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Colorado Agriscience Curriculum Section: Plant Reproduction Unit 4: Plant Reproduction Lesson Number 3: Seeds, Fruit, & Germination Colorado Agricultural Education Standards: AS 11/12.4 The student will demonstrate an understanding of physiological processes in agriculturally important plants HRT 11/12.2 The learner will understand and describe the anatomy of horticulture plants. Colorado Science Standards: SCI 1.1 Asking questions and stating hypotheses, using prior scientific knowledge to help guide their development SCI 3.1 Students know and understand the characteristics of living things, the diversity of life, and how living things interact with each other and with the environment. SCI 3.3.5 Using examples to explain the relationship of structure and function in organisms. SCI 3.3.6 Describing the pattern and process of reproduction and development in several organisms. Student Learning Objectives (Enablers) As a result of this lesson, the student will … Objective 1: Identify the anatomy of a seed. Objective 2: Understand the purpose and types of fruit Objective 3: Understand the process and requirements for seed germination. Time: Instruction time for this lesson: 55 minutes. Tools, Equipment, and Supplies Power Point or Colored Overheads Introduction to Plant and Soils Science and Technology Text (page 60) Agriscience: Fundamentals and Application Text Seeds (several different species) (3-5 seeds of each species per student) Tissue Paper (1 box) Egg Cartons (1 per student) Markers Crayons or Colored Pencils (Or Print Handouts from PowerPoint) Handout for each student Key Terms. Seeds Seed Coat Germination Embryo Cotyledons Endosperm Fruit Disseminate Stratification Scarification Viable Embryonic Root Epicotyl Hypocotyl Germination Percentage Interest Approach Assign each class member to conduct an experiment too determine how long it takes for several kinds of seeds to germinate. Place three to five seeds of a single species of plant in damp tissue paper. Place the tissue in a section of an egg carton. Keep the tissue damp without excess water. Label the seeds by writing on the carton. Check the seeds daily and add water as necessary. Keep a record of the time that is required for germination to occur. A written report should always be part of a classroom experiment. It should describe the process that was followed, supplies and equipment that were used, and results that were achieved. Summary of Content and Teaching Strategies Objective 1. Identify the anatomy of a seed. Slides 1 – 5 Slide 2: The largest seed in the world is the double coconut found in India. It can weigh up to fifty pounds. Other seeds, like those of the begonia, are as small as dust. However they may appear, their function is to grow and develop into a mature plant that will produce more seeds. Seeds are truly a wonder of nature. Seeds of flowering plants have a seed coat, an embryo or young plant, and a source of stored food. The seed coat is a protective shell surrounding the embryo and the endosperm. It protects the seed from drying and from physical injury. The seed coat also plays an important role in determining when conditions for germination or the beginning of growth are right. Slide 3: The embryo is a little plant that eventually grows and develops into the mature plant. It is in a dormant or resting phase inside the seed. It has a stem, root, and one or two seed leaves called cotyledons. Embryos of monocot plants have one cotyledon while those of dicot plants have two cotyledons. Slide 4: Food in the form of starch and protein is stored in the seed for the embryo. When germination begins, the embryo draws energy from the food to emerge from the soil and to develop leaves so it can begin to manufacture its own food. With monocot plants, much of this energy source is found in the endosperm. Dicots store all their food in the two cotyledons. Slide 5: Use a Graphic Artist E-Moment to capture the diagram of the bean and corn seed into their notes. An alternative would be to print handouts and have them label and color code the handout. Objective 2. Understand the purpose and types of fruit. Slide 6: After fertilization, the ovary wall enlarges and forms the fruit. The fruit may be either fleshy or dry. Fleshy fruits, like the tomato are juicy to prevent the seeds from drying until they are mature. They also serve to help disperse the seeds. Animals are attracted to the nutritious fruit, eat it with the seeds, and disperse or disseminate the seeds away from the parent plant. This dissemination of seed is an important evolutionary trait for the survival of the plant species. Not all fruits are fat and juicy like the tomato. The dandelion has evolved a dry, feathery fruit to take advantage of the wind for dissemination. Soybean pods, cotton boles, and the helicopters (samaras) of maple trees are technically dry fruits, too. Objective 3. Understand the process and requirements for seed germination. Slides 7 – 13 Slide 7: Display the notes on slide seven and have them transpose them into their notebooks. We will discuss the information in more detail in a few moments. Slide 8: Use a Go-With-The-Flow E-moment to acquire a large amount of information on a single, organized, and color coded page. Another option if you are short on time would be to print the full slide and make copies for a handout. The following script is describing what is occurring in slide 7 and the flow chart on slide 8. Pass out the hand out which show slides 9-13 so students can visually see what is accruing during the germination process. Seeds are designed to wait for favorable conditions to begin growth. The wait for the favorable conditions may take many years. In some cases, the embryo’s life within the seed dies before the arrival of conditions favorable for the plant’s survival. It is fascinating to think about how seeds have the ability to lay dormant for many years and then to begin growth when given the right conditions for survival. One mechanism seeds have to help ensure survival is called stratification. Stratification is the process whereby a seed must go through a period of cold temperatures before it will germinate. This mechanism makes sense. Without this waiting period, a seed could germinate during a warm spell in December and die with the arrival of freezing temperatures. Another mechanism is scarification or the breaking down of the seed coat. Some seeds have very hard, thick seed coats that provide excellent protection for the seed. However, they prevent the absorption of water and germination under normal conditions. These seeds must pass through the acid stomach of an animal to wear down the seed coat or lay in the soil where microorganisms can eat away the seed coat before they can germinate. Some trees require fire to rupture the seed coat for germination to occur. Some examples of plant seeds that require scarification are geranium, lupine, honey locust, and Kentucky coffee tree. What are the right conditions for seed germination? Environmental factors play key roles in seed germination. Water and air are needed for seeds to germinate. Oxygen is particularly important. Seeds need temperatures between 40 degrees and 104 degrees Fahrenheit, depending on the plants habitat. Naturally, plants from the tropics will need a warmer temperature than those found in the arctic. They may need total darkness or exposure to light, too. Lettuce seeds must be exposed to light before they will germinate. In fact, if any one of these environmental factors is not favorable, the seed will not germinate. The first step in the germination process is the absorption of water, which triggers a number of activities within the seed. The seed swells with moisture. The embryo changes from a dormant state to an actively growing plant. During these early stages, the embryo draws energy from starches stored in the endosperm or the cotyledons. The embryo’s root emerges from the seed and develops into the primary or embryonic root. Then, the stem of the embryo sprouts upward. After germination, the seedling needs light and minerals to begin producing its own food. Many of our most important crops are grown from seed. Corn, soybeans wheat, and vegetables are just a few crops grown for food. Bedding plants and turf grass grown in the horticulture industry are started from seeds. Trees for reforestation begin as seeds. Fiber crops, such as cotton and hemp are grown from seed as well. The quality of seed used is very important to those in production agriculture. Viable, or live, seed is valued when planting time comes around because the producer wants to see high percentage o seed germination. Seed companies run test to determine what percentage of the seeds will germinate. That information must be printed on the seed bag. A high percentage of viable seeds is the goal. Proper humidity and temperature during storage of the seeds from one growing season to the next help to maintain a high proportion of viable seeds. Slides 12 -13: Facilitate a group discussion on what factors could cause poor seed germination. Make a list on a writing surface as the get the appropriate ones. Once all factors are listed display the slides so that they may capture them in their notes. Review/Summary. Use a Show What You Know E-Moment to facilitate a review of this lesson. Application Extended classroom activity: Collect pollen from different plants. This can be done outdoors during the appropriate seasons. If outdoor collection is not possible, check with the local flower shops form discarded flowers. Next, set up a number of microscopes and examine the pollen. As a class, discuss the similarities and differences that can be seen. FFA activity: Use LifeKnowledge MS 46 to correlate knowing the structure and anatomy of a plant is just as important as knowing the different skills necessary in planning an activity or event. SAE activity: Collect various bags of seed (empty) from local farmers. Examine the labels and evaluate the contents and different germination rates. Calculate the actual cost of premium seed compared to “value” seed.
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