"Germination of Seeds" Life of Angiosperms PPT Courseware 6

Description

"Germination of Seeds" Life of Angiosperms PPT Courseware 6

1. Environmental conditions for seed germination

Read the information below:

Many crops are sown in spring, when temperatures are more favorable.

Generally, seeds are sown after rain, or some water is poured into the ground before sowing to make the soil moist, but not too wet, otherwise the seeds will easily become moldy.

Before sowing, loosen the soil so that there is sufficient air in the soil.

making plans

1. Prepare about 30 seeds of a certain plant, four cans with tight lids, a small spoon, eight napkins, four labels and glue.

2. Write 1, 2, 3, and 4 on the four labels and stick them on the four cans respectively. Turn the four canning jars upside down and place two napkins in each jar.

3. Sprinkle a little water into bottles No. 2 and No. 3 respectively to make the paper inside moist (do not sprinkle too much water, and the water cannot be soaked in the water). Pour more water into bottle No. 4 so that the seeds are completely submerged in the water. There is no water in bottle 1.

4. Spread 7 to 8 seeds on the paper in bottles 1, 2, 3, and 4 respectively, and then tighten the bottle caps.

5. Place bottles 1, 2, and 4 in the cupboard, and bottle 3 in the refrigerator. Observe after a few days to see which of the seeds in the bottle has grown into a seedling.

think about it

1. Is it okay to put 1 seed in each bottle? Why? No, using 1 pill would be too accidental.

2. What kind of seeds should I choose first? ( )

A. alive b. dead c. structurally complete

D. Full E. Insect-bitten F. wizened

3. If it is known in advance that the conditions in bottle No. 2 are the most suitable for seed germination, is it still necessary to set up bottle No. 2 in this experiment? Why?

Is necessary. If bottle No. 2 is compared with bottle No. 1, bottle No. 3, and bottle No. 4, only one condition is different for each. Therefore, bottle No. 2 can be used as a control for bottle No. 1, bottle No. 3, and bottle No. 4 respectively to eliminate the influence of other conditions on the experimental results except the conditions under study.

Effect of light on seed germination

There are a few seeds such as yellow fig, tobacco and lettuce seeds that cannot germinate in the absence of light. Such seeds are called light-demanding seeds.

The seeds of some plants, such as bluegrass and evening primrose, germinate better under light conditions.

There are also some lily plants, onions, tomatoes, and datura whose seed germination is inhibited by light. Such seeds are called photophobic seeds.

Determine the germination rate of seeds

Germination rate = number of germinated seeds/total number of measured seeds × 100%

1. Sampling testing: When it is not possible to test the test objects one by one, a small number of individuals can be selected as samples from the total number of test objects. The test results of the samples can reflect the overall situation.

2. Try to avoid the influence of subjective factors.

Method steps

1. In a petri dish with a diameter of 10 cm, spread 2 to 4 layers of filter paper or gauze.

2. Add an appropriate amount of water to the petri dish to moisten the filter paper or gauze.

3. Arrange 100 seeds evenly in the petri dish.

Class summary

1. External conditions: suitable temperature, moisture, and air.

2. Own conditions: complete viable embryos, seeds with short storage time, and seeds that have passed the dormant period.

Class exercises

1. The external conditions for seed germination are ( )

A. moisture, air and temperature

B． Proper moisture, air and temperature

C. soil, air and water

D. Moisture, soil, air, sunlight and suitable temperature

2. Different parts of the following four seeds were damaged, which ones can germinate under suitable conditions ( )

A. ①;B. ①②③;

C. ④;D. ①②③④.

extracurricular extension

The best seeds

The largest seed: On the island nation of Seychelles in eastern Africa, a plant called the coconut tree grows. Its seeds are surprisingly large, up to 50 centimeters in diameter. From a distance, they look like large baskets hanging on the tree. Each "basket" weighs more than ten kilograms, and the largest one can weigh up to 30 kilograms, making it the largest seed in the world.

The shortest-lived seeds with the fastest germination rate: On the sand dunes and saline-alkali soil deserts in Xinjiang, Gansu, Qinghai and other regions of my country, a plant called "Haxaul ammodendron" grows. This is a kind of leaf.

A shrub or small tree reduced to a scale shape. During the year, Haloxylon ammodendron has a dormant period of several months. Once spring arrives, it wakes up when it rains and blooms small dates-like flowers. The seeds it produces are small, only 2.5 mm in diameter, and live only a few hours. It has the shortest lifespan among seeds. However, Haloxylon ammodendron has very strong vitality. As long as it gets a little water, it can quickly take root and sprout buds within two to three hours. So it won the title of fastest seed germination again.

The longest-lived seed: The longest-lived seed among seeds is the ancient lotus seed. In 1952, Chinese scientists unearthed some sleeping ancient lotus seeds in the peat layer of a dry pond near Paozi Village in Pulandian, Liaoning Province. Radiocarbon dating shows that they have been sleeping for about a thousand years. Scientists used a file to break the outer hard shell of the ancient lotus seeds, and then soaked them in water. Soon the ancient lotus seeds sprouted tender green seedlings, and then bloomed into fragrant and beautiful lotus flowers, and later also bore plump fruits.

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For more information about the PPT courseware "The Germination of Seeds and the Life of Angiosperms", please click the "Germination of Seeds ppt and the Life of Angiosperms" ppt tag.

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Update Time: 2024-10-22

This template belongs to biology courseware People's Education Edition seventh grade biology volume 1 industry PPT template

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