Does adding fertilizer affect the productivity of tomato plants? To answer this question, a gardener plants 24 similar tomato plants in identical pots in his greenhouse. He will add fertilizer to the soil in half of the pots. At the end of three months he will record the total weight of tomatoes produced on each plant. Identify the explanatory and response variables, experimental units, and treatments. Choose the appropriate term for each item below. experimental units tomato plants response variable use of fertilizer, no use of fertilizer treatments total weight of tomatoes explanatory variable fertlizer