Seed Purity And Vitality
Seeds produce plants. The difference between a large and a small yield
may depend upon the kind of plants we raise, and the kind of plant in
turn is dependent upon the seeds that we sow.
Two things are important in the selection of seeds--purity and vitality.
Seeds should be _pure_; that is, when sown they should produce no other
plant than the one that we wish to raise. They should be able to grow.
The ability of a seed to grow is termed its _vitality_. Good seed should
be nearly or quite pure and should possess high vitality. The vitality
of seeds is expressed as a per cent; for example, if 97 seeds out of 100
germinate, or sprout, the vitality is said to be 97. The older the seed
the less is its vitality, except in a few rare instances in which seeds
cannot germinate under two or three years.
Cucumber seeds may show 90 per cent vitality when they are one year old,
75 per cent when two years old, and 70 per cent when three years
old--the per cent of vitality diminishing with increase of years. The
average length of life of the seeds of cultivated plants is short: for
example, the tomato lives four years; corn, two years; the onion, two
years; the radish, five years. The cucumber seed may retain life after
ten years; but the seeds of this plant too lose their vitality with an
increase in years.
It is important when buying seeds to test them for purity and vitality.
Dealers who are not honest often sell old seeds, although they know that
seeds decrease in value with age. Sometimes, however, to cloak
dishonesty they mix some new seeds with the old, or bleach old and
yellow seeds in order to make them resemble fresh ones.
It is important, therefore, that all seeds bought of dealers should be
thoroughly examined and tested; for if they do not grow, we not only pay
for that which is useless but we are also in great danger of producing
so few plants in our fields that we shall not get full use of the land,
and thus we may suffer a more serious loss than merely paying for a few
dead seeds. It will therefore be both interesting and profitable to
learn how to test the vitality of seeds.
To test vitality plant one hundred seeds in a pot of earth or in damp
sand, or place them between moist pieces of flannel, and take care to
keep them moist and warm. Count those that germinate and thus determine
the percentage of vitality. Germinating between flannel is much quicker
than planting in earth. Care should be used to keep mice away from
germinating seeds. (See Fig. 61.)
Consisting of two soup plates, some sand, and a piece of cloth]
Sometimes the appearance of a package will show whether the seed has
been kept in stock a long time. It is, however, much more difficult to
find out whether the seeds are pure. You can of course easily
distinguish seeds that differ much from those you wish to plant, but
often certain weed seeds are so nearly like certain crop seeds as not to
be easily recognized by the eye. Thus the dodder or "love vine," which
so often ruins the clover crop, has seeds closely resembling clover
seeds. The chess, or cheat, has seeds so nearly like oats that only a
close observer can tell them apart. However, if you watch the seeds that
you buy, and study the appearance of crop seeds, you may become expert
in recognizing those that have no place in your planting.
One case is reported in which a seed-dealer intentionally allowed an
impurity of 30 per cent to remain in the crop seeds, and this impurity
was mainly of weed seeds. There were 450,000 of one kind and 288,000 of
another in each pound of seed. Think of planting weeds at that rate!
Sometimes three fourths of the seeds you buy are weed seeds.
In purchasing seeds the only safe plan is to buy of dealers whose
reputation can be relied upon.
It not seldom happens that seeds, like corn, are stored in open cribs or
barns before the moisture is entirely dried out of the seeds. Such seeds
are liable to be frozen during a severe winter, and of course if this
happens they will not sprout the following spring. The only way to tell
whether such seeds have been killed is to test samples of them for
vitality. Testing is easy; replanting is costly and often results in a
Tube 1 represents one pound of redtop grass as bought; Tube 2, amount of
pure redtop grass seeds in Tube 1; Tube 3, amount of chaff and dirt in
Tube 1; Tube 4, amount of weed seeds in Tube 1; Tube 5, amount of total
waste in Tube 1; Tube 6, amount of pure germinable seeds in Tube 1]
Examine seeds both for vitality and purity. Write for farmers'
bulletins on both these subjects. What would be the loss to a
farmer who planted a ten-acre clover field with seeds that were 80
per cent bad? Can you recognize the seeds of the principal
cultivated plants? Germinate some beet seeds. What per cent comes
up? Can you explain? Collect for your school as many kinds of wild
and cultivated seeds as you can.
Let each pupil grow an apple tree this year and attempt to make it the
best in his neighborhood. In your attempt suppose you try the following
plan. In the fall take the seed of an apple--a crab-apple is good--and
keep it in a cool place during the winter. The simplest way to do this
is to bury it in damp sand. In the spring plant it in a rich, loose
Great care must be taken of the young shoot as soon as it appears above
the ground. You want to make it grow as tall and as straight as possible
during this first year of its life, hence you should give it rich soil
and protect it from animals. Before the ground freezes in the fall take
up the young tree with the soil that was around it and keep it all
winter in a cool, damp place.
Now when spring comes it will not do to set out the carefully tended
tree, for an apple tree from seed will not be a tree like its parent,
but will tend to resemble a more distant ancestor. The distant ancestor
that the young apple tree is most likely to take after is the wild
apple, which is small, sour, and otherwise far inferior to the fruit we
wish to grow. It makes little difference, therefore, what kind of apple
seed we plant, since in any event we cannot be sure that the tree grown
from it will bear fruit worth having unless we force it to do so.