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Biblioteca(s): |
Embrapa Recursos Genéticos e Biotecnologia. |
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Data corrente: |
22/07/1991 |
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Data da última atualização: |
20/03/2025 |
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Autoria: |
GOEDERT, C. O. |
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Afiliação: |
EMBRAPA/CENARGEN. |
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Título: |
Seed dormancy of tropical forage grasses and implications for the conservation of genetic resources. |
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Ano de publicação: |
1984 |
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Fonte/Imprenta: |
Reading : University of Reading, 1984. |
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Páginas: |
190p. |
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Descrição Física: |
Tese Doutorado. |
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Idioma: |
Inglês |
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Conteúdo: |
Investigation are described on the characteristics of tropical grass seeds affect their management, particularly in genebanks. Five tropical forage grass species were selected for study Brachiaria humidicola, Brachiaria decumbens, Panicum maximum, Paspalum guenoarum and Andropogon gayanus. It is shown that germination tests currently provide the best basis for monitoring viability. However two problems are particularly prevalent in tropical grasses which hinder the interpretation of germination tests; first, freshly harvested seeds often show low purity (i.e. a high proportion of immature and empty spikelets); and secondly, many of the true seeds often show pronounced dormancy (i.e. though viable they are incapable of germination without special stimuli). Investigation of the purity problems showed that in can be overcome with the use of X-ray equipament, but other methods are unreliable. Investigation of the dormancy problem led to the conclusion that advantage needs to be taken of the interaction of several dormancy-breaking agents. It is shown that simultaneous use of three of these are specially valuable alternating-temperatures, linght and nitrate ions. In particular it is important to define the optimum characteristics of alternative-temperature regimes for maximum stimulation of germination. Techniques for doing this were developed using a two-way temperature-gradient plate. Amplitude and thermoperiod were both shown to be particularly important attributes and, although the optima for each species investigated differed in detail, in no case did any optimum diverge far from a regime in which seeds were subjected to diurnal cycles of 20h at 15o and 4h at 35oC in the presence of 10-2 M KNO3 and intermittent illumination. The significance of these and other experimental results are discussed in relation to seed physiology and to the problems of the management of seed accessions in genebanks for genetic conservation. MenosInvestigation are described on the characteristics of tropical grass seeds affect their management, particularly in genebanks. Five tropical forage grass species were selected for study Brachiaria humidicola, Brachiaria decumbens, Panicum maximum, Paspalum guenoarum and Andropogon gayanus. It is shown that germination tests currently provide the best basis for monitoring viability. However two problems are particularly prevalent in tropical grasses which hinder the interpretation of germination tests; first, freshly harvested seeds often show low purity (i.e. a high proportion of immature and empty spikelets); and secondly, many of the true seeds often show pronounced dormancy (i.e. though viable they are incapable of germination without special stimuli). Investigation of the purity problems showed that in can be overcome with the use of X-ray equipament, but other methods are unreliable. Investigation of the dormancy problem led to the conclusion that advantage needs to be taken of the interaction of several dormancy-breaking agents. It is shown that simultaneous use of three of these are specially valuable alternating-temperatures, linght and nitrate ions. In particular it is important to define the optimum characteristics of alternative-temperature regimes for maximum stimulation of germination. Techniques for doing this were developed using a two-way temperature-gradient plate. Amplitude and thermoperiod were both shown to be particularly important attributes and, althou... Mostrar Tudo |
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Palavras-Chave: |
Forrageira; Genetic conservation; Genetic resource; Gramineas forrageiras tropicais; Grass; Pastagem tropical; Regiao Tropical; Seed; Seed physiology; Sementes; Tropical forage grasses; Tropical pasture. |
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Thesagro: |
Agricultura; Agronomia; Conservação; Dormência; Germinação; Horticultura; Pastagem; Planta Forrageira; Recurso Genético; Semente. |
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Thesaurus NAL: |
agriculture; agronomy; dormancy; forage; germination; seeds; storage. |
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Categoria do assunto: |
-- |
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Marc: |
LEADER 03177nam a2200469 a 4500
001 1163573
005 2025-03-20
008 1984 bl uuuu m 00u1 u #d
100 1 $aGOEDERT, C. O.
245 $aSeed dormancy of tropical forage grasses and implications for the conservation of genetic resources.
260 $aReading : University of Reading$c1984
300 $a190p.$cTese Doutorado.
520 $aInvestigation are described on the characteristics of tropical grass seeds affect their management, particularly in genebanks. Five tropical forage grass species were selected for study Brachiaria humidicola, Brachiaria decumbens, Panicum maximum, Paspalum guenoarum and Andropogon gayanus. It is shown that germination tests currently provide the best basis for monitoring viability. However two problems are particularly prevalent in tropical grasses which hinder the interpretation of germination tests; first, freshly harvested seeds often show low purity (i.e. a high proportion of immature and empty spikelets); and secondly, many of the true seeds often show pronounced dormancy (i.e. though viable they are incapable of germination without special stimuli). Investigation of the purity problems showed that in can be overcome with the use of X-ray equipament, but other methods are unreliable. Investigation of the dormancy problem led to the conclusion that advantage needs to be taken of the interaction of several dormancy-breaking agents. It is shown that simultaneous use of three of these are specially valuable alternating-temperatures, linght and nitrate ions. In particular it is important to define the optimum characteristics of alternative-temperature regimes for maximum stimulation of germination. Techniques for doing this were developed using a two-way temperature-gradient plate. Amplitude and thermoperiod were both shown to be particularly important attributes and, although the optima for each species investigated differed in detail, in no case did any optimum diverge far from a regime in which seeds were subjected to diurnal cycles of 20h at 15o and 4h at 35oC in the presence of 10-2 M KNO3 and intermittent illumination. The significance of these and other experimental results are discussed in relation to seed physiology and to the problems of the management of seed accessions in genebanks for genetic conservation.
650 $aagriculture
650 $aagronomy
650 $adormancy
650 $aforage
650 $agermination
650 $aseeds
650 $astorage
650 $aAgricultura
650 $aAgronomia
650 $aConservação
650 $aDormência
650 $aGerminação
650 $aHorticultura
650 $aPastagem
650 $aPlanta Forrageira
650 $aRecurso Genético
650 $aSemente
653 $aForrageira
653 $aGenetic conservation
653 $aGenetic resource
653 $aGramineas forrageiras tropicais
653 $aGrass
653 $aPastagem tropical
653 $aRegiao Tropical
653 $aSeed
653 $aSeed physiology
653 $aSementes
653 $aTropical forage grasses
653 $aTropical pasture
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