Chapter 4

General Characteristics of the Plant

=In the native home= of the tomato, in South America, the conditions of the soil, both as regards composition and mechanical condition, of the moisture both in soil and air, and those of temperature and sunlight, are throughout the growing season not only very favorable for rapid growth, but are uniformly and constantly so. Under such conditions there has been developed a plant which, while vigorous, tenacious of life, capable of rapid growth and enormously productive, is not at all hardy in the sense of ability to endure untoward conditions either in the character of soil, of water supply, or of temperature. A check in the development because of any unfavorable condition is never fully recovered from, but will inevitably affect the total quantity and quality of the fruit produced, even if subsequent favorable conditions result in the rapid and vigorous growth of the plant.

I know of an instance where two adjoining fields belonging to A and B were set with tomatoes, using plants started in the same hotbed from the same lot of seed. The soil was of equal natural fertility and each field received about the same quantity of manure, though that given A's was all well decomposed and worked into the soil, while that given B's was fresh and raw and simply plowed in. A's field was put into the best possible tilth before setting the plants, and the management of the plants and their cultivation were such as to secure unchecked growth from the time they were pricked out into cold-frames and set in the field until the crop was matured. As long as the plants would permit, the soil was cultivated every few days and kept in a state of perfect tilth.

B's field when the plants were set out was a mass of clods, as it had been plowed, when wet, some time before and never harrowed but once. The plants had been crowded forward as rapidly as possible in the cold-frame, and when set in the field were much higher than A's, but so soft that they were badly checked in transplanting and a great many of them died and had to be reset. The field received but one or two cultivations during the entire season. The growth of the plants in B's field was irregular and uneven instead of steady and uniform as in A's, and though some of the fruits were quite as large, they were not as uniform as A's while the yield per acre was not more than half as much nor the fruit of as good general quality. B had difficulty in disposing of his crop and often had to sell below the market, while A had no trouble in disposing of his at the highest prices for the day. B's crop was a financial loss, while A's returned a most satisfactory profit.

The key to the most successful culture of the tomato is the securing, from the start to finish, of an unchecked uniform growth, though it need not necessarily be a rapid one. The failure to do this is, in my opinion, the principal reason for the comparatively small yield usually obtained, which is very much less than it would be with better cultural management. The tomato under conditions which I have repeatedly found it practicable to secure, not only in small plantings but in large fields, has proved capable of producing from 1,000 to 1,200 or even more bushels to the acre, and the possible yield per plant is enormous.

As early as 1818 the Royal Horticultural Society of London reports the obtaining of over 40 pounds of fruit of marketable character from a single vine. An acre of such plants would give a yield of over 1,800 bushels of fruit, and many similar yields, and even greater ones, have been recorded for single plants. The yield commonly obtained, even in favorable locations, and by men who have grown tomatoes all their lives, is more often less than 200 bushels to the acre than more. The way to secure a better yield is to study carefully the nature and requirements of the plants and the adaptation of our cultural practice to them.

=Life habit of the plant.=--The tomato could be described as a short-lived perennial, but its span of life is somewhat variable. Under favorable conditions it will develop from starting seed to first ripe fruit in from 85 to 120 days of full sunshine with a constant day temperature of from 75 to 90 deg. F., and with one from 15 to 20 deg. F. lower at night. The plants will ordinarily continue in full fruit for about 50 to 60 days, after which they generally become so exhausted by excessive production of fruit and the effects of diseases to which they are usually subject that their root action and sap circulation become weaker and weaker until they die from starvation. From Philadelphia southward gardeners expect that spring set plants will thus exhaust themselves and die by late summer, and they sow seed in late spring or early summer for plants on which they depend for late summer and fall crops.

Under some conditions, particularly in the Gulf states and in California, tomato plants will not only grow to a much greater size than normal, but will continue to thrive and bear fruit for a longer time. Such a plant grown in Pasadena, Cal., was said to have been in constant bearing for over 10 months. Again, sometimes plants that have produced a full crop of fruits will start new sets of roots and leaves and produce a second and even a third crop, each, however, being produced on new branches and as a result of a fresh set of roots, those which produced the preceding crop having died and disappeared. The period of development, 85 to 120 days of full sunshine at a temperature above 75 deg. F., has been given. The full sunshine and high temperature are essential to such rapid development, and in so far as there is a lack of sunshine from clouds or shade, or the day temperature falls below 75 deg. F. the period will be lengthened, so that in the greater part of the United States the elapsed time between starting seed to ripened fruit is usually as much as from 120 to 150 days and often even longer.

=Characteristics of the root.=--The roots of the tomato plant, while abundant in number, are short and can only gather food and water from a limited area. A plant of garden bean, for instance, is not more than half the size of one of the tomato, but its roots extend through the soil to a greater distance, gather plant food from a greater bulk of soil, seem better able to search out and gather the particular food element which the plant needs than do those of the tomato. This characteristic of the latter plant makes the composition of the soil as to the proportion of easily available food elements of great importance. Tomato roots are also exceedingly tender and incapable of penetrating a hard and compact soil, so that the condition of the soil as to tilth is of greater importance with regard to tomatoes than with most garden vegetables.

Another characteristic of the tomato roots is that the period of their active life is short. When young they are capable of transmitting water and nutritive material very rapidly, but they soon become clogged and inefficient to such an extent as to result in the starvation and death of the plant. If the branches of such an exhausted plant be bent over and covered with earth they will frequently start new roots and produce a fresh crop of fruit, or if plants which have made a crop in the greenhouse be transplanted to the garden and cut back, a new set of roots will often develop and the plant will produce a second crop of fruit which, in amount, often equals or exceeds the first one. But such growths come only from new roots springing from the stem--never from an extension of the old root system.

=Characteristics of the stem and leaves.=--The growth of the stem, and leaves of the young tomato plant is very rapid and, the cellular structure coarse, loose and open. A young branch is easily broken and when this is done it shows scarcely any fibrous structure--simply a mass of coarse cellular matter which while capable, when young, of transmitting nutritive matter rapidly, soon becomes dogged and inert. This structure not only makes the active life of the leaves short, like that of the roots, but necessitates a fresh growth in order to continue the fruitfulness of the plant and renders the leaves very susceptible to injury from bacterial and fungous diseases. The rapid growth also necessitates an abundance of sunlight.

=Characteristics of the blossom.=--The inflorescence of the tomato is usually abundant and it is rare that a plant does not produce sufficient blooms for a full crop. The flowers are perfect as far as parts are concerned (Fig. 2) and in bright, sunny weather there is an abundance of pollen, but sunlight and warmth are essential to its maturing into a condition in which it can easily reach the stigma. The structure and development of the flower are such that while occasionally, particularly in healthy plants out of doors, the stigma becomes receptive and takes the pollen as it is pushed out through the stamen tube by the elongating style, it is more often pushed beyond them before the pollen matures, so that the pollen has to reach the stigma through some other means. Usually this is accomplished by the wind, either directly or through the motion of the plants.

Under glass it is generally necessary to assist the fertilization either directly by application or by motion of the plant, this latter only being effective in the middle of a bright sunny day. In the open ground in cold, damp weather the flowers often fail of fertilization, in which case they drop, and this is often the first indication of a failing of the crop on large, strong vines. I have known of many cases where the yield of fruit from large and seemingly very healthy vines was very light because continual rains prevented the pollenization of the flowers. Such failures, however, do not always come from a want of pollen but may result from an over or irregular supply of water either at the root or in the air, imperfectly balanced food supply, a sapping of the vitality of the plants when young, or from other causes. Insects rarely visit tomato flowers and are seldom the means of their fertilization.

=Characteristics of the fruit.=--The fruit of the original species from which our cultivated tomatoes have developed was doubtless a comparatively small two to many-celled berry, with comparatively dry central placenta and thin walls. In some species the cells were indicated by distinct sutures, forming a rough or corrugated fruit. It has improved under cultivation by increase in size, the material thickening of the cell walls, the development of greater juiciness and richer flavor and a decrease in the size and dryness of the placenta, as well as the breaking up of the cells by fleshy partitions resulting in the disappearance of the deep sutures and an improvement in the smoothness and beauty of the fruit. (Fig. 11.)

The quality of the fruit is largely dependent upon varietal differences, to be spoken of later, but it is also influenced by conditions of growth--such as the proportion of the nutritive elements found in the soil, the proper supply of moisture, the degree and uniformity of temperature and, most of all, the amount of sunlight. Sudden changes of temperature and moisture often result in cracks and fissures in the skin and flesh, which not only injure the appearance but affect the flavor of the fruit.