Research Question: What is the effect of laundry detergent on the growth of bean plants?
What do you think will happen?
There is a likelihood that the rate of growth in the presence of the laundry detergent pollutant would be slower than the rate of growth in the absence of the pollutant.
Why do you think about this?
Laundry detergents contain anionic surfactants that contribute to their cleaning properties. When applied to the soil, the pH of the soil is likely to increase hence affecting plant growth. Additionally, surfactants are reported to contribute to a reduction in the hydraulic conductivity of soils (Sawadogo et al. 117). Consequently, soils become impermeable to water thus affecting agricultural productivity.
The process of growth and development involves a series of biochemical reactions that are catalyzed by enzymes. These processes include photosynthesis, respiration, gaseous exchange, and transport of substances. Enzymes are protein substances that hasten the tempo of biological reactions. Being protein in nature, they are composed of amino acid residues that exhibit different charges at different pH values. The type of charge of the amino acid residues at the active site of enzymes influences the binding of enzyme and substrate hence catalysis. Therefore, different enzymes have an optimum pH for proper functioning. At elevated pH, the activity of enzymes is affected, which manifests in reduced growth rates.
Experimental Design: A controlled experiment using potted plants in a greenhouse or laboratory will be used. Each treatment will be replicated three times.
Predictor (independent variable): Different concentrations of laundry detergent
Response (dependent variable): Rate of plant growth
Control: Distilled water.
Methodology
Twelve potted bean plants at the same stage of development will be used in the experiment. Approximately 50 grams of powdered laundry detergent will be diluted in 500 ml of distilled water to form the stock solution. 150 ml of the stock solution will be diluted in 150 ml distilled water to make the medium concentration (MC) while another 50 ml of the stock solution will be diluted in 250 ml to make the low soap concentration (LC). The remaining 300 ml of the stock solution will be used as the high concentration (HC) solution.
Three bean plants will be assigned to each treatment: negative control, low concentration, medium concentration, and high concentration soap solutions. The appropriately labeled plants will be irrigated with their respective solutions three times a week for four weeks in the laboratory or greenhouse. At the end of the four weeks, the growth of the plants will be examined by measuring the length of the shoot and recording the values.
For each treatment, the average length will be obtained from the mean of the three replicates. General growth characteristics such as pigmentation of the leaves and the general health of the plant will also be recorded. At the end of the experiment, all plants will be uprooted, washed carefully to remove soil, and air-dried. The roots will be separated from the shoots. The dry weight of the roots and shoots will be measured and recorded. These characteristics will be compared against those displayed by the potted plant growing irrigated with distilled water to ascertain the impact of laundry detergent on the growth of bean plants.
Works Cited
Sawadogo, Boukary, Mariam Sou, Nowaki Hijikata, Drissa Sangare, Amadou Hama Maiga and Naoyuki Funamizu. “Effect of Detergents from Grey Water on Irrigated Plants: Case of Okra (Abelmoschus esculentus) and Lettuce (Lactuca sativa).” Journal of Arid Land 24.1 (2014): 117-120. Print.