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The muskmelon (Cucumis melo reticulatus), usually known as cantaloupe, is a coarse, trailing vine of tropical origin and consequently requires a fairly long, warm season for its development. Although not as easily grown as most vegetables, it is a popular one, and is to be found in many home gardens. It is grown commercially for home use over a wide range of territory in the United States, and there are also numerous large regions producing it commercially where muskmelons are grown on an extensive scale. In fact the industry is fairly well distributed over the entire United States. The crop is usually grown from seed planted in the field but, when produced in regions with a short growing season, a common practice is to start the plants in greenhouses, hotbeds, or cold frames. 10
Seed of the Rocky Ford Muskmelon was planted at Norman, Okla., Apr. 19. The hills were placed 6 feet apart in rows 7 feet distant. Several seeds were planted in each hill but when the plants were well established they were thinned to one plant per hill by cutting out the weaker plants. Cultivation was shallow so that the roots would not be disturbed.
Early Development.--The plants grew slowly through May and by the twenty-fourth the vines wore but 2 feet long with two to three short branches only 3 to 6 inches in length. Flower buds were appearing.
Like various other cucurbits, in their early development they had strong but rather shallow taproots and numerous strong, horizontally spreading laterals. The taproots were rather thick (5 millimeters near the soil surface but tapering to 2 millimeters at a depth of 1 foot) and extended to a depth of about 18 inches. Usually about 4 roots 3 millimeters in diameter ran horizontally 18 to 36 inches. This, it may be noted, exceeded the spread of tops. Both the taproot and its branches were white in color, somewhat fleshy, and had a characteristic spongy appearance. The longest laterals occurred at a depth of 4 to 12 inches. From 12 to 14 horizontal laterals 5 to 16 inches long were also found (Fig. 84). Shorter rootlets were so abundant that every inch of the taproot, except just below the soil surface and again near the tip, had 6 to 12 branches. Branching on all but the shorter laterals occurred at the rate of 4 to 6 rootlets per inch. Many of these on the older roots reached lengths of 2 to 3 inches but at this stage of development none were rebranched.
Fig. 84.--Rocky Ford muskmelon 35 days old.
Half-grown Plants.--Root development was again examined June 11. The vines had grown vigorously since the last examination and some were 9 feet long. On plants of average size the taproots were 7 millimeters in diameter and penetrated downward, usually with kinks and curves, to a depth of about 25 inches. No change in the general root habit had taken place. About 7 of the horizontal laterals, however, had spread very widely (maximum, 57 inches). The others were by no means so well developed. Within a distance of 18 inches from the base of the plant, in addition to the abundant simple branches, 3 or 4 laterals per foot were usually 5 to 8 inches long. These were furnished with secondary branches 0.2 to 1.5 inches long at the rate of 6 to 8 per inch. Beyond 18 inches the longest branches on the larger roots did not exceed 4 inches in length and, like the abundant shorter laterals, they were quite unbranched. The thick, glistening white, turgid root ends were 2 millimeters in diameter. They were elongating so rapidly that usually several inches of root ends were quite unbranched. In fact branches 0.5 inch long were not usual until a distance of 6 inches from the root tip was reached.
All of the rapidly growing main roots (except the tips) and their younger branches were exceptionally well clothed with root hairs. The yellowish color of the older portions of the roots near the base of the plants indicated the loss of absorbing power in this region.
Maturing Plants.--The muskmelon had passed through its period of most vigorous growth by July 24, when a final examination was made. The vines were over 12 feet long. Fully grown fruits were ripening but on other parts of the vines blossoms and fruits in various stages of development were found. As in the earlier examination, the root system consisted of two rather distinct parts; a poorly branched deeper portion of the taproot and a wonderfully developed absorbing system in the surface foot of soil.
The taproot had pursued a rather tortuous course to a maximum depth of 45 inches. Below 2 feet the branches were short, although rather abundant, and only fairly well rebranched. Between the 12- and 24-inch soil levels a few larger branches, often obliquely descending but not extensive, supplemented the smaller, shorter ones. As a whole, however, this deeper portion of the root system, as in other cucurbits, was clearly overshadowed by the extensive superficial root development.
In the surface 4 to 8 inches of soil eight strong roots with diameters from 5 to 10 millimeters originated. These roots pursued very devious courses in the fertile, moist soil, approaching or growing away from the soil surface through distances of 2 to 5 inches but having their whole course in the first foot of soil. A usual depth attained was about 6 to 8 inches. Some of the roots had a maximum lateral spread of over 15 feet, although the roots were actually much longer. Large laterals sometimes 4 to 5 millimeters in diameter arose at irregular intervals. These diverged usually at wide angles from the main root but like it pursued a pronounced horizontal course. Frequently, these reached lengths of 5 to 9 feet. A single root sometimes gave rise to as many as eight major branches.
In addition to the 8 major surface laterals 17 others were found arising from the four sides of the taproot in the surface foot of soil. These varied from 1 to 3 millimeters in diameter and 2 to 7 feet in length. They too gave rise to very numerous branches. The more vigorous of these branches were repeatedly noticed to pursue a horizontal course. Numerous others, of lesser diameter (about 0.5 millimeter) grew upward to within 1 inch of the soil surface or extended into the deeper soil, occasionally to a depth of 2 or more feet.
On the first 3 feet of the major roots absorbing laterals were sparse. But large branches, abundantly furnished with absorbing laterals, extended in all directions, some vertically downward to a depth of 2 feet. Even beyond 3 feet a few vertical branches extended well into the second foot of soil. Farther outward on the horizontal, main branches absorbing rootlets became increasingly more numerous. Some extended vertically upward to very near the soil surface. For example, in addition to the longer branches already described, laterals 1 to 4 inches long occurred at the rate of 6 to 12 per inch. On the younger portions of the roots, which were still growing vigorous ly, the branches were only 1 or 2 inches in length. The turgid, shining, bare root ends maintained a diameter of 2 millimeters and were still in a vigorous state of growth. A clear conception of this wonderfully intricate root system may best be obtained. by a study of Fig. 85. But even here only the larger main roots and their branches are shown. Nodal roots were not permitted to develop since the vines were loosened from the soil and laid aside in the process of cultivation.
Fig. 85.--Surface view of the root system of muskmelon on July 24, 14 weeks after Planting. Only the larger main roots and their branches are shown. The roots were still growing vigorously.
Summary.--The muskmelon, like the closely related cucumber, has a root system consisting of a very extensive shallow portion and a poorly developed deeper part. Just as the vines land transpiring area of the muskmelon are far more extensive than those of the cucumber, so too the root system is much larger. When the vines are 2 feet long, the taproot is only 18 inches deep, but the longest of the numerous horizontal roots extend outward 3 feet. Long, simple, secondary laterals are numerous. Half-grown plants, with vines 9 feet long, have taproots 2 feet deep. Six to eight of the horizontal laterals make a marked growth, spreading widely, some to 4.5 feet. These with their very numerous long branches, all densely furnished with smaller laterals, fill many cubic feet of surface soil. Nearer the plant the root masses are most abundant. On maturing plants, but where tops and roots are still growing, root extent is even greater. The taproots, now quite well branched in the second foot of soil, penetrate beyond the 3.5-foot level. The strong surface roots pursue their tortuous outward course, some to a distance of 3 feet beyond the 12-foot vines. Branches from these, 2 to 9 feet long, are also superficial. Many other long primary laterals are likewise clothed with delicate branches of considerable length. Thus the surface soil, many feet on all sides of the plant, is thoroughly ramified by a wonderfully extensive root system with an enormous absorbing area. It is equipped to furnish abundant supplies of water and nutrients to the very extensive aboveground parts.
Other Investigations on Muskmelon.--Roots of the Oblong Netted muskmelon were examined at Geneva, N. Y. The plants were grown in a clay loam soil with a depth of 6 to 10 inches below which occurred a tenacious subsoil of gravelly clay. The plant, examined in the middle of September, had not made a very vigorous growth.
The roots were for the most part very shallow in the soil, though we traced a single one to a depth of 16 inches. The main roots extended horizontally and at a depth of 3 to 5 inches below the surface. We traced one of these a distance of 3 feet, which was as far as the longest stem reached. Short, fibrous roots are, however, quite numerous at a depth of 8 or 10 inches. It thus appears that the muskmelon is a shallow-rooting plant but its roots draw nourishment from a large area. 43
During another season at the same station:
The roots of a plant of the Montreal Nutmeg were washed out Sept. 7. The taproot extended perpendicularly only about 4 inches, then it turned nearly at right angles, descending only gradually as it progressed. The main horizontal roots lay 2 or 3 inches below the surface, and one of these was traced to a distance of 5 feet from the base of the plant, which is further than any of the runners extended. One root ran horizontally a distance of 15 inches, when it suddenly turned downward, and was followed for fully 2 feet. At the depth of 20 inches, it branched much in the compact clay. 44
Examination of the root system of muskmelon at Saratov, Russia, was made on Sept. 12, when the plants were mature. The main mass of roots was found in the surface 16 to 20 inches of soil. The lateral roots of the first order were found to be longer than the taproot and spread in all directions. Each of these laterals had a large number of well-branched roots of the second, third, and higher orders. These formed an interlacing root network with a diameter of many feet. On sandy soil the same species had roots of a larger diameter. The length of the roots approximated that of the vines. 76
Root Habit in Relation to Cultural Practice.--The roots of muskmelon thrive best in a well-drained and, consequently, well-aerated, humus-filled soil that becomes warm early in spring. Experience has shown that any fertile, friable, well-drained soil is satisfactory provided it will maintain or is furrushed with an abundance of soil moisture from the time the plants start until the beginning of the ripening period. Good soil structure, which should not be too loose, is promoted by careful, deep plowing early in the spring and followed by repeated tillage so that the soil becomes well settled before planting. The inability of the roots to withstand water logging and consequent poor aeration has resulted in the practice of "bedding" the soil. This is essential on low, river-bottom or alluvial soils where the water table is near the surface, where excessive rains frequently occur, and where the crop is grown under irrigation. A common method is that of plowing the land in beds usually 5 to 7 feet in width with open furrows between the beds to permit rapid drainage. 10
As shown by root as well as top development, the muskmelon is a rapidly growing crop and requires an abundance of nutrients. It is fully as necessary, however, that the soil be mellow and well supplied with organic matter. Placing well-rotted manure about 6 inches deep under the hill and within easy reach of the roots is an old and excellent practice. To accomplish this the field is furrowed out both ways so that the furrows cross about 4 to 6 feet apart where the plants are to be grown. A quantity of well-rotted manure is placed into the bottom of the furrows at the intersections and is often thoroughly mixed with the soil. Soil is then compacted over the manure so that the seeds and roots will not suffer from lack of moisture by reason of large air pockets in or about the mass of manure. Manuring in the hill and thus giving the plant a vigorous start, has been found to be far superior to broadcasting the manure unless a very large quantity of it is used. Where large amounts of manure are available, the roots obtain an abundant supply of nutrients at all times by a rapid extension of their absorbing system. 91, 92
The proper method of planting is such that it not only insures a good stand but permits thinning without disturbance to the roots of the remaining plants. Hence, when planted in hills care is taken to space the seeds some distance apart; this, of course, also applies to drills. Because of the ravages of insect enemies the plants are often left unthinned until well established. Since there is danger of seriously disturbing the roots, the excess plants are often cut at the ground line instead of being pulled out.
When plants are not started from seed in the field, provision must be made for removing the soil mass undisturbed with the roots of the transplants. Hence, the use of pots, dirt bands, or pieces of inverted sod. Nor can they be grown more than 4 to 5 weeks before transplanting. 10
Cultivation should be performed with a thorough regard to root development. A deep root system may be promoted by loosening the soil to a good depth about the young plants provided the root ends are not injured. As the root system develops cultivation should be farther away from the plants. It should be shallow but frequent and continued until the vines cover the soil and the roots thoroughly ramify it. When this stage of development has been reached, it would seem that further tillage, although practiced by some growers who lay aside the vines, would do more harm than good.
The relatively shallow position of the root system makes it entirely clear why light, frequent irrigations, which wet the soil only throughout the root extent, are better than soaking ones given at longer intervals. 100
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