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Linda Wessel-Beaver and J.W. Scott

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

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Verónica Raga, Guillermo P. Bernet, Emilio A. Carbonell, and Maria J. Asins

hybrids included in both treatments in all years ( InfoStat, 2004 ). Considering rootstocks as a random effects factor, broad-sense heritability (H 2 ) was estimated for all traits evaluated in 2008 only for nucellar rootstocks (repetitions) derived from

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Dennis Ray, Steven Smith, and Mark Hurlburt

Lettuce (Lactuca Sativa L.) seeds imbibe water but most fail to germinate, This phenomenon now termed “thermodormancy” is prevalent in arid and semiarid climates like the southwest desert regions, Inheritance studies of thermodormancy were performed in two lettuce cultivars, Dabora (Dutch butterhead) and PI 251245 (a plant introduction from Egypt). Dabora will germinate up to 27 C and PI 251245 up to 36C. Reciprocal crosses were made. Pericarp color was used as a marker to determine successful crosses. Dabora X PI 251245 was used to estimate the heritability of thermodormancy by germinating seed from 10 F3 families and 160 F4 families at “high” temperatures.

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Creighton Gupton and James Spiers

To determine whether manganese tolerance in rabbiteye blueberry (Vaccinium ashei Reade) is heritable, a 10-parent diallel cross was produced. A 250 ppm Mn solution (200 ml/plant) was applied to a sand culture, of the progeny daily. Visual ratings (1 - dead plant - 13 - no Mn toxicity symptom) were made after 6 weeks. Shoot weight and Mn content of leaves were determined. Narrow-sense heritability estimates (h2) were 0.45±0.28 for Mn content, 0.49±0.27 for visual ratings, and 0.37± 0.21 for shoot weight. The genetic correlation between neither shoot weight nor visual rating and Mn content (0.11 and -0.15, respectively) was very high; however, the correlation between shoot weight and visual ratings (1.00) was extremely high. This suggests that visual ratings provide an estimate of Mn effects on plans equal to objective measurements of shoot weight. Though h2 estimates for Mn content and visual ratings were similar, the lack of genetic correlation between the traits indicates that tolerance to Mn toxicity is independent of Mn content. The high h2 for visual ratings suggests mass selection as the method of choice for improving Mn tolerance in a rabbiteye blueberry population.

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Vance M. Whitaker, Luis F. Osorio, Tomas Hasing, and Salvador Gezan

( Whitaker et al., 2011 ). Although SSC and TA varied widely among genotypes, clear trends over time could not be observed for these traits. Until recently, there have been no published reports of genetic parameters such as heritabilities and genetic

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Creighton L. Gupton and Barbara J. Smith

A study was conducted to determine if blackberry cultivars Humble, Rosborough, and Brazos transmit rosette (incited by Cercosporella rubi) resistance and to estimate heritability (h2). Plants of parents and offspring involving these cultivars were rated for rosette severity on a whole plant basis from 0 = no rosette to 7 = all buds infected or plant dead. An estimate of h2 was computed by regression of cross means on parental means. The mean rosette severity rating of plants from crosses was always intermediate between the cultivar and other parents. Only `Humble' transmitted enough rosette tolerance to be usable although `Rosborough' crosses were more tolerant than the other parents. The h2 estimate of 0.48 was fairly high but low variability among parents other than `Humble' would suggest little progress from mass selection.

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Abe Shegro Gerrano, Patrick Olusanmi Adebola, Willem Sternberg Jansen van Rensburg, and Sonja Louise Venter

, however, requires information on the genetic variability that exists among available germplasm. Information on the genetic heritability and genetic advance of the targeted traits is also important for efficient selection. This study was therefore carried

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C.A. Weber

A partial diallel design was used to investigate the inheritance of tolerance to terbacil herbicide in cultivated strawberry, Fragaria ×ananassa Duch. Two tolerant cultivars, `Honeoye' and `Earliglow', two moderately tolerant cultivars, `Lester' and `Allstar', and two susceptible cultivars, `Red Chief' and `Guardian' were used as parents to create populations that segregated for tolerance to the herbicide. Tolerance rankings of the populations closely coincided with expected rankings based on the published tolerance levels of parental cultivars. `Honeoye' and `Earliglow' derived populations had the highest average tolerance ratings, while `Guardian' derived populations had the lowest tolerance ratings. Heritability was estimated at h2 = 0.50, indicating that significant progress in increasing the tolerance of new cultivars to terbacil can be achieved through traditional recurrent selection procedures. General and specific combining abilities suggest that the tolerant cultivars in this study may be fixed in their tolerance and that increased mean tolerance will be most apparent in progenies combining tolerant and susceptible cultivars. As such, a broader pool of germplasm may be needed to develop cultivars that are more tolerant than those in this study. Chemical names: terbacil (3-tert-butyl-5-chloro-6-methyluracil)

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M. Joseph Stephens, Jessica Scalzo, Peter A. Alspach, Ron A. Beatson, and Ann Marie Connor

are certain components that are likely to be better correlated with yield and are more heritable. Dale and Daubeny (1985) showed that high yield in raspberries was closely related to high lateral numbers in Abbotsford, British Columbia, Canada, and

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M. Joseph Stephens, Peter A. Alspach, Ron A. Beatson, Chris Winefield, and Emily J. Buck

antioxidants found in relatively high concentrations in raspberries ( Barritt and Torre, 1975 ) and may contribute to high health properties of raspberry ( Olsson et al., 2004 ). These compounds are genetically inherited and have high heritability in raspberry