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
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.
Abbreviation: h 2 , heritability. 1 Research Geneticist. 2 Assistant Professor.
crosses with the ultimate goal of introgressing FRR into productive backgrounds. The objectives of this study were to: 1) determine heritability of field FRR from an array of crosses using midparent–offspring regression; 2) further genetically define the
conditions. Effective breeding requires both genetic variation and heritability for attributes of interest. Therefore, the objectives of this study were to assess variation for biochemical and physiological parameters associated with freezing tolerance in
fruit size. Although all yield components interact with environmental influences to produce total yield, from a breeding point of view, there are key components that are likely to be better correlated with yield and are more heritable. We found few
Abbreviations: CR, chilling requirement; CU, chill unit; GDH, growing degree hours; H 2 , heritability; I 50 , index of bud activity; OP, open-pollinated. 1 Present address: IAPAR-lnstituto Agronômico do Paraná, P.O. Box 2301, Curitiba, PR, Brazil
of inheritance, heritability, and the possible candidate genes are all unknown for this crop. These factors are critical impediments to efficient breeding of watermelon cultivars in a changing environment, and especially for the United States where
Realized heritability estimates of bolting percentage, pink root and fusarium basal rot severities and incidences, and percentage of single-centered bulbs were estimated for half-sib families of an intermediate-day, open-pollinated onion (Allium cepa L.) population using selection response analysis. Half-sib families were selected based upon an index that equally weighted bolting percentage, pink root and fusarium basal rot severities and incidences, percentage of single-centered bulbs, and bulb quality. Families were subjected to one cycle of half-sib family recurrent selection. Pink root and fusarium basal rot severity was reduced by 17% and 7%, respectively, with realized heritability estimates of 1.28 and 0.65, respectively. More progress for pink root severity was made than was selected. Disease incidence was reduced by 18% and 12%, respectively, with heritability estimates of 0.65 and 0.60, respectively. Very little progress was made for the percentage of single-centered bulbs and this was reflected in a heritability estimate of 0.17. Selection based upon multiple characters at the same time may reduce the effectiveness of making improvements in a single trait. However even with low to moderate heritability, improvements were made, and suggest that further improvements can be made through selection.
Abbreviations: G × E, genotype × environment; h 2 , heritability. 1 Professor. 2 Associate Professor. Florida Agricultural Experiment Station Journal Series no. R-02374. This research was supported in part by the U.S. Dept. of Agriculture under CSRS