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  • Author or Editor: E. C. Tigchelaar x
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Abstract

Changes in respiration, ethylene production, firmness, pectolytic enzyme activity and carotenoid accumulation during ripening were monitored in fruit of a segregating population of the non-ripening (nor) mutant of tomato (Lycopersicon esculentum Mill.). In fruit from mutant (nor/nor) plants, no respiratory or ethylene climacteric was observed, firmness declined very slowly with only trace levels of polygalacturonase present in mature fruit and phytoene, β-carotene and neurosporene were the major carotenes. In very old fruit (120 days’ post-anthesis), lycopene and β-carotene were the predominant carotenoids, however lycopene content was less than 10% of normal.

Ripening of fruit from heterozygous (nor+/nor) plants was delayed and occurred more slowly than for normal (nor+/nor+ ) fruit. The respiratory climacteric was partially suppressed, peak ethylene production was one-sixth of normal, fruit softening was retarded, and polygalacturonase activity was lower at comparable maturity stages. Fruit from heterozygous (nor+nor) plants accumulated lycopene, gamma-carotene, phytofluene, and phytoene at a slower rate, but β-carotene accumulation was similar to normal. A mechanism for action of nor in control of ripening is proposed.

Open Access

Abstract

The inheritance of low temperature seed sprouting ability in tomato (Lycopersicon esculentum Mill.) was found to be polygenic with dominance for inability to germinate at suboptimal temperatures. A minimum of 3 genes is suggested from F2 data and a minimum of 5 genes from backcross results. Broad sense heritability was estimated at 97%; narrow sense heritability, at 66%.

Genes controlling determinate, brachytic, and dwarf habits of growth had no significant effect upon subsequent low temperature sprouting response in the F2 generation. Significant differences in ability to germinate at low temperatures were found among reciprocal F1’s.

Open Access

Abstract

‘Lafayette‘ is a compact, determinate tomato (Lycopersicon esculentum Mill.) intended for mechanical harvest. It was named for the city of Lafayette, Indiana.

Open Access

Abstract

‘Vermillion’ is a productive, determinate, crimson tomato (Lycopersicon esculentum Mill.) with excellent fruit color. Its name, which gives attention to its outstanding fruit color, honors a county in Indiana.

Open Access

Abstract

Ripening is a dramatic event in the development of many fleshy fruits. Tomato ripening involves a number of chemical and physical changes which convert the fruit from a relatively inedible state to one of optimal quality (2, 19). These changes appear to be highly synchronized, as evidenced by the fact that respiratory patterns, rate of ethylene production, carotene development, and flavor and textural changes normally associated with the ripening process, occur in close succession during the relatively short period in which the fruit ripens (2, 22). The association of these changes with seed maturation supports the popular view that ripening is of adaptive significance in seed dispersal by rendering fruit attractive to animals responsible for dispersal.

Open Access

Abstract

Fruits from normal-ripening genotypes of tomato (Lycopersicon esculentum Mill.) attained a similar level of color regardless of stage at harvest (red, pink, breaker, and mature green). Color of fruits from F1, nor hybrids (nor × normal) when harvested red was similar to that of normal fruits but less color developed when harvested at the pink or less mature stages.

Open Access

Abstract

Estimation of breeding progress in 9 tomato populations subject to 4 generations of pedigree selection revealed significant generation differences for 5 of 12 variables measured. Cross effects were of greater magnitude than generation effects with response to pedigree selection measurable only for highly heritable characters.

Mean value of lines derived from 2 or 3 generations of pedigree selection followed by single seed descent (SSD) to F6 or F7 were similar to their corresponding pedigree lines and approximately 50% of SSD lines derived following selection to F4 surpassed pedigree lines in weighted value. Early generation pedigree selection to F4 followed by selection among F6 SSD derived lines appears to be the most rapid and effective means of sampling variability in segregating populations.

Open Access

Abstract

Computer simulation was used to compare breeding progress under self fertilization with pedigree or mass selection, single seed descent (SSD) and combinations of early generation pedigree or mass selection with SSD. Pedigree selection was the most effective selection method at high (75%) and moderate (50%) heritabilities. At low (25%) and very low (10%) heritabilities, mass selection and SSD respectively yielded the best single F6 line. Early generation pedigree selection to F4 followed by SSD was not significantly different from pedigree selection alone at all heritabilities simulated.

SSD offers greatest benefits in situations where simultaneous selection is required for several characteristics under different heritabilities. SSD alone or in combination with mass selection retained greater genetic variability for line selection in F6. Pedigree or mass selection for highly heritable characters in early generations (F2 and F3) followed by SSD and F6 selection on the basis of line performance for characters of low heritability would appear to maximize progress for most breeding situations.

Open Access

Abstract

The chlorophyll intensifíer mutations high pigment (hp) and dark green (dg) of tomato (Lycopersicon esculentum Mill.) were analyzed for their effects on fruit and vegetative characters. These mutations are nonallelic, and differences between them are primarily quantitative. Both mutations increased Vitamin C content at all stages of fruit development, and more than 90% was present in the reduced form in the mature-green and fully ripe mutant types and in normal fruit. Ascorbate levels in all fruit portions were increased by hp and dg, with the largest increase occurring in the outer pericarp. Chlorophyll in outer pericarp tissue of mutant fruit was increased 166% by hp and 320% by dg. Mutant fruit were smaller and more elongate than isogenic normal controls, but ripening was unaffected by either mutation. Vegetative and reproductive development were retarded by both chlorophyll intensifier mutations. The hp and dg mutations significantly reduced total leaf area, internode length, and whole plant fresh and dry weight, but did not reduce the number of nodes present at a particular stage of development. The effects of dg were always quantitatively greater than for hp. The similarity of effects associated with these 2 nonallelic mutants suggests that pleiotropy rather than close linkage accounts for the multiple effects of these genes.

Open Access

Abstract

The fruit ripening behavior of the green ripe mutant (Gr) of tomato (Lycopersicon esculentum Mill.) was examined. Green ripe fruit are climacteric and evolve increasing amounts of ethylene after harvest; however, the time course for these events is dramatically altered in comparison with ‘Rutgers’. Maximal rates of C2H4 evolution from Gr fruit were achieved 20 days after the initial increase, and 7 to 10 days prior to maximal respiratory rates. Fruit age at harvest did not affect either the rate or the magnitude of these processes. Wavelength scans of pigment extracts from 60 day postharvest Gr fruit indicated low levels of carotenoids. Mutant fruit also remain firm a long time after harvest. Polygalacturonase activity in Gr fruit increases with fruit age, but reaches only 3% to 5% of the total activity in ‘Rutgers’. PG activity was only slightly reduced when extracts were heated to 65°C for 5 min, suggesting that a heat stable isoenzyme of PG is predominant in mature mutant fruit in contrast to ‘Rutgers’ in which 90% to 95% of PG activity in ripe fruit is heat labile under these conditions. When heterozygous, the Gr mutation is dominant in its effects on total PG activity and on the time course from the initiation of C2H4 and respiratory increases to their maximal rates of evolution. The magnitude of other changes in heterozygous mutant fruit was intermediate between normal and homozygous Gr.

Open Access