Seed Breeding and Growing
The potentialities of every plant and its limitations are inherent,
fixed and immutable in the seed from which it is developed and are made
up of the balanced sum of the different tendencies it receives in
varying degree from each of its ancestors back for an indefinite number
of generations. A very slight difference in the character or the degree
of any one of the tendencies which go to make up this sum may make a
most material difference in the balance and so in the resulting
character of the plant produced. Different plants, even of the same
ancestry, vary greatly in prepotency or in the relative dominance of the
influence they have over descendants raised from seed produced by them.
In some cases all the plants raised from seed produced by a certain
plant will be essentially alike and closely resemble the seed-bearing
plant, while seed from another plant of the same parentage will develop
into plants differing from each other and seemingly more influenced by
some distant ancestor or by varying combinations of such influences than
of those of the plant which actually produced the seed from which they
were developed. Successful seed breeding can only be accomplished by
taking advantage of these principles of heredity and variation, and by a
wise use of them it is possible to produce seed which can be depended
upon to produce plants of any type possible to the species.
=The first essential for breeding= is to have a clear and exact
conception of precisely what, in all respects, the type shall be and
then the securing of seed which has come from plants of that exact
character for the greatest possible number of generations, carefully
avoiding the introduction by cross-pollination of tendencies from plants
differing in any degree from the desired type. Secondly, seed should be
used from plants which have been proven to produce seed, which will
develop into plants like themselves or are strongly prepotent. A
practical way to accomplish this in the tomato is as follows:
By experiment and observation form a very clear conception of precisely
the type of plant and fruits which is best suited to your needs. This
may be done by the study of available descriptions of sorts, by
conference with those who have had experience in your own or similar
climatic and soil conditions and in raising fruit for the same purposes
and, best of all, by trials of samples of different sorts and stocks on
your own grounds. Having formed such a conception, write out the
clearest possible description of exactly what you want and the ideal
plant you are aiming at, stating as fully and minutely as possible every
desirable quality and also those to be avoided. I consider not only the
formation of an exact ideal, but the writing out of a most minute and
exact description of precisely what in every particular the ideal plant
should be and the rigid adherence to that exact ideal in selection, as
the most important elements of successful seed breeding. Without it one
is certain to vary from year to year in the type selected and in just so
far as he does this, even if it be toward what might be called
improvements or in regard to an unimportant quality, he undermines all
his work and makes it impossible to establish a strain which can be
relied upon to produce an exact type.
With this description in hand, search out one or more plants which seem
the nearest to the ideal. In doing this it should be kept in mind that
the character of the seed is determined by the plant rather than by the
individual fruit. Therefore, a plant whose fruit is most uniformly of
the desired type should be chosen over one having a small proportion of
its fruits of very perfect type, the others being different and
variable. Save seed from one or more fruits from each of the selected
plants, keeping that from each fruit, or at least each plant, separate.
Give it a number and make a record of how nearly, in each particular,
the plant and fruit of each number come to the desired ideal. I regard
the saving of each lot separately and recording its characters as very
important, even when all have been selected to and come equally close to
precisely the same ideal. Quite often the seed of one plant will produce
plants precisely like it, while that of another, equal or superior, will
produce plants of which no two are alike and none like that which
produced the seed, so that often the mixing of seed from different
plants of the same general type, and seemingly of equal quality,
prevents the establishment of a uniform type.
The next year from 10 to 100 plants raised from each lot are set in
blocks and labeled. As they develop the blocks are studied and compared
with the original description of the desired type and that of each plant
from which seed was saved, and the block selected in which all the
plants come the nearest to the desired type, and which show the least
variation. From it plants are selected in the same way and to the same
type as the previous year. It is better to make selections from such a
block than to take the most superior plants from all of the blocks, or
from one which produced but one or but a few superlative ones, the rest
being variable.
It is also well to consider the relative importance of different
qualities in connection with the degree to which the different lots
approach the ideal in these respects. Such a course of selection
intelligently and carefully carried out will give, in from three to five
years, strains of seed greatly superior and better adapted to one's own
conditions than any which it is possible to purchase. A single or but a
very few selections may be made each year, and the superior value of the
seed of the remainder of the seed blocks for use in the field will be
far more than the cost of the whole work.
=Growing and saving commercial seed.=--The ideal way is for the seedsman
to grow and select seed as described above and give this stock seed to
farmers who plant in fields and cultivate it, much as is recommended for
canning, and save seed from the entire crop, the pulp being thrown away.
Only a few pickings are necessary and the seed is separated by machines
worked by horse power at small cost, often not exceeding 10 cents a
pound. They secure from 75 to 250 pounds per acre, according to the
variety and crop, and the seedsmen pay them 40 cents to $1 a pound for
it. Some of our more careful seedsmen produce all the seed they use in
this way; others buy of professional seed growers, who use more or less
carefully grown stock seed. In other cases when the fruit is fully ripe
it is gathered, and the seeds, pulp and skins, are separated by
machinery; the seed is sold to seedsmen, the pulp made into catsup, and
only the skins are thrown away. Still others get their supply by washing
out and saving the seed from the waste of canneries. Such seed is just
as good as seed saved _from the same grade of tomatoes_ in any other
way, but the fruit used by the canneries is, usually, a mixture of
different crops and grades, and even of different varieties, and
consequently the seed is mixed and entirely lacking in uniformity and
distinctness of type.
Generally from 5 to 20 per cent. of the plants produced by seed as
commonly grown either by the farmer himself or the seedsmen, though they
may be alike in more conspicuous characteristics, will show varietal
differences of such importance as to affect more or less materially the
value of the plant for the conditions and the purposes for which it is
grown. In a book like this it is useless to attempt to give long
varietal descriptions even of the sorts commonly listed by seedsmen,
since such descriptions would be more a statement of what the writer
thought seed of that variety should be rather than of what one would be
likely to receive under that name.