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A study of seed dehiscence in the genus Lotus (Fabaceae) using interspecific hybridization and embryo culture /O'Donoughue, Louise (Louise S.) January 1986 (has links)
No description available.
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A study of seed dehiscence in the genus Lotus (Fabaceae) using interspecific hybridization and embryo culture /O'Donoughue, Louise (Louise S.) January 1986 (has links)
No description available.
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A study of some of the inter-relationships between maize and the seed storage fungi as typified by Aspergillus flavus var. columnaris.Mycock, David John. January 1990 (has links)
The seed storage fungi (xerotolerant) species of the genera
Aspergillus and Penicillium} are renowned for their devastating
effects on stored grain and grain products. In view of the fact
that most of these fungi Iiberate toxins which can be harmful to
both man and his livestock this problem is becoming increasingly
relevant, particularly in developing countries. The seed storage
fungi are said to be saprophytes and opportunistic invaders of
dead or naturally dried organic matter, and as such no direct
host-pathogen relationship has been ascribed to them. This
dissertation reports aspects of an investigation into the
modes/pathways utilised by these fungi in their infection of maize
caryopses (seeds) and plants. The work involved studies on: the
effects of protracted storage on maize seeds; the morphology of
storage fungi; extra-cellular enzymes of storage fungi; the
pathways utiIised by the storage fungi in invasion of seed tissues;
and the effects of the storage fungi on the seeds. Correlations
have been made on a species basis between the extent of seed
deterioration and fungal aggressiveness. The results of these
investigations indicated that apart from affecting seed vigour and
viability, these fungi can also affect plant vigour. This latter
aspect was further investigated to determine whether a seed
storage fungus could infect germinating maize seeds, and remain
an internal contaminant of the tissues during plant growth and
development. These latter studies revealed that Aspergillus flavus
var. columnaris is capable of systemic transmission from one seed
generation to the next. This hitherto unrecognised phenomenon
apart from indicating that the fungal species is in fact a biotroph
as well as a saprophyte, also has implications In control
measures. / Thesis (Ph.D.)-University of Natal, Durban, 1990.
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Aspects of the influence of temperature on the desiccation responses of seeds of Zizania palustris (Wild rice)Ntuli, Tobias M. January 1996 (has links)
Seeds of wild rice (Zizania palustris var. interior) have been reported to show
highest survival when dehydrated at 25 QC. It has also been reported that axis cells
sustained least damage at this drying temperature.
In the present study, a linear relationship between drying rate and dehydration
temperature was established. Whereas highest positive tetrazolium staining and lowest
leakage were recorded for seeds that were dehydrated at 25 QC, maximum germination
was recorded for seeds dried at 20 QC. A proportion of seeds showed the presence of
glasses, irrespective of the dehydration temperatures used. Parameters of the glass to
liquid transition, however, correlated with neither water content nor sugar profiles.
The ratio of raffinose to sucrose was similar among all the treatments. A
hydroperoxide test revealed a linear relationship between peroxide levels and
temperature of drying although the levels of fatty acids were not correlated with
hydroperoxide levels. Butanal levels and total aldehydes evolved, on the other hand,
showed a high negative correlation with peroxide levels. Electron microscopy showed
that the variability and relative abundance of peripheral membrane complexes (PMCs)
was the highest for cells of embryonic axes dehydrated at 25 QC and the lowest for
embryonic axes of seeds dried at 10 QC. Furthermore, intramembrane particles (IMPs)
were evenly distributed in cells of axes dried at 25 or 37 QC. In contrast, membranes of
cells of axes dehydrated at 10 QC showed large IMP-free areas. The relative abundance
of IMPs was the highest for cells of embryonic axes dried at 25 QC, and the lowest for
cells of axes dehydrated at 10 QC. From these observations, it is suggested that
membrane phase transition, with the concomitant elimination of proteins, accompanies dehydration of Z. paluslris seeds at 10 QC, whereas at 37 QC peroxidation may
predominate. / Thesis (M.Sc.)-University of Natal, Durban, 1996.
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Pepper and tomato seed performance in response to imbibition and dehydration.Nemakanga, Rendani. January 2005 (has links)
The International Seed Testing Association and the Association of Official
Seed analysts define seed vigour as the ability of a seed lot to perform during
the germination process and crop stand establishment under a wide range of
environmental conditions. There are many ways to determine seed vigour, but
few satisfy the requirements of being simple, inexpensive and reproducible,
among others, to permit the seed industry to adopt seed vigour as an indicator
of seed quality when they sell seeds. Hence, the standard germination test,
which is performed under uniform and favourable conditions, is generally used
to indicate seed quality when seeds are marketed. The objective of this study
was to determine the performance of tomato and pepper seeds in response to
pre-germination hydration and dehydration relative humidities (12%, 49% and
75% RH). Before hydration, seeds were hydrated at three temperatures
(10°C, 20°C and 30°C). Hydration was performed by imbibing pre-weighed
pepper ('Santarini' and 'California Wonder'), Chilli and tomato ('Heinz',
'Marondera' and 'Roma') seeds for 2 h in 10 ml of distilled H(2)0 per 100 seeds
at 10°C, 20°C and 30°C. Dehydration was performed by change in seed mass
determined during a 72-hour dehydration at 12%, 49% and 75% RH. Seed
performance in response to imbibition and dehydration was determined by
leakage of electrolytes from seeds during imbibition, laboratory germination
capacity and seedling emergence under simulated shadehouse nursery
conditions. A pot experiment was conducted to determine the effects of seed
treatments on yield. Seed mass increased by about 50% during the 2-hour of
hydration. Dehydration was hastened by decreasing the RH, and 12% RH
significantly (P < 0.05) reduced the post-imbibition seed moisture content
compared with 49% and 75% RH. The latter two relative humidities reduced
the seed moisture content to about 10% and 15%, respectively, for all
cultivars, irrespective of imbibition temperature. Low imbibition temperature
(10°C) significantly (P < 0.01) increased electrolyte leakage, compared with
high imbibition temperatures (20°C and 30°C), which were not significantly
different from each other. At all hydration temperatures, low RH (12%) caused
a significant (P < 0.01) decrease in seed germination whereas 49% RH and
75% RH apparently had a priming effect on seeds. There was no significant
difference between imbibition temperatures, with respect to seed germination,
but 100G caused a significant decrease in germination index, a measure of
seed vigour. Seedling emergence was significantly (P < 0.01) reduced by both
low imbibition temperature (10oG) and low dehydration relative humidity (12%
RH). The negative effects of low imbibition temperature and rapid dehydration
at 12% RH were also observed as stunted seedling growth.
Principal component analysis and linear regression were used to determine a
statistical model to predict seedling emergence from germination percentage.
The model predicted emergence consistently, but it overestimated it by about
2% to 3%. It is concluded that low imbibition temperature and rapid
dehydration can be used to simulate stress to determine seed performance in
pepper and tomato. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.
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Basis for seed density and size differences of pearl millet [Pennisetum americanum (L.) Leeke]Lawan, Mahmud January 2011 (has links)
Photocopy of typescript. / Digitized by Kansas Correctional Industries
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Physiological basis of seed germination in Cleome gynandra (L.)Ochuodho, Julius Onyango. January 2005 (has links)
Dormancy characteristics and optimum conditions for germination of Cleome gynandra seeds
have not been explained. Seed storage proteins were extracted, analysed with SDS-PAGE and
sequenced. Seed proteins of Cleome were characterised by comparison with those of wild
mustard (Brassica kaber). Wild mustard showed seed proteins composed of two α-chains of
molecular weight (24-32 kDa) and another two β-chains of 18-22 kDa. The seed proteins of
Cleome comprised two α-chain polypeptides of molecular weight (25-30 kDa), two β-chain
polypeptides of molecular weight (18-20 kDa) and a smaller β-chain of 13-15 kDa. The
storage proteins occurred in the seeds as dimeric complexes of molecular weight 40-65 kDa,
which were broken into polypeptide chains of approximately 20 and 30 kDa by the reducing .
action of DTT. Comparison with proteins in the proteome library and similarity index further
confirmed that the seed proteins of Cleome had similarities with those of wild mustard. Two dimensional
SDS-PAGE showed that the two species have nine similar polypeptides and four
different ones.
Events associated with dormancy release during seed germination still require
explanation. Seeds of Cleome are characterised by low germination and there has been no
explanation for this. Changes in protein expression during germination of Cleome in the
presence or absence of light and at constant or alternating temperatures were examined. The
germination of Cleome seeds at 20 degrees C was inhibited by light, but it was improved at 20 degrees C in
darkness. There was no photoinhibition when seeds were germinated at constant 30 degrees C or
alternating 20/30 degrees C (16 h night and 8 h day) for 10 days. Four proteins were observed to
decrease in expression as germination progressed, but remained unchanged during
photoinhibition. Photoinhibition was expressed more in seeds that were harvested late, after
the pods had turned brown. These seeds showed a fifth, low molecular weight protein (13
kDa) that was absent from the immature seeds and embryos. Photinhibition is a pseudo-dormancy condition during which seed storage proteins are not utilised and the seed coat
could partially play a role in it.
The temperatures for the germination of Cleome in darkness have been determined.
However, prior to this study the effects of temperature, light and pre-germination treatments
(chilling, scarification, hydration and germination in the presence of KN0(3) or GA(3) on the
germination of the seeds of this species have not been investigated. Seeds were germinated
for 10 days and the final count of germination was used to determine seed performance. The
highest germination percentage (60% and 80%, for a 2-year old and a l-year old seed lot,
respectively) of untreated seeds was achieved when alternating temperatures of 20/30 degrees C (16
h/S h) in the dark or constant 30 degrees C in the dark were used. Among the pre-germination
treatments, only scarification (puncturing of seeds at the radicle end) improved germination.
Seeds were found to be negatively photoblastic, and the phenomenon was more pronounced
when they were germinated at 20 degrees C and 12 h photoperiod or longer. Germination of
photoinhibited seeds was, however, improved by treatment with GA(3) It is recommended that
the germination of Cleome be undertaken under conditions of darkness and at either
alternating 20/30 degrees C or continuous 30 degrees C.
Seed lot vigour and seedling vigour are two important seed quality aspects that are used
in defining the seed germination process. Seed germination is appropriately characterised by
radicle protrusion and the attainment of normal seedling structures. However, the
international rules for testing seeds combine radicle protrusion and normal seedling
attainment in separating seed germination into the first and final counts. The challenge to a
seed analyst testing the germination of a species whose first and final counts are unknown is
that there is no statistical guideline to determine these important stages of seed germination.
Cauliflower and broccoli, for which the first and final counts are published in the
international rules for testing seeds and Cleome, for which there is no data on the first and final
counts, were examined to determine the statistical significances of the first and final
counts. Analysis of variance, logistic regression, 'broken-stick' regression models and
survival analysis procedures were used. Analysis of variance showed that there were no
differences between the germination percentages on the fourth, fifth and seventh days of
germination. Low and stable standard deviations were recorded when evaluating germination
after the fourth day. The germination curves of broccoli and cauliflower did not fit the
Gompertz curve but fitted the exponential curve. The broken-stick model 'broke' the
cumulative germination curve for the Cleome seed lots into two linear curves that were
significantly different, but failed to break those for broccoli and cauliflower. However, this
study confirmed the first and final counts for broccoli and cauliflower as determined by the
international rules for testing seeds. Broken-stick modelling and life table analyses confirmed
the fourth day as being appropriate to determine the first count for Cleome germination.
There was no evidence of further seed germination after the seventh day as shown by
probability density and hazard rate. It is suggested that for Cleome, the 'first count' and 'final
count' be performed on the fourth and seventh day of the germination, respectively. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.
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Estratégias de seleção e efeito de armazenamento de sementes em populações segregantes de soja /Pereira, Elise de Matos January 2016 (has links)
Orientador: Sandra Helena Unêda-Trevisoli / Coorientador: Antonio Orlando Di Mauro / Coorientador: Cibele Chalita Martins / Banca: Everton Luis Finoto / Banca: Ivana Marino Bárbaro Torneli / Banca: Rinaldo Cesar de Paula / Banca: Gustavo Vitti Môro / Resumo: O presente estudo foi realizado com os objetivos principais de: verificar as associações existentes entre caracteres agronômicos e caracteres relacionados à qualidade fisiológica de sementes de soja; determinar alterações fisiológicas e no teor de óleo em sementes de soja, ao longo do período de armazenamento, além de selecionar progênies superiores de soja por meio de análises multivariadas. Para isto, as relações existentes entre os caracteres agronômicos de plantas e fisiológicos de sementes foram verificadas por meio da análise de correlações canônicas em sete populações e duas cultivares comerciais, em três gerações: plantas F3 e sementes F4; plantas F4 e sementes F5; e sementes e plantas na geração F4. Os caracteres agronômicos de plantas (grupo I) avaliados foram: número de dias para maturidade, altura da planta na maturidade, altura de inserção da primeira vagem, número de vagens, produção de grãos e teor de óleo. A qualidade fisiológica das sementes (grupo II), foi avaliada por meio do teste de germinação, envelhecimento acelerado, emergência e índice de velocidade de emergência. As mesmas populações e cultivares também foram avaliadas antes do armazenamento e após seis meses, armazenadas em ambiente com temperatura e umidade controladas, através de testes de germinação, vigor, teor de água e teor de óleo, em esquema fatorial 2 x 9. Para as análises multivariadas, 20 populações segregantes de geração F4, foram avaliadas para os seguintes caracteres agronômicos: númer... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This study aimed to examine the associations between agronomic traits and traits related to physiological seed quality in soybean seeds, determine physiological and oil content alterations during the storage and select superior progenies using multivariate analysis. For this, the relationships between agronomic traits and physiological of seed traits were evaluated using canonical correlation analysis in seven segregating populations and two commercial cultivars conducted in three generations: plants F3 and seeds F4, plants F4 and seeds F5 and seeds and plants in generation F4. The agronomic traits (group I) evaluated were: number of days to maturity, plant height at maturity, first pod height, number of pod per plant, grain yield and oil content. The seed physiological quality (group II) was evaluated by percentage of germination, percentage of emergence, emergence speed index and accelerated aging. The same populations and cultivars were also evaluated before the storage and after six months stored in cold room by germination test, vigor, seed moisture and oil content, arranged in a 2 x 9 factorial design. For the multivariate analysis, 20 segregating populations in generation F4 were evaluated using the following agronomic traits: number of days to flowering, number of days to maturity, plant height at maturity, first pod height, number of branches per plant, number of pod per plant, number of nodes per plant, grain yield and oil content. It was used the principal compone... (Complete abstract click electronic access below) / Doutor
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Procedimentos para avaliação do potencial fisiológico de sementes de pimentão e relações com a emergência de plântulas / Procedures for the physiological potential assessment of pepper seeds and relations with the emergence of seedlings.Gagliardi, Bruna 26 August 2009 (has links)
O presente trabalho teve como objetivos verificar a eficiência de procedimentos para avaliação do potencial fisiológico de sementes de pimentão e procurar identificar suas relações com a germinação sob diferentes temperaturas e com a emergência de plântulas. Paralelamente, foram efetuadas análises de imagens obtidas com o emprego de radiações X, procurando associar a morfologia interna das sementes ao seu desempenho e determinar possíveis causas de variações do potencial fisiológico. Utilizaram-se cinco lotes de sementes dos híbridos Reinger e Sentinel. A avaliação do potencial fisiológico das sementes foi realizado mediante a condução do teste de germinação, envelhecimento acelerado com solução saturada de NaCl (48h/41°C), emergência de plântulas (percentagem e velocidade), teste de tetrazólio (3h/45°C para embebição e 2h/5°C para a coloração das sementes) e teste de germinação (percentagem e velocidade) sob cinco faixas de temperatura (15°C, 18°C, 21°C, 25°C e 30°C), em mesa termogradiente. Para o teste de raios X, as sementes radiografadas foram classificadas em função do estádio de desenvolvimento e morfologia dos embriões; posteriormente ao teste de germinação, procurou-se relacionar a estrutura das sementes com as respectivas plântulas/sementes resultantes. Os testes de envelhecimento acelerado com solução saturada de NaCl e de tetrazólio são adequados para a avaliação do potencial fisiológico das sementes e, lotes vigorosos apresentam bom desempenho sob variações de temperatura, na germinação. O teste de raios X é eficiente na identificação de danos e anormalidades no embrião associados à germinação de sementes de pimentão. / This study aimed to verify the efficiency of procedures for the physiological potential assessment of pepper seeds and seek to identify its relationship with germination under different temperatures and the emergence of seedlings. In parallel, we performed the analysis of images, obtained with the use of radiation X, seeking to associate the internal morphology of seeds to their performance and to determine possible causes of changes of physiological potential. The study used five seed lots of hybrids Reinger and Sentinel. The evaluation of physiological potential of the seeds was achieved by conducting the germination test, accelerated aging with saturated solution of NaCl (48h/41°C), emergence of seedlings (percentage and speed), the tetrazolium test (3h/45°C for imbibition and 2h/5°C for colouration of seeds) and germination test (percentage and speed) on five tracks of temperature (15°C, 18°C, 21°C, 25°C and 30°C) in thermogradient table. For the X-ray test, radiographed seeds were classified according to the stage of development and morphology of the embryos; after the germination test, the structure of seeds were associated with the respective resulting seedlings/seeds. The accelerated aging test with saturated solution of NaCl and tetrazolium test are appropriate for assessing the physiological potential of pepper seeds, and vigorous lots show good performance under variations of temperature in germination. The X-ray test is effective in identifying damage and abnormalities in the embryo associated with germination of pepper seeds.
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Procedimentos para avaliação do potencial fisiológico de sementes de pimentão e relações com a emergência de plântulas / Procedures for the physiological potential assessment of pepper seeds and relations with the emergence of seedlings.Bruna Gagliardi 26 August 2009 (has links)
O presente trabalho teve como objetivos verificar a eficiência de procedimentos para avaliação do potencial fisiológico de sementes de pimentão e procurar identificar suas relações com a germinação sob diferentes temperaturas e com a emergência de plântulas. Paralelamente, foram efetuadas análises de imagens obtidas com o emprego de radiações X, procurando associar a morfologia interna das sementes ao seu desempenho e determinar possíveis causas de variações do potencial fisiológico. Utilizaram-se cinco lotes de sementes dos híbridos Reinger e Sentinel. A avaliação do potencial fisiológico das sementes foi realizado mediante a condução do teste de germinação, envelhecimento acelerado com solução saturada de NaCl (48h/41°C), emergência de plântulas (percentagem e velocidade), teste de tetrazólio (3h/45°C para embebição e 2h/5°C para a coloração das sementes) e teste de germinação (percentagem e velocidade) sob cinco faixas de temperatura (15°C, 18°C, 21°C, 25°C e 30°C), em mesa termogradiente. Para o teste de raios X, as sementes radiografadas foram classificadas em função do estádio de desenvolvimento e morfologia dos embriões; posteriormente ao teste de germinação, procurou-se relacionar a estrutura das sementes com as respectivas plântulas/sementes resultantes. Os testes de envelhecimento acelerado com solução saturada de NaCl e de tetrazólio são adequados para a avaliação do potencial fisiológico das sementes e, lotes vigorosos apresentam bom desempenho sob variações de temperatura, na germinação. O teste de raios X é eficiente na identificação de danos e anormalidades no embrião associados à germinação de sementes de pimentão. / This study aimed to verify the efficiency of procedures for the physiological potential assessment of pepper seeds and seek to identify its relationship with germination under different temperatures and the emergence of seedlings. In parallel, we performed the analysis of images, obtained with the use of radiation X, seeking to associate the internal morphology of seeds to their performance and to determine possible causes of changes of physiological potential. The study used five seed lots of hybrids Reinger and Sentinel. The evaluation of physiological potential of the seeds was achieved by conducting the germination test, accelerated aging with saturated solution of NaCl (48h/41°C), emergence of seedlings (percentage and speed), the tetrazolium test (3h/45°C for imbibition and 2h/5°C for colouration of seeds) and germination test (percentage and speed) on five tracks of temperature (15°C, 18°C, 21°C, 25°C and 30°C) in thermogradient table. For the X-ray test, radiographed seeds were classified according to the stage of development and morphology of the embryos; after the germination test, the structure of seeds were associated with the respective resulting seedlings/seeds. The accelerated aging test with saturated solution of NaCl and tetrazolium test are appropriate for assessing the physiological potential of pepper seeds, and vigorous lots show good performance under variations of temperature in germination. The X-ray test is effective in identifying damage and abnormalities in the embryo associated with germination of pepper seeds.
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