Inbreeding depression of 28 maize elite open pollinated varieties

Pacheco, C. A. P.; Santos, M. X. dos; Cruz, Cosme Damião; Parentoni, S. N.; Guimarães, P. E. de O.; Gama, E. E. G. e; Silva, Álvaro Eleutério Da; Carvalho, H. W. L. de; Júnior, Pedro Martins Ribeiro

doi:10.1590/s1415-47572002000400014

Cited by 17 publications

(20 citation statements)

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“…De Léon et al (1998) verificaram I% mais baixos, de 6% a 9%, em híbridos duplos para produtividade. Pacheco et al (2002) obtiveram para produtividade de grãos, em variedades elite de milho, estimativa de depressão por endogamia que variou de 34,6% a 59,2%, com média de 49,1%, confirmando que o baixo valor de I% é esperado em população melhorada por causa de sua baixa frequência de alelos deletérios, devida ao processo de seleção já ocorrido.…”

Section: Resultsunclassified

“…Sobre depressão endogâmica e constituição genética das populações, os autores Viana et al (1982), Lima et al (1984) e Pacheco et al (2002) citam que a carga genética baixa é esperada nas populações sintetizadas a partir de linhagens endogâmicas e de compostos de base genética ampla que já passaram por processo de seleção contra alelos deletérios, quando comparadas com aquelas populações de alta heterozigosidade nunca expostas a quaisquer níveis de endogamia. De Léon et al (1998) O melhoramento de populações visa essencialmente ao aumento da frequência dos genes favoráveis nas populações base.…”

Section: Introductionunclassified

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Depressão endogâmica e heterose de híbridos de populações F2 de milho no estado de São Paulo

et al. 2013

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A heterose e a depressão por endogamia são fenômenos complementares importantes nas estratégias de melhoramento, como para a obtenção de híbridos convencionais e melhoramento de populações. Este trabalho teve por objetivos avaliar híbridos de populações F 2 de milho quanto aos caracteres agronômicos, estimar a heterose em relação à média dos pais e determinar a depressão endogâmica na obtenção das populações de genitores F 2 . Foram avaliados 10 híbridos de populações F 2 , cinco populações de genitores F 2 e os respectivos híbridos comerciais (HC) quanto aos seguintes caracteres agronômicos: florescimento masculino (FM), altura de planta (AP), altura de espiga (AE) e massa de grãos (MG), em dois locais do estado de São Paulo, Mococa e Palmital, sob delineamento de blocos ao acaso. A estimativa de depressão por endogamia ao passar da geração F 1 para F 2 variou de 18,0% no HC12 a 48,1% no HC10, para MG. A heterose média em relação à média dos pais obtida para massa de grãos foi de 37,2%, representada pela elevada produtividade alcançada pelos híbridos de F 2 . Baseando-se nesses resultados foi possível evidenciar dois híbridos de populações F 2 que apresentaram potencial produtivo, alta heterose média e populações F 2 com potencial para extração de linhagens.Palavras-chave: Zea mays, vigor híbrido, endogamia, melhoramento populacional, produtividade.Inbreeding depression and heterosis of hybrids in F 2 populations of maize in the Sao Paulo State, Brazil Abstract Heterosis and inbreeding depression are complementary phenomena, both important to the establishment of breeding strategies, such as conventional hybrids and population breeding. This study aimed to evaluate the agronomic traits of hybrids in F 2 populations, estimate of heterosis in relation to the average of the parents and determine the inbreeding depression in F 2 parents populations. Ten hybrids of F 2 populations, five F 2 parents populations and the respective commercial hybrids (HC) were evaluated for male flowering, plant height, ear height and grain mass. Plants were evaluated in Mococa and Palmital counties at the Sao Paulo State and the experiment was arranged in a completely randomized block design. The estimated inbreeding depression from F 1 to next F 2 generation ranged from 18.0% in HC12 to 48.1% in HC10 for grain mass. The heterosis in relation to the parents' mean was 37.2%, represented by high yield in F 2 hybrids. Based on these results, it was possible to highlight two hybrids of F 2 populations with high yield potential, high average heterosis and F 2 populations with potential for extraction of inbred lines.

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Section: Resultsunclassified

Section: Introductionunclassified

Depressão endogâmica e heterose de híbridos de populações F2 de milho no estado de São Paulo

et al. 2013

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“…The difference between the panmitic population mean (S0) and the population mean after one generation of self-pollination (S1) is an estimate of inbreeding depression Berdahl and Ray, 2004). There are many studies related to the effects of inbreeding depression using S1 populations in several species of plants (MenaAli et al, 2008;Zaffar et al, 2001;Rojas et al, 2009;Berdahl and Ray, 2004;Pacheco et al, 2002). For instance, Rojas et al (2009) quantified the inbreeding depression for different traits in eight S1 cassava families and analyzed the variation within these eight groups of S1 families.…”

Section: Introductionmentioning

confidence: 99%

“…Berdahl and Ray (2004) determined the value of one generation of self-pollinating before selection for yield in crested wheatgrass, and yields were compared for synthetic populations derived from selection among and within S1 and open-pollinated progenies. In maize, Pacheco et al (2002) studied the inbreeding depression using a diallel experiment of 28 maize elite open-pollinated varieties. In that study, yield reductions of the populations from S0 to S1 (mean of the 10 environments) varied from 34.6% to 59.2%, with an average of 49.1%.…”

Section: Introductionmentioning

confidence: 99%

Inbreeding depression and genetic components for popping expansion and other traits in Brazilian populations of popcorn

Viana¹,

Mora²,

Miranda³

et al. 2010

Cienc. Inv. Agr.

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The aim of the study was to assess inbreeding depression and determine genetic components in landrace populations of popcorn. Six Brazilian popcorn landraces: Amarelo, Beija-Flor, Branco, Rosa-claro, Roxo and Viçosa, were subjected to self-pollination. Experiments with S0 populations and their selfing populations (S1) were conducted in a randomized complete block design. The estimates of inbreeding depression varied from 1.2% (popping expansion) to 79% (grain yield). The gene action was predominantly additive for plant height, ear height and hundred-grain-weight. The dominance genetic effects were important for index of prolificacy and grain yield. The genetic effect of popping expansion was bidirectional with null dominance and a predominance of additive gene effects. Based on these results, it was possible to identify popcorn populations suitable to extract inbred lines, develop hybrids and use in population improvement. The present study also confirmed that popping expansion is a trait that can be improved efficiently by recurrent selection programs of popcorn.

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“…The wide range of maize cultivars on the market is extremely favorable for Brazilian agriculture, because it leads to constant improvements in yield and quality (Ramalho et al 2009). The main maize breeding goals focus on yield and yield-related factors, such as uniformity, stability and adaptability (Pacheco et al 2002). Subsequently, breeding became a major driving force of the high increase of maize yield in Brazil.…”

Section: Introductionmentioning

confidence: 99%