CHAPTER XXIII 
BUD SELECTION 
The efficacy and practicability of bud selection is a subject of con- 
siderable interest especially among horticulturists. During the past de- 
cade it has received more and more attention from investigators until now 
there are under way a number of comprehensive projects which, in future 
years, should furnish definite information concerning the more important 
vegetatively propagated crop plants. If it is determined that bud selec- 
tion is an effective method of improving certain varieties either by secur- 
ing increased yield or by the discovery of superior strains, its importance 
to horticulture will have been demonstrated. It will still remain for 
horticulturists to decide as to the practicability of introducing systematic 
bud selection in the commercial propagation of those plants in which it 
has been proved to be an effective method of improvement. The efficacy 
of bud selection depends upon the nature of bud variation. 
Bud Variation in Plants.—There are two kinds of bud variations, 
viz., modifications and mutations. Modifications are common to all 
plants and are easily detected even in dormant buds. On deciduous trees, 
for example, the buds formed during one season’s growth usually show 
considerable variation in size. Such variations do not necessarily repre- 
sent inherent differences between the buds. They are usually due to 
differences in the particular combinations of conditions which exist during 
development of the buds. Phytomers exhibit fluctuating modifications 
in all other characters as well as size in response to the varying con- 
ditions of nourishment, light, temperature and other elements of the 
environment. These modifications are not transmissible and selection 
of such bud variations alone could never change the average output of 
an orchard or establish an improved strain. 
Bud mutations, on the other hand, although comparatively rare, are 
of general occurrence and the new characters induced by them are trans- 
missible. Hence in considering the efficacy and practicability of bud 
selection in a horticultural variety the first thing to be determined is the 
nature and frequency of somatic mutations in that variety. There is 
only one way in which this question can be answered completely and 
definitely and that is by extensive tests of vegetatively propagated off- 
spring. Such tests must be made under controlled conditions especially 
as regards the nature of the rootstock on which the tested scions are pro- 
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