In the spring comes the great seed-planting time on the farm, in the home garden and in the school garden. Many times the questions will be asked: Why didn't those seeds come up? How shall I plant seeds so as to help them sprout easily and grow into strong plants? To answer these questions, perform a few experiments with seeds, and thus find out what conditions are necessary for seeds to sprout, or germinate. For these experiments you will need a few teacups, glass tumblers or tin cans, such as tomato cans or baking-powder cans; a few plates, either of tin or crockery; some wide-mouth bottles that will hold about half a pint, such as pickle, olive, or yeast bottles or druggists' wide-mouth prescription bottles; and a few pieces of cloth. Also seeds of corn, garden peas and beans.

Experiment.-Put seeds of corn, garden peas, and beans (about a handful of each) to soak in bottles or tumblers of water. Next day, two hours earlier in the day, put a duplicate lot of seeds to soak. When this second lot of seeds has soaked two hours, you will have two lots of soaked seeds of each kind, one of which has soaked twenty-four hours and the other two hours. Now take these seeds from the water and dry the surplus water from them by gently patting or rubbing a few at a time in the folds of a piece of cloth, taking care not to break the skin or outer coating of the seed. Place them in dry bottles, putting in enough to cover the bottoms of the bottles about three seeds deep; cork the bottles. If you cannot find corks, tie paper over the mouths of the bottles. Label the bottles "Seeds soaked 24 hours," "Seeds soaked 2 hours," and let them stand in a warm place several days. If there is danger of freezing at night, the bottles of seeds may be kept in the kitchen or living room where it is warm, until they sprout.

Observe the seeds from day to day. The seeds that soaked twenty-four hours will sprout readily (Fig. 36), while most, if not all, of those that soaked only two hours will not sprout. Why is this? It is because the two-hour soaked seeds do not receive sufficient moisture to carry on the process of sprouting.

Our experiment teaches us that seeds will not sprout until they receive enough moisture to soak them through and through.

This also teaches that when we plant seeds we must so prepare the soil for them and so plant them that they will be able to get sufficient moisture to sprout.

Experiment.-Soak some beans, peas or corn, twenty-four hours; carefully dry them with a cloth. In one half-pint bottle place enough of them to cover the bottom of the bottle two or three seeds deep; mark this bottle A. Fill another bottle two-thirds full of them and mark the bottle B (Fig. 37). Cork the bottles and let them stand for several days. Also let some seeds remain soaking in the water. The few seeds in bottle A will sprout, while, the larger number in bottle B will not sprout, or will produce only very short sprouts. Why do not the seeds sprout easily in the bottle which is more than half full?

To answer this question try the following experiment:

Experiment.-Carefully loosen the cork in bottle B (the bottle containing poorly sprouted seeds), light a match, remove the cork from the bottle and introduce the lighted match. The match will stop burning as soon as it is held in the bottle, because there is no fresh air in the bottle to keep the match burning. Test bottle A in the same way. What has become of the fresh air that was in the bottles when the seeds were put in them? The seeds have taken something from it and have left bad air in its place; they need fresh air to help them sprout, but they have not sprouted so well in bottle B because there was not fresh air enough for so many seeds. The seeds in the water do not sprout because there is not enough air in the water. Now try another experiment.

FIG. 36.

To show that seeds need water for germination. The beans in bottle A were soaked 2 hours, those in bottle B were soaked 24 hours. They were then removed from the water and put into dry bottles.ToList

FIG. 37.

To show that seeds need air for germination. The beans in both bottles were soaked 24 hours, and then were put into dry bottles Bottle A contained sufficient air to start the few seeds. Bottle B had not enough. The water in the tumbler C did not contain sufficient air for germination. See experiment, page 72.ToList

FIG. 38.

To show that seeds need air for germination. Corn planted in puddled clay in tumbler A could not get sufficent air for sprouting. The moist sand in tumbler B admitted sufficient air for germination.ToList

Experiment.-Fill some tumblers or teacups or tin cans with wet sand and others with clay that has been wet and then thoroughly stirred till it is about the consistency of cake batter or fresh mixed mortar. Take a tumbler of the wet sand and one of the wet clay and plant two or three kernels of corn in each, pressing the kernels down one-half or three-quarters of an inch below the surface; cover the seeds and carefully smooth the surface. In other tumblers plant peas, beans, and other seeds. Cover the tumblers with saucers, or pieces of glass or board to keep the soil from drying. Watch them for several days. If the clay tends to dry and crack, moisten it, fill the cracks and smooth the surface. The seeds in the sand will sprout but those in the clay will not (see Fig. 38). Why is this? Water fills the small spaces between the particles of clay and shuts out the fresh air which is necessary for the sprouting of the seeds.

This teaches us that when we plant seeds we must so prepare the soil, and so plant the seeds that they will get enough fresh air to enable them to sprout, or, in other words, the soil must be well ventilated.

Experiment.-Plant seeds of corn and beans in each of two tumblers; set one out of doors in a cold place and keep the other in a warm place in the house. The seeds kept in the house will sprout quickly but those outside in the cold will not sprout at all. This shows us that seeds will not sprout without heat.

If the weather is warm place one of the tumblers in a refrigerator.

Why don't we plant corn in December?

Why not plant melons in January?

Why not plant cotton in November?

The seeds of farm crops may be divided into two classes according to the temperatures at which they will germinate or sprout readily and can be safely planted.

Class A. Those seeds that will germinate or sprout at an average temperature of forty-five degrees in the shade, or at about the time the peach and plum trees blossom:

Barley Beet Parsley

Oats Carrot Parsnip

Rye Cabbage Onion

Wheat Cauliflower Pea

Red Clover Endive Radish

Crimson Clover Kale Turnip

Grasses Lettuce Spinach

These can be planted with safety in the spring as soon as the ground can be prepared, and some of them, if planted in the fall, live through the winter.

Class B. Those seeds that will germinate or sprout at an average temperature of sixty degrees in the shade, or when the apple trees blossom:

Alfalfa Soy Bean Squash

Cow Pea Pole Bean Cucumber

Corn String Bean Pumpkin

Cotton Melon Tomato

Egg Plant Okra Pepper

We are now ready to answer the question: What conditions are necessary for seeds to sprout or germinate? These conditions are:

The presence of enough moisture to keep the seed thoroughly soaked.

The presence of fresh air.

The presence of more or less heat.

This teaches us that when we plant seeds in the window box or in the garden or on the farm we must so prepare the soil and so plant the seeds that they will be able to obtain sufficient moisture, heat, and air for sprouting. The moisture must be film water, for if it is free water or capillary water filling the soil pores, there can be no ventilation and, therefore, no sprouting.

SEED TESTING

In a previous experiment (page 73) the seeds planted in the wet clay did not sprout (see Fig. 38). In answer to the question, "Why is this?" some will say the seeds were bad. It often happens on the farm that the seeds do not sprout well and the farmer accuses the seedsman of selling him poor seed, but does not think that he himself may be the cause of the failure by not putting the seeds under the proper conditions for sprouting. How can we tell whether or not our seeds will sprout if properly planted? We can test them by putting a number of seeds from each package under proper conditions of moisture, heat and air, as follows:

For large seeds take two plates (see Fig. 39) and a piece of cloth as wide as the bottom of the plate and twice as long. Count out fifty or one hundred seeds from a package, wet the cloth and wring it out. Place one end of the cloth on the plate, place the seeds on the cloth and fold the other end of the cloth over them. On a slip of paper mark the number of seeds and date, and place on the edge of the plate. Now cover the whole with another plate, or with a pane of glass to keep from drying. Set the plate of seeds in a warm room and examine occasionally for several days. If the cloth tends to dry, moisten it from time to time. As the seeds sprout take them out and keep a record of them. Or leave them in the plate and after four or five days count those that have sprouted. This will give the proportion of good seeds in the packages.

For small seeds fold the cloth first and place the seeds on top of it.

Another good tester for small seeds is made by running about an inch of freshly mixed plaster of Paris into a small dish or pan and moulding flat cavities in the surface by setting bottles into it. The dish or pan and bottles should be slightly greased to prevent the plaster sticking to them. When the cast has hardened it should be turned out of the mould and set in a large dish or pan. One hundred small seeds are then counted out and put into one of the cavities, others are put into the other cavities. Water is then poured into the pan till it rises half way up the side of the plaster cast or porous saucer. The whole thing is then covered to keep in the moisture (Fig. 40).

Another method is to get boxes of finely pulverized sand or soil and carefully plant in it fifty or one hundred seeds of each kind to be tested. Then by counting those that come up, the proportion of good seeds can easily be found.

In every case the testers should be kept at a temperature of about seventy degrees or about that of the living room.

HOW THE SEEDS COME UP

Plant a few seeds of corn, beans and garden peas in boxes or tumblers each day for several days in succession. Then put seeds of corn, beans and garden peas to soak. After these have soaked a few hours, examine them to find out how the seed is constructed. Note first the general shape of the seeds and the scar (Fig. 41-4) on one side as in the bean or pea and at one end or on one edge in the corn. This scar, also called hilum, is where the seed was attached to the seed vessel.

Cut into the bean and pea, they will be found to be protected by a tough skin or coat. Within this the contents of the seed are divided into two bodies of equal size lying close to each other and called seed leaves or cotyledons (Fig. 41-5). Between them near one end or one side will be found a pair of very small white leaves and a little round pointed projection. The part bearing the tiny leaves was formerly, and is sometimes now, called the plumule, but is generally called the epicotyl, because it grows above or upon the cotyledons. The round pointed projection was formerly called the radicle, but is now spoken of as the hypocotyl, because it grows below or under the cotyledons.

Examine a dry kernel of corn and notice that on one side there is a slight oval-shaped depression (Fig. 41-1). Now take a soaked kernel and cut it in two pieces making the cut lengthwise from the top of the kernel through the centre of the oval depression and examine the cut surface. A more or less triangular-shaped body will be found on the concave side of the kernel (see Figs. 41-2 and 41-3). This is the one cotyledon of the corn. Besides this will be found quite a mass of starchy material packed in the coverings of the kernel and in close contact with one side of the cotyledon. This is sometimes called the endosperm.

Within the cotyledon will be found a little growing shoot pointed toward the top of the kernel. This is the epicotyl, and another growing tip pointed toward the lower end of the kernel; this is the hypocotyl or the part which penetrates the soil and forms roots.

Now examine the seeds that were planted in succession. Some will be just starting a growing point down into the soil. Some of them have probably come up and others are at intermediate stages.

How did the bean get up?

After sending down a root the hypocotyl began to develop into a strong stem which crooked itself until it reached the surface of the soil and then pulled the cotyledons or seed-leaves after it (Fig. 42). These turn green and after a time shrink and fall off.

The pea cotyledons were left down in the soil, the epicotyl alone pushing up to the surface. The corn pushed a slender growing point to the surface leaving the cotyledon and endosperm behind in the soil but still attached to the little plant (Fig. 43).

USE OF COTYLEDONS AND ENDOSPERM

Experiment.-Plant some beans in a pot or box of soil and as soon as they come up cut the seed-leaves from some of them and watch their growth for several days. It will soon be seen that the plants on which the seed-leaves were left increase in size much more rapidly than those from which the seed-leaves were removed (see Figs. 43 and 44). Sprout some corn in the seed tester. When the seedlings are two or three inches long, get a wide-mouthed bottle or a tumbler of water and a piece of pasteboard large enough to cover the top. Cut a slit about an eighth of an inch wide from the margin to the centre of the pasteboard disk. Take one of the seedlings, insert it in the slit, with the kernel under the pasteboard so that it just touches the water. Take another seedling of the same size, carefully remove the kernel from it without injuring the root, and place this seedling in the slit beside the first one (Fig. 45). Watch the growth of these two seedlings for a few days. Repeat this with sprouted peas. In each case it will be found that the removal of the seed-leaves or the kernel checks the growth of the seedling. Therefore, it must be that the seed-leaves which appear above ground, as in the case of the bean, or the kernel of the corn which remains below the surface of the soil, furnish the little plant with food until its roots have grown strong enough to take sufficient food from the soil.

FIG. 39.

A seed-tester, consisting of two plates and a moist cloth.ToList

FIG. 40.-A SEED-TESTER.

A plaster cast with cavities in the surface for small seeds.ToList

FIG. 41.

1. Corn-kernel showing depression at z. 2. Section of same after soaking. 3. Corn-kernel after germination has begun. The seed-coat a has been partly removed. 4. Bean showing scar or hilum at h. 5. The same, split open. 6. Bean with one cotyledon removed, after sprouting had begun. a, Seed-coat; b, cotyledon; c, epicotyl; d, hypocotyl; e, endosperm.

(Drawings by M.E. Feltham.)ToList

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