none great essay
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...