Comparison of S1 and Testcross Evaluation after Two Cycles of Recurrent Selection in Maize1

Genter, C. F.

doi:10.2135/cropsci1973.0011183x001300050009x

Cited by 33 publications

(29 citation statements)

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“…Successful Si selection has been reported by BURTON et al (1971) in BSK with a 4.1% yield gain per cycle; GENTER (1973) in VCBS with a 7% yield gain per cycle; and by GENTER & EBERHART (1974) in VCBS with a 21.5% gain in 4 cycles. However, GENTER (1973) and GENTER & EBERHART (1974) were unsuccessful in showing improvement in VLE or BSK by Si selection.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Six years of maize selection in ‘Kitale synthetic II’, ‘Ecuador 573’, and ‘kitale composite a’ using methods of the comprehensive breeding system

Darrah¹,

Eberhart²,

Penny³

1978

Euphytica

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Zea mays, maize, recurrent selection, yield.Evaluation of the results of six years of selection in the Kitale maize breeding methods study proved reciprocal recurrent selection to be an effective interpopulation improvement method. Earto-row selection was effective in improving 'Kitale Composite A' (KCA). Data from a diallel of the cycle-6 ear-to-row substrains showed that where less than 10 lines were selected, inbreeding appeared to depress gain, but differences among the various ear-to-row experiments were not significant. Intercrossing the substrains was predicted to reduce the effect of inbreeding. Yield gains in reciprocal recurrent selection and ear-to-row selection were associated with increases in ears per 100 plants. The reciprocal recurrent selection variety cross yield gain was estimated at 3.5% per year (7%/ cycle) and that of the best ear-to-row procedure at 2.6% per year. The variety cross syn-2 from reciprocal recurrent selection was predicted to improve at the same rate as the best ear-to-row procedure (E7) with one long growing season per year. Under a cropping system with two similar seasons per year, however, ear-to-row selection should be more effective than reciprocal recurrent selection or its derived syn-2. Mass selection at 10% selection intensity produced significant improvement, but not at 2% selection intensity.Sr and three half-sib selection methods were ineffective in KCA. Inbreeding and the lack of linkage equilibrium in KCA were discussed as contributing. Theoretical substrain compositing required 30 to 40 lines selected to equal the effectiveness of ear-to-row selection with 10 lines. Fullsib selection was effective in improving yield at 1.2% per year. All the recurrent selection methods showed a significant increase in ears per 100 plants. Population size was shown to be important in reducing losses due to inbreeding.If a hybrid or variety cross is potentially useable, reciprocal recurrent selection provides the best population approach. Initially, the variety cross syn-2 could be released with no additional breeding effort. Transition to variety crosses or traditional hybrids from extracted lines could be done as farmer husbandry improves and seed production facilities develop. Otherwise, open-pollinated varieties superior to existing maizes can be effectively developed using ear-to-row selection. The other methods may be effective in breeding populations when larger effective population sizes are used, but they were not effective in KCA when only 10 lines were recombined each cycle.

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Section: Resultsmentioning

confidence: 99%

“…However, GENTER (1973) and GENTER & EBERHART (1974) were unsuccessful in showing improvement in VLE or BSK by Si selection. HORNER et al (1973) used half-sib selection with an inbred tester and with the parental population as a tester to improve yield by 4.4% per cycle and 2.4x, respectively.…”

Section: Resultsmentioning

confidence: 99%

Six years of maize selection in ‘Kitale synthetic II’, ‘Ecuador 573’, and ‘kitale composite a’ using methods of the comprehensive breeding system

Darrah¹,

Eberhart²,

Penny³

1978

Euphytica

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“…The usefulness of the composites developed via RRS as source of parental lines of hybrids depends on their ability to generate superior testcrosses. Testcrosses of pairs of S 1 lines derived from C 4 were superior in yield potential and other agronomic traits in comparison with those derived from C 0, possibly because of changes in the frequencies of favorable alleles with additive and dominance effects (Genter, 1973). The superiority of the 73 C 4 ´ C 4 testcrosses for grain yield and overall phenotypic appeal (plant aspect) over the best commercial hybrid check SCH04 showed that the lines had the potential to be used as parents after several generations of inbreeding and selection to develop hybrids with desirable agronomic performance and adaptation to diverse production environments in WCA.…”

Section: Discussionmentioning

confidence: 98%

“…† Husk cover (1-5), where 1 = husk tightly arranged and extended beyond the ear tip, and 5 = ear tips exposed. Testcrosses of pairs of S 1 lines derived from C 4 were superior in yield potential and other agronomic traits in comparison with those derived from C 0, possibly because of changes in the frequencies of favorable alleles with additive and dominance effects (Genter, 1973). § Plant aspect (1-5), where 1 = excellent overall phenotypic appeal, and 5 = poor overall phenotypic appeal.…”

Section: Genetic Variancementioning

confidence: 99%

Genetic Advance in Grain Yield and Other Traits in Two Tropical Maize Composites Developed via Reciprocal Recurrent Selection

et al. 2018

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Assessment of genetic gain in two tropical maize (Zea mays L.) composites improved across years is critical in determining their future improvement and use as sources of inbred lines. Two genetically complementary tropical maize composites were subjected to four cycles of reciprocal recurrent selection (RRS) for grain yield, resistance to foliar diseases, and other desirable agronomic traits using a reciprocal S1 testcross evaluation scheme. The objectives of this study were to evaluate the effects of this selection scheme on: (i) the rate of genetic gain in grain yield and other traits, (ii) the changes in variance and heritability estimates, and (iii) changes in correlations between grain yield and other traits in the two tropical maize composites. One hundred S1 lines, each derived from the original (C0) and advanced (C4) cycles of the two composites, were crossed in pairs to form 100 C0 × C0 and 100 C4 × C4 testcrosses, which were evaluated along with 10 commercial hybrid checks in a replicated trial across eight environments in Nigeria. The observed genetic gain was 3.60% cycle−1 for grain yield. On average, the top 10 C4 × C4 testcrosses outyielded the commercial hybrids by 29% and had desirable agronomic traits and improved resistance to foliar diseases. The genetic variance estimates for C0 and C4 of each composite were significantly larger than zero for most traits. These results indicated that the RRS was effective in improving grain yield and other desirable agronomic traits without diminishing genetic variability that can be exploited for further improvement of the two tropical maize composites.

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“…Burton et al (1971) realized gains of 4.2% cycleover four cycles of selection for grain yield in Krug. Genter (1973) found that S1 recurrent selection was more effective than top-cross selection for improving population per se performance and was equal to test cross selection for improving combining ability. Besides its effectiveness in improving performance in terms of productivity, it has been useful in improving resistance to biotic stresses such as European corn borer (Penny et al, 1967), stalk rote (Jinahyon and Russell, 1969) and downy mildew (De Leon et al, 1993).…”

Section: Introductionmentioning

confidence: 98%

Advances in Improving Ukiriguru Composite B Maize (Zea mays L.) Variety through S1 Recurrent Selection

Leta

Habte

2011

East African Journal of Sciences

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S1 recurrent selection was carried out to improve grain yield, plant height, ear placement, resistance to lodging and other desirable agronomic traits in Ukiriguru composite B (UCB) maize variety. This paper presents the genetic gain and progress made in improving these traits through two cycles of selection. Three hundred and sixty, and 254 S1 families were evaluated in three environments and 36 and 25 families were selected following 10% selection intensity during the first (C1) and the second (C2) cycles, respectively. The selected families were recombined in isolated half-sib recombination blocks using remnant seeds. The progress made through selection was determined by evaluating the parent population (UCB C0), the first (UCB S1 C1) and the second (UCB S1 C2) selection cycles in six environments in a randomized complete block design in four replications. Commercial open-pollinated and hybrid varieties were included as checks. UCB S1 C2 produced mean grain yield of 8.7 t ha-1 and had a significant (P < 0.01) genetic gain of 30% (2.0 t ha-1) with mean gain of 15.0% (1.0 t ha-1) cycle-1. The selection also resulted in short plant height and low ear placement with significant (P < 0.01) genetic gain of 9.6% (30.8 cm) and 19.6% (39.6 cm), respectively, and superiority in tolerance to diseases and resistance to lodging. Still selection had significant (P < 0.01) grain yield benefit of 35.0% (3.1 t ha-1) and 29.3% (2.6 t ha-1) relative to Gibe Composite 1 and Kuleni, respectively, and showed comparable yield potential with commercial hybrids, BH660 and BH670. It was concluded that two cycles of S1 recurrent selection have brought significant genetic improvement in grain yield and major agronomic traits in UCB. Hence UCB S1 C2 was fully released and recommended for commercial production in the mid-altitude (1600-1800 masl) agro-ecologies of Jimma and Illu Ababora Zones, and similar areas in the southwestern areas of Ethiopia. After release, it was named as 'Morka' meaning 'competent', to express its yield potential which is comparable to the yield potential of popular hybrid varieties in the zones.

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Comparison of S₁ and Testcross Evaluation after Two Cycles of Recurrent Selection in Maize¹

Cited by 33 publications

References 0 publications

Six years of maize selection in ‘Kitale synthetic II’, ‘Ecuador 573’, and ‘kitale composite a’ using methods of the comprehensive breeding system

Six years of maize selection in ‘Kitale synthetic II’, ‘Ecuador 573’, and ‘kitale composite a’ using methods of the comprehensive breeding system

Genetic Advance in Grain Yield and Other Traits in Two Tropical Maize Composites Developed via Reciprocal Recurrent Selection

Advances in Improving <i>Ukiriguru</i> Composite B Maize (<i>Zea mays</i> L.) Variety through S1 Recurrent Selection

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