Paul Work

A tomato crop may be much poorer than the seed from which it grows but it can be no better.

The tomato seed is short-oval and flattened in shape, covered thickly with short silky hairs. The embryo or baby plant is coiled in a spiral and imbedded in the endosperm (reserve food supply). Three or four years is generally given as the life of the seed but it often remains viable much longer—up to 10 or 12 years in extreme cases. Good seed should germinate 85% to 90%.

Tomato seed sprouts readily, requiring fairly warm temperature, say, 70° to 75° F. for best results. It germinates very slowly at 40° to 50° F.

Breeding

Being a major vegetable crop, the tomato has received much attention from plant breeders. Objectives sought include good cannery type, resistance to the fusarium wilt and other diseases, better greenhouse forms, improved general market and home garden sorts, and varieties adapted for arduous conditions such as hot and dry summers or very short growing seasons.

The tomato is largely but not wholly self pollinated and pollen is not carried far. Thus, it is not difficult to breed to practically a pure-line condition.

Tomatoes for seed are usually ground up and the seed and fine pulp are separated from the skins and coarse material by screening. The juice, fine pulp and seeds are allowed to ferment from 24 to 48 hours, or until the jelly-like pulp is readily washed away. After washing, the seed is dried in thin layers and stored. A bushel of tomatoes may be expected to yield 2½ to 4 ounces of seed and an acre of tomatoes, from 100 to 225 pounds. These vary greatly according to varieties and conditions.

Wellington[13] and others have shown that first generation seed from crosses of suitable varieties show a marked increase of vigor (heterosis or hybrid vigor) over either parent or over the later generations. This fact would seem to offer possibilities in practical use, but it has not thus far proved of value.

Selection Methods

Many growers find it profitable to save their own tomato seed. The plant is an annual, the important characters are quite readily observed and natural crossing is not serious. For these reasons, the enterprise is not as difficult as with most vegetables, although, if done well, it makes heavy demands in labor and care at a time when the grower has much else to do.

The first step in selection is to establish clearly the ideal to be sought, recording it in detail on paper for future reference. Selections should be made on the basis of the plant, not of the individual fruit. It is the plant that is reproduced and the seed from "crown clusters" is no earlier than seed from later settings. The field should be searched soon after blooming time and plants that appear promising should be marked. These plants should be examined three or four times as the season advances, and markers pulled from plants that do not measure up to the desired standard. Suppose ten plants remain; all fruits from each of these may be saved, keeping the seed of each plant separate. All or part of the seed may be planted in separate rows the next year for further selection and to note which parents best transmit their excellent points. If only a small amount of seed is required, direct selections may be made for use in planting for the general crop. If a larger amount of seed is required, seed from one or two of the best plants should be planted in multiplication plats. Off-type plants should be removed from such plantings, but otherwise all the seed may be saved for use. Repeated selection results in constant improvement until the stock becomes a "pure line" or practically so.

Lindstrom of Iowa has led in research on the genetics of tomatoes, chromosome relations and mode of inheritance. Many scientific papers deal with inheritance methods and results. The Yearbook of Agriculture (U.S.D.A.) for 1937 contains a valuable chapter on tomato breeding. It may also be had as Yearbook Separate 1581.

Certification

As with certain other kinds of seeds, certification service for tomatoes has now been set up in several states. Certification is a most useful incentive toward care in breeding and handling and affords valuable assurance to the buyer. It is necessary to know just what is guaranteed by the certificate. It is at the same time wise to be informed as to the inclusiveness and methods of the certification.

The Ideal Variety

In breeding for better varieties of tomatoes, the following are some of the characters to be sought:

(1) A vigorous vine which is necessary to produce abundant fruit and to protect from sunscald.

(2) Resistance to disease especially to fusarium.

(3) High productiveness with moderate number of fruits per cluster—say, 5 to 8.

(4) Evenness of maturity. This is somewhat out of line with the nature of the tomato but much could be accomplished toward the goal of varieties that make their crop and are gone, eliminating long picking periods and the drag of inferior fruit toward the end of the season. The so-called determinate habit of some varieties such as Pritchard is a step in this direction.

(5) Size suitable for expected use and for market demand. Greenhouse tomatoes are generally smaller than those for cannery. Uniformity of size is increasingly important with wide-spread use of the lug-box pack and of small consumer cartons.

(6) Globular to oblong shape is desirable for market but is less important for cannery. Form should be symmetrical, even and smooth.

(7) Color should be deep and rich, fully and evenly developed, inside and out. Red is generally preferred to pink. The difference between red and pink tomatoes does not reside in the flesh but in the presence of yellow pigment in the skin of the former while the skin of the latter is without pigment. Yellow tomatoes are also extant.

(8) Skin should be thick and tough. This safeguards against damage on the way to market and favors ease of peeling. Those saladists who serve sliced tomatoes with skins unremoved, may call for a thin, tender skin but this practice finds no encouragement from discriminating partakers.

(9) Flesh should be abundant in thick walls with a minimum of watery pulp surrounding seeds. In general, a structure of many small cells is desirable.

Varieties

Earliana.—The earliness of this old and popular variety outweighs its demerits where this character is required. The past ten years have seen material improvement.

Earliana is early, of small vine, with small leaves and leaflets. Clusters are compoundly branched, with many fruits. The fruits are of medium size, deep oblate, cross section often elliptical rather than circular. There are many rough irregular fruits, varying in this respect with breeding and conditions of growth. Color is red, not too deep and tending to be poorly developed at the stem end. Interior consists of many small cells with thin walls.

Bison.—represents a group of varieties bred for rigorous climates of our most northerly states. A. F. Yeager formerly of North Dakota, later of Michigan, now of New Hampshire has led in this development.

Victor.—is a new variety bred originally by Yeager but introduced by K. C. Barrons of Michigan. It affords smoother, deeper and better colored fruits about as early as Earliana. It is determinate in habit and shy in foliage, increasing danger of sunscald. Rich soil and ample moisture are needed for its best development. Bounty and Home Garden are similar.

Penn State.—Penn State, developed by C. E. Myers of Pennsylvania, is not as early as Earliana. It is similar in fruit characters though distinctly better in color and shape. It is marked by short branches (determinate habit) and is designed to give an early crop to be followed by prompt abandonment of the planting. It is not to be confused with Penn State Earliana.

Bonny Group.—This group embraces our leading second early varieties widely used for home garden, greenhouse, market and cannery in the north. It includes Bonny Best, John Baer and Chalk Jewel with many additional names and with much confusion of characters among them.

Bonny Best is second early and of medium plant growth. Fruits are deep oblate to flattened globe, even and smooth, of good red color, with few large, thick-walled cells.

Varieties and strains of this group vary in growth and yield, in size, shape and earliness of fruit and in suitability for greenhouse, market, cannery and juice. Stokesdale and Scarlet Dawn are meritorious newer names in the group.

Marglobe.—This variety was developed by the late Dr. F. J. Pritchard from a cross between Marvel, a French variety lending resistance to fusarium and Globe, an old variety of fine size and shape. It is widely used, north and south, for market—green or ripe, for cannery and to some extent, for forcing.

Marglobe is a midseason variety, with large vine and foliage, resistant to fusarium and nailhead spot. Fruits are nearly globular, shapely and smooth, medium to large, scarlet red, with medium number of thick walled cells. Marglobe is rather subject to deep radial cracks.

Pritchard is of the general type of Marglobe but is earlier, with short branching habit and resistance to nailhead rust and to fusarium, and, perhaps, is less subject to cracking.

Greater Baltimore is used chiefly for canning in long-season districts. It is late, with large vine, large flat fruits of excellent scarlet red, outside and in, with many thick walled cells. Indiana Baltimore is a variant widely grown in the mid-west for cannery.

Rutgers was developed by L. G. Schermerhorn at the New Jersey Experiment Station for fine juice and canning characters—color, flavor and substance. Growth is vigorous and yields are heavy; fruits are large, flattened and well colored.

Gulf State Market is a second early shipping tomato, generally harvested green. It is flattened in shape, of well developed pink color and good interior.

Comet Group.—These trace mostly to English or other European origin and are increasingly used for greenhouse and for staking out-of-doors. Comet is small, flattened, slightly corrugated about the stem, of fine even red color, very firm and solid, with few very thick walled cells. Other names are Sunrise, and Lord Roberts. Several American forcing strains have been developed with at least one parent of this group—Ideal, Grand Rapids Forcing, Field Station Comet, Trellis, Michigan State Forcing, Lloyd Forcing, Blair Forcing and others.

King Humbert and San Marzano represent the small Italian oblong tomatoes that are prized for their thick walls, fine color and suitability for puree, paste and soup.

Ponderosa is popular for home garden, a "beef-steak" tomato of very large size, irregular shape, flat, pink, with many small cells and of very mild sub-acid flavor. It is best grown to single stem. Oxheart is large, heart shaped, pink and very meaty. Others of this general type may be had in red, yellow and orange flesh. In general, the whole group lacks in prolificacy.

Oddities.—Tomato fanciers often plant seed of Red and Yellow Pear, Cherry, Currant, Peach with its fuzzy skin, Plum and others. They are prized for preserves and for decoration. Ground Cherry or Husk Tomato is not a true tomato but belongs to a different genus (Physalis). It makes excellent preserves. Well do I remember sneaking off from the other kids for solitary plunder of the little row that was usually in Grandma's garden.

Comprehensive descriptions of leading varieties of tomatoes have been published by the United States Department of Agriculture in Miscellaneous Publication 160, the result of statistical and verbal notations over several years at five widely scattered stations of the country.