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Aliya Momotaz, Jay W. Scott, and David J. Schuster

. Beck-Bunn, T. Fridman, E. Frampton, A. Lopez, J. Petiard, V. Uhlig, J. Zamir, D. Tankley, S.D. 2000 Advanced backcross QTL analysis of a Lycopersicon esculentum × Lycopersicon

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Victoria Ann Surrage, Claudia Lafrenière, Mike Dixon, and Youbin Zheng

was conducted in a glass greenhouse (7.62 × 6.10 m) at the University of Guelph, Guelph, Ontario, Canada. On 20 Apr. 2008, tomato ( Lycopersicon esculentum ‘beefsteak’ tomato, cultivar Matrix F1 Hybrid, untreated; De Ruiter Seeds Inc., Lakewood, CO

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Douglas C. Sanders, Jennifer D. Cure, Pamela M. Deyton, and Randolph G. Gardner

Amount of vascular development (veininess) is an important quality factor for processing wholepack tomatoes. The influences of nutrient and soil moisture stress on the amount of vascular development in `Chico III', `Dorchester', and `Roma' tomato fruit were studied. Fruit subjected to nutrient stress showed the highest amount of veininess. Fruit exposed to moisture stress after initial fruit set did not differ from controls in amount of veininess. Amount of vascularization did not differ among cultivars. A method for quantifying veininess was developed and compared with a traditional subjective rating scale. There was a high correlation (r2 = 0.77) between the subjective rating and quantitative measurement of veininess.

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J.P. Morales-Payan, W.M. Stall, D.G. Shilling, J.A. Dusky, and T.A. Bewick

Field trials were conducted in Gainesville, Fla., to determine the influence of nitrogen fertilization on the interference effect of purple or yellow nutsedge on the yield of fresh tomato. Nitrogen (N) rates of 50, 100, 150, 200, 250, 300, and 350 kg·ha–1 were applied broadcast to the soil. Before transplanting, 1-m-wide soil beds were covered with plastic and fumigated with methyl bromide to suppress the growth on undesired weeds. Nutsedge-free and purple or yellow nutsedge-infested tomato plots were separately established. `Solar Set' tomatoes were transplanted in the middle of the soil beds, 50 cm apart in a single row. In nutsedge-infested plots, weed densities known to cause significant yield reduction in tomato (100 purple nutsedge plants/m2 and 50 yellow nutsedge plants/m2) were uniformly established perforating the plastic and transplanting viable tubers in the perforations. Purple and yellow nutsedge tubers were transplanted the same day as tomatoes and were allowed to interfere during the whole crop season. Results indicate that N rates had a significant effect on tomato fruit yield in both nutsedge-free and nutsedge-infested treatments. The presence of either purple or yellow nutsedge significantly reduced the fruit yield of tomato at all N rates. As N rates increased, tomato fruit yield reduction caused by the interference of either nutsedge species also increased. When yellow nutsedge was allowed to interfere with tomato, fruit yield loss was as low as 18% at 50 kg N/ha and as high as 42% at 350 kg N/ha. In purple nutsedge-infested tomato, fruit yield reductions ranged from 10% at 50 kg N/ha to 27% at 350 kg N/ha. N effects on nutsedge-free and nutsedge-infested tomato yields were described by quadratic equations, with maximum tomato fruit yield values being reached between 200 and 250 kg N/ha in both nutsedge-free and nutsedge-infested treatments.

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Denise M. Tieman and Avtar K. Handa

The growth of tomato fruit is the result of cell division early in development followed by cell expansion until the onset of ripening. We have utilized the mRNA differential display technique to clone genes differentially expressed in 10- and 20-day-old tomato fruit, when most fruit cells are undergoing a transition to growth by cell expansion. Of 1753 total bands observed using 30 independent primer sets, 31 differential display bands were obtained only in either 10-or 20-day - old fruit RNAs. Seven differentially expressed bands from 10-day-old fruit RNAs and six from 20-day-old fruit RNAs were cloned and characterized by sequence analysis and mRNA expression patterns in developing fruit, leaf and root tissues. Two clones had sequence similarities to 3-deoxy-D-arabino-heptulosonate-7-phosphate (DAHP) synthase or threonine deaminase genes, while the remaining clones did not correspond to previously characterized genes. Steady state levels of mRNAs corresponding to seven clones were upregulated between 10 and 20 days of fruit development, while two clones were downregulated during growth and ripening. Most clones also hybridize to mRNA species present in leaf and root tissues. Collectively, these results suggest a transition in gene expression between 10- and 20-day-old fruit development.

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Darren E. Robinson, Nader Soltani, Allan S. Hamill, and Peter H. Sikkema

Combining herbicides and fungicides can improve production efficiency; however, there is little information on the effect of these mixtures on weed control and processing tomato crop response. Six field trials were conducted from 2002 to 2004 in Ontario to study the effect of rimsulfuron and thifensulfuron applied alone or in combination with metribuzin and with or without chlorothalonil or copper fungicides on processing tomato. There was no visual injury or reduction in marketable yield of processing tomato with rimsulfuron or thifensulfuron alone or when tank-mixed with chlorothalonil or copper hydroxide. Rimsulfuron, thifensulfuron, rimsulfuron plus metribuzin, and thifensulfuron plus metribuzin could be tank-mixed with chlorothalonil without a reduction in weed control. However, efficacy of rimsulfuron and thifensulfuron were reduced when tank-mixed with copper hydroxide. The reduction in weed control incited by adding copper hydroxide was overcome with a low rate (150 g·ha–1 a.i.) of metribuzin for thifensulfuron but not rimsulfuron. Application of rimsulfuron and thifensulfuron alone or with low rates of metribuzin and chlorothalonil could provide tomato growers with a single-pass treatment for the control of troublesome weeds and diseases.

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O.A. Denton Olufolaji, Margaret J. Makinde, and J.A. Akinfasoye

Nigeria has diverse ecological conditions, ranging from mangrove swamp of the southern coastal regions to the derived Savannah of the middle belt and the Sudan/Guinea Savannah of the Northern part of the country. Using the southern wet humid rainforest condition of NIHORT, Ibadan, two germplasm evaluation trials were carried out during the rainy season of May to Sept. 1996 and 1997. Thirty-nine tomato accessions were investigated on 1 × 4-m plots at 50 x75-cm spacing in a completely randomized block design with three replications. The top 10 and the least 10 accessions were evaluated for yield in terms of number and weight of both wholesome and unwholesome fruits. In the Northern Guinea Savannah, NHLY-10; Ti 423, and Ti 420 were the best three in terms of fruit number (141 to 117) and weight (673–583 g) per m2. In the northern Sudan Savannah, Ti. 420; NHLY, Äì7 topped the list with (125–72 fruits) and 500–420 g per m2. In the southern rainforest of Ibadan, NHLY, 10; Ti 420, and Ti 423 were superior in fruit number (33–12) and weight (327–150 g/m2 to all the other accessions. However, in the derived Savannah of Ikirun, Ti 423; Roma VF, AND Ti 420 with (85–56 fruits) and(589–278 g) per m2 were quite outstanding among the seven accessions.

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Vladimir M. Samoylov and Kenneth C. Sink

Asymmetric somatic hybrids were obtained by PEG/DMSO fusion of protoplasts of a kanamycin-resistant (KmR+) interspecific tomato hybrid L. esculentum × L. pennellii with protoplasts of S. melongena eggplant. Elimination of tomato chromosomes was directed by application of 100, 250, 500, 750, and 1000 Gy of γ-rays to the donor protoplasts. The hybrid nature of selected KmR+ calli was confirmed by RAPDs, PCR amplification of the NptII gene, and Southern hybridization. Flow cytometry revealed that asymmetric hybrid plants were regenerated only from selected somatic hybrid calli that had a ploidy level close to 4n. The amount of donor DNA in three somatic hybrid plants was quantified by dot-blot hybridization with tomato species-specific probes, and was found to be 5% to 7%. Therefore, presence of four to five tomato chromosomes in asymmetric hybrid plants has been calculated. Detection of tomato-specific chromosomes in hybrid plants by RFLP analysis will be presented.

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J. W. Scott and C. L. Emmons

Ten tomato cultigens were crossed with L. peruvianum accessions PI 126443 and PI 129152. Fruit (536 total) were harvested between 15 and 65 days after anthesis (DAA). Culturable embryos were obtained from 13% of the fruit. There were 140 embryos plated, from which 36 plants were obtained (7% of fruit, 26% of embryos plated). 'Campbell 28', Fla. 7217, and Fla. 7182 were the most efficient tomato lines for producing F1 plants, there was no difference between the L. peruvianum accessions. No embryos were obtained beyond 57 DAA. No trend in embryo viability was detected between 15 and 56 DAA. Of 248 backcross fruit, 94 embryos were plated (38% of fruit) and 15 plants were obtained (6% of fruit, 16% of embryos plated). Female parents with the best percentage of plants per fruit crossed were Fla. 7217, Fla. 7215, and 'Campbell 28' with 15, 8, and 7%, respectively. No plants were obtained from 45 crosses on Fla. 7182.

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Brian A. Kahn and John P. Damicone

Drip-irrigated, stake-and-weave supported tomato (Lycopersicon esculentum) plots were established in 2005 and 2006. All plots (except controls) were treated with a kaolin particle film product (Surround WP) mixed at 0.5 lb/gal of water and applied with a pressurized hand sprayer. Sprays began after transplanting and were repeated as needed to maintain a particle film on the foliage. Sprays were discontinued either at anthesis, at first green fruit 5 cm in diameter, or at first colored fruit harvest. Multiple hand harvests were made as fruit matured. In 2005, all kaolin treatments reduced marketable fruit number and weight, whereas in 2006 there were no significant effects. Cull fruit weight and average weight per marketable fruit were unaffected by treatments during either year. Results indicate that when applied before harvest begins, Surround may not improve marketable yields of fresh tomatoes.