genotypes Crop Sci. 42 6 1950 1958 Robertson, A. 1959 The sampling variance of the genetic correlation coefficient Biometrics 5 469 485 Sharma, J.R. 1988 Statistical and biometrical techniques in plant breeding. New Age International (P) Limited Publishers
Guo-Liang Jiang, Laban K. Rutto and Shuxin Ren
Paul G. Thompson, J. C. Schneider, Boyett Graves and B. K. Kim
Twenty-four half-sib sweetpotato families were field tested for freedom from injury by sweetpotato weevil and other soil inhabiting, injurious insects (WDS). Three pairs of adult male and female weevils were applied to the crown of each plant at the beginning of storage root enlargement. Naturally occurring numbers of WDS were high enough for considerable injury from those insects. WDS injury free roots ranged from 19% in Centennial, the suceptible control, to 57% in Regal, the resistant control. The highest family mean for percent non-injured by WDS was 55%. Weevil injury free roots ranged from 67% in Centennial to 90% in Regal with 3 families producing mean weevil non-injured roots of 89%. The genetic correlation between weevil injury free and WDS injury free roots was 0.69 ± 0.28. That estimate is preliminary and based on data from one environment. Evaluations will be repeated in 1994 for estimates of GXE to derive genetic correlation estimates with less environmental interactions.
M. Joseph Stephens, Peter A. Alspach, Ron A. Beatson, Chris Winefield and Emily J. Buck
positive ( Table 3 ). For TYLD, strong (i.e., greater than 0.5) positive genetic correlations were found with BWT, CLEN, and NFRT, whereas those with NCAN and NBUD were negligible. Of particular interest are those pairs of traits for which the genetic
M. Joseph Stephens, Peter A. Alspach, Ron A. Beatson, Chris Winefield and Emily J. Buck
variance, whereas the genetic correlation includes only additive genetic variance, excludes environmental variance, and can also be derived from correlation of eBV. BLUP breeding values were obtained for the seedlings from the univariate analysis. Because
Douglas V. Shaw
The heritabilities of, and genetic correlations among, variables that describe internal and external color in fresh strawberry (Fragaria × anarrassa) fruit were estimated using factorial analyses of seedlings from 20 controlled crosses. Hunter L and a values, and a subjective score generated by comparison with color plates were obtained for seedling genotypes and their parents at two locations. Genetic effects were responsible for 33% to 61% of the phenotypic variance for color traits, after correction for location effects. Means for objective color variables differed significantly between locations, but means for subjective color scores did not. Genetic × location interaction variances were usually nonsignificant, and were < 12% of the phenotypic variance for all variables. Phenotypic and genetic correlations between objective and subjective color scores were significant and large (absolute values of r = 0.42-0.69; rg = 0.84-1.00). Multiple regression of subjective scores on L and a explained 69% and 59% of the phenotypic variation for external and internal color, respectively. Genetic correlations between measures of internal and external color were small and mostly nonsignificant, suggesting that separate sets of genes condition these traits.
Xurong Tang and Peter M.A. Tigerstedt
Eight characters relating to flowering and maturity, berry yield, and winter hardiness were estimated on the basis of intersubspecific or interprovenance hybrids to determine heterosis, heritability, and genetic and phenotypic correlations in sea buckthorn (Hippophae rhamnoides L.). Two provenances of ssp. rhamnoides, one of Finnish (Fin) and one of Danish (Dan) origin, were dominant to ssp. sinensis and Russian derived provenances (ssp. turkestanica) for most characters related to flowering or maturity. This tendency for dominance or overdominance also extended to berry yield and winter hardiness, except for hybrids between Finnish origins and Siberian (ssp. mongolica) origins. The start of maturity (Ms) and half maturity (Mh) showed the highest heritabilities (h2 = 0.88 and 0.81, respectively). The hybrids were matroclinal, suggesting that Ms and Mh may be sex-linked or cytoplasmically inherited characters. Winter hardiness was the trait with the lowest heritability (h2 = 0.02), suggesting that the climate at the testing site was not severe enough to differentiate variation among half sibs or full sibs derived from Fin x Dan, which on average proved hardier than the native parental provenance Fin. Full maturity (Mf) showed a moderate heritability but was stable across 2 years (rB = 1). High genetic correlations among Mf, Ms, and Mh (rG = 0.94, 0.96, and 1.00, respectively) suggest that these characters were controlled by the same genes. Yield showed a negative genetic correlation with all characters pertaining to flowering and maturity, indicating that selection for early flowering or early maturity should result in a gain in yield.
James J. Luby and Douglas V. Shaw
establish the environmental and experimental components that affect quality components before they can effectively hope to alter the genetic component. ASSOCIATIONS BETWEEN TRAITS: PHENOTYPIC, GENOTYPIC, AND GENETIC CORRELATIONS Because a successful
Ann Marie Connor, M. Joseph Stephens, Harvey K. Hall and Peter A. Alspach
Variance components and narrow-sense heritabilities were estimated for antioxidant activity (AA), total phenolic content (TPH), and fruit weight in red raspberry (Rubus idaeus L.) fruit from offspring of a factorial mating design. Forty-two full-sib families utilizing seven female and six male parents were evaluated in each of two years in Motueka, New Zealand. In a single year, values within individual half-sib families ranged as widely as 25.3-79.4 μg·g-1 fruit for AA, 205-597 mg/100 g fruit for TPH, and 1.06-7.69 g for fruit weight. Analyses of variance for these three variates demonstrated significant parental source variation in both individual and combined year analyses. For AA and TPH, female parental effects accounted for ≈7% to 19% of total variation, while male effects accounted for ≈6% to 8%. A partially pigment deficient R. parvifolius L. derivative female parent accounted for some of these differences. Female × male parent interaction was not significant for AA and TPH and was marginally significant for fruit weight in combined year analysis. Year had a significant effect on the overall mean AA and TPH, but contributed less than genetic effects to the overall variation in all three traits. Interactions of year with genetic effects were not statistically significant for AA or TPH, indicating that between-year rank or scale changes among families were negligible. The largest proportion of variation was found within rather than among full-sib families. However, variation among plots within full-sib families accounted for 12% to 19% of total variation, indicating environmental differences accounted for some of the observed within-family variation in AA and TPH. Antioxidant activity and TPH were highly phenotypically correlated (r = 0.93); their genetic correlation (r = 0.59) implies that substantial additive genetic factors underlie the phenotypic correlation, but that nonadditive genetic or environmental influences are also important. Both AA and TPH were weakly negatively phenotypically correlated with fruit weight (r = -0.34 and -0.33, respectively), but the corresponding genetic correlations were close to zero. Thus, selection for both high AA or TPH and high fruit weight is possible. Narrow-sense heritability estimates based on variance components from combined year data were h 2 = 0.54, 0.48, and 0.77 for AA, TPH, and fruit weight, respectively. These estimates imply a rapid response to selection is possible.
Linda Wessel-Beaver and J.W. Scott
Heritabilities (h2) and genetic correlations between percent fruit set, yield, and fruit weight were estimated from one summer planting each in Florida and Puerto Rico of 100 S, tomato (Lycopersicon esculentum Mill.) families from a synthetic population. Single-location h2 was high for all traits. Across-locations h2 was low for yield, intermediate for fruit set, and high for fruit weight. Genotype × environment interaction (G × E) was 1) the only significant component of variance for yield, 2) somewhat important for fruit set, and 3) not an important variance component for fruit weight. The greater importance of genetic variance compared to G × E variance explains why across-location heritabilities for fruit weight and fruit set were high. Genetic correlations between fruit set and weight were strongly negative, while those between yield and set were large and positive. Yields under high temperatures may increase with selection for fruit set, but a reduction in fruit weight would be expected in this population and those with similar genetic correlations.
Ann Marie Connor, Tony K. McGhie, M. Joseph Stephens, Harvey K. Hall and Peter A. Alspach
We determined variance components and narrow-sense heritability estimates for total and individual anthocyanin (ACY) content and antioxidant activity (AA) in fruit from 411 genotypes in a red raspberry (Rubus idaeus L.) factorial mating design based on 42 full-sib families derived from seven female and six male parents, harvested in 2002 and 2003. Within half-sib family total ACY content ranged from ≈1-60+ mg/100 g fruit in both seasons. The four major ACYs quantified by high-performance liquid chromatography also showed wide ranges each year. Female and male parent contributions to variation in total and individual ACYs were significant (P ≤ 0.001) in combined year analysis, and together accounted for 29% to 48% of the total variation. A substantial proportion of the female contribution was attributed to the use of a pigment-deficient R. parvifolius L. × R. idaeus hybrid derivative as a female parent. Female × male interaction was nonsignificant and contributed negligibly to total variance. Year effects accounted for <2.5% of variation in ACYs and were only marginally significant. Year interactions were negligible. Within family variation (among plots and within plot) accounted for ≈50% of the variation in total ACY and 62% to 69% of the variation in individual ACYs. Combined year narrow-sense heritability estimates were high (h 2 = 0.54-0.90 for individual ACYs, 1.00 for total ACY) among all factorial genotypes, but moderate when the progeny of the R. parvifolius derivative were excluded (h 2 = 0.45-0.78 for individual ACYs, 0.74 for total ACY). The latter estimates are applicable to breeding programs in which pigment-deficient genotypes are rarely or never used in breeding. Parental main effects were significant for AA, together accounting for 19% of total variance; female × male interaction was nonsignificant. Year effects were marginally significant and year interactions nonsignificant; together these sources of variation contributed <2% of total variation in AA. The majority of AA variation was found within- and among-plots within family. The phenotypic correlation between AA and total ACY was r = 0.53, and ranged from r = 0.21-0.46 between AA and individual ACYs; genetic correlations between AA and the ACYs were similar to the phenotypic correlations, suggesting predominantly additive genetic effects accounted for the phenotypic correlations. Linear modelling for AA based on individual ACYs and their interactions explained ≈0.53 of AA variation, substantially less than that explained by total phenolic content (R 2 = 0.88). Our results show substantial variation and moderate to high narrow-sense heritability estimates for red raspberry ACYs, but ACY content and profile information are ineffective proxies and predictors for AA in red raspberry fruit.