This is the VOA Special English Agriculture Report.
These days, if we hear about two different plants being combined, the first
thing we think of might is modern biotechnology. But the low-technology process
of grafting remains an extremely important form of genetic engineering in
agriculture.
Many kinds of plants are grown not from seeds but from
pieces cut from existing plants. Farmers cut branches or buds, young growths,
from one plant and place them on a related kind of plant.
The branch or bud that is grafted
is called a scion [pronounced SY-uhn]. The plant that accepts the graft is
called the root stock.
Over time, the parts from the two plants grow together. The grafted plant
begins to produce the leaves and fruit of the scion, not the root stock.
A graft can be cut in several ways. A cleft graft, for example, requires a
scion with several buds on it. The bottom of the scion is cut in the shape of
the letter V. A place is cut in the root stock to accept the scion.
The scion is then securely placed into the cut on the root stock. Material
called a growth medium is put on the joint to keep it wet and help the growth.
Grafting can join scions with desirable qualities to root stock that is
strong and resists disease and insects. Smaller trees can be grafted with older
scions.
The United States Environmental Protection Agency says producing stronger
plants by grafting can reduce the need to use pesticides.
Agriculture could not exist as we know it without grafting. Many fruits and
nuts have been improved through this method. Some common fruit trees such as
sweet cherries and McIntosh apples have to be grafted.
Bing cherries, for example, are one of the most popular kinds of cherries.
But a Bing cherry tree is not grown from seed. Branches that produce Bing
cherries must be grafted onto root stock. All sweet cherries on the market are
grown this way.
And then there are seedless fruits like navel oranges and seedless
watermelons. Have you ever wondered how farmers grow them? Through grafting.
The grapefruit tree is another plant that depends on grafting to reproduce.
Grapes, apples, pears and also flowers can be improved through grafting.
In an age of high-technology agriculture, grafting still holds an important
place.
graft : to unite (a shoot or bud) with a growing
plant（嫁接）
點(diǎn)擊進(jìn)入更多VOA慢速
（來源:VOA
英語點(diǎn)津姍姍編輯）
