Don't exceed the outline in the first semester of grade one.

Seed germination rate generally refers to the percentage of seeds that germinate within l0 days after soaking and absorbing enough water under suitable conditions. It is the main basis to determine the quality and practical value of seeds, and to determine the sowing amount and seed dosage. Different seeds often have great differences in germination ability, and the same seed germination ability will also change. The germination ability of seeds is influenced by many factors, such as cultivation conditions, maturity, climate at harvest, water content of seeds during storage, storage conditions and storage time. If germination is uncertain, blind soaking, accelerating germination or direct sowing may lead to uneven emergence, insufficient number of seedlings or even no emergence at all, which not only wastes food, but also delays the season and causes passive production. Careful measurement of seed germination ability, careful calculation of seed dosage and planned production can not only avoid the above situation, but also improve yield. The common method to measure the germination rate of rice seeds is: firstly, randomly take out a small number of seeds from the seed containers of the tested varieties, put them in different positions at the top, middle, bottom, edge and center, remove impurities, soak them at the water temperature of 20-30℃ for 24 hours, and then divide 65,438+000 seeds into 4 groups and arrange them evenly in 4 Petri dishes covered with filter paper or papyrus. Under the environmental conditions of 30-35℃, the number of germination was recorded daily from the beginning of the experiment to 10 day, and finally the germination rate was calculated in groups. The average value of the four groups is the germination rate of the seed, and the calculation formula is: germination rate (%) = number of germinated seeds * 100/ total number of tested seeds.

Second, the conditions required for seed germination

The necessary conditions for seed germination are water, temperature, oxygen and sunlight.

Water is the primary condition for seed germination. Seeds must absorb enough water to accelerate the physiological function of seeds, promote the activity of enzymes, facilitate the dissolution of stored nutrients and the growth of embryos, thus promoting the germination of seeds.

Temperature is also one of the necessary conditions for seed germination. After absorbing enough water and oxygen, seeds need a certain temperature to germinate, and temperature is the energy source of seed germination. The function of temperature is to promote the activity of enzyme, and the optimum temperature for seed germination is also the optimum temperature for enzyme. In addition, temperature also directly affects the speed of water absorption and respiration of seeds. In a certain temperature range, the higher the temperature, the faster the seeds absorb water, the stronger the respiration and the faster the germination.

Seed germination test needs a lot of oxygen. When the seeds germinate, the respiration is enhanced, such as the lack of oxygen respiration, which makes the seeds unsuitable for germination.

Different crops have different reactions to light when they germinate. Most crop seeds (such as corn, cereal and other seeds) are not strict with light requirements. These seeds can germinate in light or darkness. Some seeds with good light, such as tobacco seeds and celery seeds, can germinate or promote germination only under light conditions. There are also some seeds that avoid light, such as black grass seeds, which will inhibit germination when there is light. In germination test, these seeds should be treated in the dark.

Third, the process of seed germination.

When the seeds germinate. First of all, we should absorb water. Nutrients in cotyledons or endosperm are transported to radicle, embryo and hypocotyl. Subsequently, the radicle develops, breaks through the seed coat and forms roots. The hypocotyl is elongated and the embryo develops into stems and leaves.

I have also done two experiments of seed germination, which are made of mung beans. In the first experiment, all the seeds dried up, because I always forgot to add water to them, and finally the first experiment ended in failure. Then immediately ushered in the second experiment, this time I remembered the last lesson, and my seeds finally sprouted.

& lt2> No flower is smarter than orchids.

Orchids can force bees or butterflies

In a specific form or time.

Pollen spreads in the way it wants.

In this respect, orchids are unparalleled.

Darwin at the beginning

Pollination of orchids.

Described their heroic behavior all their lives.

Now it's the IQ of orchids

It is still an interesting topic.

Orchids have high IQ for three reasons.

First, orchids have wandering seeds.

Orchidaceae plants don't have big fruits.

But it's hidden in a small container

Tens of thousands, hundreds of thousands or even millions of seeds.

These seeds are as fine as dust.

The length is generally 0.05 to 6 mm.

The width is 0.0 1 to 0.9 mm.

Many are thinner than human hair.

Inside the seed coat.

There are many small rooms filled with air.

Further reduce the weight.

Lightweight figure

As soon as the seed leaves the pod, it can get the upper hand.

This free shuttle bus

Drift far away from the mother plant

In order to resist the harsh environment

The seed is surrounded by a dense layer of cells.

It can prevent moisture from penetrating quickly.

So after getting off the wind bus,

Seeds can also be made of flowing animal fur.

Go further.

Although orchid seeds have already practiced superb lightness skill.

But I didn't get enough internal force.

They are too small.

So there is no room for endosperm.

Or cotyledons, which store nutrients.

So the seeds can only die.

Their display mode is related to fungi.

When the seeds germinate

By digesting the hyphae of fungi

Provide nutrition for your own growth.

This symbiotic relationship

It exists in almost all orchids.

Different kinds of orchids

Have a special preference for different kinds of fungi.

Even at different growth stages of orchids

Have different tastes.

Secondly, orchids have the ability to survive in danger.

When the seedlings of Orchidaceae plants

Finally, after germination with the help of fungi,

They have no time to breathe.

I was forced to get involved in the next round of survival challenges.

Orchidaceae plants mostly grow in other plants.

A place where few people set foot.

Such as tree trunks and barren soil.

In this way, it can be reduced.

Competition with other plants

Strive for more space for their own development.

But there are advantages and disadvantages.

Most of these environments lack plant growth.

The required humus and moisture

At this time, orchids and fungi

Join hands against the ring.

Fungi in the eyes of most plants

Is a deadly killer.

But it is different from the roots of orchids.

Perfect combination.

Known as mycorrhiza

Fungi growing between cells of orchid roots

Can absorb minerals from the environment.

The roots of orchids

Then there are some fungal hyphae

Decompose and digest to get the required nutrition.

Although the mycorrhiza of Orchidaceae plants is very developed

Almost all of them are stuck in the surface or shallow soil.

Can't be like other plants

Dig the roots deep underground to find water.

In order to live in a humid environment

Most orchids

They settled down on the shady hillside.

However, there is too much water in the soil.

It will also make mycorrhiza rot and necrosis.

This is really a tricky thing.

It is necessary to have enough water.

It also needs a good drainage habitat.

Therefore,

The only way is to bring your own reservoir.

Orchid reservoir is really strange.

Dendritic stem of Dendrobium

Spindle-shaped pseudobulb of Lycoris radiata.

The round tuber of taro orchid.

It is a good tool for storing water.

It is with these special roots.

Orchidaceae only exists in other plants.

Forbidden zone

Opened up his own kingdom.

In addition, the deception of orchids is at its peak.

If humans are the smartest animals,

That orchid must be the cleverest plant.

Most orchids are typical insect-borne flowers.

In other words, people who need animal pollinators

Put the pollen of flowers

The stigma of another flower.

bloom and bear fruit—yield positive results

But there is no such thing as a free lunch

Pollinators certainly don't want to

Free pollination for plants.

So many insect-borne plants

In order to hire pollinators

Made a lot of nectar and pollen.

Paid a huge price for pollination.

Most of the pollen enters the pollinator's stomach.

Orchids don't want to give pollinators

Provide such benefits

So they took great pains to find another way.

Pollen of most orchids

Pack into pieces

Don't give pollinators a chance to eat.

Pollen block with sticky disc pollen block handle

Together, they form the orchid family.

Male reproductive structure

This structure will stick to the pollinator as a whole.

Pass them on to the stigma of the next flower.

In this way, it is avoided.

Waste caused by being eaten.

Although no pollen is provided

Some orchids are still given to pollinators.

Provide benefits such as nectar or wax.

However, the orchid family has 1/3 members.

Is a real miser.

While enjoying the pollination service

Do not give pollinators any benefits.

They exploit employees in various ways.

It's not worse than Zhou's peeling.

Some orchids dress themselves up.

Like a flower with nectar

For example, orchids in the national orchid

Generally speaking, petals have dark spots.

It's like telling pollinators

Here is nectar, please pollinate me.

This place is called the honey guide.

Although orchids are empty

The lips were covered with black spots.

It is equivalent to playing the sign of honey here.

If there is a poor bee who can't tell the truth from the false.

Get into the orchid and find honey to eat.

You can only pollinate orchids for free.

Besides fake honey, orchids also give off.

A sweet taste that can spread over a long distance

If orchids are in full bloom,

The whole mountain is full of its fragrance.

Color, fragrance and taste are all available.

Naturally, some bees can't stand the temptation.

It's almost at the door

Some orchids are also used.

Insects like their children and are eager to cheat them.

The master in this field is Paphiopedilum longipetalum.

The pollinator of Paphiopedilum longipetalum is Syrphidae.

As the name implies, it is a fly that eats aphids.

In fact, adults of syrphids are just like bees.

Feed on nectar and pollen

Only some syrphidae larvae.

Eating aphids

Pollinators of Paphiopedilum longipetalum

The black belt of Syrphidae is one of them.

Syrphid larva

No ability to move over long distances.

Black belt of female syrphidae

Eggs are usually laid near aphids.

This syrphid larva

There is plenty of food at birth.

Paphiopedilum longipetalum in simulated breeding ground

I have done enough articles.

Its petal base

Black chestnut has many small protrusions.

These small protrusions are simulating a large number of aphids.

such

Female syrphids eager to lay eggs

Will be attracted by these fake aphids.

Fall into the trap carefully designed by Paphiopedilum longipetalum

When laying eggs

Orchid pollination is complete.

After the female syrphid lays eggs,

Will be evacuated from Orchid Station soon.

They might think

Find a place for the children to live.

I didn't know that the children were going to face bad luck.

After hatching from the egg

Larvae will suffer from lack of food.

And starve to death for no reason.

The authorities are really clever in their calculations.

This is a mistake in your life.

Some orchids are good at using insects.

Opportunities to find a spouse

They disguised themselves as female insects.

When male insects

When trying to mate with these females,

Pollination began.

Eupatorium in Europe

The attainments in this respect are even more extreme.

Their flowers have different colors and shapes.

No different from a female wasp.

There is even a painting by Mei Lan.

Will attract many wasps.

Not only that, they also exude attraction.

The smell of male wasps

After mass spectrometry analysis

The main components of these smells

Sex pheromones of female wasps

Looks exactly the same.

Even more surprising is that.

Different kinds of Phalaenopsis

You can rely on different shapes of flowers and smells.

Attract different kinds of wasps

And the orchid itself.

Is an excellent self-pollinator

Orchids with superb deception

Sometimes you worry.

Without those pollinators

Deception turned into empty talk.

To prevent

You cannot make a silk purse out of a sow's ear.

Some orchids are prepared.

No insect pollination

It can also blossom and bear fruit and reproduce.

In 2006, researchers in China discovered that

Hedyotis macrophylla can pollinate itself.

A pollen block handle connecting the pollen block and the sticky tray.

Guest porter

After Hedyotis macrophylla was opened,

Its pollen stalk will bend inward 360 degrees.

Eventually, the pollen at the top

Accurately delivered into the stigma cavity to complete fertilization.

Sperm-egg combination

It is an important stage of seed production.

In order to produce seeds, most orchids

Trying to send pollen to the stigma

The hairy bird foot orchid is dismissive of this.

Do not accept pollen

Embryo sac in ovary of Cymbidium ciliatum

Can be directly developed into seeds without fertilization

Through these extraordinary measures

Cymbidium hybridum and Cymbidium ciliatum

Such orchids

Can be used without pollinators.

Smooth replication

You can also put the cost of attracting insects

preserve

Invest more resources in seed production.

gain two ends at once

People can cite more examples.

To prove the wisdom of orchids

Every flower and plant

I have gained useful experience for myself.

When they appear on the earth,

There is no pattern to follow.

They have to get all this from themselves.

They are ambitious.

When the forms of existence are constantly displayed

Spread all over the world and occupy your own territory.

When humans found them,

They are already at home on earth.

Maybe after human death.

They will live for a long time.

& lt3> Biodiversity helps to clean the air we breathe and the water we drink. Biodiversity provides us with food. Biodiversity provides raw materials for building our house. Biodiversity has also brought us endless beauty in nature. Exaggeration? Not at all. It is biodiversity that sustains life on this planet. By absorbing carbon dioxide, a greenhouse gas, we can breathe air. Only through the changes of soil, microorganism and meteorology can we get rid of the dirt in water, can we drink water. All species-plants, animals and microorganisms-make up life. However, we have threatened many species, which constitute the magnificent and irreplaceable life support system of the earth. But why? We are deeply suspicious of this. Are some unknown species really that important? If the species in this world are reduced to cattle, sheep, chickens, pigs and enough animals in zoos, can't we live comfortably? Why do we have to pay attention to some special pigeons or salamanders or a small plant that lives in a distant swamp? What does it matter to us that they are extinct? After all, we have many other pigeons, many other lizards and many plant residues. In fact, even if some species are extinct, many species still exist. So far, we have identified 65.438+0.75 billion species, but scientists believe that there are actually 65.438+0.3 billion or 65.438+0 billion species on the earth. So what should we worry about? Importantly, all these species are interrelated with other species, just as we depend on plants and animals for food. Along the food chain, we also depend on the animals and plants we eat-another group of plants and animals. If a particular species loses its habitat or can no longer find its usual food, it will become extinct. The whole food web (not just the food chain) will be broken. And repair is a very difficult or even impossible thing. When we destroy a species in the network of life, the whole network will collapse. The extinction of enough species will shake the whole structure on earth that makes life possible. Finally, what we do to biodiversity will eventually hurt ourselves. A large number of species and the ecosystem we live in provide us with food, medicine and building materials. Biodiversity has brought us jobs. Biodiversity is like money in the bank. We are robbing the bank. Stop the robbery