Genetic Diversity In Agriculture Essay, Research Paper

Genetic Diversity In Agriculture

Genetic variation is the raw material for the plant breeder, who must

often select from primitive and wild plants, including wild species, in search

of new genes. The appearance of new diseases, new pests, or new virulent forms

of disease causing organisms makes it imperative that the plant be preserved,

because it offers a potential for the presence of disease resistant genes not

present in cultivated varieties. Also, there are demands for new characters–

for example, high protein, improved nutritional factors, and fertility

restoration. As a result, plant breeders require a large and diverse gene pool

to meet ever changing needs.

A gene bank is a popular term that is used to describe repositories for

genes of living organisms. It is commonly used in the context of plant breeding

as I described above, but it also applies to the freezing and the storage of

animal sperm and embryos for use in animal husbandry or artificial insemination.

An understanding of crop origins and variations is necessary in

assembling genetic diversity in plant crops. In certain geographical areas

there has existed a rich source of variability in crop plants but the

encroachment of civilization has reduced the natural variability inherent in

primitive plant forms and related species of crop plants. Agricultural process,

as a result of new breeding programs, has reduced rather than increased crop

variability as improved cultivars, or varieties, are planted in wider and wider

areas and old cultivars, which may contain valuable genes, are lost. Crop

failures, which result in a smaller gene pool, have led to an increased

awareness of the need to preserve genetic diversity in plants. Efforts are

under way to increase collections of plant materials in various forms. Usually

these are preserved as seeds, but living plants, pollen, and cell cultures are

also used. In most gene banks, seeds are usually preserved under conditions of

low temperature and humidity. These collections must be periodically renewed by

growing the plants and producing new seeds. Increasing emphasis is also being

placed on preserving living collections of asexually propagated crops such as

species of fruits and nuts.

In the united states, germ plasm banks are handled in a state-federal

cooperative program. Internationally, a consortium of international, government,

and private organizations called the consultative group in in International

Agricultural research, (established in 1974), the International Board for Plant

Genetic Resources (IBPGR) to promote the activities of international plant

research centers that collect and preserve plant germ plasm.

Crop improvement is continuous. Professional plant breeders are

constantly working, through genetics, on the improvement of plants to meet

changing needs and standards. For example, with the introduction of mechanical

pickers for tomatoes, a tomato resistant to bruising by the machine was needed.

Such a variety was created by plant breeders.

Better, higher-yielding crop varieties have played an important part in

the increase in crop production per acre in the united states and some other

nations. Varieties of rice, cotton, vegetable-oil crops and sugar crops have

changed almost completely since the early nineteen fifties. By the late

nineteen sixties, most crop acreage in the united states was producing varieties

unknown to earlier decades. Best known of the improved crops are the many

varieties of hybrid corn that are planted on more than ninety-seven percent of

the total corn acreage in the united states. Government experimental

laboratories and commercial seed companies shared in the research and

development of the high-yield plant varieties that provide such superior

characteristics as resistance to cold, drought, diseases, and pests.

Improvements in livestock, such as more efficient use of feed, has added

greatly to the annual farm output. Such improvements are the result of breeding

and improved husbandry and veterinary techniques. Special purpose-stock has

been developed through selective breeding. It includes cattle that are able to

thrive in subtropical regions, hogs that yield lean bacon instead of lard, and

small and broad breasted turkeys.

Artificial insemination has become a major factor in cattle improvement.

In this technique the sperm of genetically superior bulls is used to inseminate

thousands of cows. In this way a herd can be upgraded significantly in a single

generation. However, some people feel that producing plants and animals that

conform to the needs mechanization and increased production has resulted in less

desirable farm products.

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