GNA Corn Contest: Grow the Tallest Plants! 8 th & 9 th Grade Science Classes September 2011

Corn Germination process whereby seeds sprout and begin to grow

How to Measure Your Plants For each corn plant in your cup: 1.Place the ruler where the plant is coming out of the soil. 2.Start your measurement with the “0” mark on the ruler, measuring in centimeters. 3.Stretch your leaf up to its tallest point against the ruler. 4.Record your measurement.

Calculate Your Total Height 1.Add all of your measurements together. 2.Write down your total height in centimeters and your full name on your post-it note. 15 cm Amy Student

Determining the Top Growers 1.Place your post-it note on the graph in the appropriate column. 2.Watch as our class “post-it” graph is being created! 3.Figure out how many students in the class would be equivalent to 1/3 of the students. 4.Determine the contest winners.

Group Discussion

What were your methods? 1. How many pots of plants did you grow? 2. What did you do to the pots and plants?

How do you know that what you did actually made a difference? What caused your plants to grow as they did? How do you know?

A standard all experiments should meet: 1.All experiments should include plants that receive no treatment or experience the normal situation. This is the control, or what you compare the test results against.

Question: Would it be a fair test of the effect of light, if the control plants were kept at room temperature and the test plants were kept in a heated room?

A fair test is one that is not biased. The test treatment, exposure to different colored light, is the only factor that should vary in the experiment. All other conditions--temperature, watering schedule, etc.--should be the same.

What are the factors that may change or vary in an experiment called? Variables Include conditions like light, temperature, and watering schedule

Some Information About Corn Germination

Remember… Germination= process whereby seeds sprout and begin to grow

Water Absorption Germination is triggered by absorption of water through the seed coat. Corn kernels must absorb (imbibe) about 30 % of their weight in water before germination begins. Less than optimum absorption of water may slow or stop germination.

Temperature The radicle root emerges first, near the tip end of the kernel, within 2 to 3 days in warm soils with adequate moisture. Germination will take much longer if soil temperatures hover at or below 50°F (10°C).

Troubleshooting Considerations In cold planting seasons, it is common to dig up kernels 2 weeks after planting and find only short radicle roots and no visible “spikes” (coleoptiles).

Troubleshooting Considerations When excessively cold/wet soils delay germination, the kernels are subjected to lengthier exposure to damaging factors like soil-borne seed diseases and insect feeding.

Example of a 5-day old corn plant, without soil

Final thoughts: Scientific inquiry is not about doing a perfect experiment, it is about learning how to do a good one that can answer a testable question. Even the best designed experiments can fail. These experiments are still very valuable because they allow us to determine how we should change our hypotheses and how we can design better experiments.

References PlantingScience Corn Contest Handout =pagesetter&func=viewpub&tid=17&pid=31 =pagesetter&func=viewpub&tid=17&pid=31 imeless/GerminationEvents.html imeless/GerminationEvents.html GOA GOA