gaul: induced mutants in seed-propagated species 207 



tioned (9, 14, 25, 28, 34, 48, 59, 65, 66, 71, 74, 75, 80, 82, 83, 94, 

 99, 100. 101, 104, 115, 12:5).- In the review by Prakken (83), there 

 is an appendix with a bibliography covering 789 titles and the 

 symposia, proceedings, handbooks, etc., are quoted separately. In 

 this connection the bibliography of Sparrow, et al. (102) also deserves 

 mention, since it covers nearly 2,600 titles, published between 1896 

 and 1955, on the effects of ionizing radiations on plants. 



In these numerous reviews on mutations and plant breeding 

 there is naturally much repetition. There is, therefore, no need to 

 present again a detailed picture and to quote every relevant publi- 

 cation. Instead, I shall try to give a critical evaluation of the pres- 

 ent stage and future possibilities of breeding with mutations. Cer- 

 tainly this review will sometimes be colored by my personal point 

 of view. 



First, the nature of induced mutations will be discussed, includ- 

 ing genetics and types of mutants. Then the methods of breeding 

 Avith mutations will be outlined. Thereafter, the problem of 

 induction and selection will be reviewed and some special hints 

 will be given. Finally, an attempt will be made to evaluate the 

 use of mutations in plant breeding. 



Nature of Induced Mutants 



In plants, the most comprehensive information about charac- 

 ters which can be modified by induced mutations has been obtained 

 in barley and snapdragon. Recently, however, the number of vital 

 mutations is rapidly increasing in many other species, e.g., toma- 

 toes (113, 114, 116), flax (60), soybeans (129), peanuts (41), peas 

 (35, 38, 68, 69, 126), bush beans (85), potatoes (52), and millet 

 (107, 108). There are also numerous reports on wheat and rice 

 (cf. symposium on the effects of ionizing radiations on seeds, 

 Karlsruhe, Germany, 1960, in press). Concerning barley there are 

 large collections of induced mutants in Sweden, Germany (Gaters- 

 leben, Halle, Koln-Vogelsang), and Belgium (Gembleaux), each 

 of them consisting of several hundred forms. 



The induced variability in the species mentioned is striking. 

 Practically all morphological and physiological characters can be 



-'See References, page 240. 



