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Tomato spotted wilt virus (TSWV) and Phytophthora infestans (late blight) in tomato (Solanum lycopersicum) have a worldwide distribution and are known to cause substantial disease damage. Sw-5 (derived from S. peruvianum) and Ph-3 (derived from S. pimpinellifolium) are, respectively, TSWV and late blight resistance genes. These two genes are linked (within 5 cM on several maps) in repulsion phase near the telomere of the long arm on chromosome 9. The tomato lines NC592 (Ph-3) and NC946 (Sw-5) were crossed to develop an F2 population and subsequent inbred generations. Marker-assisted selection (MAS) using three polymerase chain reaction-based codominant markers (TG328, TG591, and SCAR421) was used in F2 progeny with the goal of selecting for homozygous coupling-phase recombinant lines. From 1152 F2 plants, 11 were identified with potential recombination events between Ph-3 and Sw-5; of those, three were male sterile (ms-10). F3 progeny were generated from the remaining eight F2 recombinants, and resistance to both pathogens, or Ph-3 and Sw-5 in coupling phase, was confirmed in three of those. Recombination was suppressed fivefold in our F2 population to 1.11 cM between genes when compared with published maps of the same region. However, MAS was an efficient tool for selecting the desirable recombination events for these two pathogen resistance genes.

Compact-growth-habit (CGH) tomatoes (Lycopersicon esculentum Mill.) do not require the pruning, staking, and tying required for many fresh-market tomato cultivars. In 1990, 5-week-old transplants of the CGH tomato breeding line NC 13G-1 were grown in single rows with in-row spacings of 31, 46, 61, and 76 cm and in double rows with in-row spacings of 31 and 46 cm. NC 13G-1 produced high early and total season marketable yields when grown in either double-row treatment compared to any single-row treatment. In 1991 and 1992, 4- and 5-week-old NC 13G-1 transplants were produced in five root cell volumes (8.6, 13.6, 27.0, 37.1, and 80.0 cm3), transplanted into double rows with an in-row spacing of 46 cm, and evaluated for yield. Five-week-old transplants produced in 37.1- and 80-cm3 cells flowered sooner after transplanting and produced higher early season yields than 4-week-old transplants produced in the three smaller cells. Midseason yields increased quadratically and late-season yields decreased quadratically as root cell volume increased. Total season marketable yields did not differ among treatments. In 1991, production costs were influenced by root cell volume, but not in 1992. In 1992, net returns for the four smallest cell volumes were similar, and lower than for transplants grown in the largest cell volume. In both years, highest net returns were achieved with transplants produced in 37.1-cm3 cells. Considering the estimated 1992 net returns of $17,000/ha, production of CGH tomatoes may provide an alternative for staked-tomato growers concerned with labor availability and production costs, even though marketable yield from NC 13G-1 was lower than with a conventional cultivar under the standard system.

Eight staked, determinate tomato (Lycopersicon esculentum Mill.) cultivars were harvested when green (before breaker stage) or when pink (breaker stage and riper) in two replicated field studies. In general, total yield and average fruit size were reduced when fruit were harvested at the green stage. Harvest maturity had only a small effect on occurrence of most fruit defects, except fruit cracking, which was more severe for pink than for green fruit in the early season experiment. Although total yields for pink harvested fruit were higher than for green harvested fruit in the early season study, the high incidence of fruit crack in pink fruit resulted in similar yields of U.S. combination grade (U.S. no. 1 and U.S. no. 2) fruit for both treatments. Because the largest fruit often bring a premium price, harvesting fruit when pink probably will result in a higher price per kilogram than harvesting fruit when green. Fruit harvested green, however, are generally firmer, more crack resistant, and require fewer harvests than fruit harvested pink.

NC HS-1. Plant habit is determinate (sp) (Mutschler et al., 1987). The noncurled foliage is medium green and develops a canopy with moderate fruit coverage. The plants grow vigorously and typically outgrow the stake used in the short-stake, string-weave system. Fruit of NC HS-1 are deep oblate to flattened globular and are symmetrical with a small, smooth, blossom-end scar. Immature fruit are a glossy, uniform green (u) and ripen to an acceptable red exterior and interior color with medium firmness (subjective ratings). Fruit pedicels are jointed and separate easily from the fruit during harvest. NC HS-1 had high total and marketable yields when compared with standard cultivars in trials at Fletcher, N.C. under non–heat stress conditions. Fruit size was smaller than that of ‘Sun Leaper’ and ‘Solar Set’ and did not differ from ‘Flora-Dade’ (Table 1). NC HS-1 is resistant (I, I-2) to races 1 and 2 of Fusarium oxysporum f.sp. lycopersici (Sacc.) Snyd. and Hans., the incitant of fusarium wilt, and is resistant (Ve) to race 1 of Verticillium dahliae Kleb., the incitant of verticillium wilt. Fruit are highly resistant to radial and concentric cracking and to cuticle cracking (weather check). improved cultivar for summer production in piedmont and eastern North Carolina, where night temperatures often range from 21 to 25 °C. ‘Sun Leaper’ was tested as NC 92191 and in the Southern Tomato Exchange Program as STEP 744.

NC 2C ms-10,aa was developed by transferring the ms-10 nuclear male-sterile gene characteristics of the two lines. NC 2C ms10,aa has the same characteristics as previously described for NC 2C PVP (Gardner, 1993). Major plant and fruit characteristics controlled by single genes include determinate growth (sp), uniform light green color of nonripe fruit (u), and jointless pedicels (j-2). To compare NC 2C ms-10,aa with NC 2C PVP in hybrid seed production, both were pollinated with pollen of NC 1C PVP to produce hybrid seed of ‘Mountain Belle’. In replicated trials conducted during three growing seasons, the two hybrids did not differ in earlyor total-season yields. Fruit size tended to be slightly, but not significantly, smaller for the progeny of the male-sterile female parent. Observations of plant and fruit characteristics of the two hybrids in the replicated trials and in several other trial plots over a 3-year period indicated no visible differences for any character.

There is a good market for heirloom tomatoes that, according to many consumers, taste better than regular tomatoes. Unfortunately, most heirloom tomatoes have little disease resistance, tend to crack, are rough in appearance, and are not uniform in size. Randy Gardner recently developed several new indeterminate hybrid tomatoes with the goal of combining the flavor of heirloom tomatoes with the disease resistance, uniform size, and good shipping characteristics of more modern varieties. Two tests, using organic and conventional practices, were conducted in Waynesville, N.C., in which three popular heirloom varieties (German Johnson, Mr. Stripey, and Cherokee Purple) and four late blight resistant hybrids (NC 0455, NC 0571, NC 0576, and NC 05114), replicated four times, were grown using a high trellis system. The highest yields were obtained with German Johnson NC 0455, and NC 0576 in the conventional trial and German Johnson NC 0455, and NC 0571 in the organic trial. Public taste test results revealed that the experimental hybrid cluster type, NC 05114, was ranked by over 82% of the participants as good or excellent. NC 0455 was rated as good or excellent by >83% of the participants, which was better than the popular heirlooms Cherokee Purple and Mr. Stripey. This study demonstrated that the heirloom-type hybrid tomatoes could be successfully grown in organic and conventional systems in Western North Carolina and that two out of the four tested had flavor ratings similar to, or better than, the three heirloom varieties tested.

The influence of flat cell volume (cavity containing growing medium) on transplant growth and development of NC 13G-1, a compact-growth-habit, fresh-market tomato (Lycopersicon esculentum Mill.) breeding line, was compared to that of a normal growth habit line, NC 8288. Transplants of each line were produced in four cell volumes (3.3, 27, 37.1, and 80cm3) for 5 weeks, evaluated and then transplanted to larger containers, and grown until anthesis. During the first 5 weeks after seeding, plant dry weight did not differ between the lines; however, plant height of NC 13G-1 was ≈60% of the height of NC 8288. For both lines, number of days from sowing to anthesis decreased as root cell volumes increased. For space-efficient production of large quantities of compact-growth-habit tomato transplants, flats with root cell volumes as small as 27 and 37 cm3 can be used without greatly delaying anthesis.

‘Mountain Delight’ is the F1 hybrid resulting from the cross of ‘Piedmont’ (Gardner, 1985) x NC 8288. Both parents were developed in the North Carolina fresh-market tomato breeding program. ‘Mountain Delight’ was evaluated in trials as NC 84100 and in the 1987 Southern Tomato Exchange Program (STEP) as STEP 693. NC 8288 is an F, selection from the cross of ‘Piedmont’ × ‘Florida 1B’ (Augustine et al., 1981). NC 8288 was evaluated in the STEP trials in 1985, 1986, and 1987 as STEP 689.

Two inbred lines of fresh-market tomato (Lycopersicon esculentum Mill.), NC 20G-1 and NC 53G-1, both exhibiting prostrate growth habit (PGH), were crossed with the upright growth habit cultivar Piedmont and advanced to the F2 generation. Plants of each F2 population were grown without plant support on black plastic and subjectively rated in field plots for PGH. Extreme upright and prostrate plants were chosen from each F2 population for harvest. Mean comparisons between plants of extreme upright and prostrate habit showed increased total and marketable yields from plants with a prostrate habit. Decay and groundscarring of fruit were less in prostrate than in normally upright plants; the percentage of misshapen fruit was similar in both. The PGH character may be useful in increasing total and marketable yield of ground-culture tomatoes.

Experiments were conducted in 1989 to determine the heritability of shortened fruit maturation (SFM) period in 871213-1, an inbred cherry tomato line (Lycopersicon esculentum var. cerasiforme (Dunal.) A. Gray), and to determine the relationship between this trait and fruit size. In the first study, a cross was made between 871213-1 and NC 21C-1, an inbred cherry line. NC 21C-1 had a mean maturation period of 40.8 days compared to 32.0 days for 871213-1. A mean maturation period for the F1 hybrid of 32.9 days and 32.2 days was found using 871213-1 as the female and male parent, respectively. Analysis of the data from parental, F1, F2 and backcross generations yielded estimates of broad-sense and narrow-sense heritabilities for SFM as 0.72 and 0.56, respectively. Further analysis indicated that genetic control of SFM was quantitative in nature and highly dominant. A test for epistatic interaction showed significance. In the second study, an F2 population from the cross 871213-1 x NC 309-1, a large-fruited tomato line (Lycopersicon esculentum Mill.), was evaluated to determine if any correlations existed between fruit size and SFM. Two fruit characteristics, locule number and fruit weight, were used as estimates of fruit size. Correlations between SFM and these two characteristics were +0.28 and +0.61, respectively. Broad-sense heritability of SFM was estimated as 0.64.

Eight stamenless tomato mutants (Lycopersicon esculentum Mill.) were intercrossed in a half-diallel design to determine allelic relationships. Two allelic series were represented among the mutants. One series included sl, sl2, sl5, cs, and fl. The 2nd series included bn, sl?, and pms. No allelic interactions occurred between members of the 2 series. Fruit and seed set resulting from cross-pollinations varied greatly among the mutants. The stamenless types, with the exception of sl2, do not appear to be promising for use in producing hybrid tomato seed because of poor fruit and seed set.

Early blight, incited by Alternaria solani (Ellis and Martin) Jones and Grout, is a severe foliar disease of tomatoes in western North Carolina. Resistance breeding, initiated in 1976 at the Mountain Horticultural Crops Research and Extension Center, Fletcher, N.C. has resulted in the development of NC EBR-1 and NC EBR-2. Both lines exhibit a moderate level of foliar resistance to early blight.

A mutant of the tomato (Lycopersicon esculentum Mill. cv. Flora-Dade) was characterized by straight pedicels oriented in an upright position. A genetic study indicated the mutant character was controlled by a single recessive gene, which has been tentatively designated as up-right pedicel (up). The up locus is linked to the jointless pedicel (j-2) character of ‘Flora-Dade’, with a crossover distance of 8.5 units.

NC50-7, ‘Cherokee’ and ‘Mountain Pride’ are mid-season, determinate (sp gene) tomatoes (Lycopersicon esculentum Mill.) developed at the Mountain Horticultural Crops Research Station, Fletcher, N.C. ‘Cherokee’ and ‘Mountain Pride’ are adapted to vine-ripe harvest for local market and shipping. NC507 is useful as a parent in breeding for firmness and crack resistance and, in addition, is the male parent of the F1 hybrid ‘Mountain Pride’.