248 



734.-THE IMPORTANCE OF SELECTION IN VEGETA- 

 TIVE PROPAGATION. 



By W. R. Buttenshaw, M.A., B.Sc, Scientific Assistant on the Staff 

 of the Imperial Department of Agriculture. 



The question whether plants propagated by vegetative processes 

 could be improved or permanently modified by selection has often 

 been debated. In most of the processes of vegetative propagation the 

 new growth is merely an extension of the growth of the parent, and 

 consequently, the new plant produced in this way is much like its 

 parent. But since even among the different branches of one tree there 

 can be variation — sometimes sufficiently obviously to become a ' bud 

 spot ' — it is easy to imagine that cuttings produced from the same 

 parent may develop considerable variation. 



It is Avell recognized by gardeners that a new individual produced 

 from a cutting possesses certain characters which may or may not 

 differ from all other similar parts of the parent plant ; in other 

 words, hardly any two cuttings possess exactly the same characters ; 

 that it is also necessary to make use of careful selection when » 

 propagating plants by a vegetative process is therefore apparent. 



A very complete series of experiments has been carried out by 

 Messrs. B. T. Galloway and P. H. Dorset, of the Division of Vegetable 

 Pathology of the U. S. Department of Agriculture, to determine to 

 what extent violet plants could be improved in productiveness, 

 vigour, and ability to resist disease by a careful selection of cuttings. 

 A detailed account of these experiments is given by Mr. Herbert J. 

 Webber in the Year Book of the U. S. Department of Agriculture 

 for 1898 (pp. 373-5). He says : ' The results already show that 

 productiveness is remarkably increased, and they also clearly 

 demonstrate that violet cuttings can gradually be improved by a 

 <<ntinuous selection of the cuttings used in propagation and of the 

 plants from which these are obtained. The method consists in 

 selecting a number of the finest looking plants before they begin to 

 bloom, placing beside each a stake to which a blank tag is attached, 

 and carefully recording on each tag the daily pick of saleable 

 flowers from the plant, so that at the end of the season the number of 

 flowers produced by each plant is known. The cuttings for the en- 

 suing year are taken only from the plants producing the greatest 

 yields, and which are known from continual observation through the 

 -eason to be desirable in other ways. The pedigree cuttings thus ob- 

 tained are again subjected to selection, and only those which root well 

 and form good, vigorous, young plants are finally used. 



The following is an interesting example of the nature of the 

 results obtained : Five plants Avere selected from a plant which, in the 

 previous season, had yielded eighty-five flowers. Three out of these 

 five gave a much greater yield than the parent (127, 109, and 103), the 

 remaining two gave eighty-two and eighty-four, respectively. The 

 average yield of the five plants is thus 101, or sixteen flowers more 

 than that of the parent. 



