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.)

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 short crop.

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

How A Plant Feeds From The Air