Document Type

Dissertation - Open Access

Award Date


Degree Name

Doctor of Philosophy (PhD)

Department / School

Plant Science


In order to determine the nature of the inheritance of colchicine-induced mutations on a mutant derived by colchicine treatment from the sorghum variety Experimental 3, a true-breeding mutant P15 was crossed with its full sib P6 and F2 and F3 progenies were studied. Estimates of the number of genes which affected the expression of six different characters that had been mutated by colchicine treatment were obtained. The characters studied were days to heading, plant height, width of leaf, number of tillers, seedling base colot, and awn development. The estimated number of mutated genes for each of the six characters is listed below. Days to heading: 5 or 6 Plant height: 3 Width of leaf: at least 1 Number of tillers: at least 1 Seedling base color: 1 Awn development: 1 In order to compare the colchioine induced mutation for strong-awns with an irradiation-induced mutation for the same character, the colchicine mutant P15 was crossed with an awned segregate obtained after irradiation of Experimental 3. The F1 plants were all strong-awned and their progeny did not exhibit transgressive segregation. The colchicine mutant was also crossed with 39 -30 –S, a strong-awned ancestor of Experimental 3. Again the F1 plants were all strong-awned and no transgressive aggregation occurred. This evidence indicates that the gene for awn development may be the same in the three lines of material. Colchine treatment of a plant of the variety Experimental # caused at least twelve (in all probability more) immediate mutations for the characters studied. It is concluded on the basis of this and earlier work that these mutations are inherited in a manner indicating that they are of the nature of point mutations.

Library of Congress Subject Headings



Includes bibliographical references



Number of Pages



South Dakota State University