Plant-breeding; comments on the experiments of Nilsson and Burbank . Fig. 23. Stiff-branched Svalof oats. with many of the existing types and, in the end, perhaps,with all of them. In this way, the production of one reallynew unit will tend to double the number of the existingtypes, and, in tlie cases of many ,L:ardeii llowers, where such NILSSONS DISCOVERY 83 crosses have been artificially made, the fact that one newcharacter by this means yields a very large number of newvarieties is universallv known, and one of the most ordin-. Fig. 24. Svalof oats with spreading branches. arv means of pro
Plant-breeding; comments on the experiments of Nilsson and Burbank . Fig. 23. Stiff-branched Svalof oats. with many of the existing types and, in the end, perhaps,with all of them. In this way, the production of one reallynew unit will tend to double the number of the existingtypes, and, in tlie cases of many ,L:ardeii llowers, where such NILSSONS DISCOVERY 83 crosses have been artificially made, the fact that one newcharacter by this means yields a very large number of newvarieties is universallv known, and one of the most ordin-. Fig. 24. Svalof oats with spreading branches. arv means of producing novelties. Tvloreover, if one newunit may double the number of the separate types, a secondnew unit may tend t() increase it fourfold, a third eightfold,and so on. From this calculation it mav l)e seen that even 84 PLANT-BREEDING a thousind separate types of coml:»inations do not requiremore than ten mutually independent changes. Or, in otherwords, the wide range or \-ariability observed on grain licldsmay be the effect of the production of a few novelties, com-bined with a sufficient degree of intercrossing. Hence, itfollows that one real change of some character in a year, oreven in ten or more years, must be considered as wholly suf-ficient for an explanation of the observed variability. If wetake it that these changes ai)pear suddenly, or in other words,are mutations, then an ordinary degree of mutability, suchas is ([uite common with horticultural plants, seems to beall that is re([uired to explain the numerous
Size: 1396px × 1790px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpublisherchicagoopencourtpu
