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Zhuping Fan, Yike Gao, Ling Guo, Ying Cao, Rong Liu, and Qixiang Zhang

, 2000 ). Therefore, systematic scientific research is important to investigate trait inheritance in bearded iris. Heritability evaluation is one of the most fundamental steps in a breeding program to gain access to new genetic changes and to create new

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P. E. Hansche

Abstract

The feasibility of genetically curtailing the period of sexual repression in peach and nectarine seedlings was studied by assessing the propensity of 2-year-old seedlings in a dwarf peach and nectarine breeding stock to produce flowers and fruit. Mean flower number, in a breeding stock comprising about 6300 seedlings from about 300 families, was estimated to be 9 per 2-year-old seedling; with a narrow sense heritability 0.16 ± 0.02. Mean fruit number in this population was estimated to be 3.7 per 2-year-old seedling; with a heritability of 0.33 ± 0.03. It was estimated that 3 cycles of “mass selection” on this trait could increase mean fruit number to about 13 per 2-year-old seedling, thus facilitating a reduction in the minimum length of selection cycles in this breeding stock from 3 to 2 years.

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Ali Akbar Ghasemi Soloklui, Ali Gharaghani, Nnadozie Oraguzie, and Armin Saed-Moucheshi

., 2000 ). Genetic studies on winterhardiness of pomegranate are limited. A review of the literature on temperate fruit crops shows that heritability estimates have been generated for several aspects of freezing tolerance in a few fruit crops (including

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John R. Stommel, Mary J. Camp, Judith M. Dumm, Kathleen G. Haynes, Yaguang Luo, and Anne Marie Schoevaars

attributes are few. This may be attributed to the expertise and resources often required to conduct postharvest assessment of quality attributes. The current report evaluates the heritability of postharvest attributes that contribute to fresh-cut product

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Shuyin Liang, Xuan Wu, and David Byrne

-sense heritability. Heritability is the proportion of variance that is due to genetic components and can be used to determine the appropriate breeding approach. Heritability varies widely for the same trait in the same crop because of statistical designs, different

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Paul E. Hansche and Buck Boynton

Abstract

Heritabilities were estimated for 4 measures of bruise-induced enzymatic browning in peaches (Prunus persica L.) Batsch. Two were direct measures: intensity of the brown color (IB) and the diameter of the brown region (DB). Two were indirect measures: activity of polyphenyloxydase (PPO) and the concentration of polyphenols (PPC). The heritability of IB was moderately high (0.35 ± 0.04). That of DB was not significantly different from zero (0.08 ± 0.06). The heritability of PPC was reasonably high (0.38 ± 0.05), and that of PPO moderate (0.26 ± 0.04). Because the heritabilities of IB and PPC are about equal, the rate of reduction in IB resulting from selection on PPC should not be expected to be as great as that resulting from direct selection applied to IB. Thus, at present it appears that the direct measure of IB provides breeders with the best measure, among the 4 studied, of the susceptibility of seedlings to bruise-induced enzymatic browning.

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Hassan Hajnajari, Bahaeddin Chashnidel, Kourosh Vahdati, Mohsen Ebrahimi, Alireza Nabipour, and Esmaeil Fallahi

traits for progeny selection in the breeding program demands genetic studies to distinguish the environmental and the genetic variances from the phenotypic variances, to calculate the expected genetic contribution in the form of heritability, and to

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Jesse Vorwald and James Nienhuis

successful product, knowledge is needed regarding the heritabilities and genetic relationships among seed and popping characteristics in a temperate-adapted nuña bean population derived from Andean landraces. The objective of this research was to develop a

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Uri Lavi, Emanuel Lahav, Chemda Degani, Shmuel Gazit, and Jossi Hillel

Genetic variance components for avocado (Persea americana Mill.) traits were estimated to improve avocado breeding efficiency. The additive and nonadditive genetic variance components were calculated from the variances between and within crosses. In all nine traits examined, i.e.-anise scent, fruit density, flowering intensity, fruit weight, harvest duration, inflorescence length, seed size, softening time, and tree size-a significant nonadditive genetic variance was detected. Additive genetic variance in all traits was lower and nonsignificant. The existence of major nonadditive variance was indicated also by narrow-sense and broad-sense heritability values estimated for each trait. Therefore, parental selection should not be based solely on cultivar performance. Crosses between parents of medium and perhaps even low performance should also be included in the breeding program.

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Paul E. Hansche

Abstract

Means and heritabilities were estimated for the 2 fruit quality defects of dw/dw peach and nectarine [Prunus persica (L.) Batsch] genotypes that obstruct the commercial exploitation of the advantages inherent in their dwarf growth habit. The average dw/dw peach has substandard taste and too little blush for commercial acceptance. The average dw/dw nectarine also has substandard taste. In addition, it has substandard surface polish. The heritability of taste (as measured by percentage of soluble solids) in UCD's dwarf peach breeding stock was estimated to be 0.17 ± 0.04. The heritability of amount of surface blush was estimated to be 0.19 ± 0.04. The heritability of percentage of soluble solids in UCD's dwarf nectarine breeding stock was estimated to be 0.35 ± 0.04; of sweetness 0.19 ± 0.09; and of flavor 0.16 ± 0.06. The heritability of skin polish was estimated to be 0.24 ± 0.13. As expected, dw appears to have little or no effect on means or heritabilities of fruit weight, fruit firmness, or ripe date. The implications of these results are discussed.