Germination, Growth, and Environmental Factors Lab

Plants, like other living things, need a variety of resources from their environment to survive. These include sunlight, water, carbon dioxide, and nutrients. Plants also compete with each other and with plants of different species. Individual plants cannot move from one place to another, so each plant must obtain what it needs from its immediate surroundings. In this lab, you will design an investigation to determine the effects of some type of limiting factor on the growth of plants.

Materials:

Various germinated plants, soil/grow medium, plant pots, ID stakes, metric ruler, fertilizers, grow chamber.

Procedure:

  1. Determine limiting factors that may affect the growth of plants.
  2. Once your factor has been determined, design an experiment to determine if it has an effect on plant growth.
  3. Complete a design guide for your experiment, get this approved.
  4. Carry out your experiment.

Analysis:

Determine whether your test factor had an effect on the growth of your plants.

Experiment Notes:

It is not essential to use Wisconsin Fast Plants for this lab. Students will not be pollinating or growing successive generations so the life cycle time is not important.

Again if you choose to use local plant seeds you should set the chamber to mimic the environmental conditions in your area.

This lab can be run in a number of different ways.  Students can brainstorm the factors individually or in groups and then design the lab using the guide below, or some other format.

Since it can take up to two weeks for many common garden plants to germinate I usually start them ahead of time, using large germination trays. This way I can have all the seeds germinated and ready at the same time. The students then choose the type of plant(s) for their experiment. The students transfer the plants to 4or 6 spot bedding plant trays for the experiment. Small plastic food storage containers can be used for watering trays.

For all experiments, fertilizer should be added to the watering tray. It’s very easy to burn the plans with direct application. The specific fertilizer depends on the type of plants used. Comparing fertilizers is a good experimental factor to choose.

Other factors include intensity/type/length of light, type of growth medium, type/brand/amount of fertilizer, temperature, amount of water/humidity, and the effect of wind. Students can also test the effect of any of the previous factors on different types of plants.

Analysis of the data will depend on the level of the students. Middle school students may use qualitative observations only. General Science students should be able to determine average growth (mean, median, mode). AP Biology students should be able to use a t-test to analyze the averages, as well as graphing the data with a reliability of the mean calculation.

Contributed by David Prescott, Head of Science Faculty, St. John's-Ravenscourt School