Sample records for topcrossing
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Code of Federal Regulations, 2011 CFR
2011-01-01
... or top-cross breed of such sheep, having hair formed in knuckled curls. (b) The term Broadtail Lamb... breed of sheep or top-cross breed of such sheep, having hair formed in flattened knuckled curls with a...; or (2) any other lamb skins having hair in a wavy or open curl pattern. ...
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Code of Federal Regulations, 2013 CFR
2013-01-01
... or top-cross breed of such sheep, having hair formed in knuckled curls. (b) The term Broadtail Lamb... breed of sheep or top-cross breed of such sheep, having hair formed in flattened knuckled curls with a...; or (2) any other lamb skins having hair in a wavy or open curl pattern. ...
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Code of Federal Regulations, 2014 CFR
2014-01-01
... or top-cross breed of such sheep, having hair formed in knuckled curls. (b) The term Broadtail Lamb... breed of sheep or top-cross breed of such sheep, having hair formed in flattened knuckled curls with a...; or (2) any other lamb skins having hair in a wavy or open curl pattern. ...
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Code of Federal Regulations, 2012 CFR
2012-01-01
... or top-cross breed of such sheep, having hair formed in knuckled curls. (b) The term Broadtail Lamb... breed of sheep or top-cross breed of such sheep, having hair formed in flattened knuckled curls with a...; or (2) any other lamb skins having hair in a wavy or open curl pattern. ...
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de Lima, V J; do Amaral Junior, A T; Kamphorst, S H; Pena, G F; Leite, J T; Schmitt, K F M; Vittorazzi, C; de Almeida Filho, J E; Mora, F
2016-12-02
The successful development of hybrid cultivars depends on the reliability of estimated combining ability of the parent lines. The objectives of this study were to assess the combining ability of partially inbred S 3 families of popcorn derived from the open-pollinated variety UENF 14, via top-crosses with four testers, and to compare the testers for their ability to discriminate the S 3 progenies. The experiment was conducted in the 2015/2016 crop season, in an incomplete-block (Lattice) design with three replications. The following agronomic traits were evaluated: average plant height, grain yield (GY), popping expansion (PE), and expanded popcorn volume per hectare. The top-cross hybrid, originating from the BRS-Angela vs S 3 progeny 10 combination, was indicated as promising, showing high values for specific combining ability for GY and PE. For the S 3 progenies that showed high and positive GCA values for GY and PE, the continuity of the breeding program is recommended, with the advance of self-pollination generations. Fasoulas' differentiation index discriminated the BRS-Angela tester as the most suitable for identifying the superior progenies.
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Rodrigues, C S; Pacheco, C A P; Guedes, M L; Pinho, R G V; Castro, C R
2016-09-23
The aim of this study was to identify inbred progenies of S 0:1 maize (Zea mays L.) plants that were efficient at a low level of technology and responsive at a high level of technology through the use of topcrosses. Two contrasting environments were created using two levels of base fertilization and topdressing, so that the levels of nitrogen, phosphorus, and potassium were applied four times higher in one environment than in the other. We used S 0:1 progenies derived from commercial hybrids in topcrosses with two testers (an elite line from the flint heterotic group and an elite line from the dent heterotic group). The progenies and three controls were evaluated in an augmented block design in Nossa Senhora das Dores, SE, Brazil in the 2010 crop season. The average grain yield in the high-technological level was 21.44% greater than that in the low-technological level. There were no changes in progeny behavior in the two technological levels for grain yield. The testers did not differ in the average grain yield of the progenies at the two technological levels. Therefore, it is possible to select progenies derived from commercial hybrids that have an efficient response to fertilization.
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Breeding potential of elite Pee Dee germplasm in Upland cotton breeding programs
USDA-ARS?s Scientific Manuscript database
Successful plant breeding programs begin with parental line selection. Effective parental line selection is facilitated when the breeding potential of candidate parental lines is known. Using topcross families involving germplasm representing eight US public cotton breeding programs, we evaluated th...
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Registration of Warhorse wheat
USDA-ARS?s Scientific Manuscript database
'Warhorse' (Reg. No. CV-1096, PI 670157) hard red winter (HRW) wheat (Triticum aestivum L.) was developed and released by the Montana Agricultural Experiment Station in September 2013. Warhorse is of unknown pedigree, derived from a composite of three topcrosses made to the same F1 population in 200...
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Genetic characterization of the North Carolina State University maize lines
USDA-ARS?s Scientific Manuscript database
Since 1980, 150 North Carolina State University maize inbreds have been developed and released on the basis of superior performance for topcross yield and other traits of agronomic importance. During this time there has been great emphasis placed on breeding with exotic germplasm, with 86 NCSU inbr...
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USDA-ARS?s Scientific Manuscript database
Chromosome substitution lines (CSL) have been developed for selected chromosomes from two tetraploid species of Gossypium and have been shown to be effective ways to target introgression of useful alleles from exotic tetraploid species into Upland cotton, G. hirsutum L. Genetic effects of chromosome...
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USDA-ARS?s Scientific Manuscript database
Crosses between Gossypium barbadense L. and Upland (G. hirsutum L.) have produced limited success in introgressing fiber quality genes into Upland cotton. Chrosome substitution lines (CSL) have chromosomes or arms from G. barbadense, line 3-79, substituted for the corresponding chromosome or arm in ...
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USDA-ARS?s Scientific Manuscript database
Backcross breeding is an important method to improve elite cultivars for traits controlled by a small number of loci but has been used less frequently to improve quantitatively controlled traits. Resistances to Fusarium ear rot and contamination by the associated mycotoxin fumonisin in maize are qua...
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USDA-ARS?s Scientific Manuscript database
Upland cotton, Gossypium hirsutum L. is planted on most of the hectareage of cultivated cotton in the United States and the world. The cultivated tetraploid species G. barbadense L. produces extra long, strong, and fine fibers. Breeders would like to move fiber quality alleles from this species in...
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Bohn, Martin O; Marroquin, Juan J; Flint-Garcia, Sherry; Dashiell, Kenton; Willmot, David B; Hibbard, Bruce E
2018-02-09
Over the last 70 yr, more than 12,000 maize accessions have been screened for their level of resistance to western corn rootworm, Diabrotica virgifera virgifera (LeConte; Coleoptera: Chrysomelidae), larval feeding. Less than 1% of this germplasm was selected for initiating recurrent selection or other breeding programs. Selected genotypes were mostly characterized by large root systems and superior root regrowth after root damage caused by western corn rootworm larvae. However, no hybrids claiming native (i.e., host plant) resistance to western corn rootworm larval feeding are currently commercially available. We investigated the genetic basis of western corn rootworm resistance in maize materials with improved levels of resistance using linkage disequilibrium mapping approaches. Two populations of topcrossed doubled haploid maize lines (DHLs) derived from crosses between resistant and susceptible maize lines were evaluated for their level of resistance in three to four different environments. For each DHL topcross an average root damage score was estimated and used for quantitative trait loci (QTL) analysis. We found genomic regions contributing to western corn rootworm resistance on all maize chromosomes, except for chromosome 4. Models fitting all QTL simultaneously explained about 30 to 50% of the genotypic variance for root damage scores in both mapping populations. Our findings confirm the complex genetic structure of host plant resistance against western corn rootworm larval feeding in maize. Interestingly, three of these QTL regions also carry genes involved in ascorbate biosynthesis, a key compound we hypothesize is involved in the expression of western corn rootworm resistance. © The Author(s) 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
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[Genetic improvement of breeding materials in tropical and sub- tropical maize].
Sansern, Jampatong; Chaba, Jampatong
2011-12-01
In the present study, 122 maize local cultivars and adapted exotic germplasm from Thailand were used to develop open pollinate varieties (OPVs) using modified ear-to-row scheme, top-cross or test-cross programmes. Ten new maize OPVs with distinct characters were created based on the precise breeding objectives and directional design. The selection of breeding materials was based upon three factors: elite performance, broad adaptability, and genetic diversity. The synthesizing system provided four features: genetic mixing and recombination, equal comparable genetic contribution, mild selection pressure, and maximum intermating for genetic equilibrium (i.e., the female traits were close for the genetic com-positions). Subsequently, Suwan 1 composite and its deritives (Suwan 2, Suwan 3 composite, Suwan 5 and KS24 synthetics), KS6 and KS28 synthetics with the dent type of different origins, and Caripeno DMR composite, KS23, and KS27 synthetics with the dent type of Non-Suwan 1 origin were developed. These OPVs had been improved for 2~13 cycles using S1 recurrent selection method. About 50 inbred lines were developed from these OPVs, and 16 elite single (three-way) crosses were combined and released from these inbred lines. At present, at least one parental inbred line of all the tropical hybrids was derived from Suwan (KS) germplasm in Thailand. Based on the theory of the synthesizing OPVs and developing inbred lines, this paper discussed the genetic moderate diversity, relationship, heterotic group, and patterns for synthesizing OPVs, and inspiration for composed OPVs to heterosis breeding.