Search Results
Abstract
F1 hybrids between high sugar and acid lines of tomato (Lycopersicon esculentum Mill.) were rated higher in sweetness, ‘tomato-like’, and overall flavor intensity than the high-acid parent common to the crosses. Titratable acidity and soluble solids content were responsible for most of the observed differences in sweetness. The results indicate that improved tomato flavor can be achieved by genetically enhancing sugar and acid content. Rapid gains in flavor quality might be achieved in horticulturally acceptable types through F1 hybrids.
Media and nutrient variables were investigated to develop methods of reducing the incidence and severity of fusarium crown rot incited by Fusarium oxysporum Schlecht. f. sp. radicis-lycopersici Jarvis & Shoemaker (FORL), a disease problem of current importance with tomato Lycopersicon esculentum Mill. Root-dip inoculated seedlings were transplanted into trays of a 1 Canadian peat: 1 vermiculite medium that had been prepared with factorial combinations of CaCO, (0.75 or 3.0 kg·m), Ca(NO) or (NH) SO (each at 225 mg N/liter), and NaCl at 0 or 2000 mg Na/liter as the experimental treatments. Crown rot was more severe with the lower CaCO rate, with (NH) SO, and supplemental NaCI. Data on fresh weight of seedlings expressed as percentage values relative to the noninoculated controls supported observations on disease severity.
Abstract
Male-sterile, male-fertile, exserted stigma, and exserted stigma with positional sterile (ps) genotypes of tomato (Lycopersicon esculentum Mill.) were pollinated at daily intervals from one day before to 2 days after anthesis (A-1, A0, A+1, A+2, respectively) in 2 field experiments and one greenhouse experiment. A male-sterile with gene ms-10 35 had greater seeds per pollination than other genotypes in all 3 experiments. Seeds per pollination produced in the greenhouse was greater than that of a similar field experiment at all pollination stages except A-1, where seed production was similar. Seeds per pollination was less at A-1 than at later pollination stages. This was due to significant differences in seeds per fruit in all experiments and percentage of fruit set in 2 of 3 experiments. There was no selfing in the 2 male-sterile genotypes in any experiment and no selfing for exserted stigma with ps in the field experiments. There was about 2% selfing with ps at A+2 in the greenhouse. Selfing with stigma exsertion alone ranged from 2% to 22% in the field and from less than 1% to about 5% in the greenhouse. The relationship of selfing with pollination stage was not clear for the exserted stigma genotype.
Fresh market tomatoes (Solanum lycopersicum L.) handled through dump tanks and flumes at packinghouses can absorb water via stem scar tissues. This water uptake can lead to internalization of various hazardous bacteria, including Erwinia carotovora (Jones), the causal agent of bacterial soft rot. Studies were conducted to determine if the interval between harvest and water immersion affected water uptake for ‘Florida 47’ and ‘Sebring’, cultivars with high and low water uptake, respectively. Fruit were held for 2, 8, 14, and 26 hours after harvest for the fall season and 2, 4, 6, 8, and 14 hours for the following spring season before water immersion. Mature green fruit were weighed, submerged in water for 2 min and then reweighed to determine water uptake. During the submergence, air pressure was applied such that the fruit were exposed to a static water-head equivalent to 1.3 m. In the fall season ‘Sebring’ fruit absorbed significantly less water than ‘Florida 47’ fruit at 8 and 26 hours after harvest. In the spring season fruit of ‘Sebring’ absorbed significantly less water than ‘Florida 47’ at all times after harvest, confirming results of previous studies. In the fall season, the time interval between harvest and treatment did not affect water uptake for either cultivar. By contrast, in the spring season fruit absorbed significantly greater amounts of water at 2 hours as compared with 4, 6, 8, and 14 hours after harvest, whereas similar amounts of water were absorbed at 4–14 hours after harvest. Therefore, to minimize the tendency of fruit to absorb water, packinghouse managers should hold freshly harvested fruit for at least 4 hours before immersing them in the dump tank.
Harvested tomato (Solanum lycopersicum L.) fruit can absorb water via stem scar tissues. Decay incidence {bacterial soft rot (Erwinia carotovora Jones), sour rot (Geotrichum candidum Link), bacterial sour rot [Leuconostoc mesenteroides (Tsenkovskii) van Tieghem ssp. mesenteroides], and certain species of Lactobacillus Beijerinck} has been positively linked with the degree of water absorption. Previous studies have shown that cultivars differ in their tendencies to take up water during a simulation of packinghouse handling procedures. The inheritance of water absorption tendency was examined in two seasons of tests where six inbred tomato lines were intercrossed to develop a complete diallel. Following harvest at the mature-green stage, fruit were weighed, submerged in water for 2 min, and then reweighed to determine water absorption. Parental lines were tested in three seasons. Two parental lines, Fla. 7776 and Fla. 7946, were always in the low-absorption grouping, and NC84173 also had relatively low absorption. Fla. 8059 and Fla. 7777 were always in the high-absorption group, and Fla. 8000 tended to have high absorption. General combining ability for the low water absorption fruit characteristic was significant for both seasons with a higher level of significance in the spring over the fall season (P ≤ 0.001 and P ≤ 0.05, respectively), while specific combining ability was not significant for either season. Thus, the low water absorption fruit characteristic appears to be additively inherited. Accurate knowledge of parental absorption should allow prediction of hybrid performance. None of the hybrids absorbed unexpected amounts of water over both seasons. Reciprocal effects were significant (P ≤ 0.05) for fall, and maternal effects were significant (P ≤ 0.05) in spring. However, there was no general trend in water absorption due to the direction of the cross and thus no clear evidence for cytoplasmic inheritance. Water absorption was much greater in spring than in fall. Based on previous observations, the greater absorption in spring was due to higher field temperatures. Because of such environmental effects, parent lines should be replicated and tested over several seasons to accurately assess their relative water absorption. Crosses between consistently low water absorption parents should provide low-absorption hybrids, but testing of hybrids before release is suggested to verify this.
Three methods to inoculate Lycopersicon esculentum 'VF Pink' seedlings with tomato spotted wilt virus (TSWV) were compared. Treatments were 1) two inoculations by hand (rubbing leaves with a sterile cotton swab), 2) a single inoculation using a paint sprayer at 3.56 × 105 N· m-2, and 3) two spray inoculations. All three methods were effective (>95% infection) under moderate temperatures in the spring, but hand inoculation was not effective under hot conditions in the summer. In another experiment, spray inoculation was used to compare effects of light intensity and the leaf inoculated on susceptibility of L.. hirsutum PI 127826, L. pimpinellifoliom LA 1580 and `VF Pink' to TSWV isolate 85-9. All three genotypes were susceptible under full sun and 60% shade cloth in the greenhouse. Inoculation of youngest leaves produced the highest virus titer. Background optical density for noninoculated plants differed between lower and upper leaves in the ELISA assay.
Seedlings of eight accessions of L. hirsutum and susceptible L. esculentum `VF Pink' controls were spray inoculated twice in the greenhouse with tomato spotted wilt virus (TSWV) Arkansas 85-9. Plants lacking symptoms were reinoculated, then evaluated for TSWV by enzyme-linked immunosorbent assay (ELISA). Controls were consistently infected; sixty noninfected L. hirsutum were propagated by cuttings and inoculated with TSWV isolates T2 (lettuce), G-87 (gloxinia), 87-34 (tomato) and a mixture of the four isolates. All selections became infected in at least one test, but systemic infection was often delayed. Additional wild Lycopersicon species and numbers of accessions evaluated for resistance to TSWV include L. cheesmanii (9), L. chmielewskii (17), L. hirsutum (24), L. hirsutum f. glabratum (17), L. parviflorum (4) and L. pennellii (44). No new sources of strong resistance have been identified yet. Evaluation of additional species and accessions is continuing.
Abstract
‘Ozark Pink’ VF is an indeterminate, pink-fruited tomato (Lycopersicon esculentum Mill.) developed at the Univ. of Arkansas to replace ‘Traveler 76’ (2), which is susceptible to verticillium wilt. ‘Ozark Pink’ provides the excellent flavor quality of traditional Arkansas pink tomatoes with improved fruit size and disease resistance over ‘Traveler 76’. Fruits also are larger and firmer than ‘VF Pink’ (3), which was grown primarily in southeastern Arkansas. ‘Ozark Pink’ is adapted to stake culture and vine-ripe harvest for local market, shipping short distances and for home gardens throughout Arkansas and the Ozark Mountain area. Pink cultivars remain the most popular type sold as bedding plants and at roadside stands in Arkansas, although part of the commercial acreage now grows red-fruited cultivars.
Tomato (Lvcopersicon esculentum) line E427 contains Fusarium wilt resistant gene I-3 on chromosome 7 and I-2 (and presumably the linked I) genes on chromosome 11. E427 was crossed with `Bonny Best' (i, i-2, i-3) and backcrosses (BC) to `Bonny Best' and F2, seed were obtained. Self pollination of 187 BC and 150 F2 plants were made. Progeny were screened against Fusarium races 1, 2, and 3 and lines with recombinant ratios were self-pollinated and rescreened until homozygous. Five lines were resistant to races 2 and 3 but susceptible to race 1. These had the isozyme band got-2 linked to I-3, RFLP markers linked to I-3 and no RFLP markers linked to I-2. Five lines were resistant to race 1 but susceptible to races 2 and 3. These had the susceptible qot-2 band and no RFLP markers linked to I-3 or I-2. F2 complementation tests of 2 of these lines with `Manapal' (I) indicated they contained I. Three lines were resistant to race 2 but susceptible to races 1 and 3. These had the susceptible qot-2 band, I-2 linked RFLP markers, and no I-3 linked RFLP markers.