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Document Type

Thesis - University Access Only

Award Date

1989

Degree Name

Master of Science (MS)

Department / School

Biology

First Advisor

P. L. Spinkski

Abstract

Variability is the basis of all crop improvement and breeding programs. There are many difficulties encountered when using a traditional breeding system. First, there is a limited source of new variations. Since spontaneous mutations occur infrequently in most species sources of variation are restricted to the discovery of new genotypes and the genetic combinations produced through breeding programs. Secondly, sexual systems can be difficult to manipulate. There are· environmental problems, incompatible time of anthesis, and internal problems with pollination, fertilization, or embryo development. If a crop improvement system which does not involve sexual structures is chosen new genetic combinations are limited and difficult to obtain. Finally, these systems are often very time-consuming. After selecting a new variant, years of crossing and backcrossing may be required before achieving the desired genotype. Mutation breeding, inducing mutations using chemical, radiation, or physical means could be a new source of variability. Mutation breeding works well with vegetatively propagated plants. Because of their normally heterozygous nature, mutations, whether spontaneous or induced, are commonly exhibited in the treated individual. Since Saintpaulia (African violet) shoots appear to develop from one cell, or occasionally from a few cells, an in vitro mutation system could potentially produce large numbers of nonchimeric mutants. In three months Bilkey and Hildebrandt obtained as many as 20,000 plantlets from one leaf cutting using tissue culture. Using traditional leaf cuttings commonly only five or six plants are produced. Not only is there the potential for increased shoot production and increased variability but African violets could be propagated with increased cost efficiency. In conjunction with a decreased space requirement for stock plants, flowering could be achieved in less time. There are several advantages associated with using petiole tissue rather than leaf tissue. There is greater ease in sterilization, as well as ease in sectioning the tissue for culture. Finally, if working with limited amounts of tissue which have not yet proven easily cultured the leaf cutting can be used as a backup. The production of new cultivars and the savings in space and time invested in an African violet crop could plausibly offset the initial investment in tissue culture facilities and equipment. The objectives of this project were: 1) to determine which BA concentration would result in the optimal growth of shoots, 2) to evaluate the relative productivity of regions along the petiole length, 3) to determine the time and origin of shoot initiation, and 4) to induce variation using colchicine treatment of petiole sections in vitro.

Library of Congress Subject Headings

Saintpaulia -- Micropropagation
African violets -- Micropropagation
Saintpaulia
African violets

Format

application/pdf

Number of Pages

61

Publisher

South Dakota State University

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