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  • Author or Editor: Wayne B. Sherman x
  • Journal of the American Society for Horticultural Science x
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Abstract

Attempts to select for flower bud chilling requirement (CR) at the seed stage were made in 58 families obtained from crosses and open-pollination of low chill selections and cultivars of peach and nectarine [Prunus persica (L.) Batsch] from the Florida breeding program. A nonsignificant correlation (r = 0.08) between midparent bud CR and family seed CR was obtained. A low significant correlation (r = 0.21**) was obtained between individual seed CR and the CR of the resultant seedling. Seed coat removal had no effect on these correlations. Narrow sense heritability for bud CR as determined by parent-offspring regression was 0.50 ± 0.06. The small range in CR of the seed and pollen parents, 300 to 450 and 200 to 400 chill units, respectively, may explain the low correlation values obtained. The data suggest that it is impractical to screen for seedling CR based on seed CR where the CR for climatic adaptability must be held within a range of less than 300 chill units.

Open Access

Southern analysis of two ripening-related polygalacturonase (PG) genes of peach [Prunus persica (L.) Batsch] detected a restriction fragment length polymorphism (RFLP) in one that had been previously identified as encoding the endoPG enzyme of melting flesh fruit. This RFLP distinguished the melting flesh cultivars Flavorcrest and Flordaking from the nonmelting flesh cultivars Carolyn, Early Gold Queen, Fla. 86-28C, and Fla. 9-26C. Complete deletion of endoPG-related genomic sequences was demonstrated in the nonmelting flesh variety Fla. 9-20C. In a blind trial, segregation of the endoPG RFLP was followed in relation to the melting flesh trait in a population of 20 trees from `Fla. 86-28C' × `Springcrest' in which the trait was segregating 1:1. Cosegregation of the RFLP with the trait occurred for 17 out of 20 trees. Practical aspects of scoring the melting flesh trait in a genetically variable population may account for incomplete segregation. EndoPG protein was detected by western blotting in fruit of the melting flesh cultivars Flavorcrest and Fragar, but not in fruit of the nonmelting flesh cultivar Carolyn. Results from this study and earlier work are used to discuss the hypothesis that the endoPG gene corresponds to the melting flesh (M) locus of peach.

Free access

Abstract

Detached shoots of double-flowered peach [Prunus persica (L.) Batsch] selections Fla. 6-1 and Fla. 0-5 were successfully opened in floral solutions containing 1 to 10% sucrose in deionized water. Addition of 8-hydroxyquinoline citrate (8-HQC), gibberellic acid (GA3), or 6-benzylaminopurine (BA) to solutions did not extend vase life. Solution uptake rate decreased over the 8-day life of the shoots and was influenced by solution molarity. Xylem plugging by pectic-type materials increased with time in solution. Addition of 1% ethanol to the floral solution hastened time of first opening, decreased the extent of xylem plugging, and extended vase life. Ethanol at 2% extended vase life and increased solution uptake rate over solutions containing sucrose alone.

Open Access

Abstract

A 10-year analysis of the high-density nursery (HDN) in the breeding of low-chilling peach and nectarine [Prunus persica (L.) Batsch] cultivars indicated selection was effective during the first cropping year for chilling requirement, fruit development period, size, color, shape and firmness but not for crop load, which needs to be evaluated at normal spacing over several years. The HDN system effectively has advanced the breeding program by promoting short generation time, reducing labor and space, and allowing for rating of some characters within 2 years from seed.

Open Access

Abstract

Starch gel electrophoresis of leaf tissue samples was used to distinguish pineapple [Ananas comosus (L.) Merr.] cultivars. Isozyme genotypes at two peroxidase and three phosphoglucomutase loci allowed the unique identification of 15 of the 27 cultivars examined. The hypotheses that some cultivars originated as either sports or hybrids were confirmed by the allozyme data.

Open Access

Potential maturity indices were determined for two melting-flesh (FL 90-20 and `TropicBeauty') and two nonmelting-flesh (`Oro A'and Fl 86-28C) peach [Prunus persica (L.) Batsch.] genotypes. A range of developmental stages was obtained by conducting two harvests and separating the fruit based on diameter. Fruit in each category were divided into two groups. One group was used to determine potential maturity indices: soluble solids, titratable acidity, soluble solids to titratable acidity ratio, peel and flesh color on the cheeks and blossom end, cheek and blossom-end firmness, ethylene production, and respiration rate. The other group was stored at 0 °C for 1 week and ripened at 20 °C for 2 days to simulate handling conditions and presented to a trained sensory panel, which rated the fruit for three textural aspects (hardness, rubberiness, and juiciness) and six flavor aspects (sweetness, sourness, bitterness, and green, peachy, and overripe character). Principal component (PC) analysis was used to consolidate the results of the descriptive sensory evaluation into a single variable that could be correlated with the objective measurements at harvest. The attributes that best correlated with the first sensory PC of each genotype, and thus are promising maturity indices, were as follows: for FL 90-20, peel hue, peel L, and cheek firmness; for `TropicBeauty', peel L, cheek firmness, and blossom-end firmness; for `Oro A', cheek firmness, blossom-end firmness, and cheek chroma; and for 86-28C, blossom-end firmness, cheek hue, and cheek firmness.

Free access

A study to compare the response to postharvest chilling (4 °C) for up to 3 weeks of melting-flesh (MF)—FL 90-20, FL 90-21W, and FL 91-16—and nonmelting-flesh (NMF)—`Oro A', FL 90-35C, and FL 90-47C—peach (Prunus persica L.) genotypes revealed that MF fruit were notably more susceptible to the development of mealiness than NMF types. Cell separation in mealy fruit was demonstrated by the release of mesocarp cells to an aqueous medium, allowing determination of mealiness severity. At a histological level, chilling brought about an impressive expansion of the intercellular spaces in MF mesocarp tissue but did not affect NMF fruit. A decrease in flesh electrical resistance after 1 week of chilling was observed only in MF fruit. However, electrical resistance increased in MF and NMF fruit following 2 and 3 weeks at 4 °C. Electrical resistance also decreased with ripening of MF fruit but did not change when NMF fruit were ripened. Unlike NMF fruit, the MF genotypes FL 90-21W and FL 91-16 showed an increase in respiration rate due to chilling. The rate of ethylene production decreased after 1 week at 4 °C in MF and NMF genotypes. However, two MF and two NMF genotypes exhibited rising ethylene levels after the second week of storage at 4 °C, while ethylene production in one MF and one NMF genotype continued to decline.

Free access