284 MUTATION AND PLANT BREEDING 



methodological shortcomings, the limited profit of the mutation 

 experiments on vegetatively propagated plants reported so far may 

 be explained by the fact that practically none of these mutation 

 experiments were planned or carried out as real plant breeding 

 projects. We have been lacking, and are still lacking, most of the 

 knowledge that would permit us to do so. We still know much too 

 little about the possibilities of the mutation method and still less 

 about its limitations. As long as the chief aim in plant breeding is 

 to produce basically new and, from many points of view, improved 

 varieties, I believe the cross breeding method will still be the back- 

 bone of the breeding program. At least this appears to be the situation 

 in fruit breeding. 



But it may well turn out that after 20 years' expensive and hard 

 work we are left with a variety that is nearly perfect in nine of ten 

 important characteristics. In order to get the fully acceptable variety 

 we might have needed 100,000 seedling trees instead of the 10,000 

 we could afford. Then, the mutation method might be the only way 

 of coming closer to our aim. 



At Alnarp, Sweden, they have had a new seedling clone of apple 

 under test and consideration for quite a few years. It has good quality 

 and good handling properties but lacks distinct appeal in appearance. 

 This year we were shown a beautiful, red spontaneous mutation of 

 this variety. Obviously the basis for releasing this new variety on 

 the market has changed completely with the detection of this red 

 sport. 



The organizers of this conference on mutation and plant breed- 

 ing have raised some questions: How fully has natural variation been 

 used? Should more emphasis be placed on its utilization? Will muta- 

 tion induction be the one method when this variation is exhausted? 

 Again these questions can not be given one answer. If I may limit 

 myself to fruit again, I think one can say that we have, in general, an 

 overwhelming natural variation, a variation so rich that I think it 

 could not possibly be exhausted within reasonable time. The difficulty 

 is to bring all the desired characters together into one and the same 

 variety; so generally, we would not have to irradiate material only in 

 order to get variation. 



But if we go to single fruit kinds or to single characters, the 

 variation is not always so rich nor so easily available. In black currants 



