Determining the Influence of Temperature on Plants · Vernalization Warm season crops Interest Approach. Use an interest approach that will prepare the students for the les- ... oats,

Lesson C4–2

Determining the Influence of

Temperature on Plants

Unit C. Plant and Soil Science

Problem Area 4. Environmental Factors Affecting Plant Growth

Lesson 2. Determining the Influence of Temperature on Plants

Content/Process Statement: AGS1, APS5

Core Content Standard: SC-H-3.4.1, SC-H-3.4.2, SC-H-3.5.3, SC-H-3.6.1

Skill Standard: H-OD002, P-OB006

Academic Expectation: 1.1, 2.1, 2.2, 2.3, 2.5, 2.6

Student Learning Objectives. Instruction in this lesson should result in students

achieving the following objectives:

1. Discuss the effect of temperature on plant growth.

2. Describe plant responses to temperature.

3. Explain hardiness.

4. Explain growing degree days.

Kentucky Agricultural Education Lesson Plan Library — Animal, Plant, and Soil Science

Unit C. Problem Area 4. Lesson 2. Page 1.

List of Resources. The following resources may be useful in teaching this lesson:

Recommended Resources. One of the following resources should be selected to accompany the

lesson:

Parker, Rich. Introduction to Plant Science. Albany, New York: Delmar. 2000

Other Resources. The following resources will be useful to students and teachers:

Osborne, Edward W. Biological Science Applications in Agriculture Danville IL: In-

terstate Publishers, Inc. 1994

Lee, Jasper and Biondo, Ron. Introduction to Plant and Soil Science & Technology, 2nd

Edition. Danville, Illinois: Interstate Publishers, Inc. 2003

List of Equipment, Tools, Supplies, and Facilities

Writing surface

Overhead projector

Transparencies from attached masters

Copies of student lab sheet

Terms. The following terms are presented in this lesson (shown in bold italics):

Cool season crops

Hardiness

Growing degree day (GDD)

Metabolism

Plant heat-zone map

Plant hardiness zone map

Stratification

Thermoperiod

Thermoperiodic

Vernalization

Warm season crops

Interest Approach. Use an interest approach that will prepare the students for the les-

son. Teachers often develop approaches for their unique class and student situations. A possible

approach is included here.

Bring a bunch of bananas to class and display them in view of the students. Some students might ask

about the bananas. Tell them you would like to grow bananas so you can have fresh bananas throughout

the year. This might be received with skepticism, at which time the students could be asked what is wrong

with that. A series of questions could be asked in response. Is our soil not the right type? Is the air not ap-



propriate? Do we not get enough rain? The students will soon identify temperature as a problem. Con-

tinue the discussion by talking about how plants have become adapted to different temperature ranges.

Summary of Content and Teaching Strategies

Objective 1: Discuss the effect of temperature on plant growth.

Anticipated Problem: How does temperature affect plant growth?

I. Temperature is an important factor governing plant growth.

A. All of the chemical reactions in a plant, including photosynthesis and respiration, fall

under a term, metabolism. The speed at which metabolism occurs is affected by tempera-

ture. This is because the enzymes that drive the reactions are sensitive to temperature.

Cool or cold temperatures slow metabolic processes, while warmer temperatures speed

the processes.

B. Most plants show optimum growth when night temperatures are 10 to 15 degrees cooler

than day temperatures. Under ideal conditions photosynthesis occurs at a high rate dur-

ing the day. The cooler temperatures at night slow respiration. For growth to occur, the

rate of photosynthesis must exceed that of respiration. High temperatures can speed the

rate of respiration beyond that of photosynthesis. As a result, the products of photosyn-

thesis are used more rapidly than they are produced. In many plants, photosynthesis

shuts down at temperatures above 86°F. So, during hot summer days plants draw upon

stored energy reserves.

Begin the lesson with an interest approach to capture the attention of the students. Clearly state the objec-

tives of this lesson and terms to be defined. Have the students read appropriate selections from the recom-

mended text materials. They should note key points presented in the text. Obtain a PowerPoint presenta-

tion or build a PowerPoint presentation to be used as a guide for classroom instruction. Utilize the text

and transparency masters in this lesson in the PowerPoint presentation. TM: C4–2A—Relationship of

Temperature to Respiration Rates, should be used to illustrate concepts associated with this objective.

Have students take notes during lecture-discussion. Ask questions during instruction to gauge student un-

derstanding of the concepts. Provide experiential learning by having the students conduct the laboratory

activity, LS: C4–2A—Temperature and Plant Growth.

Objective 2: Describe plant responses to temperature.

Anticipated Problem: What are some plant responses to temperature?

II. Different species of plants respond differently to temperature. Temperatures also play a role

in different plants functions.

A. The change of daily temperatures is called thermoperiod. When changes in daily temper-

atures influence plant responses, such as flowering, the plants are said to be



thermoperiodic. Poinsettias and chrysanthemums are thermoperiodic plants. They initi-

ate flowers when temperatures become cooler and days grow shorter.

B. Wheat, oats, barley, rye, spinach, and lettuce are cool season crops meaning they prefer

cooler growing temperatures and are tolerant of frost. When temperatures rise in combi-

nation with longer days, spinach and lettuce initiate flower production. Warm season

crops require warmer temperatures for best growth. Cotton, corn, soybeans, and sor-

ghum are an example of a warm season crop. Another warm season crop, tomatoes, will

not flower if temperatures are cool.

C. Some plants require a cold treatment for physiological processes to occur. This is known

as vernalization. Tulips and narcissus require vernalization to flower. Some cereal grains,

including winter wheat, also require vernalization. Apples require 1,000 to 1,200 hours

of temperatures between 32°F and 45°F to break their rest period.

D. Seeds of some plants have a dormancy mechanism that is broken by a cold period. The

seeds do not germinate until the seed has undergone a cold period. This cold require-

ment for seeds is known as stratification.

Continue with the PowerPoint presentation. Emphasize terms and key points students should place in

their notes. Add examples related to plant growth in the agriculture and horticulture industry to help ex-

plain terms and concepts. Engage the students in the discussion. Invite an agronomist or botanist to appear

as a guest speaker to discuss the effects of temperature on plant growth.

Objective 3: Explain hardiness.

Anticipated Problem: What is hardiness?

III. Plants can be classified as hardy or non-hardy depending on their ability to withstand cold

temperatures. Hardiness is a plant’s ability to tolerate cold temperatures.

A. The USDA has established a plant hardiness zone map for the United States, that re-

flects the average minimum winter temperatures for given areas. The map shows eleven

zones of temperatures. It is valuable in selecting plants adapted for growing in those ar-

eas.

B. Heat also plays a role in the performance of plant species. Some plants are more sensi-

tive to heat than others. The plant heat-zone map has been developed by the American

Horticultural Society to help identify areas in which landscape plants can flourish. The

map shows 12 zones. Each zone reflects a rating of summer heat based on the average

number of days above 86°F. Eighty-six degrees is a temperature at which plants are un-

able to process water fast enough to maintain normal functions. Plants also experience

damage to cellular proteins.

Continue with the PowerPoint presentation. Use TM: C4–2B—Plant Hardiness Zone Map and

TM: C4–2C—Plant Heat-Zone Map, with an overhead projector to discuss hardiness and heat zones.

Show students key points they should place in their notes. Engage the students in the discussion.



Objective 4: Explain growing degree days.

Anticipated Problem: What is growing degree day?

IV. Growing degree days (GDD) is a measure of temperature requirements for plants and can

be used to estimate growth and development.

A. The basic concept of growing degree days is that plant development will occur when

temperatures exceed a base temperature. For corn, the maximum temperature plus the

minimum temperature in a day divided by 2 minus 50. Fifty is selected as the constant

because corn grows very little at temperatures of 50°F or below. Growth is also checked

when temperatures rise above 86°F, so all temperatures recorded above 86°F are counted

as 86 in the formula. Most corn hybrids have fairly specific GDD specifications.

Example: If a low temperature was 60°F and the high was 90°F, the GDD would be 60 +

86 = 146 divided by 2 = 73 – 50 = 23 GDD. The GDD are added during the growing

season. If a variety of corn required 2,450 GDD, it would require 107 days to maturity

using the figure calculated in the example.

Have the students read related sections of text materials identified in the resources list. Require students to

take notes on the major points presented in the chapter. Follow the reading session with a discussion on

growing degree days. Have the students expand their notes based on the discussion. The discussion can

also serve as a way to monitor students’ mastery of the material. Reinforce student understanding with

problems related to growing degree days.

Review/Summary. Conclude the lesson by restating the student learning objectives. Re-

view the material that has been covered in class. Call on students to explain the content associ-

ated with each objective. Use their responses as the basis for determining any areas that need

re-teaching. Questions at the end of the chapters in the textbooks may also be used in the re-

view/summary.

Application. Application can involve one or more of the following student activities using

the attached lab sheets:

TM: C4–2A—Relationship of Temperature to Respiration Rates

TM: C4–2B—Plant Hardiness Zone Map

TM: C4–2C—Plant Heat-Zone Map

LS: C4–2A—Temperature and Plant Growth

Evaluation. Evaluation should focus on student achievement of the objectives for the les-

son. Various techniques can be used, such as student performance on the application activities. A

sample written test is attached.



Answers to Sample Test:

Part One: Matching

1 = b, 2 = h, 3 = g, 4 = c, 5 = i, 6 = j, 7 = f, 8 = e, 9 = a, 10 = d

Part Two: Completion

1. Cool or cold, warmer

2. 10, 15

3. 86°

4. Warm season

5. hardy, non-hardy

6. Poinsettias, chrysanthemums

7. Tulips, narcissus

8. cold period

9. water

10. 50

Part Three: Short Answer

1. The speed at which metabolism occurs is affected by temperature. This is because the

enzymes that drive the reactions are sensitive to temperature. Cool or cold temperatures

slow metabolic processes, while warmer temperatures speed the processes. Most plants

show optimum growth when night temperatures are 10 to 15 degrees cooler than day

temperatures. Under ideal conditions photosynthesis occurs at a high rate during the

day. The cooler temperatures at night slow respiration. For growth to occur, the rate of

photosynthesis must exceed that of respiration. High temperatures can speed the rate of

respiration beyond that of photosynthesis. As a result, the products of photosynthesis are

used more rapidly than they are produced. In many plants, photosynthesis shuts down at

temperatures above 86°F. So, during hot summer days plants draw upon stored energy

reserves.

2. Wheat, oats, barley, rye, spinach, and lettuce.

3. Cotton, corn, soybeans, tomatoes, and sorghum.

4. The basic concept of growing degree days is plant development will occur when temper-

atures exceed a base temperature. For corn, the maximum temperature plus the mini-

mum temperature in a day divided by 2 minus 50. Fifty is selected as the constant be-

cause corn grows very little at temperatures of 50°F or below. Growth is also checked

when temperatures rise above 86°F, so all temperatures recorded above 86°F are counted

as 86 in the formula. Most corn hybrids have fairly specific GDD specifications.



Sample Test Name_____________________________________

Test

Lesson C4–2: Determining the Influence of

Temperature on Plants

Part One: Matching

Instructions. Match the term with the correct response. Write the letter of the term by the defini-tion.

a. Cool season crops f. Plant hardiness zone map

b. Hardiness g. Stratification

c. Growing degree day (GDD) h. Thermoperiod

d. Metabolism i. Thermoperiodic

e. Plant heat-zone map j. Vernalization

_______ 1. A plant’s ability to tolerate cold temperatures.

_______ 2. The change of daily temperatures.

_______ 3. Cold requirement for seeds to germinate.

_______ 4. A measure of temperature requirements for plants and can be used to estimate

growth and development.

_______ 5. Plants that respond to changes in daily temperatures.

_______ 6. Cold treatment required for physiological processes to occur.

_______ 7. Map reflects the average minimum winter temperatures for given areas.

_______ 8. Map that shows 12 zones that reflect a rating of summer heat based on the average

number of days above 86°F.

_______ 9. Crops including wheat, oats, barley, rye, spinach, and lettuce that prefer cooler

growing temperatures and are tolerant of frost.

_______ 10. All of the chemical reactions in a plant, including photosynthesis, and respiration.

Part Two: Completion

Instructions. Provide the word or words to complete the following statements.

1. ________________ temperatures slow metabolic processes, while ___________ tempera-

tures speed the processes.



2. Most plants show optimum growth when night temperatures are _____ to _____ degrees

cooler than day temperatures.

3. In many plants, photosynthesis shuts down at temperatures above ___F.

4. __________ ____________crops require warmer temperatures for best growth.

5. Plants can be classified as _____________or __________________ depending on their abil-

ity to withstand cold temperatures.

6. ____________________ and _______________________ are thermoperiodic plants.

7. ___________ and ____________________ require vernalization to flower.

8. Seeds of some plants have a dormancy mechanism that is broken by a _______ ________.

9. Eighty-six degrees is a temperature at which plants are unable to process ___________ fast

enough to maintain normal functions.

10. ________ is selected as the constant for corn because corn grows very little at temperatures

of 50°F or below.

Part Three: Short Answer

Instructions. Provide information to answer the following questions.

1. Why is temperature important to a plant’s metabolism?

2. What are five cool season crops?

3. What are four warm season crops?

4. How are growing degree days determined?



TM: C4–2A

RELATIONSHIP OF

TEMPERATURE TO

RESPIRATION RATES



Rela

tive

rate

ofre

sp

iratio

n

15

10

5

A

B

32 50 68 86 104 122

Temperature ( F)o

TM: C4–2B

PLANT HARDINESS

ZONE MAP



Zone 1 Zone 7

Zone 5 Zone 11

Zone 3 Zone 9

Zone 2 Zone 8

Zone 6

Zone 4 Zone 10

Below -50°F 0 to10°F

-20 to -10°F Above 40°F

-40 to -30°F 20 to 30°F

-50 to -40°F 10 to 20°F

-10 to 0°F

-30 to -20°F 30 to 40°F

1

7

2

8

3

4

9

5

10

11

11

6

TM: C4–2C

PLANT HEAT-ZONE MAP



30

45

60

90

Fewer than 1 1 5 9

2 6 10

3 7 11

4 8 12

1

7

14

45

60

90

120

7

14

30

120

150

180

More than210

150

180

210

to

to

to

to

to

to

to

to

to

to

Days Above 86° Days Above 86° Days Above 86°Zone Zone Zone

LS: C4–2A Name_____________________________________

Lab Sheet

Temperature and Plant GrowthObjective:

Students will contrast the growth of plants grown in environments with different tempera-

tures.

Materials:

Three cups or 4 inch pots per lab group

Potting soil

Bean seeds

Ruler

Thermometers

Procedure:

1. If using cups, puncture the bottom of each cup to allow for the drainage of excess water.

Label the pots. Fill the pots or cups with potting soil. Firm the soil and add more to bring

it level with the top of the pots or cups.

2. Plant three bean seeds one half inch deep in the center of each pot or cup. Water thor-

oughly. Place one pot in an area of room temperature (70–78°F), one in a warm area

(above 78°F), and the third where temperatures are cool (below 70°F). All three con-

tainers should receive bright light. Different areas in a greenhouse would work well. A

hot pad could be used to provide the additional heat for the warm conditions.

3. Locate thermometers at the plant level in each area. Water the containers thoroughly

when they approach drying.

4. When the seedlings are about 5 centimeters tall, remove two plants by pinching the

stems.

5. Observe the plants every day. Record the temperatures, plant heights, and leaf counts

every three days on the table provided.



Date

Room Temperature Warm Temperature Cool temperature

Temp. Height Leaf # Temp. Height Leaf # Temp. Height Leaf #



Documents

Determining the Influence of Temperature on Plants · Vernalization Warm season crops Interest Approach. Use an interest approach that will prepare the students for the les- ... oats,