Class: 6
Purpose: to study the features of seed germination depending on environmental conditions.
Tasks:
Educational
- To form and systematize knowledge about the conditions for seed germination, about the need for a certain temperature, humidity, availability of air, reserve nutrients, about the depth of planting seeds in the soil, light mode.
- To establish the dependence of the vital activity of seeds on environmental conditions, rules for storing seeds, agricultural techniques for sowing seeds.
Developing
- To develop knowledge about the conditions for seed germination, general biological concepts, beliefs in the natural character of biological phenomena and their material conditioning.
- Develop knowledge of experimental techniques, the ability to observe the germination process, record the results, formulate conclusions
- Develop the ability to use terminology, work with various information sources, test the accuracy of theoretical knowledge in practice.
- Develop intellectual skills: the ability to observe, analyze, compare, establish causal relationships, draw conclusions.
Educational
- To foster a sense of responsibility, accuracy, accuracy, an interested attitude to learning, cognitive interest in the subject, respect for nature.
Elements of acquired competencies
- the formation of skills in working with various sources of information, independently select the information necessary for solving educational problems, transform it;
- own methods of joint activities in a group, couple, speak with an oral message;
- to indicate their understanding and misunderstanding in relation to the problem being studied, to speak orally about the results of their research, to organize a self-assessment of their educational activities, reflection.
Equipment: information sheets, test results (laboratory equipment), multimedia projector, presentation, a set of seeds, tables, pictures "Amazing Nearby", DVD disc "Conditions for seed germination", tape recorder, TV.
Lesson plan
Let's walk slowly through the meadow
And "Hello!"
Let's tell each flower.
You must bend over the flowers
Not to rip or cut
And to see their kind faces
And show them a kind face.
S. Vurgun
1. "I have everything, I must become beautiful, big green, like my parent. For now, peace. And I am still happy. And the world around me, though small, is alive" (Seed).
(slide show 3) Why is the seed the germ of a new plant? (conversation).
2. Tests: select the correct statements.
1. During germination, seeds absorb carbon dioxide and release oxygen. (-)
2. During germination, the embryo feeds on the supply of nutrients from the endosperm or cotyledons. (+)
3. Sprouted wheat kernels have a sweetish taste. (+)
4. The seedling of a plant is formed as a result of the division of the cells of the embryo. (+)
5. Small seeds germinate better and produce strong seedlings. (-)
6. When the seeds breathe, heat is generated. (+)
7. Dry seeds do not breathe. (-)
8. Seedlings of dicotyledonous plants have a fibrous root system. (-)
9. For seed germination moisture, air, warmth are required. (+)
10. The root appears first in the seedling. (+)
(Students work in a notebook, if they are not sure of the answer, circle the number).
Teacher: Do you have any difficulties, questions? In today's lesson, we will answer all the questions.
- We have to fill in the schemes:
1. germination conditions; (on the diagram board)
2. Types of germination.
Find out what are the stages of seed germination?
Groups have been formed to work. Each group received tasks in advance and with the help of experiments, having received a certain result, draw a conclusion about the role of a certain environmental factor in seed germination. Using the information, students in each group explain the importance of a particular factor in seed germination. They make notes in notebooks, discuss problematic issues, and draw conclusions.
II. Comprehension:
1. Conditions for seed germination.
Teacher's story. It turns out that in most plants, seeds that have fallen into the soil cannot begin to germinate immediately. They need a rest period - the time during which the embryo of the seed ripens outside the fetus. When the dormant period is over, the seeds, once in favorable conditions, can begin to germinate. This means that being in the seed, the embryo begins to grow and develop. For example, cucumbers can begin to germinate after being dormant for several years. We can say about such seeds that they do not lose their moisture content for a long time, that is, the ability to germinate. In another way, we can say that they have a long shelf life (usually indicated on bags with seeds). Germination, i.e. the ability of seeds to germinate under appropriate conditions is determined by the percentage of seeds from which normal seedlings have developed. Demonstration of experiments to determine seed germination ... (SLIDE 4)
What is germination? (SIDE 5)
The main function of seeds is to spread and reproduce plants. In order to give life to a new plant, the seed must germinate. Seed germination is the process of embryo growth. A young plant that appears during seed germination is called a sprout.
In order for a seed to germinate, the embryo must be alive.
Which seed will sprout? (SLIDE 6)
(In the figure, the dead parts of the seed are shaded).
Why do seeds die? Hypotheses are put forward: from mechanical damage, exposure to pests and diseases, storage duration. When collecting, it is necessary to observe the conditions for keeping the seeds alive, as well as to store them correctly.
What conditions are necessary for the embryo to develop?
Group 1 report. "The role of water in seed germination".
The same amount of seeds is placed in two glasses. In the first glass, the seeds are left dry, and in the second a little water. After 3-4 days in a glass where there was water, the seeds germinated.
CONCLUSION: Water is necessary for seed germination, since the embryo can only consume the dissolved nutrients of the seed.
(Students of other groups, after watching the film, review the conclusions of the first group)
ADDITIONAL INFORMATION.
Water activates substances that contribute to the conversion of insoluble starch (storage substance) into soluble glucose, which moves to the growth zone, cells, feeding, begin to divide and increase in size. The embryo uses soluble compounds and the seed germinates.
Different plant seeds require different amounts of water to germinate. (SLIDE 7)
Seeds of drought-resistant plants (millet) absorb water several times less than their own weight, seeds of cucumbers and zucchini absorb more water than millet. But the seeds of rice, which always grows "standing in water", germinates very well under water.
Group II report. "The role of oxygen in seed germination".
Seeds were placed in two glasses. In one - they poured water so that it partially covered the seeds, in the other water to the brim. We left it warm. A few days later, we got the result: the seeds partially flooded with water swelled and germinated, and those completely flooded with water swelled, but did not germinate.
OUTPUT: the water column in the glass did not allow air to reach the seeds. Without oxygen, the seeds and the embryo died. (SLIDE 7) Demonstration of the film and review of the output.
ADDITIONAL INFORMATION.
Why do you need oxygen? For the growth of the embryo, energy is needed, which is contained in nutrients. During breathing, oxygen is used to release energy and is used by the embryo for growth. This process is accompanied by the release of heat.
Breathe and dry seeds if alive. But in dry seeds, this process is very weak. Therefore, store seeds in well-ventilated areas, keep them in paper bags or sacks, but do not pack them in airtight plastic bags.
Group III report. "The role of temperature in seed germination".
One part of the seeds was placed in a warm place, the other in the refrigerator. A few days later, we observed: in the warmth, the seeds quickly gave roots, and the seeds in the refrigerator only slightly hatched, and some did not germinate.
CONCLUSION: when germinating, it is necessary to take into account the temperature conditions, to know at what temperature certain seeds germinate. Demonstration of the film and discussion of the conclusion.
ADDITIONAL INFORMATION.
Seed germination is influenced by temperature conditions. Some plants need a lot of heat to germinate their seeds, while others germinate at fairly low temperatures. For example, seeds of cucumber, pumpkin, pepper germinate at a temperature of +15, +18 degrees, these are heat-loving plants. They are often first germinated at home and in the form of seedlings are already planted in the warm season in the beds. Seeds of peas, radishes, dill can sprout at a temperature of +2 degrees. These are cold-resistant plants. The listed features are taken into account when determining the timing of sowing. ... (SLIDE 8)
Filling out the scheme "Germination conditions" in the notebook and on the blackboard. Demonstration (SLIDE 9)
These are important conditions for seed germination.
Do you think any other factors will affect seed germination?
Influence of the depth of planting seeds into the soil. Demonstration of the film and discussion. (SLIDE 10)
When planting seeds, the planting depth must be taken into account.
When planting seeds, consider:
1. The planting depth depends on the size of the seed:
a) the larger the seed, the deeper it is sown.
b) small seeds are embedded in the soil not very deeply, and some even sow on the soil surface, lightly sprinkling them with a layer of soil no more than 2 mm
c) large sows to a depth of 5 cm
d) medium-sized - to a depth of 2-3 cm
2. The seeding depth depends on the quality of the soil.
Seeds are sown deeper into sandy soil than into dense clay soil, because sandy soil is looser than clay soil, it loses moisture faster and dries out. In clayey, there is enough moisture, but already at a shallow depth there is very little air in it. In clay soil, it is difficult for seedlings to break through to the surface towards the light.
(SIDE 11). Distribute the seeding depth.
(The students are offered seeds on the table, which must be classified according to the depth of planting in the soil).
Influence of the amount of reserve nutrients on seed germination.
Demonstration of the film and its discussion with students.
Output: The size of the seedling depends on the supply of nutrients in the seed. The more substances, the larger the seedling. For sowing, you must select large, healthy seeds.
Effect of light on seed germination.
But there are some exceptions. Some seeds are classified only as dark-similar ones, for example, small-fruited camelina will not germinate in the light, and phacelia, bedbug, Persian Veronica will not germinate in the light.
Some seeds germinate only in the light. Hybrid petunia seeds will germinate only in the light.
The seeds of plants growing in excessively humid places, bogs, will germinate in the presence of light. But for most of the seeds, the presence of light is optional.
We add to our scheme more factors that affect seed germination.
But in order for the seeds to remain alive by the time of planting, it is necessary to observe the storage conditions for the seeds.
- The seeds are stored well dried. (Asks the question "Why?", Students answer). During the germination period, the seeds breathe actively, energy and heat are released, the seeds heat up and can die from high temperatures, lose germination. In humid conditions, diseases and mold can appear, which also leads to the death of seeds. In granaries, ventilation is installed, the room is systematically ventilated.
- Before storage, seeds are treated with special preparations for diseases and pests.
Also, sowing agrotechnology is of great importance.
- It is necessary to know the timing of sowing seeds.
- Planting depth of seeds of different sizes.
- Loosening the soil before sowing to retain moisture and air.
- The ratio of seeds to temperature conditions during germination.
- Soil properties
Superficial damage to the hard shells of some seeds (clover, lupine, melilot) in special machines to accelerate seed germination. Water and air penetrate to the embryo faster, and this accelerates seed germination.
2. Stages of seed germination.
Types of seed germination. Working with the diagram on the board and SLIDE 13.
There are two types of germination - underground and aboveground. What is the difference? Which type of germination is more perfect and why?
Output students do:
Aerial germination - cotyledons are brought to light and turn green (beans, radishes). Underground - the cotyledons remain in the soil (peas, wheat, sunflower).
SLIDE 14. During germination of caryopses of cereals, the cotyledon remains in the seed, and the first leaf breaks through the soil like a ram, protecting the bud from damage.
Output: underground is considered more perfect, as it provides protection from being eaten by animals, trampling, temperature fluctuations and other adverse factors.
The seeds of those plants in which the cotyledons are carried out should not be embedded deeply during sowing, since the seedlings will not be able to break through the thick layer of soil and will die.
III. Reflection.
1. Tests that were offered at the beginning of the lesson. SLIDE 15.
Pupils arrange the numbers of the questions in three columns on the information sheets in the table. What did you already know? What information was new to you? What do you disagree with? What turned out to be the most important? What do you need to remember?
2. Sinkwine and a poem by students.
3. Working with the presentation: (SLIDES 16 to 20).
In the 6th grade, we began to study the section of biology - botany - plant science. With each lesson, we receive more and more information about plants and today's lesson is no exception.
We learned that plants are the main oxygen suppliers for all life on Earth. (slide 16). Plants bring beauty and harmony to our lives. We never stop admiring them (slide 17).
Plants are a food source for all heterotrophs - animals, humans. We use green parts of plants, fruits, vegetables, berries, mushrooms, seeds for food (slide 18, 19).
But in order to continue to use the gifts of plants, a person must be careful with nature. (slide 20).
4. Differentiated tasks.
1st and 2nd level:
Choose the correct answer:
A 1. Water is necessary for seed germination because: 1) there are minerals in water 2) organic substances are dissolved in water 3) the embryo can use only nutrients dissolved in water 4) during germination, it is necessary to increase the mass of seeds.
A 2. In an experiment that clarified the need for light for germination of seeds, the following results were obtained: the seeds germinated both in the light and in the dark. Therefore: 1) both conditions are necessary for germination of seeds 2) light is necessary for germination of seeds 3) light is not needed for germination of seeds 4) the experiment showed nothing.
A 4. What conditions are needed for seed germination? 1) water, light, heat 2) nutrients, a whole germ, water, heat and air 3) soil 4) light.
A 5. What does the embryo of a germinating seed feed on at first? 1) water and soil minerals 2) water 3) nutrients deposited in the endosperm or cotyledons 4) does not feed on anything.
A 6. Requires the highest temperature (above 10 degrees) for germination of seeds of plants: 1) barley 2) rye 3) carrots 4) melons.
B 1. Determine the sequence of events during the germination of the bean seed:
A) the appearance of cotyledons and a stem with a bud
B) the appearance of green leaves
C) the appearance of the root
D) dropping the cotyledons
E) swelling of the seed
C 1. Which seeds can be planted deeper than others, and why? Onion, cucumber or bean seeds.
Answers: A 1-3; A 2 - 3; A 3 - 1; And 4 - 2; A 5 - 3; A 6 - 4; B 1 - DVABG; C 1 - beans, as it contains a large supply of nutrients.
Level 3:
Creative tasks.
1. The biology teacher asked the students to collect calendula seeds. The students collected the seeds in a plastic bag, tied it tightly so as not to spill it. After a few days, they handed over the seeds to the teacher. However, instead of good seeds, the teacher saw blackened and damp seeds. What happened to the seeds? What mistake did the schoolchildren make?
2. What is the biological meaning of the proverb: "Do not expect a good tribe from a bad seed"? Small and puny seeds have a small embryo, contain a small supply of nutrients, germinate slowly and unsupportedly, give low-vigorous seedlings. The seed yield of such plants is low.
3. You are an agricultural agronomist. Will you take into account the exposure of the slopes (northern or southern) when carrying out agrotechnical techniques (sowing, harvesting) on slope lands? Why? The north-facing slopes and the south-facing slopes receive unequal amounts of solar energy. The southern slopes are heated more, the northern ones less. Therefore, on the southern slopes, sowing and harvesting should be done earlier, and later on the northern ones.
4. There are two types of seed germination: aboveground - the cotyledons are carried to the soil surface and underground - the cotyledons remain in the soil. A) what type of seed germination is more perfect and why? B) Do they take into account the peculiarities of seed germination when cultivating plants? Underground seed germination is considered more perfect, since it provides cotyledons with protection from being eaten by animals, trampling, temperature fluctuations and others. The seeds of those plants in which the cotyledons are carried outside should not be embedded deeply when sowing, since the seedlings will not be able to penetrate the thick layer of soil and will die.
5. Why do they say so? "This oats in the mud, you will be a prince" or "Spring day feeds the year." In spring, the soil dries out quickly and it is impossible to be late with sowing seeds. Otherwise, the yield will decrease due to non-compliance with the conditions for sowing seeds.
6. Why is it dried, ventilated and cooled before filling the grain storage? Seeds will not be stored in damp and warm storage. They will start to sprout, heat up, mold, and rot.
Mutual verification of 1 and 2 levels. Grading
5... SLIDE 21... Look at the dwarfs, please. They all have different moods. Which gnome is closest to you in mood? Which gnome would you take with you when you left class today?
6. Homework paragraph 38, notes in a notebook. Additionally: a crossword puzzle, make tests according to p. 38.
Literature.
- N.F. Bodrova "Study course" Plants. Mushrooms. Lichens "- Voronezh, 2008
- N.I. Galushkova "Biology. Bacteria. Mushrooms. Plants" - Volgograd, 2007
- DI. Traitak "Book for reading on biology. Plants" - M .: Enlightenment, 1996
- S.N. Lebedev "Lessons in biology with the use of information technology" - M .: Globus, 2009
- S.L. Ostrovsky "How to make a presentation" September 1, 2010
- A.V. Khutorskoy "Key competencies in the lessons of the natural science cycle" - M .: CDO "Eidos" 2009
- Selevko G.K. "Modern educational technologies"
Lesson topic: Germination of seeds. Conditions for seed germination.
The purpose of the lesson: To show the role of the seed in the individual development of plants, to acquaint students with the conditions for seed germination, the dependence of this process on environmental factors, to form the knowledge necessary for the correct sowing of seeds, about the growth and nutrition of seedlings; continue to develop skills to discuss problematic issues, analyze, work with various sources of information.
Lesson Objectives:
1.Educational
To form and systematize knowledge about the conditions for seed germination, about the need for a certain temperature, humidity, availability of air, reserve nutrients, about the depth of planting seeds in the soil, light mode.
To establish the dependence of the vital activity of seeds on environmental conditions, rules for storing seeds, agricultural techniques for sowing seeds.
2. Developing
To develop knowledge about the conditions for seed germination, general biological concepts, beliefs in the natural character of biological phenomena and their material conditioning.
Develop knowledge of experimental techniques, the ability to observe the germination process, record the results, formulate conclusions
Develop the ability to use terminology, work with various information sources, test the accuracy of theoretical knowledge in practice.
Develop intellectual skills: the ability to observe, analyze, compare, establish causal relationships, draw conclusions.
3. Educational
To foster a sense of responsibility, accuracy, accuracy, an interested attitude to learning, cognitive interest in the subject.
Equipment:
Seeds of beans, peas, rice. pumpkins, oats, sunflowers, Petri dishes, beakers, a computer with a multimedia projector, a presentation on the topic "Conditions, seed germination", tables: "structure of seeds of monocotyledonous and dicotyledonous plants"
Lesson type: combined, laboratory work "conditions necessary for seed germination"
Teaching methods: problematic, partial-search
Preparatory experimental part of the lesson:
The teacher sets a goal for the students, introduces them to theoretical material, methods of setting up and conducting an experiment.
10 days before the lesson, students, under the guidance of a teacher, lay down experiments that demonstrate the conditions necessary for seed germination. During the experiment, the students observe the germination process, care for the germinating seeds and seedlings.
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Preview:
Open lesson in biology
Teacher: Shchekoturova Yu.S.
Class: 6 "B"
Lesson topic: Germination of seeds. Conditions for seed germination.
The purpose of the lesson: Show the role of the seed in the individual development of plants, acquaint students with the conditions for seed germination, the dependence of this process on environmental factors, form the knowledge necessary for the correct sowing of seeds, about the growth and nutrition of seedlings; continue to develop skills to discuss problematic issues, analyze, work with various sources of information.
Lesson Objectives:
1.Educational
- To form and systematize knowledge about the conditions for seed germination, about the need for a certain temperature, humidity, availability of air, reserve nutrients, about the depth of planting seeds in the soil, light mode.
- To establish the dependence of the vital activity of seeds on environmental conditions, rules for storing seeds, agricultural techniques for sowing seeds.
2. Developing
- To develop knowledge about the conditions for seed germination, general biological concepts, beliefs in the natural nature of biological phenomena and their material conditioning.
- Develop knowledge of experimental techniques, the ability to observe the germination process, record the results, formulate conclusions
- Develop the ability to use terminology, work with various information sources, test the accuracy of theoretical knowledge in practice.
- Develop intellectual skills: the ability to observe, analyze, compare, establish causal relationships, draw conclusions.
3. Educational
- To foster a sense of responsibility, accuracy, accuracy, an interested attitude to learning, cognitive interest in the subject.
Equipment:
Seeds of beans, peas, rice. pumpkins, oats, sunflowers, Petri dishes, beakers, a computer with a multimedia projector, a presentation on the topic "Conditions, seed germination", tables: "structure of seeds of monocotyledonous and dicotyledonous plants"
Lesson type: combined, laboratory work "conditions necessary for seed germination"
Teaching methods: problematic, partial-search
Preparatory experimental part of the lesson:
The teacher sets a goal for the students, introduces them to theoretical material, methods of setting up and conducting an experiment.
10 days before the lesson, students, under the guidance of a teacher, lay down experiments that demonstrate the conditions necessary for seed germination. During the experiment, the students observe the germination process, care for the germinating seeds and seedlings.
During the classes
Introductory speech of the teacher.
In the 6th grade, we began to study the section of biology - botany - plant science. With each lesson, we receive more and more information about plants.and today's lesson is no exception.
Let's remember what is the significance of plants in nature and human life?
We learned that plants are the main oxygen suppliers for all life on Earth. Plants bring beauty and harmony to our lives. We never tire of admiring them.
Plants are a food source for all heterotrophs - animals, humans. We use green parts of plants, fruits, vegetables, berries, mushrooms, seeds for food.
But in order to continue to use the gifts of plants, a person must know how to care for them, properly grow, germinate.
Question: How does a plant begin its life?
Answer: A plant begins its life from a seed.
Question: What is a seed?
Answer: The seed is an embryo that has stalled in its development. (Entry in notebooks)
Teacher: Let's remember what the seed is made of?
The teacher, together with the students, remember all the parts of the seed, examine them and make notes in notebooks.
Now is not the time to germinate seeds, but nevertheless you all germinated them, and I am with you. Well done!
And how to give life to a seed, what conditions are necessary for seed germination, is the topic of today's lesson. We write down the topic of the lesson in a notebook:“Germination of seeds. Conditions necessary for seed germination ”.
Seeds of wheat, corn, peas and other plants are stored dry for a long time in granaries. There are known cases of preserving seed germination for ten years. Seeds found in the thickness of ice, tombs, do not lose their viability even for hundreds of years.
Question: Let's think about what germination is?
Germination is the transition of seeds from dormancy to growth and development of a seedling from it..
The resulting plant from a seed is called a sprout. It takes a lot of time for a seedling to look like an adult plant. The seeds must survive a dormant state.
Question: What is the meaning of this state?
Answer: An important adaptive value, as it protects seeds from premature germination.
Only seeds with a living embryo are capable of germinating and giving rise to a new plant, since it can die from damage by harmful insects, from drying out, from long-term storage of seeds and other reasons. In order to grow a high yield of cultivated plants, a person takes care of the sowing material.
Problem: How do you get a healthy, complete and strong sprout?We will try to find the answer to this question during today's lesson.
In the process of seed germination, their stages are distinguished, each of which performs its own functional load.
Seed germination stages:
Stage 1 - Water absorption
Stage 2 - Swelling of seeds
Stage 3 - Increase in size. Cell division.
Stage 4 - The appearance of the root.
Stage 5 - The emergence of an embryonic shoot.
Germination of seeds begins with the absorption of water by them: they swell. Both viable and non-viable seeds swell. Swollen non-viable seeds rot, and viable seeds germinate. Water activates substances that contribute to the conversion of insoluble starch (storage substance) into soluble glucose, which moves to the growth zone, the cells of the embryo begin to divide and increase in size. The first visible sign of growth is the appearance of a root. It breaks through the skin of the seed, grows downward, anchoring the seed in the soil. Then a bud appears - an embryonic shoot.
Question: What are the conditions necessary for the seed to germinate?
Let's try to do some research.
The purpose of our research is "Studying the conditions for seed germination"
We assumed that seeds are needed for germination: water and air, heat, soil, food, light.
1. We investigate the need for water and air for seed germination.
For this: dry pumpkin seeds were placed in the first glass, in the second - the seeds were slightly filled with water so that they had access to air, in the third - the seeds were filled with water, filling the glass to half, so that the layer of water did not allow air to pass to the seeds. Six days later, they found: in the first glass the seeds remained unchanged, in the second - the roots appeared in the seeds, in the third - the seeds died without access to air, rotted.
From the experiment, we can concludethat the seeds germinate in the presence of water when air is available. Water is needed to dissolve the storage nutrients contained in the seed (in the endosperm or cotyledons) for the initial growth of the embryo.
The water displaced the air from the glass, which the seeds needed to breathe. The seeds of different plants require different amounts of air and water. For example, rice seeds germinate even under water with very little air. After sowing the rice, the field is flooded with water. The seeds of most flowering plants require an abundance of air and will not germinate under water.
2. Investigate the need for heat for seed germination.
Some plants need a lot of heat to germinate their seeds, while others germinate at fairly low temperatures. For example, seeds of cucumber, pumpkin, pepper germinate at a temperature of +15 +18 degrees Celsius (these are heat-loving plants). Seeds of peas, radishes, dill can sprout at a temperature of +2 degrees Celsius (these are cold-resistant plants). Consider Figure 136 in the textbook)
Experiment with a thermophilic plant - pumpkin. One part of the seeds was placed in a warm place at a temperature of +20 degrees, the other in a cool one at a temperature of +5 degrees.
Five days later, we observed: in the warmth, the seeds quickly gave roots, then the stalks, and the seeds, which were in a cool place, only weakly "hatched"
From the experiment, we can conclude:when germinating seeds, it is necessary to take into account the temperature conditions, to know at what temperature certain seeds germinate.
Question: What conditions are necessary for seed germination?
Answer: Water, air and heat.
Question: What are these factors called?
Answer: These are factors of inanimate nature..abiotic factors.
Question: Do you think these factors are sufficient for seed germination?
Answer: No
3) let's explore the effect of storage nutrients on seed germination
The endosperm of monocotyledons and cotyledons of dicotyledonous plants contain nutrients for the initial growth of the embryo. ...
Full-fledged pumpkin seeds were placed in the first Petri dish, with two cotyledons, in the second - seeds from which one cotyledon was removed.
Five days later, full-fledged seeds with two cotyledons sprouted safely, gave roots, stems and cotyledon leaves. In the second, only a part of the seeds from one cotyledon germinated; in the non-germinated seeds, the embryo did not have enough nutrients for germination.
Then, in the first glass, a seedling obtained from a full-fledged seed was planted, in the second - a seedling from a seed with cotyledons removed. The first seedling was healthy, strong, and developed much faster. The second is small and weak.
The conclusion was drawn from the experiment:the size of the seedling depends on the supply of nutrients in the seed. The more substances, the larger the seedling. ...
4. Let's explore how the depth of planting of seeds in the soil affects.
For the experiment, we took pumpkin seeds and planted them in the soil at different depths. In the first glass, the seed was placed at a depth greater than required by the embedding rules, in the second - according to the embedding rules, to a depth of up to three centimeters. In the first case, the seed germinated longer in time, in the second - faster and the seedling developed faster.
The embedment depth depends on:
1.seed size:
A. small seeds are buried in the soil not very deeply to a depth of 1-2 cm, these are the seeds of plants such as onions, turnips.
B. medium seedsburied in the soil to a depth of 2-4 cm, these are the seeds of plants such as radishes, cucumbers
B. large seedsburied in the soil to a depth of 4-5 cm, these are the seeds of beans, peas.
Students' work with the text of paragraph 38, p. 185
Orchids have the smallest seeds. The length of an orchid seed is no more than 1 mm, 1 million orchid seeds weigh less than 28 g. The size of the seed does not in any way affect the size of the plant that will grow from it: orchids grow larger than others with larger seeds. And a huge mahogany begins its life with a tiny seed no more than 1.6 millimeters long.
2.soil quality.
Seeds are sown deeper into sandy soil than into dense clay soil, because sandy soil is looser than clay soil, it loses moisture faster and dries out. There is enough moisture in clayey moisture, but already at a shallow depth there is very little air in it. In clay soil, it is difficult for seedlings to break through to the surface towards the light.
5. Let's explore how light affects seed germination.
For the experiment, oat seeds were planted simultaneously in two pots. One pot was placed in a dark cabinet, the other was left in the light. After five days, the seeds sprouted at the same rate both in the light and in the dark.
From the experiment, we can conclude thatthat the germination of seeds does not depend on the presence of light, especially for seeds with a dark skin (sunflower seeds), since it does not transmit light.
Some seeds are classified only as dark-similar ones, for example, small-fruited camelina, bedbug, Persian Veronica.
Some seeds only germinate in light. These are the seeds of a string, tobacco.
6. The teacher makes a conclusion about what conditions are necessary for seed germination.
Students write in the slide outline notebook.
7. Question: Explain the meaning of the saying: "One day feeds a year"
In order for the seeds to remain alive at the time of planting, the storage conditions of the seeds must be observed.
Question: The seeds are stored well dried. "Why?"
During the germination period, the seeds breathe actively, energy and heat are released, the seeds heat up and can die from high temperatures, lose germination. In humid conditions, diseases, mold can appear, which leads to the death of seeds.
In granaries, ventilation is installed, the room is systematically ventilated.
With insufficient ventilation and high humidity in the granary, the grain temperature can quickly rise to 60 degrees. The grain becomes unsuitable for sowing. Therefore, it is stored in elevators and the humidity and temperature are constantly measured with a moisture meter with a thermometer.
Sowing agrotechnics is of great importance: the need to know the timing of sowing seeds, loosening the soil before sowing, soil properties.
Plants give us life
Even children know about it
But how do they appear
Plants in the world?
They grow from seeds
What we have seen with you more than once
But why, you ask,
Do they not germinate every time?
My answer will be very simple
You will find in the book:
"For seed germination
Conditions are needed! "
And the first, of course,
The presence of water, and secondly, warm
Whether winter or summer
And the air whose composition is so complex
For germination they need.
And if you add it all up
Sun, air and water
A little time, a little time
And with you, we'll see how from the seed
So familiar to man
Green little leaf
Shows a thin pen
Like leaves from maple buds.
Conclusion:
Teacher: So, for the germination of seeds, you need: water, air, heat, seed nutrients, and in order to get a good harvest, you must observe the sowing time and the depth of planting seeds, which depends on the size of the seeds and the properties of the soil.
Questions for students:
What experiences do you remember most of all, made an impression?
What experiments did you want to repeat?
What was interesting in the lesson?
What was important in the lesson?
Where can the knowledge gained in this lesson come in handy?
Consolidation of the acquired knowledge in the lesson
Homework:paragraph No. 38, tasks in a notebook with a printed base No. 139-143
Summing up the lesson:the teacher sums up the work, assesses the students actively working in the lesson.
A research lesson is a lesson that maximizes the level of cognitive activity of schoolchildren, encourages them to study diligently. All students in the class work intensively during the lesson, with interest and desire.
Listen carefully - thinking
Watching - thinking
Read - thinking
They will complete practical tasks - thinking.
1. For the didactic goal, the lesson "Conditions for seed germination" is a lesson in studying new material, in terms of the content of the elements of research activity - the lesson "Sample research" (initial level).
2. Didactic tasks of the lesson: help students to independently develop conditions and form a definition of the basic concept; teach them to be informed about this concept.
3. Pedagogical tasks of the lesson: to acquaint students with the peculiarities of the process of scientific knowledge, the stages of research activities; teach them to distinguish between problems, form and select useful hypotheses, interpret data, draw conclusions; to interest students in research activities.
4. The main thing in the lesson is the joint search for the truth.
The research lesson expands the range of students' reading, forms the ability to independently find a solution to the problem posed, referring to various sources and experiment, to prove their opinion, to build speech correctly.
5. Students work in groups of 4-5 people, in which students are united on the basis of their inclinations, interests, abilities, psychological preferences. Each group is given a task, instructions for performing an experiment, an algorithm for which it is necessary to prepare a report. The groups carry out research work, thanks to which the school's task is to teach students to acquire knowledge. Students solve a problematic issue and gain some of the new knowledge by independently performing and discussing the experiment. Before performing an experiment, students only know the purpose of the experiment, not the expected result.
Group No. 1. was asked to answer the questions: Do you need water for seed germination? How does water get into a seed?
Group No. 2. was asked to answer the question: Do seeds need oxygen for germination?
Group No. 3. was asked to determine how temperature conditions affect seed germination.
Group No. 4 was asked to answer the question: Is light needed for seed germination?
Group 5 was given the task to determine seed germination.
6. In the lesson, each group makes a short report and demonstrates the results of the work: answers questions, conducts introspection, draws conclusions.
The lesson is taught by the teacher. He sets tasks, leads the discussion, sums up the results.
Such a lesson for students is a transition to a different psychological state, a different style of communication, positive emotions, a feeling of oneself in a new quality. All this is an opportunity to develop one's creative abilities, evaluate the role of knowledge and see its application in practice, feel the interconnection of different sciences, this is independence and a completely different attitude to one's work.
For a teacher, such a lesson, on the one hand, is an opportunity to better know and understand students, evaluate their individual characteristics, and solve intra-class problems (for example, communication). On the other hand, this is an opportunity for self-realization, a creative approach to work, the implementation of your own ideas.
Target: study of the conditions for seed germination.
Tasks:
- to acquaint students with the process of seed germination, nutrition and growth of seedlings,
- develop the ability to observe, establish causal relationships,
- generalize and draw conclusions, apply the knowledge gained in practice, develop skills of independent work with a textbook,
- cultivate respect for plants.
Equipment: the results of experiments to identify the conditions necessary for seed germination;
table "Germination of seeds", "Structure of the seed".
Lesson type: research lesson.
Textbook: V.V. Pasechnik Biology. 6th grade. Bacteria, fungi, plants: Textbook for general educational institutions. - M .: Bustard.
DURING THE CLASSES
I. Updating knowledge
Teacher: The life of a flowering plant begins with seeds. Plant seeds differ in shape, color, size, weight, but they all have a similar structure.
- What structure does a bean seed have? (Trainer on interactive whiteboard)
- What is the structure of a wheat grain? (Trainer on interactive whiteboard)
- What is the difference between the embryos of dicotyledonous and monocotyledonous plants?
- What is a seed?
II. Learning new material
1. The teacher formulates a cognitive task.
Teacher: While the seed is in a dormant state, life processes in it are sluggish and it is very difficult to notice them, but as soon as the seed gets into favorable conditions, they are activated, and the seed germinates and gives life to a new plant.
Video "Germination of wheat seeds" 1C: School. Biology, Grade 6 Plants. Bacteria. Mushrooms. Lichens. Educational complex. Publishing center "Ventana-Graf", text of the textbook with illustrations, 2006.
Teacher: How do you know exactly under what conditions germination starts? What is needed for a plant to develop from a small solid seed? To do this, you need to ask them. Plants should be asked questions so that they can answer briefly "yes" or "no". They answer not with words, but with their height.
2. Conditions for seed germination. (Conversation on the results of experiments to identify the conditions necessary for seed germination, laid down in advance.)
Teacher: Each of you asked your own question to the bean shifts, placed the seeds in different conditions. How did the seeds respond to the conditional questions?
We will hear the report of the "Water" group ( Annex 1
, slides 3, 4, 5)
Student: Our group "Water" in a conversation with plants asked the seeds: Do you need water for germination?
We took two glasses to get an answer. 10 beans were placed at the bottom of the glasses. In the first glass, the seeds were left dry. In the second, a little water was poured to the bottom. Three days later, in a glass where there was water, the seeds germinated. In a glass without water, the seeds did not change.
Output: water is a necessary condition for seed germination.
Student: How does water get into a seed?
We took 16 beans. In four they covered the micropyle with plasticine, in four the hem, in four the entire rind, leaving the scar and micropyle open, and four did not touch it and poured some water. Four days later, we received an answer to the question. The seeds which were smeared with micropile did not swell. Seeds with smeared scars have sprouted. Seeds, which had the peel covered, but the scar and micropyle were left open, sprouted. Seeds left unchanged also sprouted.
Output: The seed breathes through a small hole in the seed passage (micropyle), water enters the seed through it, after which the seed swells and germinates.
Teacher: Plant seeds require different amounts of water to germinate. For example, pea seeds absorb water one and a half times their mass. Water kernels of corn require half their mass, and for a drought-resistant cereal, millet, a fourth of the mass of sown kernels.
Water penetrating into the seed causes it to swell. The seed increases in volume. Reserve nutrients in the endosperm and cotyledons pass into a soluble state. They liquefy and become available for use by a living embryo. Nutrients provide initial nutrition for the embryo.
- The next question for beans is asked by the group "Air" ( Annex 1 , slides 7, 8)
Student: The Air group asked the seeds: Do the seeds need oxygen for germination?
To get the answer, 10 beans were placed in two glasses. The first glass was filled to the brim with boiled chilled water. In the second glass, the seeds were only moistened. The glasses were covered with glass and placed in a warm place. After three days, in a glass with a little water, the seeds germinated. In a glass filled with water, the seeds swelled, but did not germinate. Here, the water displaced the air from the glass, which the seeds needed to breathe.
Output: air oxygen is an important condition for seed germination and seedling development.
Teacher: The seeds of different plants need different amounts of air. Rice and timothy seeds will germinate even under water with very little air dissolved in it. The seeds of most flowering plants require an abundance of air and do not germinate under water.
- To continue the conversation with the seeds, I invite the "Temperature" group ( Annex 1 , slides 9, 10, 11)
Student: Our group determined whether temperature conditions affected seed germination.
For this, we took two glasses of beans. A little water was poured into the bottom of each glass so that the seeds could germinate. One glass was placed in a warm place, the other in the cold, in the refrigerator. When the seeds, placed in a warm place, germinated, they were compared to seeds placed in the cold. We saw that the seeds did not germinate in the cold.
Output: Germinating seeds need warmth.
Teacher: If the seeds have enough water and air, but not enough warmth, they will not germinate and will eventually die. The seeds of most plants germinate only at temperatures of 10-15 ° C and above.
Temperature conditions for seed germination:
Some plants need a lot of heat to germinate their seeds, others a little. Plants, the seeds of which require a high temperature during germination, are called heat-loving, and those germinating at low temperatures are called cold-resistant.
a) thermophilic (+ 15 ° С + 25 ° С) - cucumber, pumpkin, pepper, beans, corn.
b) cold-resistant (+ 2 ° С + 5 ° С) - peas, radishes, onions, parsley, wheat, rye.
- The group "Light" will finish the conversation with the seeds ( Annex 1 , slides 12, 13)
Student: In a conversation with bean seeds, the question was asked: Is light needed for seed germination?
To get the answer to the question, we took two glasses, and placed 10 beans in each. Then one glass was placed in the dark (in a closet), the other was left in the light. Four days later we received an answer. Seeds that were kept in the dark developed better and germinated more than in the light.
Conclusion: No light is needed for seed germination.
Teacher: What conditions are necessary for seed germination? ( Annex 1 , slide 14)
Students: Seed germination requires water, air and heat.
3. Seed germination, seeding depth
Teacher: The ability of seeds to germinate is called germination.
- How to determine seed germination?
Student: To determine the germination of seeds, I counted 100 wheat seeds in a row, without a choice, spread them out on wet filter paper. After 4 days and after 10 days, the number of germinated seeds was counted. The first count shows how much the seeds germinate together, the second - what is their final germination capacity. Germination is estimated as a percentage by counting the number of germinated seeds out of 100 sown, taking 100 seeds sown as 100%.
1st sample - 100 sown, 94 germinated
2nd test - 100 sown, 95 germinated
3rd sample - 100 sown, 93 germinated
4th test - 100 sown, 94 germinated
Average germination rate: 94 + 95 + 93+ 94/4 = 94%
The ability to determine seed germination is necessary to prepare for sowing seeds. Germination determines the economic suitability of seeds.
Teacher: You can sow seeds in a timely manner, but if they are embedded in the soil shallow, the hot rays of the spring sun can dry them out. And if the seeds are too deep, the seedlings will be bad: the seedlings do not have enough air, it will be difficult for young shoots to break through to the surface. Therefore, it is necessary to sow seeds at a certain depth.
- To what depth should the seeds be embedded in the soil?
The seeding depth depends on the seed size. The larger the seeds, the deeper they are embedded in the soil. Large seeds have enough nutrients and sprouts do not die, breaking through from great depths for a long time.
Practice has established that small turnip and onion seeds should be sown to a depth of 1-2 cm, medium-sized seeds, for example, radish seeds, cucumbers, - to a depth of 2-4 cm, large seeds of beans, peas, beans - to a depth of 4-5 cm. if large seeds are sown less deeply, they may not have enough moisture.
The seeding depth also depends on the quality of the soil. Seeds are embedded deeper into sandy soil than into dense clay soil. This is due to the fact that sandy soil is looser than clay soil, it loses moisture faster and dries out. This is why finely seeded seeds may not get enough moisture and dry out. The clay soil in the upper layers contains a lot of moisture, but already at a shallow depth it contains very little air. Seeds should not be placed deeply in such soil. They will suffocate here from lack of oxygen. In addition, it is difficult for seedlings to break through the dense clay soil to the surface towards the light.
4. Germination of seeds. (Teacher's story on slides 15, 16, 17, 18 Appendices 1 with writing the diagram on the board and in notebooks.)
Teacher: What is observed during seed germination?
When bean seeds germinate, the young root developing from the embryonic root breaks the skin and comes out. It grows rapidly and hardens in the soil. Then the embryonic stalk begins to grow, which raises the cotyledons and the kidney above the soil surface. An aerial bean stalk with leaves develops from it. That is, the cotyledons are brought into the light and become green, such germination is called aboveground (linden, radish).
In peas, wheat, oak, the cotyledons remain in the soil. The aerial shoot develops from the bud of the embryo. This sprouting is called underground sprouting.
Once in favorable conditions, the seeds germinate.
- What is germination?
Germination is the transition of seeds from a dormant state to the growth of an embryo and the development of a seedling from it.
III. Consolidation of what has been learned
Novice gardeners should know what conditions are needed for seed germination. Land and water alone are not enough to prepare future seedlings. The surrounding space should correspond to the parameters of the life of a particular plant. In nature, they take into account the time of the year, the terrain, and also mount greenhouses if necessary.
Environment and region
Before you begin to determine what conditions are needed for you need to know if the plant is capable of living in this area. You can grow it at home, but suddenly it will stretch to a huge size ... Therefore, you need to familiarize yourself with the description of the properties of the selected culture and the features of planting. The structure of the soil, the number of waterings per day, the addition of top dressing to the soil are taken into account.
Often these points differ when considering what conditions are needed for the germination of exotic plant seeds. In the northern regions, they can only grow in a greenhouse. In the south, nature is more favorable, they can be planted in open beds. But no one can give guarantees of normal growth if the required prescriptions are not followed.
In the latter case, another factor plays an important role - the number of sunny days per year. Do not forget to take this into account when considering what conditions are needed for seed germination. Therefore, the planting site is equipped with special fluorescent lamps that perform an additional function - heating the soil. Temperature is very important when getting small shoots of a new plant.
What is needed?
Consider what factors are important for seed germination at home. Not every plant grows even with proper care. By creating the necessary conditions, they increase their chances of survival. For intensive growth it is required:
- Fertile soil- sold in a specialized gardener's department in hypermarkets or a flower shop. It must meet safety requirements for humans, be treated against pathogens. The composition of the mixture is often described on the packaging.
- Specific temperature- often higher than room temperature.
- Air- clean, not gassed.
- Lack of nearby powerful emitters of electromagnetic and heat waves.
- Adequate amount of sunlight or artificial light per day.
- Soil nutrition with water and minerals.
Air
The presence of oxygen is necessarily implied. He participates in the metabolic processes of all living cells. For plants, its presence is vital. The sprouts are pulled out of the ground, consuming a huge amount of air. With its lack, the process of cell development is significantly slowed down, and in its complete absence, plant necrosis can begin.
Oxygen is important not only for plants, but also for any living creature. It is not recommended to use candles and other open fires in the seedling room. If you have to do this, you should ventilate the room more often. When covering the soil with a film, do not close the planting site tightly. Air must flow to the soil surface.
Light
The sun's rays are the basis of all life on Earth. All plants strive upward, towards the sun, and the growth rate depends on the constancy of illumination. This factor must be taken into account for seed germination. Special lamps are produced that are substitutes for natural light.
Plants produce carbon dioxide at night. Therefore, it is not recommended to place seedlings in sleeping rooms. With a large number of indoor plants in the morning, a headache is often caused by a lack of oxygen. It is necessary to ensure a constant flow of air to the soil with seeds.
In complete darkness, some plant growth is still observed. But the resulting sprouts are not able to fully develop in the future. They become fragile, lifeless. The color of their leaves is closer to yellowish than green shades.
Water
What does biology say? Seed germination is arranged in such a way that the main forces for cell division are drawn from water. Chemical processes cannot take place without liquid, so you should water the seedlings as planned. Often the seeds are allowed to germinate without land, in water. This process is less time consuming. As soon as the first roots appear, the resulting seedlings are planted in the soil.
The plant consists, like the human body, mostly of water. It feeds cells with essential minerals, participates in metabolism and growth processes, removes decay products. Thanks to the liquid, nutrients are dissolved in the soil. But under the influence of heat, seeds can germinate even at the storage stage.
To do this, they need high humidity, light and a comfortable temperature. However, in the memory of plants there is a mechanism that perceives the seasons. So, during a thaw in spring, seeds begin to grow even in the complete darkness of the basement. They are able to perceive the changing seasons.
Warmly
Active growth occurs when the temperature for seed germination is above 20 degrees Celsius, ideally at least 25. Cold delays the process of growing seedlings. The southern regions are rich in vegetation, its diversity is sometimes striking. This is due to the warm climate, which provides intensive cell growth.
In the northern regions, the vegetation freezes with the arrival of cold weather. Only with the arrival of warmth does everything come to life again. The temperature in the room is always above zero, so ensuring the right lighting becomes the main concern. The effect of low temperatures can be tested by placing the container of seeds in the refrigerator. The growth process will slow down significantly.
If, under the influence of warm sunlight, the first shoots appear the next day or in the evening, then in a cold place, at a temperature not higher than +3 degrees, the first signs of growth can be seen only after five days.
Additional measures
The conditions for seed germination must be observed in any case, then it will take a minimum of time to obtain healthy seedlings. Additional measures are the creation of a favorable soil composition for the growth of a particular plant species. Some crops require a specific (neutral, slightly acidic, or otherwise) medium for growth. This is where pH matters. Most often, its value is in the range from 5 to 8.
Plants do not like stagnant water, so it is not recommended to water the seeds abundantly. The removal of excess moisture from the soil is taken into account. Small holes are made from the bottom of the pots. The upper layers of the soil are periodically loosened to allow oxygen to penetrate through the soil compacted with water.
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