Narrow-sense heritabilities and genetic correlations of ornamental quality traits of Antirrhinum majus (snapdragon) were evaluated with special reference to cut flower postharvest longevity (PHL). Inbreds P1 (16 days PHL) and P2 (3 days PHL) were hybridized to produce an F1 (P1 × P2) that was self-pollinated to produce an F2 population. The F2 were self-pollinated to produce F3 families and advanced through single-seed descent by self-pollination to the F5 generation. P1, P2, F1, F3, F4, and F5 were evaluated for ornamental quality traits. Quality traits were found to be quantitative and normally distributed. Narrow-sense heritability (h2) estimates were high and consistent across generations examined; PHL h2 ranged from 0.79 to 0.81 ± 0.06. Phenotypic and genotypic correlations revealed underlying physiological and pleiotropic interactions relevant to breeding programs aimed at simultaneous improvement of ornamental quality traits. PHL is inversely related to cut flower strength and days to flower, -0.44 ± 0.04 and -0.43 ± 0.44. Buds at discard is positively correlated to cut flower and plant diameter, cut flower weight and days to flower, 0.77 ± 0.05, 0.58 ± 0.06, 0.71 ± 0.06, and 0.77 ± 0.07, respectively. Gain from selection for quality traits of interest can be rapid.
In 1983-1987, a Gardner color difference meter standardized to a pink tile (L=70.5, a=+23.9, b=+9.3) and equipped with an aperture of 3.8 cm (1983-1986), 1.9 cm (1987), or 1.0 cm (1988-1989) was used to measure lightness (L) and intensity (chroma) of `Georgia Red' sweetpotato [Ipomoea batatas (L.) Lam.] seed roots cut into longitudinal sections. Individual roots were selected with good color when L<68 and chroma≥39 and fair color when L≥72 and chroma <35 (1983-1985), L<65 and chroma≥42 for good color and L≥80 and chroma <25 for fair color (1986), L≤66 and chroma≥41 for good color and L≥85 and chroma≤20 for fair color (1987). In each year, roots falling between the defined selection values were discarded. In 1988, root sections from a common 1983-ancestor parent root were bulked for plant propagation if L and chroma values were similar. Subsequent measurements of these bulk populations were made in 1989. Measurements by a color difference meter were helpful in making objective judgements in selecting for internal color of sweetpotato. Also, these measurements were helpful in following changes in internal color through several generations of vegetative propagation.
Flavor quality is one of the most difficult traits to select in plant breeding programs due to the large number of sensory panelists required, the small number of samples that can be evaluated per day, and the subjectivity of the results. Using sweetpotato [Ipomoea batatas (L.) Lam.] as a model, clones exhibiting distinctly different flavors were analyzed for sugars, nonvolatile acids, and aroma chemistry to identify the critical flavor components. Differences in sugars, sucrose equivalents, nonvolatile acids, and 19 odor-active compounds were identified that accounted for differences in flavor among the clones. Using the intensity of the aroma per microliter for each of the 17 most important aroma-active compounds (maltol, 5-methyl-2-furfural, 2-acetyl furan, 3-furaldehyde, 2-furmethanol, benzaldehyde, phenylacetaldehyde, β-ionone, 1,2,4-trimethyl benzene, 2-pentyl furan, 2,4-decadienal, 2,4-nonadienal, linalool, geraniol, cyperene, α-copane and a sesquiterpene) and the relative sweetness of individual sugars × their respective concentrations, multivariate (principal component and cluster) analysis allowed accurate classification of the clones according to flavor type without sensory analysis. The level of precision was such that sweetness, starch hydrolysis potential, and the concentration of β-carotene could be accurately predicted by quantifying specific volatiles. Analytical assessment of flavor would greatly facilitate the accurate evaluation of large numbers of progeny, the simultaneous selection of multiple flavor types, and the development of superior new cultivars for a wide cross-section of food crops.
Numerous cultivars of lacebark elm (Ulmus parvifolia) have been introduced recently without adequate testing of their hardiness. A block of commercial cultivars plus numerous experimental numbers were established to observe differences in growth form, ornamental characteristics, and cold hardiness. Laboratory freezing tests were conducted from November to March over a 3-year period to determine acclimation and deacclimation to low temperatures. Stem sections approximately 5 cm long were sealed in test tubes and placed in a low-temperature programmable freezer maintained at 0°C. Samples were cooled by approximately 6°C per hour from 0 to –48°C and held for 1 h at each temperature. Samples were then removed, allowed to thaw at room temperature, and held for 7 to 10 days. Stem samples were sectioned longitudinally to observe browning in xylem and bark tissues. During the winter of 1995–96, no visible injury could be noted on trees in the field in spite of very dry, desiccating weather with temperatures reaching –23°C. Laboratory freezing tests indicated acclimation to –30°C by 18 Dec. 1995 on several cultivars. During warm periods in February, deacclimation occurred on many selections to –18°C, whereas others maintained a killing point of –30°C. Growth form, bark exfoliation, and fall color varied among cultivars.
Three experiments were conducted to delineate gametophytic selection of the fused vein trait in Cucurbita pepo L. Gametophytic subvitality was verified by comparing fused vein and normal pollen tube growth. Microscopic examination of partitioned, co-pollinated flowers revealed fewer and slower growing fused vein tubes than normal. The effects of gametophytic subvitality on seed yield and inheritance were shown by manipulating the severity of reproductive competition. Fused vein, normal, and F1 lines were pollinated with fused vein, normal, 50:50 mix, and F1 pollen at three different pollen loads. Analysis showed that fused vein pollen generated significantly fewer seed per fruit in all lines. In ensuing F2 and testcross populations, a reduction in load and thus competition significantly increased the number of fused vein individuals. Leaf number and area for normal, fused vein, F1, F2, and testcross plants were assessed to test pleiotropic effects on growth common to gametophytic subvitals. Although normal and fused vein lines differed in leaf number and size, their total leaf areas were not significantly different. F2 and testcross plants showed no difference between normal and fused vein individuals; leaf size and number were independent of leaf morphology.
Abstract
In the paper “Genetic Advance through Mass Selection for Tenderness in Sweet Corn” by Glenn M. Ito and James L. Brewbaker (J. Amer. Soc. Hort. Sci. 106(4):496-499.1981) there are errors in the numbering of and textual references to the figures and tables. Table 1 on page 497 should be labeled Table 4, Table 2 on page 497 should be labeled Table 1, Table 3 on page 498 should be labeled Table 2, and Table 4 on page 499 should be labeled Table 3. Figure 1 on page 497 should be labeled Figure 3, Figure 2 on page 498 should be labeled Figure 1, and Figure 3 on page 498 should be labeled Figure 2. Accordingly, line 7 of the section beginning “Correlation of bite-test scores and pericarp thickness measurements” on page 498 should refer to Table 4; the last line on page 498 should refer to Figure 3; and line 8 of the first paragraph, second column, of page 499 should refer to Table 2. All other textual references correspond to the correct table and figure numbers as presented above.
, China) according to the manufacturer’s instructions. The cDNAs were diluted 1:10 with nuclease-free water before qRT-PCR analyses. Selection of potential reference genes. The 10 candidate genes evaluated in this experiment were based on the mei
Commercial garden and greenhouse chrysanthemums [Dendranthema ×grandiflora (Ramat.) Kitam. (syn. Chrysanthemum xmorifolium Ramat.)] are facultative short-day plants for flower bud initiation, obligate short-day plants for flower bud development, and are categorized into short-day response groups. Flower initiation can be delayed by high night temperatures. Recent research has identified true day-neutral genotypes. The purpose of this investigation was to test environments for selecting genotypes that are both day-neutral and heat-delay insensitive. One greenhouse and 18 garden genotypes were selected. A series of environments were used to select for day-neutral genotypes and then differentiate between these genotypes for heat delay insensitivity: short days, long days/red light, long days/far red light and high temperatures, and natural day lengths under field conditions. Day-neutral selections from these environments were then grown in a fifth environment of long days/continuous far red and red light with high temperature. Data were collected on the number of days to first and third flower, long day leaf number, stem length, number of strap-shaped leaves subtending the terminal flower, internode lengths, number of nodes with axillary branching, and flower bud development of the first to the sixth flowers. Genotypes required 3 to 8 weeks for complete flower bud initiation/development. Flowering responses in the first four environments were highly significant for both the first and third flowers. Genotypes ranged from obligate short-day to day-neutral for the first six flowers. Three day-neutral genotypes were selected that differed significantly for all traits in the fifth environment; flower bud development with the first six flowers occurred with only one genotype, 83-267-3. Broad sense heritability estimates ranged from h2 = 0.75 for number of nodes with axillary branching, h2 = 0.79 for long day leaf number and number of strap-shaped leaves, to h2 = 0.91 for stem length. An ideotype for day-neutral and heat-delay-insensitive garden chrysanthemums was developed for use in breeding programs.
appropriate selection ( Belay, 2018 ). Path coefficient analysis, or path analysis, has been widely used to understand production better and to determine the nature of the relationships between fruit and their constituent components, and to identify those
traits for progeny selection in the breeding program demands genetic studies to distinguish the environmental and the genetic variances from the phenotypic variances, to calculate the expected genetic contribution in the form of heritability, and to