The Wisconsin tobacco reporter. (Edgerton, Wis.) 1877-1950, 1910-03-04

BY JAMES JOHNSON, ASSISTANT IN HOR-
TICULTURE.
The Improvement of tobacco through
the medium of seed is known as tobac-
co breeding. The valuable results OBJ
tanned by plant breeders with other
crops have made the tobacco growers
desirous of obtaining similar results.
Tobacco breeding, however, is beset
with greater difficulties than those ac-
companying other lines of plant breed
| ing. This is due largely to the extreme
| responsiveness of the tobacco plant to
environmental conditions, to the impor-
tant processes which must follow the
harvest, and to the length of time
which they consume. The underlying
principle of tobacco breeding is, of
course, the production of types more
suitable to the region in which it is
grown, and is more valuable from the
standpoint of the manufacturer: A
great field of work, however, lies close
ly interviewer with this from the ex-
perimenters standpoint. That is, the
study of the laws of variation and
heredity, which govern the production
of these new types of plants, and it is
this work which largely makes the
work of plant breeding fascinating.
The methods for the improvement of
tobacco through breeding may be class
flied under three heads:
/. The production of new strains by
means Of the selection and protection
of individual plants with variety.
2. BY the crossing of individual
plants from the strains thus produced.
3. By the crossing of plants of diff
ferent varieties.
It is well known that grower who
has become skilled in the selection of
seed plants, obtains by continuous Sc
lection and isolation from other fields,
after number of years, type of leaf
quite different from the variety he
started with. This type, if it is made
sufficiently pure by continuous selec-
tion, becomes a strain Of the original
variety. In rare cases he obtains a
sufficiently uniform and valuable type
as to be worthy of Introduction among
other growers. The production of
strain in this manner is slow and la
borious task, due largely to the chang
ing ideals of the grower and the effect
of interpollination.
The process of selection of tobacco
then is to go through the plantation
Just previous to the opening of the first
flowers, and select those plants which
show some apparent advantage over
their neighbors in such characteristics
as earliness, size of plant, number of
leavGs1 and general conformation OF the
plant. This selection is accomplished
by what is known as ''bagging." 1t
consists in placing twelve-pound ma
nilla bag over the flower buds of the
plant in order to assure the self-fertil-
ization of the seed. 1t is possible to
select in this way from one acre of to-
bacco, 1000 or more plants which are
apparently better than their neighbors.
At the time of ripening, however. the
great majority of these plants show
only average characteristics, and are
therefore discarded in the following
more detailed selections. Some of the
plants selected at first, however, may
show some apparent variation worthy
of further investigation. Such plants
are labeled, given a number, and their
characteristics described under this
number in record book. The seed
from these self-fertilized tobacco plants
are saved separately from each other.
The following season this seed can
be sown in different plats and the plants
transplanted into separate rows IN the
field. Here they are allowed to grow
and mature under exactly the same
conditions, and from time to time the
progress of the progeny from each par
ent are compared. In many cases the
progeny of different parents are very
much alike, and we must assume that
any characteristics in which they differ
01x, I.7a 70 0t1I a
iations,'' but if the experimenter deals
with sufficient number OF individual
parent plants, he will in many cases
obtain marked differences between the
offspring Of the different parents. In
many cases these differences will be
uniform throughout the offspring OF
each individual, showing the parent
plant bred true from self-fertlllzed
seed. When such cases are obtained,
we have reason to assume that Iney
are mutations, or that we nave $50
lated new strain. A second and third
trial are usually necessary to determine
whether we have isolated new strain,
or merely a hybrid which will not breed
true to seed thereafter. At the same
time, of course, it must be judged as to.
it's commercial value both IN the held,
shed, and in the fermenting case. BY
this method, then, we are not compar-
ing Individual plants, but the offspring
of individual plants, which is the only
true method of selection.
The second method which may be
practiced for the improvement Of to-
bacco is that of crossing individual
strains within the variety. BY the pre-
ceding method it is possible to get new
and pure strains of tobacco. But 1t is
often the case that where one predoml-
nant desirable characteristic is obtained
in type of tobacco, as for instance,
the number of leaves, the other char
acteristics are only average. 1t now,
another strain has desirable charac-
teristic, as for instance, shape OF leaves,
it is possible to cross these strains by
hand pollination, and obtain seed which
represents these two strains. The pos
sibilities are that this seed may produce
some plants which have both the desir-
able characteristics of number and
shape of leaves. This will then be a
hybrid between the two, and more val
liable than either parent, provided we
can make this plant come true to seed