plants were prevented from growing healthy. Both potassium and phosphate are essential macronutrients in plant growth. According to the University of Minnesota website, potassium “stimulates early growth, improves the efficiency of water use, and is vital for stand persistence, longevity, and winter hardiness of alfalfa.” Our experiment clearly showed that while all other essential nutrients were provided, omitting KH2PO4 had a significant negative impact on the growth rate and health of tomato plants. Further comparisons to the control reinforced our hypothesis that all macro and micronutrients must be present in the solution for successful plant growth.
References
Rehm, G., & Schmitt, M. (n.d.). Potassium for Crop Production. University of Minnesota Extension. Retrieved May 5, 2012 from http://www.extension.umn.edu/distribution/cropsystems/dc6794.html.
Richardson, Eden. "Hydroponically Grown Tomato Plants." 2009. JPG file.