The inheritance of antioxidant activity (AOA) and its association with seedcoat color was investigated in cowpea [Vigna unguiculata (L.) Walp.]. Four advanced cowpea lines, ARK95-356 (black seedcoat) and ARK98-348 (red seedcoat), which were high (H) in AOA, and ARK96-918 (cream seedcoat) and LA92-180 (cream seedcoat), which were low (L) in AOA, were selected from the 2002 Regional Southernpea Cooperative Trials. They were crossed in a complete diallel mating design, generating F1, F1′ (1st generation and 1st generation reciprocal cross, respectively), F2, F2′ (2nd generations from F1, F1′), BC1, and BC2 (backcrosses to parents 1 and 2, respectively) populations. Individual seeds were ground and samples were extracted in methanol and analyzed for AOA using the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. Combining ability tests using Griffing's Method I Model I indicated presence of highly significant general combining ability (GCA), specific combining ability (SCA), and reciprocal (RE) and maternal (MAT) effects, with pigmented lines exhibiting positive GCA and MAT, while nonpigmented lines exhibited negative GCA and MAT. AOA in the F1 was not significantly different from the maternal parent, with seedcoat color also resembling the maternal parent. Segregation for seedcoat color was observed in the F2 and F2′. Additive, dominance, and epistatic effects were significant. The broad sense heritability estimate was 0.87. Minimum number of genes responsible for AOA was estimated at five. Factors governing high AOA appeared to be the same as those responsible for seedcoat color, with apparent pleiotropic effects. In conclusion, breeding for high AOA in cowpea is possible using highly pigmented parental lines.
The postproduction quality of 33 cultivars and 178 Pennsylvania State Univ. breeding lines of Pelargonium ×domesticum L.H. Bailey was evaluated in a simulated consumer environment. Petal abscission was the primary factor that reduced postproduction ratings (PPR). The heterozygosity of some cultivars was indicated by the range of PPR of progeny from self-pollinations. This range of PPR implies that P. ×domesticum has genetic variation for postproduction quality that can be used in a breeding and selection program. Few progeny with high PPR were produced from either self- or cross-pollinations involving parents with low PPR. Many of the superior progeny resulted from parents with high PPR. Therefore, progeny with improved postproduction quality can be developed by selecting parents with high PPR.
Abstract
In the tomato (Lycopersicon esculentum Mill.) the ability of PI 341988 to germinate at 10°C is controlled by a recessive gene, tentatively symbolized Itg.
Abstract
Heritability estimates for fire blight resistance in pear were obtained by regressing progeny means on midparental phenotypes. Approximately half of the variability in resistance in pear was additive (h2 = 0.52), but there was also evidence for nonadditive genetic effects compatible with a proposed qualitative gene for sensitivity. A method was established to estimate relative average combining ability for fire blight resistance. Progeny means of individual parents were adjusted to the grand progeny mean of 8 intercrossed testers based on common progeny.
Twenty-one control-pollinated families of lilac (Syringa) were evaluated for the presence of powdery mildew (Microsphaera syringae). Because disease developed first in the lower portions of the plant and moved up, infection was scored from the lowest (1 =only on the lower quarter of the plant) to the highest quarter of the plant (4=present on all quarters of the plant). Family means for mildew score ranged from 2.3 to 3.8 and averaged 3.1, and for height ranged from 59 to 107 cm and averaged 82 cm. Narrow sense and broad sense he&abilities were estimated to be 0.08 and 0.27 respectively. Since any selections will be clonal, this relatively large proportion of non-additive variance can be fully utilized. There was a significant positive correlation between family means of height and mildew score (0.58); however, the phenotypic correlation between height and mildew score was -0.11. For this population the genetic correlation between mildew infection and height was positive (the taller families on average had mildew farther up the plant), but the environmental correlation was negative.
Abstract
Fifty-four seedlings of Vactinium ashei Reade, selected for large fruit and high fruit quality from 3000 seedlings of 8 crosses, were scored for dates of 50% anthesis and 50% fruit-ripening in 1981 and 1982. The earliest-ripening selection was 7 days earlier than the earliest cultivar in 1981 and 15 days earlier in 1982. Repeatability (seedling correlation between years, r = .84) was high for ripening date but somewhat lower for flowering date (r = .61) and flowering-to-ripening interval (r = .62). Most of the variation in ripening dates and in the flowering-to-ripening interval was genetic, but variation in flowering dates was due more to year effects than to genetic effects.
Three individuals in progeny from each of 39 crosses and their parents in Japanese persimmon (Diospyros kaki Thunb.) were evaluated for fruit ripening time. Analysis of variance for the progeny, which estimated between- and within-cross variance, and the regression of the mean value in a full-sib family on the mid-parental value (MP) revealed that the genetic differences among crosses could be explained solely by MP. Genotypic values of individuals in progeny from a cross were assumed to be normally distributed around the regression line with within-cross genetic variance. Based on the parental mean performance of 3.5 fruit on a single tree for three years, the coefficient of regression of mean values in a full-sib family on MP was 0.99 ± 0.10, and the proportion of individuals in progeny having genotypic values ripening earlier than early October was estimated as 52%, 24%, and 7% for three sets of mid-parents differing in their ripening time, i.e., early, middle, and late October, respectively. On the basis of the parental mean performance in 10 fruit on a single tree without yearly repetition, the regression coefficient was estimated as 0.91 and the proportion was estimated as 44%, 20%, and 6% for the three sets of mid-parents, respectively.
The expected proportion of individuals in progeny having genotypic values for fruit weight over a given selection criterion to the total individuals derived from a cross was estimated by multiple-regression analysis in which inbreeding coefficient (F) and midparental (MP) value were independent variables and progeny mean was the dependent variable in Japanese persimmon (Diospyros kaki Thunb.). A total of 117 seedlings from 39 crosses was used. Genetic differences of progenies among crosses could be explained solely by F and MP, the effect of the former being greater than the latter. The expected proportion of progenies with large fruit decreased as MP decreased and severely decreased as F increased. Based on the parental mean of 35 fruit on a single tree for 3 years, the proportion of individuals in progeny with fruit weight >200 g was estimated as 34%, 21%, and 12% for 0, 0.125, and 0.25 F values, respectively, in individual from a cross with MP = 200 g.