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- Author or Editor: M. Allen Stevens x
- Journal of the American Society for Horticultural Science x
Abstract
There is continual change in the acidity of tomato fruits during development and maturation. The concn increases during development and reaches a maximum near incipient color, then decreases until well beyond maturity. The inheritance of citrate and malate concn in ‘Tondo Liscio’ (TL) and PI 263713 (PI) is controlled by a single gene for each compound. The dominant alleles, which were linked in the coupling phase in PI, condition a high concn of citrate and a low concn of malate. Recombination was about 18%. Study of divergent tomato accessions indicated that there are factors which condition higher and lower concn of citrate than the range delimited by TL and PI. There appears to be more than one malate factor controlling higher concn, but many tomato accessions are similar to the dominant low parent (PI). Current evidence indicates that there is no practical reason to breed for a specific citrate/malate ratio.
Abstract
Flavor evaluation studies with ‘Campbell 146’ and ‘Campbell 1327’ indicated that 2-isobutylthiazole concn and solids/acid ratio are important to the flavor difference between these 2 cultivars.
Fifty-five tomato lines from divergent sources were analyzed to study relationships among components contributing to quality variation. There were highly significant correlations among major components contributing to solids. As total solids increased, the proportion of reducing sugars, the predominant organic compounds, increased. Despite a highly significant negative correlation between pH and titratable acidity, there was a wide range in the [H+]/titratable acidity ratio. The data indicate that differential buffering is primarily responsible for this variation and that phosphate content of the fruit is a prime factor in differential buffering. Citrate, but not malate, concn was correlated with titratable acidity.
Abstract
Investigation of the polyene-carotene and volatile compound content of tomatoes showed that there is a high correlation between the following relationships: Geranylacetone and farnesal with phytofluene plus 2 ζ-carotene plus neurosporene: 6-methylhept-5-en-2-one and citral with neurosporene plus 2 lycopene plus 2 prolycopene plus γ-carotene plus δ-carotene: β-ionone with γ-carotene plus 2 β-carotene plus α-carotene; α-ionone with δ-carotene plus α-carotene. Also, there appears to be a relationship between farnesylacetone and 2 phytoene plus phytofluene. The basis for establishing these relationships was oxidation of the polyene-carotenes at the first conjugated diene bonds. These relationships may exist because the volatile compounds result from oxidation of the polyene-carotenes.
Abstract
The volatile compounds of tomato cultivars ‘Campbell 146’ and ‘Campbell 1327’ were studied by gas-liquid chromatography. Heritable concentration differences were found for 3 compounds identified by retention time and infrared spectroscopy as 2-isobutylthiazole, methyl salicylate and eugenol. Investigation of concentrations and flavor thresholds indicated that they probably contribute to tomato flavor.
A study of the inheritance of the 3 compounds indicated that 2-isobutylthiazole concentration was determined by a single gene with additive effects. Concentrations of methyl salicylate and eugenol were determined by single genes closely linked in the coupling phase, with dominance for low concentration.
Abstract
Inheritance of the viscosity potential of tomato (Lycopersicon esculentum Mill.) fruits was studied using parents and F1, BCP1, BCP2, and F2 progeny from the crosses VF145-7879 × VF109 and VF145-7879 × 9039-M. Differences in viscosity from both crosses were controlled by 3 or fewer genes. In the VF145-7879 × VF109 cross there was bimodal distribution of BCP1 and F2 progeny which supports relatively simple inheritance. Partition analysis of the VF145-7879 × 9039-M cross supported the view that 3 or fewer genes were involved in viscosity difference. The heritability estimates were high for both crosses (0.75 and 0.68) and analysis of genetic variance showed that additive genic effects were most important. In the VF145-7879 × VF109 cross there was small, but significant, additive × dominance interaction whereas in the VF145-7879 × 9039-M there was no interaction but there were dominance effects. Study of the heritabilities of 5 components of the alcohol-insoluble solids did not clarify the genetic analysis of viscosity potential. Possible effects of competition for photosynthate on the genetic analysis are discussed.
Abstract
Changes in acid content in fruits of tomato (Lycopersicon esculentum Mill.) left on the vine compared with those of fruits removed from the vine at one stage each of development and ripening. Developing fruits detached 28 days after anthesis had an increase in total acidity attributable to increased malic and citric acid concentrations. Detached developing fruits accumulated organic acids more rapidly than attached fruits. Mature fruits detached at the breaker stage decreased more in total acidity than attached fruits which was reflected in a decrease in malic and citric acids, with a greater decrease in malic acid. The data indicate that organic acid accumulation in detached fruits is determined by metabolism at the time of detachment.
Abstract
The inheritance of malate in tomatoes was investigated by gas-liquid chromatography with trimethylsilyl derivatives. Studies of progeny from the crosses ‘Campbell 146’ x ‘Campbell 1327’ and ‘Delsher’ x PI 255842-SI indicated that concentration of malate is determined by a single factor with dominance for low concentration.
Abstract
High-temperature responses of heat-tolerant tomato (Lycopersicon esculentum Mill. cvs. Saladette, PI 262934, BL6807, S6916, CIAS161, and VF36) were studied at 38/27°C day/night temperature. Flower production was reduced in all cultivars except BL6807 which partitioned a greater proportion of total assimilates to the flowers. Only ‘Saladette’ and VF36 showed a total lack of stigma exsertion, which in effect is functional male sterility. Pollen production was reduced in all cultivars, and there was a lack of pollen dehiscence. Several techniques were used to evaluate gamete viability. There was poor agreement among the 3 methods used to assess pollen viability. ‘Saladette’ suffered the least reduction for in vitro germination but had the greatest loss in seed set when high-temperature pollen was used. Seed set is probably the most reliable method to measure gamete viability. CIAS 161 and S6916 had the least reduction in pollen viability according to seed set criteria. Ovule viability is much more difficult to adequately evaluate. According to seed set criteria PI 262934 ovules suffered the least damage due to high temperatures. Whether the male or female gamete was affected more severely depended on genotype. Pollen viability was greatly reduced in PI 262934 but ovule viability was less severely affected. In BL6807 ovule viability was more severely reduced than pollen viability.
Abstract
Three tomato (Lycopersicon esculentum Mill.) lines with divergent viscosities and their F1, BCP1, BCP2, and F2 progeny were analyzed for serum viscosity, gross viscosity, and five alcohol insoluble solids (AIS) components. The components were water soluble polysaccharides and polygalacturonides, water-insoluble polysaccharides and polygalacturonides, and acid-hydrolyzed polysaccharides. Stepwise regression analysis of data from parents and progeny was used to establish the relationships between a change in composition and a change in viscosity. The polygalacturonides accounted for most of the variation in gross viscosity among the parental lines. The data indicate that water-insoluble, pectinol-solubilized polysaccharides have the potential for making a large contribution to viscosity at higher concn. The water-soluble polysaccharides and complex polysaccharides (solublized in H2SO4) contributed little to gross viscosity. The sugars identified in the AIS were arabinose, ribose, xylose, mannose, galactose, and glucose. Galacturonic acid was the only organic acid detected. Concentration of the compounds varied among the fractions and among the parental lines.
Abstract
The genetics of high-temperature fruit set was studied with a complete diallel cross using 5 cultivars with excellent high temperature tolerance and a California cultivar lacking stigma exsertion. The cultivars differed genetically for number of flowers per cluster, percent fruit set, number of seeds per fruit and stigma exsertion. At normal and high temperatures recessive genes are associated with greater flower number and heritability for this character was high. Percent fruit set is under the control of a largely additive system with a moderate heritability at high temperature. Nonallelic gene interaction was involved in seed set and dominance components exceeded additive at both temperatures. Heritability for seed set was low at high temperature. Stigma exsertion at high temperature is controlled by partially dominant genes with a high diallel additive component and heritability. The results suggest that a scheme of selection for specific combining ability would be useful to combine the strengths of the high temperature tolerant lines with needed characters from a successful cultivar.