Seed germination In <i>Acacia auriculiformis</i>: developmental aspects

Pukittayacamee, P.; Hellum, Anne

doi:10.1139/b88-061

Cited by 13 publications

(6 citation statements)

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“…Para essa determinação, os parâmetros mais comumente utilizados são baseados na morfologia interna (Borisjuk et al 1995), externa e/ou comprimento de frutos e sementes (Walbot et al 1972;Adams & Rinne 1981;Figueiredo & Pereira 1985), no peso fresco e teor de umidade (Pukittayacamee & Hellum 1988), ou em ambos (Amaral 1990). Segundo Adams & Rinne (1981), a desidratação impõe o processo de maturação das sementes.…”

Section: Introductionunclassified

Formação das substâncias de reserva durante o desenvolvimento de sementes de urucum (Bixa orellana L. - Bixaceae)

2001

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Recebido em 31/5/2000. Aceito em 22/9/2000 RESUMO -(Formação das substâncias de reserva durante o desenvolvimento de sementes de urucum, Bixa orellana L. -Bixaceae). As sementes de urucum não germinam durante os primeiros estádios de seu desenvolvimento devido em parte à insuficiência de materiais de reserva. A análise in situ do material de reserva das sementes revelou que ocorrem principalmente proteínas e amido nas células do endosperma. Durante os estádios iniciais do desenvolvimento, o formato dos grãos de amido mostrou-se elíptico, devido a menor quantidade de amilose. Durante o desenvolvimento, os grãos tornaram-se mais esféricos devido ao aumento de amilose em relação a amilopectina. As células do endosperma não possuem corpos protéicos, mas armazenam proteínas. Durante o desenvolvimento houve acúmulo de proteínas dispersas pelo citoplasma. No estádio final do desenvolvimento, as proteínas tornaram-se compactadas devido à desidratação das sementes, que faz parte do processo global de maturação de sementes ortodoxas. A utilização de fluorescência natural revelou a presença de aminoácidos aromáticos no conteúdo protéico, principalmente triptofano e tirosina. Nestas sementes o conteúdo de matéria seca alcançou o máximo quando a semente apresentou cerca de 60% de umidade. Nesta fase a semente apresentou capacidade germinativa máxima.Palavras-chave -proteína, amido, urucum, sementes, maturação, Bixa ABSTRACT -(Formation of reserve substances during the development of annatto, Bixa orellana L. -Bixaceae, seeds). Annatto seeds do not germinate during early stages of their development because of insufficient reserve substances. In situ analysis showed that the principal reserves are proteins and starch, deposited in endosperm cells. During the early stages of development, the starch grains were elliptic, because amylose was the minor component. During development, these grains became more spherical due to an increase in amylose relative to amylopectin. Endosperm cells do not contain protein bodies, but they accumulate proteins dispersed in the cytoplasm. At the final stage of development the proteins became compacted due to the dehydration of the seeds wich is part of the

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Section: Introductionunclassified

Formação das substâncias de reserva durante o desenvolvimento de sementes de urucum (Bixa orellana L. - Bixaceae)

2001

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“…We suggest that the lack of dormancy observed in A. linifolia is an artefact of using freshly collected seeds, and the development into hard seeds, while relatively slow, is within a time frame that ensures minimal loss to germination. Other studies have reported several PY species that have non-dormant seeds at dispersal, with PY developing on exposure to low humidity levels (Pukittayacamee and Hellum, 1988; Tozer and Ooi, 2014). Tozer and Ooi (2014) found that this occurred rapidly for Acacia saligna once humidity dropped below 20%, meaning that initially non-dormant seeds of this PY species were likely to ‘harden’ within a few days of dispersal in their native habitat, and still be incorporated into the seed bank.…”

Section: Discussionmentioning

confidence: 99%

Do dormancy-breaking temperature thresholds change as seeds age in the soil seed bank?

Liyanage

Ooi

2016

Seed Sci. Res.

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In fire-prone ecosystems, many species regenerate after fire from persistent soil seed banks. Species with physically dormant (PY) seeds have dormancy broken by fire-related heat. The magnitude of post-fire recruitment, to predict response to varying fire severity, is commonly estimated by testing dormancy-breaking temperature thresholds of fresh PY seeds. However, seeds spend years in the soil during the inter-fire period, and determining whether dormancy-breaking thresholds change over time is essential to accurately predict population persistence. Germination of four south-eastern Australian PY species from the Fabaceae family (Acacia linifolia, Aotus ericoides, Bossiaea heterophylla and Viminaria juncea) were studied. Dormancybreaking temperature thresholds vary inter-specifically and the species represented either high or low dormancy-breaking threshold classes. Freshly collected seeds, and seeds that had been buried in the field or stored in dry laboratory conditions for 6 and 18 months were subjected to a fire-related range of heat treatments (40¿100°C). Seed ageing increased germination response to heat treatments, effectively lowering the dormancy-breaking thresholds of three species. The fourth species, A. linifolia, initially had a relatively large non-dormant fraction which was lost as seeds aged, with older seeds then displaying PY broadly similar to the other study species. Patterns of threshold decay were species-specific, with the thresholds and viability of low-threshold species declining more rapidly than high-threshold species. The non-dormant fraction did not increase over time for any of our study species. Instead of increasing their non-dormant fraction, as is common in other vegetation types, these fire-prone PY species displayed a change of dormancy-breaking temperature thresholds. This is an important distinction, as maintaining dormancy during the inter-fire period is essential for population persistence. While changes in sensitivity to dormancy-breaking treatments have previously been reported as seeds age, our study provides the first test of changes to temperature thresholds, which increases the range of germination response from the seed bank under varying fire severity. In fire-prone ecosystems, many species regenerate after fire from persistent soil seed banks. 25Species with physically dormant (PY) seeds have dormancy broken by fire-related heat. The 26 magnitude of post-fire recruitment, to predict response to varying fire severity, is commonly 27 estimated by testing dormancy-breaking temperature thresholds of fresh PY seeds. However, 28 seeds spend years in the soil during the inter-fire period, and determining whether dormancy-29 breaking thresholds change over time is essential to accurately predict population persistence. 30Germination of four south-eastern Australian PY species from the Fabaceae family (Acacia 31 linifolia, Aotus ericoides, Bossiaea heterophylla and Viminaria juncea) were studied. Dormancy-32 breaking temperature thresholds vary inter-specifically ...

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“…Results have varied among Racosperma spp., among seedlots of the same species, and within the same seedlot. The proportion of hardcoated seeds in a sample may be influenced by many factors including the environmental conditions during the growth of the plant, the degree of maturation of the seeds when collected, and duration and type of seed storage (Willan 1985, Pukittayacamee andHellum 1987). Hence, it is difficult to prescribe an "optimum" treatment (or range of treatments) that is highly effective in stimulating germination in most Racosperma seeds (Doran and Gunn 1987).…”

Section: Introductionmentioning

confidence: 99%

Acid scarification and hot water soaking of Racosperma auriculiforme seeds

Khasa¹

1993

The Forestry Chronicle

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Nine methods of overcoming seed-coat dormancy of Racosperma auriculifotme (provenance KZNO) from Zaire were investigated. Soaking seeds in concentrated sulphuric acid for 15 or 30 min and then rinsing for 15 min with tap water produced the best results for laboratory testing as well as operational application. Boiling water from which the heat source has been removed and in which the seeds are placed and soaked until the water is cool (12-24 h) is the most suitable and economical method for social forestry programs at the village level in Zaire.Key words: Acacia, germination, Leguminosae, Racosperma, seed-coat dormancy, social forestry En vue de briser la dormance due aux teguments des graines d'Aracosperma auriculifonne (Provenance KZNO) rCcoltCes au Za'ire, neuf mCthodes ont Cte Ctudiees. Le trempage de graines dans I'acide sulfurique concentre durant 15 ou 30 min. suivi d'un rin~age B I'eau de robinet pendant 15 min, a donnC les meilleurs resultats aussi bien pour des tests de germination en laboratoire que pour une application opCrationnelle. Le trempage de graines dans I'eau bouillante, retiree de la source de chauffage jusqu'au refroidissement (12-24h) est la mCthode la plus approprike et Cconomique au niveau du village pour des programmes de foresterie sociale au Zaire.

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Seed germination In Acacia auriculiformis: developmental aspects

Cited by 13 publications

References 0 publications

Formação das substâncias de reserva durante o desenvolvimento de sementes de urucum (Bixa orellana L. - Bixaceae)

Formação das substâncias de reserva durante o desenvolvimento de sementes de urucum (Bixa orellana L. - Bixaceae)

Do dormancy-breaking temperature thresholds change as seeds age in the soil seed bank?

Acid scarification and hot water soaking of Racosperma auriculiforme seeds

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