Alejandro G. 9.2
Mr. Jared
Science
Artificial Plant propagation
Introduction
Plants just like humans reproduce, the most common being through sexual activities. Sexual
plant propagation is one method for plants to keep their species going. Propagating sexually
always uses two pools of genetic code to determine the characteristics of the new plant. The
characteristics are then determined by the genes passed on from both plants; this may create a
stronger or weaker plant. Nevertheless the new plant will have either kept the same genetic
code, or will have slight changes or alterations. Such as color, form and many other mutations
that may occur. Plants that use sexual propagation go through a long process to produce an
offspring. Two plants of the same species must give interact sexually and one has to have
been successfully fertilized. A seed, whether in a fruit or a seed alone, is the result of a
successful fertilized ovary. These seeds or seed must then find its way into a suitable
environment to sprout.
Specific plants though have a completely different method of keeping their species going.
Plants like mosses and ferns are asexual. Asexual meaning that the plant is able to reproduce
without having to go through the long process sexual propagation requires. Unlike sexual
propagation, there is only one gene pool, the father plants’ gene pool. Asexual propagation
doesn’t rely on any other plants for reproduction, meaning that it will become a clone of the
father plant, down to the last gene. This immediately cuts out the possibility of having
variations of an asexual plant. Asexual propagation does not require seeds of any kind; the
father plant can use a range of methods to create another plant in its image. This has its
advantages and disadvantages, creating clones means it will act as the father plant. If it is a
typical farm plant and it does not give a good harvest, clones of the father plant will do the
exact same. On the upside, if it does give a good harvest, so will all the other clones.
Traits like durability to weather and immunity to diseases are also passed down. This may be
a large disadvantage to the plant. If environmental changes such as increased humidity and
less sunlight are introduced into the plants habitat and they are not suited towards it may lead
to disaster for the plant. Since all the plants have the same genetic material as the father plant,
they have a very slim chance of all surviving. Simply because if one plant is negatively
affected, all the others can too, meaning plants in that area may as well be wiped out.
Diseases pose a threat towards asexual plants as well in the same way the environmental
changes can.
Propagation by definition is to naturally reproduce. Artificial propagation though is when
humans initiate propagation through the reproductive properties of asexual plants. Humans
have used artificial propagation for many reasons. One of them being quality control, using
asexual properties of a plant allows it to have the exact same characteristics as its father.
Since the cloned plants’ genes won’t change, you are able to clone the cloned plant and
multiply the number of handpicked plants.
Methods
Cutting is by far one of the most popular choices for artificial propagation.
“Softwood, or green tip cuttings, are by far the most popular form of propagation, and is used
most frequently in the propagation of herbs, vegetables, annual and perennial flowers, as well
as many houseplants. Softwood cuttings are most commonly taken in the spring, however the
advent of hobby greenhouses, cold frames and high powered indoor grow lights, have
expanded the opportunities for growers to root softwood cuttings virtually anytime of the
year.”(plantpropagation.com)
Farmers use this method to plant multiply their vegetables and control the quality of their
crops. If a farmer is fond of a particular plant, either because of its health or a certain positive
characteristic, using cutting propagation he is able to clone the plant. The clone will have the
exact same attributes as the father plant had. This leads to better crop quality and if the
certain plant has a higher output of fruit or vegetables, this will also increase the harvest sizes
the farmer will be able to make.
This also gives serious gardeners a huge advantage. Annual and perennial plants both are
very tough plants to get a hold of their seeds; this can be overcome through cutting. Since you
can “clone” the plants there is no need to wait for seeds. As a result, fragile or plants that
don’t give off much seeds will have others of their species in case that the father plant dies.
There is unfortunately a downside to this method. In comparison to buying large amounts of
seeds, the father plant, not matter how strong, will only be able to provide a limited amount
of buds to use for cutting before you use up the entire plant. You are able to wait until the
plant heals and regenerates but this takes a lot of time and would be inconvenient.
Layering is a very effective method to artificially propagate
any overgrown shrubs, or simply clone a plant you like. This
method is best done with semi or fully hardwood plants as you
will need to wound the plant. A small hole is dug near the base
of the plant, and one of the lower branches is then pulled down.
It is then bent into a U so that it enters the hole and leaves out
the other end, wounding the plant on the branch that was pulled
down will stimulate roots to grow.
Air layering, another method of layering also uses wounding the plant, just with deeper and
more precise cuts. This method cuts a ring of bark off where roots are wanted to form. This
area is then wrapped with a moisture retaining material to stimulate growth. This method
requires cutting the bark in a way that you get past the phloem but not so deep as to cut into
the xylem. This causes roots to sprout from the wound then cutting off the section of the
wound. The upper part of the plant with developed roots can then be planted normally and the
bottom part can be replanted to sprout more branches.
Tissue culture is another artificial propagation method. Tiny cuts of a leaf of the plant being
reproduced are taken and then sterilized. The best way to sterilize the leaf cuttings is by
immersing the tissue in a solution of sodium hypochlorite (laundry bleach) and rinsing in
sterile distilled water. To optimize the number of plants from this method, a complicated but
very effective method exists.
“1. The explant is placed in a sterilized liquid medium on a shaking machine. This medium
contains water, minerals, vitamins, sugar (energy for growth by respiration), and dilute auxin
(usually indole-butyric acid). The auxin stimulates the cells of the explant to divide rapidly to
form callus. The callus is broken up by the shaking action. Thus the liquid medium becomes
loaded with small callus pieces.
2. The callus pieces are now spread across a sterile solid medium. The medium contains
water, minerals, vitamins, sugar, and cytokinins. The medium is solidified into a gel by
adding a small amount of agar. The container is kept under light. The combination of
cytokinin and light causes shoots to be initiated on each callus piece.
3. The shoots are moved onto a solid medium that contains water, minerals, and agar.
Depending on the species, there may also be some auxin in the medium. The auxin from the
leaves on the shoots (or in combination with auxin from the medium) cause root initiation.
4. The plants can be moved to soil and slowly eased from humid conditions to successively
drier conditions. Ultimately the plants can be moved to field conditions.” (plantphys.info)
Factors
Economic
Large companies or local farmers both have techniques they use to better their harvest every year. It
can either be types of compost, fertilizers and many other variables. Plants though can only grow at
certain rates, no matter how much growth stimulants are given. The health of the plant is also decided
purely on the two plants that created its seed. All these factors can bring down the quality and quantity
of a crop. If a plant grows slower than average, its offspring may as well. If it produces little fruit, its
offspring may do the same.
All this can be quite a fatal gamble for the planter. This is where artificial propagation kicks in. Plants
can be cloned through various methods, through cuttings, tissue culture, air layering and many more.
It becomes immensely convenient for farmers to use any of these methods to bring their crops to the
best possible state. Farmers like to provide good quality food, but when planting seeds, you place the
fate of your future plants’ characteristics to chance. When a farmer finds himself with a perfect plant,
he is able to clone it to have its genes (with favorably characteristics) passed on to the next generation
of plants. This ensures that quality is at its best since it has the exact same genetic coding as its father
plant.
Economic wise, the farmer or company will be able to mass clone a favorable plant through mass
tissue culture. The amount of plants of good quality produced means the producers will be able to
provide a constant product with guaranteed quality. The middle man buying from the producer will at
some point if they run a good business begin to buy in bulk from the farmer because of the constant
quality. This would keep money flowing in the local economy and keeping the farmer in business.
A small downside to this is supply and demand. The producers have to have an efficient and quick
enough method to provide the middle man with large supplies of the products. Another obstacle
producers will have to face is the amount of manpower involved. Each time a plant is artificially
propagated, it has to be tended for and cared for to see it grows well. One man can look after only so
many plants. And if artificially propagating in large numbers is the main concern, hiring more people
may cut profits down significantly.
Environmental
Plantago erosa var.fengdouensis (also known as “floral panda”) a perennial small herb, once
had a population of 27 throughout the world in 2007. This rare plant was saved from
extinction by Wang Yong a doctor Wuhan Botanical Garden. It was found on an isle in the
Yangtze River on april 2001, and to protect the plants from the floods of the river. They were
moved from the isle to the botanical garden in hope that they preserve the rare species. From
then on to 2007, the population only decreased. The reason for this is the size of seeds the
plant produced through natural propagation. The seeds the “floral pandas” produced were
simply so big that it made it hard to propagate through wind or water. Since the population
was decreasing at such a rate that it would eventually fall into extinction, the wuhan botanical
garden decided that the most practical way to save the plant was through artificial
propagation. Since then flora panda has been predicted to reach numbers of up to 1000 by
2012.
This incident showed just how crucial artificial propagation is in saving a certain plant from
the brink of extinction. Plants in general have to reproduce, some through natural or asexual
methods, but nevertheless they reproduce. Each plant will have specific methods either
through seeds or pollen etc, at some point in time though they will struggle to continue the
species. This can either be caused by environmental reasons, such as the floral panda
encountered, or because of human interference. Plants aren’t able to evolve in under a few
months or weeks, meaning they can come very close to extinction. When time is of the
essence and the population is dwindling, artificial propagation gives biologist and botanists a
huge advantage. This contributes towards the environment in many ways. The ecosystem
being the fragile system it is, has a balance it holds with all living things in its perimeter. The
floral panda hasn’t had any specific documentation of any organisms depending on it. Even
with that fact, if the shrub was to go extinct, more pressure would have been added towards
the ecosystem in order to provide for other living organisms. Artificial propagation proved its
usefulness in saving this species, it was so successful that the plant was later reintroduced to
the outside in 2008.
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