scholarly journals Heritability and Genetic Variance Estimates for Fruit Weight in Watermelon

HortScience ◽  
2007 ◽  
Vol 42 (6) ◽  
pp. 1332-1336 ◽  
Author(s):  
Gabriele Gusmini ◽  
Todd C. Wehner
Keyword(s):  
Quantitative Methods ◽  
Genetic Variance ◽  
Recurrent Selection ◽  
Citrullus Lanatus ◽  
Field Trials ◽  
Fruit Weight ◽  
Phenotypic Variance ◽  
Environmental Variance ◽  
Small Fruit ◽  
Variance Estimates

Fruit weight in the cultivated watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai var. lanatus] ranges from 1 kg to over 100 kg. In recent years, preference of consumers has shifted toward fruit of smaller sizes than the large sizes traditionally used for parties and picnics. This has produced increased interest in the genetics of fruit weight, especially among watermelon breeders. The objectives of this study were to determine the inheritance of fruit weight. Six adapted cultivars having very large or very small fruit weight were crossed in a half diallel. Field trials were conducted at two locations in North Carolina (Clinton and Kinston). Large-fruited parents had higher phenotypic variance than small-fruited parents. Environmental variance was higher than genetic variance (mean, 7.58 and 3.82, respectively) at Kinston, NC. At Clinton, NC, genetic and environmental variances were similar (mean, 9.45 and 8.99, respectively) for 67% of the families. Narrow- and broad-sense heritability estimates were low to intermediate (mean, 0.59 and 0.41, respectively). A high number of effective factors (mean, 5.4) was found to influence fruit weight in watermelon. Watermelon breeders should use quantitative methods such as recurrent selection for population improvement to change fruit weight in the development of new cultivars.

Performance of new tropical pumpkin genotypes under varying cultural practices

1969 ◽  
Vol 90 (3-4) ◽  
pp. 193-206
Author(s):  
Linda Wessel-Beaver ◽  
Obed Román-Hernández ◽  
Luisa E. Flores-López
Keyword(s):  
Seed Production ◽  
Cultural Practices ◽  
Field Performance ◽  
Field Trials ◽  
Fruit Weight ◽  
Production Program ◽  
Small Fruit ◽  
Poor Seed ◽  
Planting Distance ◽  
Standard Cultivar

New tropical pumpkin (Cucurbita moschata Duchesne) genotypes were evaluated for yield, flesh (mesocarp) color, pest resistance and seed production as compared with the standard cultivar Soler in six field trials at three Puerto Rico locations during a two-year period (2003-2005). Genotypes included an open-pollinated population (PRShortvine-1) and four lines (E0305-1, E0305-2, E0305-3 and E0305-4) with a semi-bush growth habit, as well as a new long-vine open-pollinated population (PRLongvineSLR). Various within-row (0.9- and 1.9-m) and between-row (1.9- and 3.8-m) planting distances were tested. Not all genotypes nor planting distances were included in each trial. PRLongvineSLR was partially resistant to the melonworm (Diaphania hyalinata), whereas lines E0305-1 and E0305-2 were very susceptible. These same lines, as well as PRShortvine-1, were also susceptible to downy mildew, Pseudoperonospora cubensis. All genotypes produced similar yields. Within-row planting distance generally had no effect on fruit weight, fruit number and yield. All new genotypes had good flesh thickness (>4 cm) and small fruit cavities. Flesh color of PRShortvine-1 and PRLongvineSLR tended to be more orange than that of Soler. Lines E0305-3 and E0305-4 had poor seed production, whereas seed production in fruits of PRShortvine-1 and PRLongvineSLR was similar to that of Soler. Despite some shortcomings, PRShortvine-1 and PRLongvineSLR are two advanced open-pollinated populations that should be considered for formal release on the basis of their field performance, good fruit quality and ability to produce profitable amounts of seed in a seed production program. 

scholarly journals In-row Spacing Influences Triploid Watermelon Yield and Crop Value

2002 ◽  
Vol 12 (3) ◽  
pp. 437-440 ◽  
Author(s):  
Carl E. Motsenbocker ◽  
Ramon A. Arancibia
Keyword(s):  
Cultural Practices ◽  
Citrullus Lanatus ◽  
Fruit Weight ◽  
Row Spacing ◽  
Plastic Mulch ◽  
Marketable Yield ◽  
Farmers Market ◽  
Subsequent Decrease ◽  
Small Fruit ◽  
Triploid Watermelon

Triploid watermelon (Citrullus lanatus), commonly called seedless watermelon, is increasing in popularity and market share. The optimum in-row spacing of triploid watermelon has not been studied previously. Triploid watermelon `Crimson Jewel' and `Honeyheart' were grown with drip-irrigation and black plastic mulch at 1-, 2-, 4-, 6-, and 8-ft (0.3-, 0.6-, 1.2-, 1.8-, and 2.4-m) in-row spacings in 1996 and 2-, 3-, 4-, 5-, 6-, 7-, and 8-ft. (0.6-, 0.9-, 1.2-, 1.5-, 1.8-, 2.1-, and 2.4-m) spacings in 1997 to determine the effect of in-row plant spacing on fruit yield. Marketable yield of `Crimson Jewel' was not affected by in-row spacing while narrower in-row spacing resulted in greater `Honeyheart' yield both years. For both cultivars, narrower spacing resulted in the highest number of fruit per acre, but primarily more extrasmall and small fruit. Fruit number per plant, fruit weight per plant, and individual fruit weight were higher at wider spacings, and yield per acre was lower. The data suggest that triploid watermelon yield, fruit weight and number can be adjusted by in-row spacing. Narrower in-row spacing can maximize yields, depending on the specific grower's cultural practices. In wider in-row spacings, the yield of medium and large fruit is maintained with a subsequent decrease in extra small and small fruit. Gross returns per acre were only different for farmers' market prices, not wholesale, and net returns were not significantly influenced by in-row spacing.

The Changes in Genetic and Environmental Variance With Inbreeding in Drosophila melanogaster

Genetics ◽  
1999 ◽  
Vol 152 (1) ◽  
pp. 345-353 ◽  
Author(s):  
Michael C Whitlock ◽  
Kevin Fowler
Keyword(s):  
Drosophila Melanogaster ◽  
Large Scale ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Inbred Lines ◽  
Residual Variance ◽  
Phenotypic Variance ◽  
Population Bottlenecks ◽  
Environmental Variance ◽  
Components Of Variance

Abstract We performed a large-scale experiment on the effects of inbreeding and population bottlenecks on the additive genetic and environmental variance for morphological traits in Drosophila melanogaster. Fifty-two inbred lines were created from the progeny of single pairs, and 90 parent-offspring families on average were measured in each of these lines for six wing size and shape traits, as well as 1945 families from the outbred population from which the lines were derived. The amount of additive genetic variance has been observed to increase after such population bottlenecks in other studies; in contrast here the mean change in additive genetic variance was in very good agreement with classical additive theory, decreasing proportionally to the inbreeding coefficient of the lines. The residual, probably environmental, variance increased on average after inbreeding. Both components of variance were highly variable among inbred lines, with increases and decreases recorded for both. The variance among lines in the residual variance provides some evidence for a genetic basis of developmental stability. Changes in the phenotypic variance of these traits are largely due to changes in the genetic variance.

scholarly journals Genetic Control of O3 Sensitivity in a Cross Between Two Cultivars of Snap Bean

2000 ◽  
Vol 125 (2) ◽  
pp. 222-227 ◽  
Author(s):  
Richard A. Reinert ◽  
Gwen Eason
Keyword(s):  
Genetic Control ◽  
Genetic Variance ◽  
Additive Genetic Variance ◽  
Phenotypic Variance ◽  
Narrow Sense Heritability ◽  
Snap Bean ◽  
Reciprocal Crosses ◽  
Blue Lake ◽  
Environmental Component ◽  
Variance Estimates

Identification of genetic control of ozone (O3) sensitivity is desirable for selection of plant cultivars which are indicators of O3 stress. A cross was made between two cultivars of snap bean (Phaseolus vulgaris L.), `Oregon 91' (P1) and `Wade Bush' (P2), an O3-sensitive and O3-insensitive cultivar, respectively. Ten genetic populations (generations), `Oregon 91' (P1), `Wade Bush' (P2), F1, F2, backcrosses to both parents, and all reciprocal crosses, were field planted in each of two summers and evaluated for injury to O3. Ozone responses for the reciprocal crosses were not significantly different for any generation, so injury ratings from the reciprocal crosses were combined for each generation to provide six populations (P1, P2, F1, F2, BC1, and BC2) for analysis. When components of genetic variation were estimated from the six generations, additive genetic variance was the most important component in the total genetic variance available, although dominance variance was also a significant component. There was an inconsistency in the magnitude and the direction of the factors contributing to the dominance effects and also a large environmental component making up the phenotypic variance. Estimates of broad-sense heritability and narrow-sense heritability were 60% and 44%, respectively. Results suggest that O3-sensitive and O3-insensitive selections could be screened and evaluated in an ambient O3 environment. Several generations will be necessary, however, to develop `Bush Blue Lake' type selections that vary only in sensitivity to O3.

scholarly journals Genetic variance and covariance components related to intra- and interpopulation recurrent selection in maize (Zea mays L.)

1998 ◽  
Vol 21 (4) ◽  
pp. 537-544 ◽  
Author(s):  
Carlos Alberto Arrabal Arias ◽  
Cláudio Lopes de Souza Júnior
Keyword(s):  
Zea Mays ◽  
Genetic Variance ◽  
Recurrent Selection ◽  
Zea Mays L ◽  
Inbred Lines ◽  
Additive Effects ◽  
Covariance Components ◽  
Per Se ◽  
Variance And Covariance Components ◽  
Variance Estimates

New genetic variance and covariance components related to intra- and interpopulational recurrent selection methods have been theoretically developed by Souza Jr. (Rev. Bras. Genet. 16: 91-105, 1993) to explain the failure of these methods to concomitantly develop hybrid and per se populations. Intra- and interpopulation half-sib progenies of 100 genotypes were sampled from maize (Zea mays L.) populations BR-106 and BR-105 to estimate variance and covariance components and to compare the expected responses to reciprocal (RRS), intrapopulational (HSS), and modified (MRS) recurrent selection in interpopulation hybrid, populations per se, and to determine heterosis. Four sets of 100 progenies, two intra- and two interpopulational, were evaluated in partially balanced 10 x 10 lattices arranged in split-blocks with two replications in two years (1991/92 and 1992/93) and two locations in Piracicaba, SP. Data for ear weight, plant and ear height, and ear by plant height ratio were recorded. Populations and interpopulation crosses were high yielding and showed high breeding potential for production of hybrids from inbred lines. Mid parent and the highest parent heterosis were relatively high, but lower than values reported for these populations under other environmental conditions. Additive variance estimates of populations per se and interpopulation crosses confirmed the high potential of these materials. The magnitude of the variance estimates for the deviations from intra- and interpopulation additive effects (<img src="http:/img/fbpe/gmb/v21n4/1918f1.jpg" alt="1918f1.jpg (1262 bytes)" align="middle"> for BR-106 and <img src="http:/img/fbpe/gmb/v21n4/1918f3.jpg" alt="1918f3.jpg (1259 bytes)" align="middle">for BR-105) and covariance between additive effects with these deviations (<img src="http:/img/fbpe/gmb/v21n4/1918f2.jpg" alt="1918f2.jpg (2022 bytes)" align="middle"> for BR-106 and <img src="http:/img/fbpe/gmb/v21n4/1918f4.jpg" alt="1918f4.jpg (1995 bytes)" align="middle"> for BR-105) indicated that these new components can significantly influence the effectiveness of breeding methods. Genetic component estimates for BR-105 had relatively small errors, with <img src="http:/img/fbpe/gmb/v21n4/1918f4.jpg" alt="1918f4.jpg (1995 bytes)" align="middle"> negative for all traits. Estimates of <img src="http:/img/fbpe/gmb/v21n4/1918f1.jpg" alt="1918f1.jpg (1262 bytes)" align="middle">and <img src="http:/img/fbpe/gmb/v21n4/1918f2.jpg" alt="1918f2.jpg (2022 bytes)" align="middle"> had relatively larger errors for BR-106. The MRS method was more effective than the RRS and HSS methods in producing hybrids from inbred lines. The choice of a population tester for the MRS method based on population means per se may be incorrect. The additional use, when possible, of intra- and interpopulation additive genetic variances from each population would be more appropriate.

scholarly journals Genetic analysis of early field growth of loblolly pine clones and seedlings from the same full-sib families

2007 ◽  
Vol 37 (1) ◽  
pp. 195-205 ◽  
Author(s):  
Brian S Baltunis ◽  
Dudley A Huber ◽  
Timothy L White ◽  
Barry Goldfarb ◽  
Henry E Stelzer
Keyword(s):  
Loblolly Pine ◽  
Genetic Variance ◽  
Recurrent Selection ◽  
Growth Traits ◽  
Genetic Correlations ◽  
Field Trials ◽  
Population Based ◽  
Environment Interaction ◽  
Clonal Population ◽  
Sib Families

Field trials established with clones and seedlings from the same families provide an opportunity for comparing full-sib family performance across propagule types. More than 1200 different clones together with over 14 000 zygotic seedlings from the same 61 full-sib families of loblolly pine (Pinus taeda L.) were tested on multiple sites across Florida and Georgia. The genetic variance associated with several early growth traits partitioned differently depending on propagule type. Most of the genetic variance associated with growth in the clonal population was additive, while the estimate of dominance in the seedling population was greater than estimates of dominance in the clonal population, based on single-site analyses. Apparently, a lack of randomization of the seedlings prior to field establishment caused full-sib families to appear more different, inflating estimates of dominance genetic variance. Parental and full-sib family ranks were stable regardless of propagule type as indicated by type B genetic correlations. In the clonal population, little genotype × environment interaction was observed across sites at the parental, family, and clonal levels for all traits. The high genetic correlations between propagule types provide further assurance that selections made through traditional tree-improvement activities for recurrent selection for general combining ability in seedling trials can also be used successfully for breeding families to test in a clonal forestry program.

scholarly journals Environmental Variance Components of Fruit Ripening Date as Used in Both Phenotypic and Marker-assisted Selection in Japanese Pear Breeding

HortScience ◽  
2011 ◽  
Vol 46 (11) ◽  
pp. 1540-1544 ◽  
Author(s):  
Sogo Nishio ◽  
Masahiko Yamada ◽  
Yutaka Sawamura ◽  
Norio Takada ◽  
Toshihiro Saito
Keyword(s):  
Fruit Ripening ◽  
Variance Components ◽  
Genetic Variance ◽  
Japanese Pear ◽  
Pyrus Pyrifolia ◽  
Phenotypic Variance ◽  
Environmental Variance ◽  
Single Tree ◽  
Sib Families ◽  
Qtl Effects

The effectiveness of detected quantitative trait loci (QTLs) and molecular markers associated with them in tree fruit breeding is measured by the percentages of the variance associated with detected QTL effects accounting for not phenotypic variance, but genetic variance of the trait. The genetic variance can be obtained by subtracting environmental variance from the phenotypic variance. Once accurate environmental variance components are obtained for a given selection field, environmental variances under any number of replications and measurement repetitions can be estimated. We estimated environmental variance components of fruit ripening date measured by days in a Japanese pear (Pyrus pyrifolia Nakai) breeding field in the National Institute of Fruit Tree Science, Tsukuba, Ibaraki, Japan. We estimated variance among fruits within a tree (σf2) as 25.6, among trees within a genotype (σt2) as 0.2, among years (σy2) as 9.4, associated with genotype × year interaction (σgy2) as 7.9, and associated with tree × year interaction (σty2) as 1.2. Because σf2 was the largest environmental variance component, increasing the number of fruit evaluated would most effectively reduce the environmental variance, and tree replication would not because of very small σt2 and σty2. The 95% confidence limit of a genotypic value was ± 10 days in the evaluation of five fruits on a single tree in a year and ± 7 days over 2 years. Broad-sense heritability in a family, each offspring in which was evaluated using five fruits on a single tree in a single year, was estimated at 0.83 for three full-sib families analyzed.

scholarly journals Quantitative Analysis of Generations for Inheritance of Fruit Yield in Watermelon

HortScience ◽  
2013 ◽  
Vol 48 (7) ◽  
pp. 844-847 ◽  
Author(s):  
Rakesh Kumar ◽  
Todd C. Wehner
Keyword(s):  
Citrullus Lanatus ◽  
Fruit Size ◽  
Fruit Yield ◽  
Individual Plant ◽  
Progeny Testing ◽  
Phenotypic Variance ◽  
Environmental Variance ◽  
Actual Distribution ◽  
Selection Scheme ◽  
Polygenic Inheritance

There is a large genetic diversity for fruit size and yield in watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai var. lanatus]. Current cultivars have high fruit quality but may not be the highest yielders. This study was designed to estimate variance components and heritability of fruit yield (Mg·ha−1), fruit count (th·ha−1), and fruit size (kg/fruit) in a cross involving high-yielding ‘Mountain Hoosier’ with low-yielding ‘Minilee’. Six generations (PaS1, PbS1, F1, F2, BC1Pa, and BC1Pb) were developed and tested in Summer 2008 at two locations in North Carolina. Discrete classes were not observed within the F2 segregating population. The actual distribution of the F2 population for fruit yield, fruit count, and fruit size deviated from the normal distribution. ‘Mountain Hoosier’ had higher parental and backcross variance than ‘Minilee’. High F2 variance for fruit yield indicated large phenotypic variance. There was a larger environmental variance than genetic variance associated with the yield traits. Estimates of broad- and narrow-sense heritability were low to medium. A large number of effective factors indicated polygenic inheritance for fruit yield and fruit size. Gain from selection for yield is amendable by selection. As a result of this complex inheritance, selection based on individual plant selection in pedigree method may not be useful for yield improvement in this population. Hence, a selection scheme based on progeny testing using replicated plots, perhaps at multiple locations, is recommended.

scholarly journals Estimation of Genetic Variance of Starch Digestibility in Sweetpotato

HortScience ◽  
1995 ◽  
Vol 30 (2) ◽  
pp. 348-349 ◽  
Author(s):  
Dapeng Zhang ◽  
Wanda W. Collins ◽  
Maria Andrade
Keyword(s):  
North Carolina ◽  
Ipomoea Batatas ◽  
Genetic Variance ◽  
Genotypic Variation ◽  
Screening Method ◽  
Starch Digestibility ◽  
Phenotypic Variance ◽  
Environmental Variance ◽  
Dominant Component

Two experiments that included 25 sweetpotato [Ipomoea batatas (L.) Lam] genotypes were planted in various environments across North Carolina, and an in vitro screening method was used to investigate genotypic and environmental variance and genotype × environment (G × E) interactions of starch digestibility in sweetpotato. Significant genotypic variation of starch digestibility was found in both experiments. Some clones have starch digestibility equivalent to that of corn. Variance analysis from both experiments indicated that genotypic variance was the dominant component in starch digestibility. G × E interaction only accounted for 6.8% of the phenotypic variance in one experiment and for 5.9% in the other one. These results suggested that starch digestibility of sweetpotato could be improved to a level as that of corn through conventional breeding.

scholarly journals Higher Temperatures Decrease Fruit Size in Strawberry Growing in the Subtropics

Horticulturae ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 34
Author(s):  
Christopher Menzel
Keyword(s):  
Fruit Size ◽  
Negative Relationship ◽  
Titratable Acidity ◽  
Fruit Weight ◽  
Soluble Solids ◽  
Marketable Yield ◽  
Significant Relationships ◽  
Small Fruit ◽  
Solids Content

Five strawberry (Fragaria × ananassa Duch.) cultivars were grown in Queensland, Australia to determine whether higher temperatures affect production. Transplants were planted on 29 April and data collected on growth, marketable yield, fruit weight and the incidence of small fruit less than 12 g until 28 October. Additional data were collected on fruit soluble solids content (SSC) and titratable acidity (TA) from 16 September to 28 October. Minimum temperatures were 2 °C to 4 °C higher than the long-term averages from 1965 to 1990. Changes in marketable yield followed a dose-logistic pattern (p < 0.001, R2s = 0.99). There was a strong negative relationship between fruit weight (marketable) and the average daily mean temperature in the four or seven weeks before harvest from 29 July to 28 October (p < 0.001, R2s = 0.90). There were no significant relationships between SSC and TA, and temperatures in the eight days before harvest from 16 September to 28 October (p > 0.05). The plants continued to produce a marketable crop towards the end of the season, but the fruit were small and more expensive to harvest. Higher temperatures in the future are likely to affect the economics of strawberry production in subtropical locations.

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