Responses to Divergent Selection for Fiber Concentration at Two Disease Potentials in Smooth Bromegrass

Han, Lixin; Casler, Michael D.; Grau, C. R.

doi:10.2135/cropsci2001.41130x

Cited by 14 publications

(14 citation statements)

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“…The highly consistent and positive genetic correlation between NDF and forage yield in Years 1 and 2 is consistent with numerous previous studies (Casler, 1999; Han et al, 2001; Hovin et al, 1976; Marum et al, 1979; Surprenant et al, 1988). Across harvests, locations, and years, NDF concentration averaged 477 to 687 g kg −1 , averaging 593 g kg −1 for the entire study (Casler, 2002).…”

Section: Discussionsupporting

confidence: 92%

“…B reeding for increased intake potential of perennial grasses for ruminant livestock, by selection for reduced NDF concentration, have been plagued by persistent reductions in forage yield (Casler, 1999; Han et al, 2001; Surprenant et al, 1988). Because NDF is approximately equal to cell‐wall concentration (Van Soest, 1994), a positive genetic correlation between NDF and forage yield may be a biological necessity.…”

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confidence: 99%

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Agricultural Fitness of Smooth Bromegrass Populations Selected for Divergent Fiber Concentration

Casler

2005

Crop Science

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Selection for reduced neutral detergent fiber (NDF) concentration has been used as a mechanism of improving intake potential of perennial grasses by ruminant livestock. However, reduced NDF concentration is typically associated with reduced forage yield, although the reasons for this genetic correlation are unknown. The objectives of this study were to determine the relative contributions of pleiotropy, linkage, and drift to the genetic correlation of NDF concentration with four agricultural fitness traits: forage yield, survival, seed yield, and lodging. These traits were measured on four smooth bromegrass (Bromus inermis Leyss.) populations that had undergone one cycle of divergent selection for NDF concentration. Selection responses for forage yield were linear and homogeneous, suggesting pleiotropic effects. Growth and expansion of the cell wall appears to be essential for accumulation of forage yield, lending a certain allometry to these two traits. However, natural selection within swards appeared to regulate this response, because forage yield responses disappeared by the third production year. Selection responses for survival and lodging were linear, but nonhomogeneous, suggesting linkage. Selection responses for seed yield appeared to be regulated by all three phenomena, with drift (asymmetry) the most important. Seed yield is highly sensitive to inbreeding depression, which occurs as a result of drift. Short‐term divergent selection experiments, analyzed by a factorial ANOVA model, provide a mechanism to identify genetic phenomena responsible for observed genetic correlations.

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Section: Discussionsupporting

confidence: 92%

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confidence: 99%

Agricultural Fitness of Smooth Bromegrass Populations Selected for Divergent Fiber Concentration

Casler

2005

Crop Science

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“…(Descriptions of the NIRS equations statistics are in Table 2.) Hemicellulose concentrations were estimated as the difference between NDF and ADF, and CEL concentrations were estimated as the difference between ADF and LIG, respectively (Claessens et al 2005;Han et al 2001). Total cell wall (CW) concentration was estimated by summing the NDSF and NDF concentrations.…”

Section: Laboratory Analysesmentioning

confidence: 99%

“…For example, selection was effective for reduced NDF in reed canarygrass (Phalaris arundinaceae L.) (Surprenant et al 1988), smooth bromegrass (Bromus inermis L.) (Han et al 2001;Casler 1999Casler , 2002, and timothy (Phleum pratense L.) (Claessens et al 2004(Claessens et al , 2005. Furthermore, selection was successful for increased neutral detergent soluble fiber (NDSF) or pectin (Fonseca et al 1999;Tecle et al 2006), reduced ADF (Coors et al 1986) and lignin in alfalfa (Kephart et al 1990), reduced ADF, CEL, HEM, and LIG in smooth bromegrass (Carpenter and Casler 1990), reduced ADF, LIG and CEL, and reduced ratios of LIG to CEL, LIG to HEM, LIG to HEM'CEL, and increased ratio of HEM to CEL in timothy (Claessens et al 2004(Claessens et al , 2005.…”

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confidence: 99%

Divergent phenotypic selection for alfalfa cell wall fractions and indirect response in digestibility

Tecle¹,

Hansen²,

Pell³

et al. 2008

Can. J. Plant Sci.

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. 2008. Divergent phenotypic selection for alfalfa cell wall fractions and indirect response in digestibility. Can. J. Plant Sci. 88: 891Á898. An alfalfa (Medicago sativa L.) breeding strategy to decrease slowly digestible or indigestible fiber and simultaneously increase digestible fiber could improve forage quality without reducing total fiber. The objectives were: (1) to estimate selection responses from divergent and opposite direction selections of (i) hemicellulose (HEM) and acid detergent fiber (ADF), (ii) acid detergent lignin (LIG) and HEM'cellulose (CEL) and (iii) CEL and HEM'LIG, and (2) to determine correlated responses in in vitro true digestibility (IVTD). Selection progress was evaluated in replicated plot trials at two locations, sampled for 2 or 3 yr. Selection for divergent HEM and ADF resulted in change only for ADF [10.9 g kg (1 dry matter (DM)]. Selection for divergent LIG and HEM' CEL, resulted in same direction change in LIG (3.3 g kg(1 DM). Selection for divergent CEL and HEM'LIG resulted in change only in CEL (5.1 g kg(1 DM). Low LIG and high HEM'CEL, and low ADF and high HEM populations had 9.7 and 8.3 g kg(1 DM higher IVTD than their counterparts, respectively. The first cycle of selection for the fiber components simultaneously in the opposite directions was not successful. However, reduced LIG or ADF concentration appears to increase alfalfa forage digestibility and decrease total fiber concentration.

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“…Most efforts to breed for increased intake potential of perennial grasses for ruminant livestock, by selection for reduced neutral detergent fiber (NDF) concentration, have been plagued by persistent reductions in forage yield (Casler, 1999;Han et al, 2001;Surprenant et al, 1988). Because NDF is approximately equal to cell wall concentration (Van Soest, 1994), a positive genetic correlation between NDF and forage yield may be a biological necessity.…”

mentioning

confidence: 99%

Partial Decomposition of the Genetic Correlation between Forage Yield and Fiber Using Semihybrids

Casler

2013

Crop Science

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Voluntary intake potential of a forage crop is generally considered to be the most important feed characteristic regulating animal performance. Efforts to develop forage crops with increased intake potential have been associated with reduced plant fitness, prompting a need to modify breeding objectives and methods. The objective of this study was to determine if semihyrids could be used to restore all or a portion of the forage yield lost to drift during selection for low neutral detergent fiber (NDF) in smooth bromegrass (Bromus inermis Leyss.). A total of 48 semihybrids were created by pair crossing within four base (original) populations, four high‐NDF populations, and four low‐NDF populations. Genetic variation declined progressively with increased NDF concentration. Midparent heterosis was positive and significant for four of six semihybrids at the low‐NDF level. Two of these semihybrids also had positive and significant heterosis for NDF, reflecting the typical positive genetic correlation between yield and NDF. However, two of these semihybrids had no heterotic effect for NDF, resulting in partial decay of the genetic correlation due to a combination of linkage and drift acting on alleles that independently control these two traits. Because about one‐third of this genetic correlation is malleable by manipulation of linkage and drift, there is potential to produce low‐NDF smooth bromegrass populations without sacrificing forage yield potential.

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Responses to Divergent Selection for Fiber Concentration at Two Disease Potentials in Smooth Bromegrass

Cited by 14 publications

References 20 publications

Agricultural Fitness of Smooth Bromegrass Populations Selected for Divergent Fiber Concentration

Agricultural Fitness of Smooth Bromegrass Populations Selected for Divergent Fiber Concentration

Divergent phenotypic selection for alfalfa cell wall fractions and indirect response in digestibility

Partial Decomposition of the Genetic Correlation between Forage Yield and Fiber Using Semihybrids

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