For Students Engineering Design in Oregon Science Classrooms Page 2 of 2
Name ____________________________________________________________ Period ________________
Engineering Design Handout for Frankenplants
Scenario: You are home gardener who hasn’t had much luck growing tomatoes. For the last two years, you have lost all your plants to root rot.
Problem: Identify the problem(s) your tomato grafts should address.
Heirloom tomatoes are susceptible to root diseases. We would like to grow a plant that produces heirloom tomatoes but is resistant to root diseases.
Criteria: What should your graft be able to do? Be specific.
Produce large, tasty tomatoes but still have a strong root system that is disease resistant.
Priorities: Rank the criteria you identified above in order of importance. Be sure to explain you rankings.
Answers will vary based on the student. Be sure they explain their rankings and discuss as a class which is more important for a tomato plant: a strong root system or high production.
Constraints: What might limit your ability to graft two tomato plants? What might limit the effectiveness of the graft you create?
· Diameters of stems must match up and fit grafting clips.
· Size of plants. Young (thin) plants are hard to cut, but older (thicker) plants are often don’t heal as well.
· Placement of graft must be high enough to always be above the soil line both when the plant is in the seedling tray or pot and when it is planted in the garden.
Evaluation:
On a separate sheet of paper, write two paragraphs which evaluate the effectiveness of your class’s grafts.
1. Your first paragraph should address the following questions:
a. Which of designs were the most effective in terms of criteria, priorities, and constraints?
Answers will vary.
a. What were the more likely explanations for failed grafts?
ü Seedlings stems were too thin for grafting clips.
ü Selected seedlings were unhealthy to begin with
ü Rootstock and scion weren’t the same diameter at the graft.
ü Poor grafting technique. In particular if there is too much of a gap between the cut-stems, adventitious root shoots might start growing off the scion or the scion will wither.
ü Grafting chamber is too hot which can dry plants out or slow graft union healing.
ü Grafting chamber is has too much or too little humidity with can either soften and break down the graft union or allow it to dry out and heal poorly.
ü Grafting chamber lets in too much light which weakens and dries out the newly grafted plants.
ü Plants were bumped or jarred during the healing process.
ü Plants were removed from the chamber before healing completely.
b. What is a trade-off associated with grafting and how did effective grafts deal with this trade-off?
One trade off is concerns the placement of grafts. A higher graft is less likely to come into contact with the soil once planted but may produce a more fragile plant during the healing process. Putting the graft lower may make it easier for the grafted plant to heal but increases the chance that the graft location will come in contact with soil later.
Another trade off is plant size. Older plants are easier to cut and graft because they have thicker stems, but these larger plants take longer to heal and are more likely to wilt in the grafting chamber. Young plants heal quickly but are harder to graft.