For seed germination, an optional condition is. Seed germination

Seed germination conditions

Definition 1

Germination- this is the transition of seeds from a state of dormancy to the growth of the embryo and the development of a seedling from it.

A necessary condition for seed germination is a dormant period. If this period is significantly delayed, it should be artificially disturbed.

Methods of violation of the rest period

There are three methods of disturbing the rest period:

• Stratification;
• Scarification;
• Rinsing with water.

Definition 2

Stratification- preparation of seeds for germination.

In order to prepare the seeds, they are mixed with moistened sand for a period of $ 30 to $ 90 days at a certain temperature of $ 5 ^ \ circ \ C $. The exposure time depends on the type of plant. During this period of time, physical and biochemical processes take place in the seeds, which contribute to the germination of the seed.

If the skin is damaged, access to air and moisture is opened for the seed, which contributes to their swelling and germination. The damage is possible mechanical, or is caused by short-term exposure to strong sulfate acid.

Definition 4

Rinsing with water- the process of removing substances from the seed that inhibit germination.

Environmental factors for seed germination

Also of great importance for seed germination is the germination energy. Germination energy depends on environmental factors and characterizes the sowing quality of seeds.

Water, temperature, light, air, physiological active substances are factors of seed germination.

Effect of air on germination

During germination, the seed breathes, while absorbing oxygen, which is necessary for redox reactions in cells. These reactions stimulate the division and growth of cells in the embryo. In order to make sure of the need for air, we will conduct an experiment.

Example 1

Take three glasses and place dry wheat seeds in them. We will cover the first glass with a saucer, in the second, along with the seeds, we will put wet cotton wool and also cover with a saucer, and the third we will fill with water. Let's leave it for a couple of days. In the third case, the seeds will not germinate, but only swell, since for the germination itself, the seeds do not have enough air, which is necessary for breathing.

Effect of light on germination

The reaction to light is due to its effect on the exchange of stimulants or inhibitors in seeds. This is how light-loving and dark-loving plants are distinguished. Many seeds germinate better in a dark place.

Effect of water on germination

Water is needed to swell the seeds. During the swelling, the skin of the seed is damaged, then the root and stalk of the embryo appear. Water helps the seed absorb the nutrients it needs for proper germination. To convince the necessity of this factor, we will conduct an experiment.

Example 2

Take two containers and place the bean seeds there. We simply cover the first one with a saucer, and in the other we put wet cotton wool and also cover it. After a couple of days, we will notice that in the second case, the seeds have sprouted.

The amount of water for different types of plants is different. So for legumes, more water is needed in relation to cereals.

Germination temperature value

Temperature conditions are equally essential for germination. A certain plant has its own favorable temperature. Some crops germinate at $ + 2 ^ \ circ \ C $, others above $ + 15 ^ \ circ \ C $. Knowing the temperature preferences of crops in agriculture, a sowing calendar has been developed.

Heat-loving plants germinate at high temperatures, they come from warm latitudes, and at low temperatures cold-resistant plants germinate - people from the northern regions.

Physiologically active substances for germination

In order for the embryo to grow, it must feed. Seed nutrients are found in the endosperm or in the cotyledon. With a limited supply of physiological active substances, the embryo will develop slowly, or may completely die. To prevent this, farmers apply starter fertilizers. Absorbing nutrients in the embryo, metabolism occurs: oxygen absorption and carbon dioxide release.

Remark 1

Thus, we can conclude. Seed germination requires water, heat, light, air and nutrients. And if you exclude at least one of the factors, the seeds will not germinate.

The transformation of substances in the germinating seed

When the seed germinates in the endosperm and cotyledons, the decomposition of storage substances, including proteins, occurs. Simultaneously, synthetic processes begin in the embryo due to the substances that flow to it.

The total amount of nitrogenous substances remains at the same level, despite the fact that energy breakdown of proteins occurs, because amino acids and asparagine accumulate.

The amount of starch decreases sharply, but the amount of soluble sugars does not decrease. The sugars are consumed in the respiration process, which occurs very vigorously in the germinating seed. As a result of respiration, energy-rich substances ADP and ATP are directly formed, water, carbon dioxide and thermal energy are released. Sugars form fiber and hemicellulose. Minerals remain constant. Cations regulate osmotic pressure and colloidal chemical processes in new cells.

Plant seeds do not germinate immediately; they can remain dormant for a long time. Once in favorable conditions, they germinate, forming a new plant. Thus, germination- this is the transition of seeds from a state of dormancy to the growth of the embryo and the development of a seedling from it.

The main prerequisite for seed germination is the ingress of water into the seed through the seed inlet. After water ingress, the seed swells, the nutrients dissolve in the water and the embryo can already use them to start its growth and development.

However, water is far from the only condition for seed germination. Air, or rather the oxygen in it, is no less important. After all, the embryo of the seed, like all living organisms, breathes. Even dry seeds breathe, albeit very weakly. Therefore, seeds should not be stored in airtight containers such as plastic bags. The seeds germinate in the soil because it contains enough air.

Another condition for seed germination is the presence of reserve nutrients in them. The embryo must be nourished in order to grow. Since he himself cannot yet synthesize organic substances, they must come from somewhere. This site is the cotyledons or endosperm. If the supply of nutrients is small, then the embryo either develops slowly or dies.

Thus, the plant embryo, absorbing the nutrients of the seed and the oxygen of the air, carries out the metabolism. In the process of metabolism, it releases carbon dioxide.

Temperature also plays an important role in seed germination. Different temperatures are favorable for the germination of seeds of different plants. Some germinate at temperatures above +15 ° C (cucumbers, peppers, corn), others just slightly above +2 ° C (dill, radishes, wheat, rye, carrots). Therefore, in agriculture, different plants are sown at different times, some in April, and some at the beginning of summer.

Plants whose seeds can only germinate normally at high temperatures are called thermophilic. Plants whose seeds germinate at low temperatures are cold-resistant.

The reason seeds germinate at different temperatures is due to the origin of the plants. Plants that originated in warm latitudes are thermophilic. Natives of the northern regions are cold-resistant.

Light can also be a condition for seed germination. There are plants whose seeds can only germinate in the dark or only in the light. Most of the time, seeds germinate best in the dark.

When sowing seeds, the depth to which they are placed in the soil (sowing depth) is important. In this case, they are guided by the following rule: the larger the seeds of the plant, the deeper they are embedded in the soil. Very small seeds are sown directly on the soil surface, and beans seeds, for example, are planted 4-5 cm.

Teacher: Rahimova Arzu Maharramovna.

Municipal autonomous educational institution
Secondary school № 44 of Tomsk

Item: biology.

Class: 6, general education.

Topic: Conditions necessary for seed germination.

Appendix to the lesson: presentation.

Lesson form: lesson with elements of design and research technologies.

The lesson on the topic "Conditions necessary for seed germination" is held in the 6th grade in the section of the study of the topic "Seed".

Relevance.

At the present stage of training, it is necessary to pay special attention to the individual development of the personality, the search and development of the student's creative abilities, teaching the skills of independent solution of the tasks set for oneself. To form students' ability to think independently, apply knowledge, be able to plan activities, pose questions and be able to find answers to them. Ability to effectively collaborate in a variety of mini-groups. All this should inevitably lead to the search and implementation of new pedagogical forms and technologies in education. One of these forms is the research and design and research activities of students.

The essence of the research method is the teacher organizing the search, creative activity of students to solve new problems and problematic tasks. The purpose of this method is the full assimilation of the experience of creative activity by schoolchildren.

With the help of the research method, creative assimilation of knowledge is organized, that is, this method teaches students to apply the knowledge they know to solve problematic problems and obtain new knowledge as a result of such a solution. In addition, it ensures the mastery of the methods of scientific knowledge in the process of searching for these methods. Obviously, the research method is a condition for the formation of interest, the need for independent, creative activity in students

The nature of the assignments for the research method: home practical assignments; solving analytical problems; tasks are short-term and require a certain period of time (week), group tasks.

In the research lesson, I set two goals:

1) Teaching the subject (didactic goal).

Tasks:

encourage students to acquire

General educational skills (working with a textbook, compiling tables, making observations in writing, formulating thoughts in internal and external speech, exercising self-control, introspection, etc.);

Special knowledge and skills (assimilation of factual material on the subject);

Intellectual skills (analyze, compare, generalize, etc.).

Tasks:

to form students' research knowledge and skills:

Knowledge of the specifics and features of the process of scientific cognition,

stages of research activities;

Knowledge of scientific research methods;

Ability to identify problems, formulate hypotheses, plan an experiment in accordance with a hypothesis, integrate data, draw conclusions.

Equipment: beans, pea seeds, Petri dishes, beakers, a computer with a multimedia projector.

Preparation for the experimental part of the lesson:

The class is divided into 7 groups (one of them is expert). The whole class participates in the work. The division into groups is carried out on a voluntary basis, which allows you to eliminate possible problems of interpersonal communication of students.

Each group has a scientific name: botany; young people; practice; young chemists; young agronomists, young researchers, academic council. For each group, the teacher sets goals, introduces theoretical material, methods of setting up and conducting an experiment.

10-14 days before the lesson, expert groups of students, under the guidance of a teacher, lay down experiments that demonstrate the conditions necessary for seed germination. During the experiment, students observe germination, take care of germinating seeds and seedlings, take photographs of objects of study, prepare speeches in accordance with the assignments.

The main stages of the lesson.

Lesson steps		Research topic	Temporary implementation
Immersion in the topic through a problematic task.
	botanists	"What is the structure of Bean and Wheat Seeds?"
		"What conditions are necessary for seed germination?"
	practices	What does the embryo eat at the beginning of germination?
	young chemists	do seeds breathe?
	young agronomists	Why are seeds sown at different times?
	young researchers
	Academic Council	expert
Summary after each presentation

The groups work according to the proposed algorithm. Before starting it, it is necessary to distribute roles for more effective work: the group leader (leader), the experiment organizers, the person analyzing the results, the speaker or co-speakers.

Group work algorithm:

1. Formulate the purpose of the study.

2. Set research tasks.

3. To put forward versions, hypotheses, identify problems.

4. Conduct an experiment.

5. Record the result.

6. Checkout the result

7. Make a conclusion (analysis, generalization)

8. Present the results of the research.

During the classes

1 hour (40 min.)

Immersion (3 min).

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.

We know that a plant begins its life from a seed. And how to give life to a seed, what conditions are necessary for seed germination, is the topic of today's lesson. And so we opened the notebooks and write down the topic of the lesson "Germination of seeds."

You are given a task, the answer to it you must give at the end of the lesson.

In the encyclopedia for children and schoolchildren in the section on archaeological excavations it is written: “Scientists have found wheat seeds that have lain in the ground for more than 1000 years and have not sprouted, although they have not lost the ability to germinate. Why did this happen? After all, seeds usually germinate a few days after sowing. "

To solve this problem, we will be helped by the groups that conducted the research work.

botany;

practice;

young chemists;

young agronomists.

young researchers.

There is an academic council in the lesson, which will summarize the work of all groups and decide whether we have coped with the problematic issue.

Botanists. Our group studied the question "What structure do beans and wheat seeds have?"

Consider a dry wheat fruit - a weevil. The oblong grain of wheat is on the outside covered with a golden-yellow leathery pericarp, which has grown so tightly with the seed coat that it is impossible to separate them. If you cut a wheat grain lengthwise, you can see on the cut that most of the grain is mealy endosperm, the cells of which contain nutrients. The wheat germ is small and can only be seen under a magnifying glass. It has a root, a stalk and a kidney. But he has one cotyledon. It does not contain a reserve of nutrients, it adheres tightly to the endosperm and looks like a thin plate. When the seed germinates, nutrients from the endosperm cells are delivered to the embryo through the cotyledon.

So, wheat seed has:

pericarp, fused with seed coat; embryo; endosperm.

Consider the structure of a bean seed. The outside of the seed is covered with a seed coat. It protects the seed from excessive drying out. If you take a bean seed that has swollen in water and peel it off, an embryo will be found under the seed coat. It consists of two cotyledons and a root, stalk and bud located between them.

So, the seed of a bean consists of a seed coat and an embryo, and the reserves of nutrients are in the cotyledons.

Plants whose seeds consist of one cotyledon are called monocotyledonous.

Plants whose seeds consist of two cotyledons are called dicotyledons.

Teacher. Thanks to the botanists for the interesting information.

Question to the class - What is the name of the process of formation of a young plant from a seed - germination.

It turns out that in most plants, seeds that have fallen into the soil cannot germinate immediately. They need a rest period - the time during which the embryo of the seed ripens outside the fetus. Pine seeds should rest for almost a whole year, freeze in winter and warm up in the rays of the spring sun. When the dormant period is over, the seed is ready to begin its work of growing into a young plant. Willow seeds can sprout as soon as they fall from the tree to the ground.

And also the seeds must have germination, that is, the ability to germinate under appropriate conditions. Germination rate is determined by the percentage of seeds from which normal seedlings have developed.

What is sprouting?

Seed germination is called their transition from dormancy to vegetative growth of the embryo and the formation of a young plant from it.

So, we learned how seeds behave when they just start to germinate. And what happens next (video of seed germination)

Brief description of the film.

1. When a seed germinates, a small root appears first? In order to look out, he has to break the seed coat.

2. If the seed is in the soil, the root always grows vertically downward. Following this, active growth of the stem begins in the embryo of the seed. At first, crawling out of the ground into the light, it forms a loop, which gradually straightens out and brings the heavily "thinned" cotyledons to the surface.

3. Between them the kidney is clearly visible. She, too, grew up and began to turn green.

And so the guys will write it down in their notebooks.

According to the method of germination, plants are divided into two types:

1.underground type,

2. overhead type.

In any type of germination, a young plant develops from the embryo of the seed. It is called a "sprout".

The sprout is formed due to the enhanced division of the educational tissue of the embryo. In the future, an adult plant capable of reproduction will grow from the seedling, and everything will be repeated again and again.

And how to get a healthy seedling, full-fledged and strong? Our expert teams were looking for the answer to this question.

young people; practice; young chemists; young agronomists, young researchers.

The purpose of our research is "Studying the conditions for seed germination"

1st group Yunnats

Our group was interested in the question: "What conditions are necessary for seed germination?"

The same amount of seeds was placed in two glasses. In the first glass, the seeds were left dry. A little water was poured into the second. Both glasses were covered with glass and placed in a warm place. Five days later, in a glass where there was water, the seeds germinated. In a glass without water, the seeds did not change.

Experience shows: “Water is needed for seed germination ”

Water is essential for seed germination as the embryo can only consume dissolved nutrients.

Different plants require different amounts of water to germinate seeds. For example, pea seeds absorb 1.5 times their mass. Therefore, the seeds of peas and some vegetable plants are soaked before sowing. Corn grains require 2 times less weight.

We took two saucers, put the same amount of grams of peas and corn on them. Filled both saucers with the same amount of water. After a while, we compared the saucers. There was no water in the saucer containing the pea seeds. And on the saucer where the corn seeds lay, the water remained. And after that we made sure that for each plant you need different amounts of water.

We have carried out the following experiment. Some seeds were placed in two glasses. The first glass was filled to the brim with water. In the second glass, the seeds were only moistened. The glasses were covered with glass and placed in a warm place. Five days later, in a glass with a small amount of water, the seeds germinated. In a glass filled with water, the seeds swelled, but did not germinate, but died. Here water displaced air, necessary for the seeds to breathe.

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.

Some seeds were placed in two glasses. To the bottom of each glass

poured some water so that the seeds could germinate. The glasses were covered with glasses. 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 refrigerator. We saw that the seeds did not germinate in the cold.

Experience shows that seeds need warmth to germinate.

If the seeds have enough water and air, but not enough heat, they will not germinate, eventually die. Some plants need a lot of heat to germinate their seeds, others a little. For example, seeds of cucumbers, pumpkins will germinate at a temperature of + 15ْ, + 18ْC, and pepper seeds at + 25ْC. Seeds of peas, radishes, dill come off at a temperature of +2, + 5ْC. These features of seeds are taken into account when determining the timing of sowing. Plants whose seeds require a high temperature during germination are called heat-loving, and those germinating at low temperatures are called cold-resistant.

Teacher. Now we are going to draw up the "Plant types in relation to temperature" diagram.

Student writes the scheme on the board, and the guys in the notebook.

Teacher. Does light need to germinate seeds?

The ratio of seed germination to light can be checked by the simplest experiment. We took two plates and put a cloth on each of them, moistened it and placed 20 beans on each of them to germinate. Covered with a damp cloth. Then they placed one plate in the dark (in a cupboard), the other was left in the light. After 7 days, we saw that the seeds of beans, which were kept in the dark, developed better and germinated more of them than in the light.

Experience confirms that no light is needed for 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. These are the seeds of a string, tobacco, seeds of plants growing in excessively humid places, swamps.

But for most of the seeds, the presence of light is not necessary. .

Students record them in notebooks

Teacher. Well done young people! Guys! Now let's remember in what process plants need light

The answer is photosynthesis.

What substance is formed in the process of photosynthesis.

The answer is starch.

What does the embryo eat at the beginning of germination? Let's listen to the practitioners.

Practices. In the course of research work, we found out that at the moment of germination, the embryo uses the stored nutrient reserves. During seed germination, the starch contained in the endosperm under the action of special substances turns into sugar, which is soluble in water, the sugar solution flows to the embryo. This is easy to see if you taste the sprouted grains of wheat or rye. They have a sweetish taste.

The value of nutrients in seed germination can be easily verified by experience.

On a damp gauze mat, we put bean seeds of the same size. When they swelled, the cotyledons were cut off. We made sure that the seedling does not grow without cotyledons. Indeed, the cotyledons contain nutrients without which the seedling cannot live. If you cut off one cotyledon, the seedling will have only half of all stored nutrients, and from lack of nutrition it will be frail and weak.

From this experience, you can make the following conclusion: “The more nutrients, the larger the seedling”. This is why a bean sprout grown from a whole seed is much larger than the other sprouts.

.Therefore, for sowing, you need to take large seeds.

Teacher. Guys! Do seeds breathe? The group "young chemists" will tell us about their research.

Young chemists. Humans and animals need oxygen to breathe. Oxygen supports combustion. A lighted torch burns well because the air contains oxygen. this is because breathing produces carbon dioxide that does not support combustion.

We already know that air is needed for seeds to germinate. Do seeds breathe? Do you need oxygen to breathe? What gas is released when seeds breathe? To answer these questions, let us pose an experiment.

We took 2 jars of colorless transparent glass. In one of them, they put dry, non-germinated seeds, and in the other, the same number of germinated seeds. Both jars were tightly closed with lids and placed in a dark place. The next day, checked whether the composition of the air with the seeds has changed? They put a lighted match attached to a wire into the jar. The match continues to burn, because the air in the bottle with dry seeds has remained almost unchanged. Non-germinating seeds breathe poorly, and therefore the oxygen supply in the bottle is almost completely preserved. Then they opened a bottle of sprouted seeds and lowered the candle to the very bottom. The candle will go out, because the sprouting seeds used up oxygen from the air in the bottle for breathing, and released a large amount of carbon dioxide.

Experience shows that germinating seeds absorb oxygen and emit carbon dioxide, that is, they breathe. This is natural, since plants are living organisms.

Conclusion: Air oxygen is an important condition for seed germination and seedling development.

The seeds breathe day and night. Heat is generated in time. If you put a thermometer in a jar with germinating seeds, well closed on all sides with cotton wool and felt, it is easy to notice an increase in temperature.

The heat generated by the respiration of the seeds heats them up. Especially a lot of heat is released during the respiration of germinating seeds. Raw germinated seeds breathe more vigorously than non-germinated ones. The raw seeds folded in a thick layer germinate and quickly heat up. The embryos of such seeds do not die. Seeds lose their germination. To prevent this from happening, the seeds are stored only dry and stored in dry, well-ventilated rooms. The access of air to the seeds must be constant. This is also necessary for dry seeds, although they breathe weaker than germinating ones. Such conditions for storing seeds are created in modern granaries. (elevators).

Teacher. Thanks to the group of chemists. Guys! What conditions are necessary for seed germination?

Students. For seed germination, the following conditions are necessary: ​​water, air, heat, temperature and seed nutrients.

young researchers.

We were asked to observe the effect of aloe juice on seed germination and compare the results.

We received information from the teacher, aloe juice is. biogenic stimulant which affect the growth of the embryo.

Based on this information, we decided to observe how fresh aloe juice will act on the germination of beans.

For this, we laid down an experiment: with water (control), with the addition of fresh juice

Was delivered purpose: observe how aloe juice will act on the division and growth of the cells of the embryo of bean seeds.

The first stage - with water (control), the second option - a few drops (5-6) of aloe juice from the leaf were randomly added to the humid environment of the Petri dish:

Table 1. Germination of bean seeds.

	Water (control)	Aloe juice (fresh)

As can be seen from the table, the rate of seed germination is higher on the first day was observed in a bowl of water. On the second day, we saw a noticeable jump in seed germination in a cup of fresh aloe juice, where all the seeds eventually sprouted on the third day.

Thus, juice from aloe leaves promotes faster germination of seeds and has been proven that aloe juice is biogenic stimulant.

We will continue our work. And in particular with different seeds and in different concentrations of aloe juice.

Teacher... Thanks to our researchers

The next step is planting seeds.

In early spring, seeds are sown only for cold-resistant plants (wheat, oats, barley, peas). The seeds of these plants germinate at low temperatures and an abundance of moisture.

The seeds of plants that are more demanding for heat have to be sown when the soil warms up enough. However, sowing seeds of heat-loving plants (corn, beans, cucumbers, pumpkin, melon, tomato) should not be delayed either.

Seeds must be sown at a certain depth.

The seeding depth depends on the size and properties of the soil. The larger the seeds, the deeper they are sown. 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, such as radish and cucumber seeds, to a depth of 2–4 cm. Large seeds of beans, peas, and beans require a depth of 4–5 cm. if large seeds are sown less deeply, they will not have enough moisture.

Teacher. In an effort to grow plants, a person creates all the conditions necessary for the germination of seeds, and in order to get a good harvest, it is necessary to observe the timing of sowing seeds and the depth of their embedding in the soil. A group of agronomists will tell us about this.

Agronomists. Our group was tasked with answering the questions: why are seeds sown at different times? What determines the seeding depth?

Our group did the following experiment: we took 2 glasses and planted small wheat grains in one, and large ones in the second. In total, we have planted 6 seeds (3 small and 3 large). At the beginning, they poured a layer of earth of 2 cm, then planted the first grain, then poured another 2 cm of soil - planted the second grain, poured another 2 cm and planted the third grain. All were covered with a 1 cm layer of earth and watered. The same was done with large grains. After 3 days, the first seedling appeared, the one that was closer to the surface, the next day a second seedling appeared, planted after the first germinated, on the third day the seedling appeared, which was planted the very first, that is, the deepest of all. A similar picture was observed with large grains.

Conclusion: seeding depth is one of the most important factors in seed sowing.

Soil properties also affect the seed placement depth. In sandy soils, seeds are sown somewhat deeper than in clay soils. There is very little moisture in the upper layers of sandy soil. Therefore, seeds sown in such a shallow soil will suffer from a lack of moisture. Air in sandy soil penetrates deeper, and moisture is better retained in deeper layers.

Clay soil is denser and heavier. Already very close to the surface, there is little air in it, and there is enough moisture in the upper layers. Therefore, it is not recommended to sow seeds too deep in clay soil. Strict adherence to the terms and rules for sowing is of great importance for increasing the yield of cultivated plants.

From the experiment, it was concluded that 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.

Teacher. Guys! And if all conditions are created for seed germination. And the seeds didn't sprout. Why?

Answer. The seeds did not germinate because they contained the dead embryo.

Teacher. Only seeds with a living embryo are capable of germinating and giving rise to a new plant.

I think you have not forgotten about the question I asked you at the beginning of the lesson. So why are wheat seeds that have lain in the ground for more than 1000 years and did not germinate, although they did not lose the ability to germinate. Why did this happen?

The answer is that for this it was necessary to comply with all the conditions for seed germination.

Now is the time to give the floor to the Academic Council.

Academic Council. It was very interesting in the lesson. The guys in groups did a lot of research work, demonstrated many experiments, and we learned that the following conditions are necessary for seed germination: water, air, heat and nutrients. And I will read a poem composed by the guys in our class using the Internet.

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 first, of course
Availability of water,
And secondly,
Warmly,
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
And with you, we'll see how from the seed
So familiar to man
Green little leaf
Shows a thin pen.

Teacher. Thanks to the academic council, I think you all agree with their findings.

What experiments, carried out by expert groups, were more memorable and impressed? What experiments did you want to repeat? Let's formulate the main thing that was highlighted in the lesson. What was interesting in the lesson? What was important in the lesson? Where can the knowledge gained in the lesson come in handy?

Students answer questions, share their impressions of what they have seen, express their desire to conduct experiments on their own to establish the conditions for seed germination. Teacher asks those wishing to conduct experiments at home the course of work and the algorithm for staging one or another experiment.

Thanks to all the groups. Well done!

D / s: § 11, answer questions.

Thank you for the lesson. The lesson is over. All the best.

List of used literature:

1. Ivanov means in traditional medicine. - M .: Military publishing house, 1992.

2. Verzilin with house plants. - M .: Pedagogy - Press, 1995.

3. Papkovskaya scientific research: A course of lectures.- Minsk: Informpress, 2002.

4..www. golden-yc. ***** / pages / 13.html.

Seed germination requires water, air, heat and light for many plants.

A particularly great stimulating effect on seed germination is exerted by Red light.

Water penetrates under the seed skin through a small hole - the vas deferens, as a result of which the seed swells. The need for water for swelling primarily depends on the composition of the seeds. Seeds rich in fat absorb 30-40% of the total mass of water, rich in starch 50-70%, seeds with a large amount of protein - about 90% of water. Water is also needed to dissolve the seed nutrients that the growing embryo is consuming. Seed swelling is accompanied by intense enzyme activity. In seeds, reserve nutrients are in the form of complex organic compounds. For example, in order for the solid polysaccharide starch to be used by the embryo, it must be hydrolyzed under the influence of the diastase enzyme, which saccharifies the starch to a soluble maltose disaccharide. Other complex substances are also broken down by the action of the corresponding groups of enzymes. This releases the energy used in the biochemical processes of the seedling.

Only seeds with living embryos can germinate and give rise to a new plant.

The reasons for the death of embryos are different:

1. from damage by harmful insects;
2. from damage by mold fungi;
3. from drying out during storage;
4. from too long storage, etc.

So, when the seed germinates a number of sequentially occurring processes can be distinguished:

1. the seeds absorb large amounts of water and swell;
2. at a favorable temperature and access to air - O2 (necessary for respiration, which is rapidly increasing), the enzymes of the seed cells pass from an inactive state to an active one;
3. under the action of enzymes, insoluble reserve substances are converted into soluble (starch - into sugar, fats - into glycerin and fatty acids, proteins - into amino acids);
4. the embryo, using soluble organic substances, starts to grow, and first the root grows, and then the shoot.

Dormant period

- a prerequisite for seed germination. Dormancy can be forced, associated with the lack of necessary conditions for germination (dormancy of dry seeds). Organic rest is determined by the properties of the seed itself. In most cases, metabolic processes occur in such seeds (respiration is sometimes the growth of the embryo), but germination is inhibited. Such seeds, even under conditions favorable for germination, do not germinate at all, or germinate poorly. The ability of seeds to be in forced dormancy or organic dormancy was developed in plants in the process of evolution as a means of experiencing a season unfavorable for seedling growth. Therefore, not all seeds have the ability to germinate immediately after ripening (apple and maple seeds need long rest).]

The main reasons that prevent seed germination:

1. water resistance of the peel;
2. the presence in the pericarp of substances that inhibit germination;
3. underdevelopment of the embryo;
4. physiological mechanism of inhibition of germination.

The main methods of violation of the rest period:

1. stratification - seeds are mixed with wet sand - the process of preparing seeds for germination;
2. scarification - damage to the skin to accelerate germination;
3. rinsing with water to remove substances that inhibit germination from seeds;
4. treatment with physiologically active substances (gibbirilin, cytokinin).

Seeds can germinate only at a certain temperature: winter rye - at 2-4 degrees, and cucumber seeds - at 15-16 degrees. Heat-demanding plants are sown later, when the soil warms up enough.

Another very important condition for seed germination is air, so the seeds must be sown in loose soil, which contains a sufficient amount of oxygen. Oxygen is essential for redox processes in cells. These processes stimulate the division and growth of embryonic cells.

Conclusions:

1.In order for the seeds to germinate, you need air, water, heat.
2. If there is no condition, the seeds will not germinate.

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, spare 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. pumpkin, oats, sunflower, 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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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: 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.

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 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 necessary 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 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 seeds with two cotyledons sprouted safely, gave roots, stems and cotyledonous leaves. In the second, only 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-like 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.