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  • 1
    Electronic Resource
    Electronic Resource
    Genetic shifts in smooth bromegrass under grazing: changes in nutritional value and preference for surviving vs. original genotypes (2000)
    Oxford UK : Blackwell Science Ltd
    Grass and forage science 55 (2000), S. 0 
    Details
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Genetic shifts in plant morphology and reproductive characters under grazing may potentially affect nutritive value and preference. This research was conducted to determine the response of smooth bromegrass (Bromus inermis Leyss.) populations to long-term grazing. Genotypes from five populations of smooth bromegrass that survived 9 years of grazing were compared with genotypes of each population grown from original seed. Plant height was measured and biomass estimated for each genotype, before and after grazing by sheep, in order to assess preference. Genotypes were also tested for nutritive value. The selective effect of competition during establishment and maintenance under grazing was accompanied by genetic shifts in smooth bromegrass plants in these pastures. Survivors had greater plant biomass despite having a decrease in plant height of up to 5%. Preference for survivors, quantified as percentage consumption by sheep, was up to 3% units less than for original populations. The nutritive value of survivors was similar to that of original populations, except for one population, which had a lower neutral-detergent fibre among the survivors after grazing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2494.2000.00238.x
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  • 2
    Electronic Resource
    Electronic Resource
    Half-sib family selection for forage yield in orchardgrass (2002)
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 121 (2002), S. 0 
    Details
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Genetic variation for forage yield of orchardgrass is abundant, but there are few reports of progress from selection for increased forage yield. The objective of this study was to estimate direct effects of selection from one cycle of half-sib family selection for forage yield in orchardgrass. Eleven selected populations were compared with their parent populations within three maturity groups. Populations were evaluated under hay management at three locations and management-intensive rotational grazing at two locations. Nine of the 11 selected populations differed, by an average of 7.4%, from their parent population in forage yield. Nine of the selected populations also showed changes in Drechslera leafspot reaction, all indicating a negative genetic correlation with forage yield. Selection for high forage yield tended to result in greater ground cover and later relative maturity. However, changes in net herbage accumulation (NHA) under rotational grazing were generally not significant and were uncorrelated with changes in forage yield, indicating that forage yield of hay plots is not correlated with the NHA of grazed plots. Although genetic gains in forage yield measured under hay management were very favourable relative to other reports from the literature, the lack of correlated progress under grazing management indicates that directed selection for NHA of orchardgrass should be conducted under grazing management.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1439-0523.2002.00665.x
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of Inbreeding and Genetic Variation on Forage Quality Traits and Dry Matter Yield in Dactylis glomerata L. Subspecies (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 98 (1987), S. 0 
    Details
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Cultivated 4× clones, 2× germplasm and their respective S; progeny were utilized in this study. Dry matter yield and forage quality data (in vitro dry matter disappearance, cell wall constituents, total nitrogen) were obtained on composited vegetative plant material harvested during four successive 4-week growth periods in the greenhouse. There was no detectable average inbreeding effect for any of the traits. The group mean of the diploids was significantly lower for in vitro dry matter disappearance than the tetraploid group mean. However, two out of six diploid 51 families exceeded the highest tetraploid family for this trait. The diploids had significantly higher cell wall constituents than tetraploids except for acid detergent lignin. There was more variation for any trait at the diploid level than at the tetraploid level among S1 families as well as within families. Dry matter yield and total nitrogen were significantly correlated in diploids and in tetraploids. However, little variation was detected lot total nitrogen at either ploidy level. The results suggest that selection for improved quality in progeny from interploidy crosses may be more efficient by first selecting at the diploid level followed by scaling to the tetraploid level, rather than selection at the tetraploid level after hybridization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1439-0523.1987.tb01123.x
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  • 4
    Electronic Resource
    Electronic Resource
    Methods of Visually Rating Maturity in Tetraploid Dactylis L. (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 105 (1990), S. 0 
    Details
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Plant maturity descriptors are important for many forage breeding decisions and in forage production research. The objectives of this study were to evaluate the effects of genotypes, maturity rating scale, maturity rating unit, and observer on visual evaluations of maturity in Dactylis glomerata. Tetraploid clonal material was planted at three locations in Wisconsin in August of 1986. All plants were rated for maturity in early June 1987; locations were rated within 3 days of each other. For most family-location combinations, parents were more advanced in maturity than offspring family means. Family maturity could not be predicted from mean parent maturity scores. Genotype × location was the only significant interaction. On the average, the single digit rating scale led to an earlier assigned maturity value than the two-digit scale. The discrepancy between the rating scales was dependent on location. High phenotypic correlations between rating units and between rating scales suggested that ratings can be done on a whole-plant basis using either scale. However, if maturity is used as a covariate for another trait, a two-digit scale is preferred.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1439-0523.1990.tb00448.x
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  • 5
    Electronic Resource
    Electronic Resource
    Genetic variation within eight populations of perennial forage grasses (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 117 (1998), S. 0 
    Details
    ISSN: 1439-0523
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Information on both mean performance and genetic variation is important in determining the value of germplasm for breeding via recurrent selection. The objectives of this experiment were to evaluate different methods of controlling spatial variation for forage yield, and to estimate genetic variances and heritability in eight perennial forage grass populations. Polycross families of two populations of smooth bromegrass (Bromus inermis Leyss.), two populations of hybrid wheatgrass (Elytrigia×muctonata (Opiz ex. Bercht.) Prokud.), and four populations of orchardgrass (Dactylis glomerata L.) were field tested for 2 years. Spatial variation was present in all three progeny tests, but was well accounted for by either the incomplete block design or a nearest neighbour analysis (NNA) of yield potentials. Low rank correlations between adjusted family means for the incomplete block design vs. the NNA created the unanswered question of which would provide a more appropriate estimate of family mean performance. Genetic variation was detected in six out of eight populations for forage yield, four out of six populations for ground cover, all four orchardgrass populations for maturity and one of four orchardgrass populations for leafspot reaction (caused by Drechslera spp.). Excessive year-family interactions prevented detection of genetic variation for leafspot reaction in the other populations. Heritability estimates ranged from 0.30 to 0.42 for forage yield. In all three species, there was a trend toward a negative relationship between population mean and genetic variance, suggesting that less elite populations may need to contribute other traits to be useful in the short term.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1439-0523.1998.tb01933.x
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  • 6
    Electronic Resource
    Electronic Resource
    Theoretical Inbreeding at Selectively Neutral Loci in Uniparental Mass Selection and Recurrent Selection with Polycrossing of Selected Plants (1999)
    Springer
    Crop science 39 (1999), S. 1009-1015 
    Details
    ISSN: 1435-0653
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: i is determined mainly by the number of plants selected in Cycle i - 2, while the total number of plants in Cycles i - 1 and i - 2 and the number of seeds contributed to the seed bag by each selected plant in Cycle i - 2 also have some effects. For recurrent selection with polycrossing of selected plants, the inbreeding coefficient of Cycle i is determined mainly by the number of plants selected in Cycle i - 1 while the number of plants selected in Cycle i - 2 and the number of seeds contributed to the seed bag by each selected plant in Cycle i - 2 also have some effects. To make an inference regarding the use of cycles from uniparental mass selected or to compare the efficacy of uniparental mass selection with recurrent selection that includes intercrossing or polycrossing of selected plants or lines, one should use the seed derived from one generation of open pollination in isolation for uniparental mass selection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/
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  • 7
    Electronic Resource
    Electronic Resource
    Structural Responses to Selection for Reduced Fiber Concentration in Smooth Bromegrass (1999)
    Springer
    Crop science 39 (1999), S. 1435-1438 
    Details
    ISSN: 1435-0653
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Bromus inermis Leyss). Three cycles of phenotypic selection led to reduced whole-plant NDF concentration, primarily due to reductions in NDF of stems (-5.7 to -5.8 g kg-1 cycle-1) and leaf sheaths (-3.1 to -4.9 g kg-1 cycle-1). Selection at both the vegetative growth stage (primarily leaf blades) or heading growth stage (all shoot components present) led to similar changes in shoot-component NDF concentrations. Selection on the basis of vegetative samples did not lead to structural changes. Conversely, selection on the basis of headed samples led to an average reduction of -7.5% cycle-1 in stem component concentration, which was compensated largely by increases in leaf blade and sheath component concentrations. Increases in leaf∝stem ratio may partially explain reductions in forage yield associated with reduced NDF concentration. Future selection efforts should attempt to avoid this response by using samples composed of a single shoot component. The NDF concentrations in various shoot components in smooth bromegrass appear to be positively correlated with each other.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/
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  • 8
    Electronic Resource
    Electronic Resource
    Genetic variation and covariation in a population of tetraploid Dactylis L. accessions (1991)
    Springer
    Theoretical and applied genetics 81 (1991), S. 253-264 
    Details
    ISSN: 1432-2242
    Keywords: Germ-plasm evaluation ; Germ-plasm preservation ; Grass breeding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Efficient utilization of divergent germ plasm sources in breeding cultivated Dactylis glomerata L. ssp. glomerata Domin depends on knowledge of quantitative variation within and among accessions. This study was undertaken to quantify variation and covariation for forage yield, maturity, disease reaction, and ground cover within a population of tetraploid Dactylis accessions. Variation was observed among families within the population for each variable. Most genetic variation (73%–93% of the family sums of squares) was within country sources or within accessions. Thus, country boundaries, which are traditionally important factors used in defining limits of plant exploration expeditions, have limited expected use in targeting future exploration for specific sources of high yield, disease resistance, or ground cover. Maturity was the exception to this; late-maturing accessions were identified as originating exclusively from the USSR. Some relationships among traits, such as that for yield and disease reaction, differed for accessions and cultivars. Several accessions and families within accessions were identified to have performance superior to most or all cultivars included in this study. Existing germ plasm from several countries was identified to have potential in breeding orchardgrass, while that from other countries appeared to have little or no potential in supplying germ plasm for hay production in humid-temperate environments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00215731
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  • 9
    Electronic Resource
    Electronic Resource
    Correlated responses in forage yield and nutritional value from phenotypic recurrent selection for reduced fiber concentration in smooth bromegrass (1999)
    Springer
    Theoretical and applied genetics 99 (1999), S. 1245-1254 
    Details
    ISSN: 1432-2242
    Keywords: Key words Recurrent Selection ; Fiber ; Forage yield ; Digestibility ; Inbreeding ; Forage crops ; Pollination methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Selection for reduced fiber concentration in forage crops is considered to be an effective approach to improve the voluntary intake potential of forages. The purpose of this study was to determine the effectiveness of several modifications to phenotypic recurrent selection for reducing neutral detergent fiber (NDF) concentration and its effect on correlated variables of smooth bromegrass (Bromus inermis Leyss). The selection methods were based on differences in the growth stage sampled (vegetative vs heading), the method of determining NDF in the laboratory (wet-laboratory vs near-infrared reflectance spectroscopy), and the method of intercrossing selected individuals (in situ vs replicated polycross). Selection at the vegetative growth stage was most effective, probably, due to minimal sampling variation within plants. Polycrossing generally increased gains due to more effective interpollination, but increased cycle time by 50%, resulting in similar gains per year for in situ pollination vs polycrossing. Selection for reduced NDF did not generally affect the digestibility of the NDF fraction. Selection for reduced NDF led to reduced forage yield for all selection methods, due partly to a genetic correlation with NDF and partly to inbreeding depression. Three potential solutions were proposed to break the apparent association between reduced NDF and forage yield: increase effective population size, practice combined selection for both traits, and/or make chance hybrids between genetically divergent low-NDF strains. An empirical assessment will most likely be required to determine the best of these three potential solutions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220051330
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  • 10
    Electronic Resource
    Electronic Resource
    Selection strategies for developing smooth bromegrass cell wall ideotypes (1989)
    Springer
    Theoretical and applied genetics 78 (1989), S. 775-782 
    Details
    ISSN: 1432-2242
    Keywords: Cell wall ; Ideotype breeding ; Selection ; Smooth bromegrass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A random sample of 80 families of the B8HD smooth bromegrass (Bromus inermis Leyss.) population were tested in three environments for forage yield and cell wall constituents. Expected progress from one cycle of family selection was computed for single-trait selection and multiple-trait restricted selection. Expected gains were compared to desired goals and actual results from one cycle of phenotypic selection. Desired goals were: Model I = reduced lignin and cellulose, with increased hemicellulose, resulting in no change in cell wall content; Model II = reduced lignin and cellulose with no change in hemicellulose; or Model III = reduced lignin, cellulose, and hemicellulose. Single-trait selection for high hemicellulose in first harvest or low cellulose in second harvest had the best expected responses, of any single trait, for Model I. Possible undesirable effects of selection for low cellulose would be a reduction in forage yield potential. Multiple-trait restricted selection was judged to be more effective, with responses all in the desired direction, by specifying increased hemicellulose in index development. Selection in second harvest was expected to have similar responses as first harvest, except for a greater increase in forage yield. Development of Models II or III is expected to be difficult due to a negative correlation estimate between first and second harvest cell wall concentration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00266657
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