Determining the Influence of Temperature on Plants

Transcription

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

2 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 Other Resources. The following resources will be useful to students and teachers: Osborne, Edward W. Biological Science Applications in Agriculture Danville IL: Interstate Publishers, Inc Lee, Jasper and Biondo, Ron. Introduction to Plant and Soil Science & Technology,2 nd Edition. Danville, Illinois: Interstate Publishers, Inc 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 lesson. 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- Unit C. Problem Area 4. Lesson 2. Page 2.

3 propriate? Do we not get enough rain? The students will soon identify temperature as a problem. Continue 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 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. 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 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. Begin the lesson with an interest approach to capture the attention of the students. Clearly state the objectives of this lesson and terms to be defined. Have the students read appropriate selections from the recommended text materials. They should note key points presented in the text. Obtain a PowerPoint presentation 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 understanding 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 temperatures influence plant responses, such as flowering, the plants are said to be Unit C. Problem Area 4. Lesson 2. Page 3.

4 thermoperiodic. Poinsettias and chrysanthemums are thermoperiodic plants. They initiate 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 combination with longer days, spinach and lettuce initiate flower production. Warm season crops require warmer temperatures for best growth. Cotton, corn, soybeans, and sorghum 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 requirement 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 explain 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 reflects 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 areas. B. Heat also plays a role in the performance of plant species. Some plants are more sensitive 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 unable 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. Unit C. Problem Area 4. Lesson 2. Page 4.

5 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 = 146 divided by 2 = = 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. Review the material that has been covered in class. Call on students to explain the content associated 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 review/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 lesson. Various techniques can be used, such as student performance on the application activities. A sample written test is attached. Unit C. Problem Area 4. Lesson 2. Page 5.

6 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, Warm season 5. hardy, non-hardy 6. Poinsettias, chrysanthemums 7. Tulips, narcissus 8. cold period 9. water 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 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. Unit C. Problem Area 4. Lesson 2. Page 6.

7 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 definition. 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 temperatures speed the processes. Unit C. Problem Area 4. Lesson 2. Page 7.

8 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 ability 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? Unit C. Problem Area 4. Lesson 2. Page 8.

9 TM: C4 2A RELATIONSHIP OF TEMPERATURE TO RESPIRATION RATES 15 Relative rate of respiration 10 5 A B o Temperature ( F) Unit C. Problem Area 4. Lesson 2. Page 9.

10 TM: C4 2B PLANT HARDINESS ZONE MAP Zone 1 Below -50 F Zone 7 0 to10 F Zone 2-50 to -40 F Zone 8 10 to 20 F 11 Zone 3-40 to -30 F Zone 9 20 to 30 F Zone 4-30 to -20 F Zone to 40 F Zone 5-20 to -10 F Zone 11 Above 40 F Zone 6-10 to 0 F Unit C. Problem Area 4. Lesson 2. Page 10.

11 TM: C4 2C PLANT HEAT-ZONE MAP Days Above 86 Zone Days Above 86 Zone Days Above 86 Zone Fewer than to to to to to to to to to to More than Unit C. Problem Area 4. Lesson 2. Page 11.

12 LS: C4 2A Name Lab Sheet Temperature and Plant Growth Objective: Students will contrast the growth of plants grown in environments with different temperatures. 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 thoroughly. 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 containers 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. Unit C. Problem Area 4. Lesson 2. Page 12.

13 Room Temperature Warm Temperature Cool temperature Date Temp. Height Leaf # Temp. Height Leaf # Temp. Height Leaf # Unit C. Problem Area 4. Lesson 2. Page 13.