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Stephen J. Tancred, Aldo G. Zeppa, Mark Cooper, and Joanne K. Stringer

A major objective of the apple (Malus domestica Borkh.) breeding program in Stanthorpe, Australia, is to develop early ripening, high-quality cultivars. The heritability and inheritance of ripening date was investigated. Regression of offspring on midparent harvest dates and estimation of best linear unbiased predictions for parents were used to demonstrate that apple harvest date is highly heritable. Predominantly, additive genetic components of variance are responsible for the variation. Despite the existence of some specific combining ability variance and some non-normal family distributions, the best strategy for a breeder to predict the harvest date of progeny is to calculate the mean harvest date of parents.

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T.E. Thompson and J.F. Baker

Abbreviation: h 2 , heritability. 1 Research Geneticist. 2 Assistant Professor.

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Xuan Wu, Shuyin Liang, and David H. Byrne

its first flush and growth phase during the spring and early-summer months, but also during the second growth phase in mid- to late-summer and fall months. The broad-sense heritability of rose architectural traits has been estimated using a set of

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M. Courtney, M. Mcharo, D. La Bonte, and W. Gruneberg

increased iron and zinc content as ascertained by broad-sense heritability estimates using a novel technique. Materials and Methods Plant material and experimental design. Field research was done at the Sweetpotato Research Center at Chase, LA

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Gabriele Gusmini and Todd C. Wehner

, 1988 ). Several methods of estimating heritability and predicting selection response are available. Primarily, these methods partition the total variance into genetic and environmental variances, and the genetic variance into additive and dominance

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Jennifer Johnson-Cicalese, James J. Polashock, Josh A. Honig, Jennifer Vaiciunas, Daniel L. Ward, and Nicholi Vorsa

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

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Dennis T. Ray, Maren Elizabeth Veatch-Blohm, Valerie Hunter Teetor, and Bruce Walsh

characteristics with high heritabilities, indicating low environmental effects. Heritability estimates of the traits associated with rubber concentration and rubber yield have been variable. In a study by Dierig et al. (2001) , variance from measured traits of

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Rachel A. Itle, Eileen A. Kabelka, and James W. Olmstead

of both parents. A colorimeter may enable faster and more accurate selection of desirable individuals at various stages in a breeding program for flesh color. In addition, knowledge of the heritability of flesh color genes would give the plant

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Paul G. Thompson, John C. Schneider, and Boyett Graves

Narrow-sense heritabilities (h2) for sweetpotato weevil (Cylas formicarius elegantulus) resistance were estimated in 2 breeding populations. Population A included clones from US programs with previously reported moderate levels of weevil resistance. Population B included clones of US origin plusplant introductions from 14 countries. Parents and progenies were included in field evaluations with no wild weevils present. Weevils were cultured and applied to each plant. Population A was evaluated for 2 years and population B for 1. The GXE estimate for population A was also used for population B. Heritabilities were estimated by parent offspring regression and variance component analysis. Average h2 for percentage noninjured roots were 0.35 and 0.47 for population A and B, respectively. Intermating highest performing genotypes from both populations should increase h2 by increasing frequencies of resistance genes. A moderate rate of increase in resistance levels should result from selecting and intermating resistant genotypes.

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Austin L. Grimshaw, Yuanshuo Qu, William A. Meyer, Eric Watkins, and Stacy A. Bonos

or traffic tolerance in any turfgrass species. Understanding the genetic and environmental effects on the phenotypic expression of a trait is useful to develop a breeding strategy to improve the trait. Heritability determines the amount of variability