Vegetable Improvement Newsletter No. 4, February 1962

Compiled by H.M. Munger, Cornell University, Ithaca, New York

1. Glossy Broccoli

John J. Natti and John D. Atkin

New York Agricultural Experiment Station, Geneva, NY

A bright green plant was found in a commercial field of Waltham 29 broccoli. This plant lacked the normal bloom and was termed glossy. It was hoped that the character would be due to a single recessive gene which could be used as a seedling marker in the female parent to produce F₁ hybrid broccoli. Any self-pollination within the female line would automatically show as a glossy plant, and these plants could be eliminated either at thinning or at transplanting.

Subsequent genetic tests, however, have indicated that the plant originally found was actually heterozygous and that the glossy character is due to a single completely dominant gene.

This line was found to be practically completely self- incompatible, and it has been extremely difficult to obtain selfed seed even by bud pollination. The pollen is functional when placed on other plants, and normal seed is obtained when the glossy plant is pollinated with foreign pollen. The plants are perfectly vigorous except that, when transplanted under dry conditions, the lack of-bloom leads to excessive dehydration of the tissues immediately following transplanting. Under these conditions the plants can suffer considerably.

Further work has indicated that the resistance to mildew being incorporated in other lines is not due to the waxy character of the resistant lines, although the wax aids in mildew control because of its water-repellency.

There has been some interest in this material as a possible new vegetable for processing. However, after blanching, the appearance of this material and of normal broccoli is identical. A glossy variety or hybrid might be desirable for home garden use.

No seed of the glossy-line is available at the present time due to difficulties in obtaining selfed seed.

2. Cabbage Breeding

W.C. Barnes

Clemson College Truck Experiment Station, Charleston, SC

The problem of obtaining seed from spring crop cabbage harvested in April has always been serious.

If the entire plant is stored to break the rest period it is ready to come out about August 1. If placed under any but a controlled temperature condition, rot eliminates most plants and reversion to vegetative state claims the remainder. Fairly good seed production can usually be obtained by use of fluorescent lights in an air-conditioned room held at 68-72F where the plants are held until late September. Flowering usually begins about the time plants are removed from the constant temperature room, hence pollination is under natural conditions.

In 1961 most plants were lost in a severe freeze while in the seed bed. All survivors were in lines being selected for cold tolerance and a few produced good type heads. At maturity, the heads were sectioned, so that each piece contained a portion of the core, with a piece of leaf about 2 x 5 inches and a bud. These were soaked in a rooting hormone solution for about 5 minutes, rooted in sand-peat media and potted off. Small plants formed rapidly and these were moved to the North Carolina Mountain Horticultural Research Station, near Asheville, for planting in the field. Growth was fairly normal, and small to medium size heads were formed by mid August. The entire plants were returned to Charleston for the cold storage rest period. By January 1, some plants had flower buds and all were elongating.

With anything like fair success, this system results in 10-20 plants from each of the original heads selected and avoids the use of the expensive constant temperature room.

3. Anastamosis in Cabbage

S.H. Yarnell and Walter A. Hills

U.S. Vegetable Breeding Laboratory, Charleston, SC

The outer leaves of the plant become attached to each other as in a graft and the tissue must be torn apart to separate the leaves. The union formed is sufficiently strong to deform the head as it develops, Sometimes the developing head partially eludes this binding ring of leaves and develops to one side. All such plants are smaller than normal. The inner leaves developing later in the fall season are unaffected.

Continued selection for the character with controlled pollination has given the following percentages of anastamosis: 1955 - 11.0, 1956- 84.8, 1957 - 100.0, 1958 - 95.3, 1959 - 23.5, 1960 - 93.3, and 1961 - 90.2. This suggests that relatively few recessive genes are involved. Evidently growing conditions affect expression of the character. Attempts to anastamose leaves of adjoining siblings were unsuccessful possibly because the anastamosed plants were moved and tied together after identification of the character, which seemed to be after the period for its development.

4. Divided Midrib and Split Leaf in Cabbage

S.H. Yarnell and Walter A. Hills

U.S. Vegetable Breeding Laboratory, Charleston, SC

These are closely related variable characters which tend to merge. Both are found in the same families, although some families producing plants with divided midrib may have no split leaf. The extreme condition of split leaf has a double but unsplit petiole and a completely split blade. In less extreme forms the split extends only part way down the blade. Divided midrib varies somewhat in distinctness and may have one or more genes in common with notch. It is possible that all three leaf characters - split leaf, divided midrib, and notch - have some genes in common. (Notch was described in A.S.H.S. Proc. 61:447- 450. 1953).

5. Protuberances in Cabbage

S.H. Yarnell and Walter A. Hills

U.S. Vegetable Breeding Laboratory, Charleston, SC

These often grow from the upper surface of the mid-rib. They are typically slender, and an inch or more in length, but are sometimes an irregular fan-shape. The proportion of plants exhibiting protuberances has always been low - always under 10 percent and usually under 5 percent. This does not support the suggestion of a single partially dominant gene (J. Genet. 16:363- 385. 1926).

6. Hood Leaf in Cabbage

S.H. Yarnell and Walter A. Hills

U.S. Vegetable Breeding Laboratory, Charleston, South Carolina

In the extreme form the outer leaves assume a hood shape due to a more rapid growth of the central areas of the blade. A band around the edge of the blade is often at right angles to the mid- rib. Degree of severity varies widely and the abnormal leaves of some plants are hard to distinguish from the curved leaves loosely surrounding the head of a normal plant. The character can cause considerable commercial loss as the extreme condition is unmarketable. The percent of affected plants ordinarily ranges from about 2 to 55 but as much as 99.6 percent has been recorded. Data were first obtained in 1957 when there was 0.4 to 15.0 percent of hood leaf.

7. Cripple Leaf in Cabbage

S.H. Yarnell and Walter A. Hills

U.S. Vegetable Breeding Laboratory, Charleston, SC

The epidermis of the upper surface of the leaf breaks down in narrow irregular wedge-shaped sections. Not all leaves of a plant are affected. It has the appearance of a virus and this is not yet eliminated as a possible cause. The character has been noted for five years and has thus far behaved in much the same way as the other abnormal leaf types under under study. That is to say, it has not spread to adjacent stocks in the field, or to adjacent plants in the row. Proportions of plants affected range all the way from less than 1 to 100 percent. Like most of the abnormal characters under observation there was less in 1959 than in other years.

8. Observations on Cabbage Bolting

John J. Natti and John D. Atkin

New York Agricultural Experiment Station, Geneva, NY

In the cabbage breeding program being conducted at the N.Y. State Experiment Station at Geneva, many of the lines which show the most promise as kraut varieties are very resistant to bolting under greenhouse conditions. Although most cabbage varieties will bolt readily after 60 days treatment at 40?F, some of these lines will not bolt normally even after 90 days of cold storage treatment. This failure to bolt is a serious problem in the breeding program and preliminary experiments have been conducted to try to find a solution. It is very desirable to examine the interior of the heads in the breeding program in order to develop good head quality. Because of this, stumps rather than entire plants are often used for seed production. With the problem lines, stumps are much more susceptible to bolting than are entire plants. In one experiment a breeding line of mature plants was divided into two classes. In one class the entire plants were stored; in the other only the stumps were stored. Axillary buds on the stumps developed, and flowers were produced in relatively short order whereas, with the heads, many of the plants failed to bolt at all and in the others the bolting was very much delayed. It has also been found that immature plants are more susceptible to bolting following cold storage than are fully mature plants.

When cabbage is given a cold treatment and then moved into a high temperature environment, the plants will often initiate reproductive growth but will then revert to the vegetative stage.

9. Possible Genetic Nature of Resistance to Tipburn of Cabbage

John J. Natti and John D. Atkin

New York State Agricultural Experiment Station, Geneva, NY

Tipburn is not a new disease, and there is some confusion concerning its naming. In 1932, Dr. Chupp of Cornell University used the name "tipburn" to describe marginal necrosis of cabbage leaves resulting from potash-phosphorus imbalance. In 1946, Shafer and Sayre of the Geneva Experiment Station described another disorder which occurs in the interior of mature or maturing heads of cabbage. The affected heads cannot be distinguished from healthy heads by external appearance, and usually only one to three leaves in the head are affected. These leaves may be adjacent or widely separated. The earliest symptoms consist of the darkening of the veins and a purple to gray cast to the affected tissues which at this stage are fresh and turgid. These tissues gradually dry and become tan to brown and papery in texture. The area of affected tissue may range from a narrow zone along the leaf margins to the involvement of almost the entire leaf. Sayre and Shafer named this disorder "internal breakdown". However, workers in Wisconsin and Europe have recently called this latter disorder "internal tipburn" and later "tipburn". Since the name tipburn has come to be widely used to describe the internal breakdown, it will be so used here, although priority for the name tipburn should go to the marginal necrosis described by Dr. Chupp in 1932.

Tipburn occurs in New York practically every year, but is generally of minor significance. There was a serious outbreak in 1942 and then again in 1961. Because of the very low incidence of the disease, it has been practically impossible to breed for resistance in New York although considerable success has been enjoyed in Europe and Wisconsin.

The primary objective of the breeding program at the New York State Experiment Station is to develop F₁ hybrids for kraut production. Because of this, a wide range of inbreds have been developed. In 1961 there was a very severe outbreak of tipburn in the cabbage breeding plots. At maturity every head was cut open and examined for tipburn. The results were very much unexpected in that a given inbred would be practically free of tip burn or heavily infected. Usually less than 10 or more than 80 per cent of the heads of an inbred were infected. If a large number of genes were involved in the resistance of tipburn, one would suspect that there would be a complete range of susceptibility in the inbreds whereas, if only one or a small number of genes were involved, one would expect that the different inbreds could be either highly resistant or susceptible. The results obtained can be explained by assuming that one or a small number of genes are responsible for resistance to tipburn.

Since a cabbage variety is simply a collection of biotypes, one would expect that the gene or genes for resistance could occur at different frequencies in different varieties. This would account for the wide range of resistance found in commercial varieties.

10. Problems Encountered in Breeding Red Cabbage

John J. Natti and John D. Atkin

New York State Agricultural Experiment Station, Geneva, NY

A small acreage of red cabbage is grown in New York for salad and for pickled red cabbage. Although red cabbage is very attractive because of the color, its texture and flavor are poor, and the varieties now on the market produce relatively poor yields in comparison to kraut cabbage varieties.

Crosses were made between the Red Danish cabbage commonly grown in the area and large yellows resistant kraut types in order to develop a large, high-yielding good quality yellows resistant red cabbage. The F₃ was intermediate in color and yielded just slightly more than the green parent whereas the yield of the red parent was only approximately 60 per cent of that of the green parent.

When the F₂ was planted it was found that there was a complete range of color from the green parental type to a red approaching the red parental type. However, it appeared that there was a definite correlation between small head size and dark red color. At harvest time the heads were arbitrarily divided into six color classifications, and the average head weight was determined for each color classification. Two years' data are summarized in the accompanying table. It will be noted that, although more than 6500 F₂ plants were grown, only 6 of these were classified as dark red parental type, and subsequent progeny testing indicated that these 6 plants were not homozygous for dark red color. It will be noted further that there was a definite correlation between small head size and dark red color.

The underlying cause or causes of the correlation between small head size and dark color have not been determined. It is possible that a yield gene or genes are closely linked to some of the color factors. A second theory is that the dark red color itself inhibits yield due to a possible reduction in photosynthetic activity. Work to determine the actual cause of the phenomenon mentioned above is being continued.

In summary, the inheritance of dark red color in cabbage is very complex, and in an F₂ population the head size is reduced as the color intensity increases.

Correlation between head weight and color in the F₂ of Red x Green cabbage.

11. A Simplified Method for Emasculating Lettuce Flowers

O.H. Pearson

Seed Research Specialists, Hollister, California

The structure of the lettuce flower makes emasculation impossible in the commonly accepted definition of the term. The petals are closely associated with the stamens, and the multiple structure of the head usually results in a tangle of petals, stamens and pistils. Preparation of the head for crossing is usually done by waiting until dehiscence and removal of the pollen on the stigmas by an air or water jet. I have had indifferent success with this method.

Consideration of the sequence of growth in a dehiscing flower has suggested an alternative method which was tried with considerable success in the spring of 1961. About two hours before a head opens its flowers, the tip of the head is cut off with a razor blade about 1/16th inch above the tips of the sepals. About an hour later inspection will show the stigmatic lobes protruding about 1/8th inch above the severed staminal column, still closed, and carrying a ball of pollen. This can be blown off with a compressed air jet from a three-gallon hand sprayer. The styles will be twisted around in the process, but in a few moments will straighten out, and in another half hour will expand and open, and be ready for pollination. Transfer of pollen from the male plant is accomplished simply by using the male parent flower head as a daubing brush. Undoubtedly season of year and temperature will affect the time intervals suggested. Using this technique, every flower so treated set seed, and the checks showed only one or two percent of the flowers setting seed.

This method may be used by others. However, description of it to several experienced lettuce breeders suggested that its use is not widespread, and possibly worthy of consideration by others.

12. Okra Breeding

E.M. Meader, E.G. Corbett, and Lih Hung

New Hampshire Agricultural Experiment Station, Durham, NH

Okra varieties well adapted to southern states do not crop in New Hampshire. Flowering is delayed commonly until early September and growth of the large vigorous plants is soon curtailed by fall frosts (average dates September 20 to 25). Even in 1961, when first killing frost was delayed and notes were taken October 16: Goldcoast (originated in Louisiana) averaged but 1 to 2 pods per plant, while PI 217511 and PI 249620 had many immature pods as well as 4 or 5 dry pods that gave mature seeds. Emerald (originated in New Jersey) proved early as did N.H. F₄ breeding lines.

When crosses of Dwarf Long Green Pod x Red Wonder were made in the greenhouse, it was theorized that flowering under long photoperiod might be associated with early maturity and, in turn, total usable crop. The F₁, F₂, and F₃ were likewise grown inside where 15-and-half hour photoperiod was maintained by use of 100-watt Mazda bulbs spaced 4 feet apart above the benches. Successively, only those F₂ and F₃ plants that flowered promptly under these conditions were selected for seed.

In the field-grown F₄, early flowering was apparent and usable pods could be harvested by the middle of August from seeds sown direct the first week of June. Selection for adaptation to long photoperiod seemingly had favored early maturity. Two early dwarf lines with angular green pods are available for testing from open-pollinated N.H. field-grown seeds. Nothing is known of the percentage of possible natural crossing that may have occurred from insects that visited the flowers. By following a similar procedure, crosses with round pod types are anticipated so as to transfer this desirable character into productive lines of okra sufficiently early for northern states.

13. New Genetic Characters in Pepper, Capsicum annum L.F.

L.F. Lippert and B.O. Bergh

University of California, Riverside, CA

Two new plant characteristics have been isolated from C. annum in the greenhouse. One character described as "chlorophyll-deficient" results in uniform yellowing of the true leaves of the seedling. This chlorotic condition is maintained in all new growth; however, the older foliage increased in chlorophyll until it approaches the green color of normal foliage. The plants are smaller, self-fertile and breed true for the character. Seed of a segregating heterozygous plant produced 12 chlorophyll-deficient and 38 normal seedlings, indicating the gene to be inherited as a single recessive.

The second character is also identifiable in the first true leaf stage of the seedling as a variegated white and green mottle of the leaves. The white and green areas are very distinct with little or no gradation of color. The condition persists in new foliage, although not all leaves show the same variegated pattern. A number of the plants exhibited a white zone on the stem corresponding to the node of the first true leaves, and the zone remained evident as the plant matured. The variegated plants are self-fertile and breed true. No segregation datum is available on this character.

14. Two New Pepper Varieties from California

L.F. Lippert and P.G. Smith

Department of Vegetable Crops, University of California, Davis, CA

The Department of Vegetable Crops, University of California, has available for trial seed of a high color Mexican chili pepper for dehydration and a pungent yellow wax pepper of the Floral Gem type for fresh market.

The Mexican chili (60M4) was developed by selection from a cross between a tobacco mosaic resistant Bell pepper and a field selection of Mexican chili. The material was backcrossed 3 generations to Mexican chili and selected for high color for 3 additional generations. The current level of extractable color is 30-32 Lovibond or 4700 to 5100 ug/g carotenoid pigment concentration on dry powder basis. The plants are medium height, with a good crown set of medium to large fruit. The material is resistant to tobacco mosaic virus but susceptible to cucumber mosaic; however, yields have been satisfactory even with moderate virus infection. Seed of 6OM4 is available for advanced trial for use as a high color line or as a source of high color in Mexican chili breeding programs.

The yellow wax pepper (56M229) is a mass of F₃ plants from the cross Floral Gem x Fresno Chili. The fruit are medium size, highly pungent and resemble Floral Gem in shape and color. This pepper is homozygous resistant to TMV and yielded well in coastal and inland desert areas of California where other viruses were present. This material is recommended for trial in fresh market pepper areas where viruses affect present Floral Gem types.

Address requests for seed of these two pepper varieties to Dr. Paul G. Smith, Department of Vegetable Crops, University of California, Davis, or Dr. L.F. Lippert, Department of Vegetable Crops, University of California, Riverside.

15. Quality in Relation to Bush Habit in Table Queen Squash

H.M. Munger, D.H. Wallace, and C.L. English

College of Agriculture, Cornell University, Ithaca, New York

Bush varieties of winter squash in the species Cucurbita pepo and Cucurbita maxima have not received wide acceptance. This appears to be due in part at least to their relatively low quality as compared with viney strains of the same types. We have attempted to overcome this objection in C. pepo by first selecting a Table Queen inbred of uniformly high quality (Cornell 51-26-7) and then backcrossing repeatedly to it while selecting for bush habit. The bush habit consists of shortened internodes, was found in a single plant of the variety Golden Table Queen, and was inherited as described by Shifriss (A.S.H.S. Proc. 50:330-346).

A composite of homozygous bush lines derived from the 5th backcross to 51-26-7 was put in trial under the number 56-303. Reports on this material plus our own observations indicated that the bush squash did not equal 51-26-7 in quality. Therefore, a number of the component lines of 56-303 were tasted individually, and considerable variation was apparent. However, the best quality lines turned out to be those with the least shortening of internodes. Lines homozygous for the single major gene for bush habit look much alike at the time flowering begins and all tend to set fruit close to the center of the plant. Runners emerge from the bushy plants after the first fruits are set and vary in length from about 3 feet from base of plant to runner tip in the North Carolina bush Table Queen lines, to 4-5 feet in most of the 56-303 lines, and to 6-8 feet in the higher-quality lines.

A replicated planting of the various lines was grown in rows 6 feet apart with hills 3 feet apart in 1961 and baked fruits evaluated by a taste panel of 14 people on November 21. 56-303 was included twice, one entry having the vines cut off so as to retain the bush form throughout the season.

The results given in Table 1 suggest that quality may be related to length of vine up to a certain point but that it may be possible to shorten the vine considerably and have fruit set close to the base without impairment of quality.

Table 1. Quality ratings of Table Queen squash tasted by 14 people on Nov. 21, 1961.

1=very poor, 2=poor, 3=acceptable, 4=good, 5=very good.

16. Mooregold Squash

O.B. Combs

Department of Horticulture, University of Wisconsin, Madison, WI

Mooregold squash (Cucurbita maxima) was developed through further selection and selfing, beginning in 1958, from lines originally selected by the late Professor James G. Moore from crosses involving Golden Hubbard, Rainbow and Greengold. The initial objective of a small to medium-sized squash with thick, high quality flesh but without the "turban" characteristics of Buttercup and the green mottling characteristic of Greengold has been attained.

Mooregold fruits are bright orange in color with indistinct salmon stripes, weigh 4 to 5 pounds and are slightly flattened in shape measuring 6 to 7 inches in diameter and 4 to 5 inches in depth. Fruits are uniform in size and shape; the fruit cavity is small and the seeds are white. The flesh is smooth in texture, orange in color and approximately 1/2 inch thicker at the shoulder than that of Buttercup. Fruit quality is highest at full maturity but immature fruits are also of very good eating quality. Both stem and blossom ends are slightly concaved. The rind is flinty, somewhat irregular from slight undulations and radial creasing-near the stem end; no appreciable checking, growth cracks or callousing has been observed. Limited tests indicate that this new variety is satisfactory for freezing and the fresh fruits are considered superior to Buttercup in storage quality.

Vines of Mooregold are vigorous and productive. Yields during the past two seasons have been comparable to or better than Buttercup. Fruits ripen in approximately 100 days or in season with Buttercup.

Approximately 40 pounds of stock seeds, produced under isolation at the Hancock Branch Station, are available for commercial increase.

17. Inheritance of Fruit Characters and Growth Habit in C. pepo L.

Prem. Nath and Charles V. Hall

Horticulture Department, Kansas State University, Manhattan, KS

Four commercial varieties were selected for the study. Royal Acorn fruits are turbinate tapering abruptly from the medial to the apex with ribs and furrows. Caserta and Black Zucchini fruits are nearly cylindrical and very slightly enlarged at the apex. Early Golden Bush Scallop fruits are disc shaped with furrows and ribs.

Crosses were made in the greenhouse in 1960 and 1961 and the different generations and parents were planted in the field in the summer of 1961. Observations on fruits were made both in the immature and mature stage and on the growth habit at the end of the season.

Fruit Shape: When the turbinate type (Royal Acorn) was crossed with the cylindrical type (Black Zucchini) the F₁ progenies resulted in intermediate elongated fruits gradually tapering to both ends. In the F₁ generation a 3:1 ratio of intermediate to cylindrical fruits occurred. The backcross of F₁ with cylindrical type gave a 11:4 ratio of cylinder to intermediate; whereas backcross with turbinate type gave a ratio of 1:2 cylinder to intermediate shape. Similar results were obtained from the cross between Royal Acorn and Caserta.

The cross between disc (Early Golden Bush Scallop) and cylindrical shaped (Black Zucchini) produced all intermediate shaped fruits, elongated tapering to both ends, in the F₁ generation. In F₂ generation and backcrosses, fruit shape segregated between the disc to cylinder types with none being typical of either parent, according to Sinnott and Durham (J. Hered. xiii(4):177-186), one or more factors may produce minor effects.

Fruit Color: Fruit color was also observed in all generations. Black Zucchini, Caserta, and Early Golden Bush Scallop were harvested in the immature fruit-stage (edible stage); whereas Royal Acorn being fall squash was harvested in the matured fruit stage.

The cross between the dark green Black Zucchini and the deep yellow Early Golden Bush Scallop resulted in green with sometime very light yellow mottling at early stage of the fruit development in the F1 generation. In the F₂ generation a 3:1 ratio of green to yellow was observed and this agrees with Shifriss (Proc. Amer. Soc. Hort. Sci. 50:330-346) in the early stage of fruit development. The backcross population failed to produce a 1:1 ratio.

The cross between the dark green broken striped Caserta and the yellow Early Golden Bush Scallop, produced only green broken striped fruits, but with different intensities of stripes at the early stage of fruit development in the F₁ generation. In the F₂ generation a 3:1 ratio of green-stripe to plain yellow occurred but with varying degree and intensity of stripes. The backcross gave a 1:1 ratio of green-stripe to yellow even in the small population and the immature fruit stage.

The cross between dark green broken striped Caserta and dark green Royal Acorn produced fruits with dark green broken stripes in the F₁ generation. In the F₂ generation the dark green stripes (Caserta) showed simple dominance over green (Royal Acorn) but at the same time the green background of Royal Acorn was dominant over the light green (Caserta). Both effects combined together to produce green background and dark green stripes but with varying degree of striping. The backcross population again was inadequate to give conclusive evidence.

Growth Habit: Growth habit was also observed since Royal Acorn was a vine type, whereas all others were bush type. The vine habit consisted of a single trailing main stem with long side branches and lengthened internodes, whereas the bush type had one or more upright relatively short stem or stems with shortened internodes.

From the cross between Royal Acorn (vine type) and Black Zucchini (bush type) all plants were of the vine type but varying length in the F₁ generation. The F₂ generation produced a 3:1 ratio of vine to bush at the end of the season, which agrees with Shifriss (Proc. Amer. Soc. Hort. Sci. 50:330-346). But the length of vine varied from longer than to shorter than the parent. The backcross of the F₁ with the bush type parent gave a 14:1 ratio of bush to vine; whereas backcross with vine type gave a 1:4 ratio of bush to vine.

In another cross when Black Zucchini was replaced by Caserta, similar results were observed.

18. Breeding Methods for Compact Tomatoes

L.C. Peirce

Department of Horticulture, Iowa State University, Ames, IA

It seems probable that some changes in standard field methods will be brought about by an increasing emphasis on small tomato plants adapted to once-over harvest. Several breeding lines selected from a standard 6' x 3' spaced planting were tested at Ames, Iowa, in 1961 in spacings of 6' x 3', 6' x 2', 6' x 1', and 6' x 1/2'. Apart from the yield per acre and competitive effect per se, the relative response of lines suggested that several changes in technique might be considered. Lines selected for superiority under conditions of no competition did not necessarily excel under competitive spacing. Data is needed to reveal if early generation selection in diverse population densities would give different results. If a type is being developed for high population cultures, would progress be accelerated by selecting superior types from high density F2 and F3 populations? Complications might arise if diverse plant types were used as parents. In this instance, F3 lines might constitute the first close-spaced population.

Similarly, direct seeding might be used more in early generations of a breeding program if the objective is a variety adapted to this type of culture. Work by others with the variety, Fireball, indicates that its phenotypic expression is modified by changes in cultural practices. It is possible, therefore, that similar modification may be brought about on single plant segregates or breeding lines.

19. A Method for Estimating Time of Single Harvest in the Tomato

K.W. Johnson, M.L. Tomes, and E.C. Stevenson

Purdue University, Lafayette, Indiana

In breeding tomatoes for mechanical harvest, yield trials must be conducted on a single harvest basis. Timing the single harvest for maximum yield is critical. In experiments designed to determine the loss in yield due to a single harvest as compared to a consecutive harvest schedule, a method for estimating time of single harvest became apparent.

Replicated experiments were conducted in 1960 and 1961 with direct seeded plants of the dwarf-vined Epoch variety. In both years, populations of 17,424 plants per acre were used. The data presented in Table 1 show the scheme followed.

Table 1. Comparison of yield (tons/acre) for single and consecutive harvest schemes in the Epoch tomato variety - 1960.

In 1960, the maximum consecutive harvest was on 9/7 while the largest single harvests were on 9/14 and 9/23. Similar results were obtained in 1961. In both years, the optimum time for a single harvest was about a week following the maximum harvest of the consecutively picked plots.

Time of single harvest could be estimated by planting an extra plot of each variety being tested and picking it consecutively. When the yields are equal to or lower than the previous week's harvest, the single harvest plots would be ready for picking. In the Epoch variety there is approximately a two-week period in which they can be picked or in which they will "store" on the vine without excessive deterioration providing adequate fungicide is applied. With varieties like Roma this period would be longer; with other varieties the period might be shorter.

The concept could also be applied on a commercial scale. Sample plots in a field would be harvested consecutively until the yields were equal to or Less than the previous harvest. At this time, the rest of the field should be ready for a single harvest. If the varieties have fruits with long vine storage, then some scheduling into the cannery could be accomplished.

20. A Possible Method for Selecting Mature Plant Characters in the Seedling Stage

A. Stoner and K.W. Johnson

Purdue University, Lafayette, Indiana

A common problem of tomato breeders is that of not being able to grow enough plants of segregating generations. Selection in the seed or seedling stage would facilitate this problem and also allow for more efficient use of field space. Research conducted in Germany prior to 1941 (Fryxell, P. A. 1954. Agron. Jour. 46:433-434) indicated a relationship between the osmotic value of germinating seeds (as measured by ability to germinate in solutions of high osmotic pressure) and resistance to cold, drought, salinity and disease in the mature plant, i.e., the higher the osmotic value the higher the resistance. The following experiments were conducted to corroborate this relationship in tomatoes.

Solutions of sucrose, sodium chloride, mannitol and polyvinylpyrrollidone were tested to determine their use in adjusting the osmotic pressure of the germinating solutions. A 4 atmospheres sucrose solution appeared the most desirable. Three separate replications of 100 seeds from each of 22 tomato varieties were germinated in a 4 atm sucrose solution at 70?F. A water control was run simultaneously. To adjust for differences in initial viability, the data were recorded as the number of seeds germinating in the control divided into the number germinating in the sucrose solution.

On the basis of the adjusted germination percentages the varieties fell into the following groups.

In comparing mature plant characteristics of the varieties within a germination group there was no apparent character common to all varieties. However, the fact that four definite germination categories were present would indicate that differences in the varieties did exist. As to what these differences are or if they are correlated with any mature plant characters remains to be determined.

Although these experiments were of a preliminary nature and no definite conclusion could be reached, the results would indicate further experiments would be in order. It would also seem that it might be tested in other crops, e.g. solids in muskmelon, watermelons, onion, etc.

21. The Effect of Date of Direct Seeding on Peak Harvest in the Tomato

M.L. Tomes, K.W. Johnson, and E.C. Stevenson

Purdue University, Lafayette, Indiana

Scheduling harvests throughout the season appears to be one of the major problems with mechanical harvesting. To determine whether the harvest season can be spread sufficiently by varying the date of direct seeding, successive-planting trials were carried out in both 1960 and 1961. Two varieties, Epoch (dwarf) and Tecumseh, were direct seeded in replicate trials on 5/6, 5/16, 5/23, and 6/3 (1960) and on 5/14, 5/23, 6/1, and 6/12 (1961).

Conditions for germination were ideal for each planting in the 1960 trial and the plots were harvested in the conventional manner on 8/29, 9/7, 9/13, 9/21, 9/29, and 10/11, 1960. The largest single harvest for Epoch was on 9/13 for those seeded on 5/6, 5/16, or 5/23. Only the planting seeded 6/3 gave an appreciable delay. Here the largest single harvest was the last picking on 10/11. With the variety, Tecumseh, seeding on 5/6 or 5/16 peaked on 9/13. Planting 5/23 gave the highest yield on 9/29 and on 6/3 - 10/11.

In 1961 the plots were harvested only four times on 9/8, 9/20, 9/28 and 10/10. Epoch gave the highest average yield on 9/20 regardless of the seeding date. Tecumseh peaked on this date for 2 of the 4 seedings, but the 2nd planting reached a peak on 9/28 and the 4th on 10/10. In 1961 the weather during the seeding period was cold and these plots were extremely dry. The early seedings were much delayed.

Under the conditions of these trials, varying the seeding date would be an unreliable method of spreading the optimum harvest. In a breeding sense, the need for early varieties of suitable quality is stressed as a more reliable solution to the problem.

22. Sources of Variability for the Improvement of Tomato Fruit Quality

A.E. Thompson, R.W. Hepler, R.L. Lower, and J.P. McCollum

University of Illinois, Urbana, IL

A replicated experiment was conducted at Urbana in 1961 to evaluate relative fruit-quality constituents of 21 tomato varieties and breeding lines. Fruits were harvested at the turning stage and ripened under controlled conditions at 65?5?F for 7 and 14 days before analysis. A complete report of this research will be published as an Illinois A.E.S. Bulletin in 1962.

Lines that may serve as future sources of variability in plant breeding programs.

Sources of seed used in the experiment are as follows:

* Received, selfed and selected at the Illinois Agricultural Experiment Station for 8, 4, and 2 generations respectively, before 1961.