The First Book of Farming. C. L. Goodrich
the plant from the soil without tearing it free from the roots.
It is also on account of this very thorough reaching out through the soil that the roots are able to supply the plant with sufficient moisture and food.
We have doubtless observed that most of these roots are very slender and many very delicate. How did they manage to reach out into the soil so far from the plant? Or where does the root grow in length? To answer this question I will ask you to perform the following experiment:
Experiment.—Place some kernels of corn or other large seeds on a plate between the folds of a piece of wet cloth. Cover with a pane of glass or another plate. Keep the cloth moist till the seeds sprout and the young plants have roots two or three inches long. Now have at hand a plate, two pieces of glass, 4 by 6 inches, a piece of white cloth about 4 by 8 inches, a spool of dark thread, and two burnt matches, or small slivers of wood. A shallow tin pan may be used in place of the plate. Lay one pane of glass on the plate, letting one end rest in the bottom of the plate and the other on the opposite edge of the plate. At one end of the piece of cloth cut two slits on opposite sides about an inch down from the end and reaching nearly to the middle. Wet the cloth and spread it on the glass. Take one of the sprouted seeds, lay it on the cloth, tie pieces of thread around the main root at intervals of one-quarter inch from tip to seed. Tie carefully, so that the root will not be injured. Place the second pane of glass over the roots, letting the edge come just below the seed, slipping in the slivers of wood to prevent the glass crushing the roots. Wrap the two flaps of the cloth about the seed. Pour some water in the plate and leave for development. (Fig. 12.) A day or two of waiting will show conclusively that the lengthening takes place at the tip only, or just back of the tip. Is this fact of any value to the farmer? Yes. The soft tender root tips will force their way through a mellow soil with greater ease and rapidity than through a hard soil, and the more rapid the root growth the more rapid the development of the plant. This teaches us again the lesson of deep, thorough breaking and pulverizing of the soil before the crop is planted.
We have learned that the roots grow out into the soil in search of moisture and food, which they absorb for the use of the plant. How does the root take in moisture and food? Many people think that there are little mouths at the tips of the roots, and that the food and moisture are taken in through them. This is not so, for examination with the most powerful microscopes fails to discover any such mouths. Sprout seeds of radish, turnip or cabbage, or other seeds, on dark cloth, placed in plates and kept moist. Notice the fuzz or mass of root hairs near the ends of the tender roots of the seedlings (Fig. 13). Plant similar seed in sand or soil, and when they have started to grow pull them up and notice how difficult it is to remove all of the sand or dirt from the roots. This is because the delicate root hairs cling so closely to the soil grains. The root hairs are absorbing moisture laden with plant food from the surface of the soil particles. The root hairs are found only near the root tips. As the root grows older, its surface becomes tougher and harder, and the hairs die, while new ones appear on the new growth just back of the root tips, which are constantly reaching out after moisture and food. The moisture gets into the root hairs by a process called osmose. The following interesting experiment will give you an idea of this process or force of osmose.
FIG. 10.
A plow stopped in the furrow, to show what it does to the roots of plants when used for after-cultivation. Notice the point of the plow under the roots.ToList
FIG. 11.
A corn-plant ten days after planting the seed. To show how quickly the roots reach out into the soil. Some of the roots were over 18 inches long.ToList
Experiment.—Procure a wide-mouthed bottle, an egg, a glass tube about three inches long and a quarter-inch in diameter, a candle, and a piece of wire a little longer than the tube. Remove a part of the shell from the large end of the egg without breaking the skin beneath. This is easily done by gently tapping the shell with the handle of a pocket-knife until it is full of small cracks, and then, with the blade of the knife, picking off the small pieces. In this way remove the shell from the space about the size of a nickel. Remove the shell from the small end of the egg over a space about as large as the end of the glass tube. Next, from the lower end of the candle cut a piece about one-half inch long. Bore a hole in this just the size of the glass tube. Now soften one end of the piece of candle with the hole in it and stick it on to the small end of the egg so that the hole in the candle comes over the hole in the egg. Heat the wire, and with it solder the piece of candle more firmly to the egg, making a water-tight joint. Place the glass tube in the hole in the piece of candle, pushing it down till it touches the egg. Then, with the heated wire, solder the tube firmly in place. Now run the wire down the tube and break the skin of the egg just under the end of the tube. Fill the bottle with water till it overflows, and set the egg on the bottle, the large end in contact with the water (Fig. 14). In an hour or so the contents of the egg will be seen rising in the glass tube. This happens because the water is making its way by osmose into the egg through the skin, which has no openings, so far as can be discovered. If the bottle is kept supplied with water as fast as it is taken up by the egg, almost the entire contents of the egg will be forced out of the tube. In this way water in which plant food is dissolved enters the slender root hairs and rises through the plant.
Experiment.—This process of osmose may also be shown as follows (Fig. 15): Remove the shell from the large end of an egg without breaking the skin, break a hole in the small end of the egg and empty out the contents of the egg; rinse the shell with water. Fill a wide-mouthed bottle with water colored with a few drops of red ink. Fill the egg-shell partly full of clear water and set it on the bottle of colored water. Colored water will gradually pass through the membrane of the egg and color the water in the shell. Prepare another egg in the same way, but put colored water in the shell and clear water in the bottle. The colored water in the shell will pass through the skin and color the water in the bottle. Sugar or salt may be used in place of the red ink, and their presence after passing through the membrane may be detected by taste.
CONDITIONS NECESSARY FOR ROOT GROWTH
We have learned some of the things that the roots do for plants and a little about how the work is done. The next thing to find out is:
What conditions are necessary for the root to do its work?
We know that a part of the work of the root is to penetrate the soil and hold the plant firmly in place. Therefore, it needs a firm soil.
We know that the part of the root which penetrates the soil is tender and easily injured. Therefore, for rapid growth the root needs a mellow soil.
We know that part of the work of the root is to take moisture from the soil. Therefore, it needs a moist soil.
We know that part of the work of the root is to take food from the soil. Therefore, it needs a soil well supplied with plant food.
We know that roots stop their work in cold weather. Therefore, they need a warm soil.
Another condition needed by roots we will find out by experiment.
Experiment.—Take two wide-mouthed clear glass bottles (Fig. 16); fill one nearly full of water from the well or hydrant; fill the other bottle nearly full of water that has been boiled and cooled;