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Role of the seed coat in the dormancy of wheat (Triticum aestivum) grains.Rathjen, Judith Rebecca January 2006 (has links)
Title page, contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / Pre-harvest sprouting (PHS) is an important economic problem which affects a significant proportion of the Australian wheat crop through quality downgrading. Grain dormancy is the most effective means of overcoming germination in the wheat spikelet at harvest maturity. It has been a consistent observation over a long period of time that dormant red-grained wheat genotypes are almost more dormant than dormant white-grained genotypes. In white-grained wheat, there are two factors which contribute to dormancy, embryo sensitivity to abscisic acid (ABA) and an interacting and unknown seed coat factor. The proposed dormancy model is that complete dormancy can only be achieved with the coordinate expression of these two factors. This primary objective of this project was to determine the role of this putative seed coat factor in grain dormancy of white-grained wheat."--Abstract. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1259900 / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2006
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Role of the seed coat in the dormancy of wheat (Triticum aestivum) grains.Rathjen, Judith Rebecca January 2006 (has links)
Title page, contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / Pre-harvest sprouting (PHS) is an important economic problem which affects a significant proportion of the Australian wheat crop through quality downgrading. Grain dormancy is the most effective means of overcoming germination in the wheat spikelet at harvest maturity. It has been a consistent observation over a long period of time that dormant red-grained wheat genotypes are almost more dormant than dormant white-grained genotypes. In white-grained wheat, there are two factors which contribute to dormancy, embryo sensitivity to abscisic acid (ABA) and an interacting and unknown seed coat factor. The proposed dormancy model is that complete dormancy can only be achieved with the coordinate expression of these two factors. This primary objective of this project was to determine the role of this putative seed coat factor in grain dormancy of white-grained wheat."--Abstract. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1259900 / Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2006
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Maize alpha-amylase: purification and properties and induction by gibberellic acidZimmerman, Rosalind Kane January 1987 (has links)
Alpha-amylase synthesis can be induced in wheat and barley half-seeds by addition of gibberellic acid (GA) to the incubation medium. In maize, induction in de-embryonated kernels by exogenous GA has been reported in some studies but not others.
Alpha-amylase induction was investigated in maize by measuring activity in extracts from whole and de-embryonated kernels incubated with and without GA during germination. Alpha-amylase activity was first detected on the 3rd day of germination in whole kernels and GA-treated endosperms and on the 4th day in the controls. Thereafter both whole kernels and GA-treated endosperms followed approximately the same time course in α-amylase activity with the control lagging a day behind. Studies indicated that maximum α-amylase activity occurred on the 7th day in whole kernels and GA-treated endosperms and the 8th in control endosperms.
Maize α-amylase was purified using differential solubility, column chromatography, glycogen precipitation and polyacrylamide gel electrophoresis, of these, the best purification method was glycogen precipitation.
Maize α-amylase exhibited isozymes. The isozyme patterns were qualitatively similar in all samples and throughout incubation. Wheat and barley α-amylase isozymes have been divided into two groups on the basis of a number of characteristics. Genetics analysis revealed these isozymes to be the result of two multigene families. To shed light on the genetic basis of the maize α-amylase isozymes, physicochemical characterization was initiated. Studies of pH and temperature profiles and optima showed no differences between maize isozymes. The pH optima was pH 5 and the temperature optima was about 37°C. / Master of Science
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The effects of various root exudates on broomrape germinationBallard, Barbara Jean January 1979 (has links)
no abstract provided by author / Master of Science
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Soilless media for seed germination and growth of tomato transplants, and for the rooting of certain herbaceous stem cuttingsRay, Frederick Harding January 1974 (has links)
Media containing Weblite were compared to various media for its effectiveness in germination, plant growth and rooting. The 2M media were compared by determining the percentage germination and the dry weight after U2 days of Lycopersicon esculentum cv Better Boy, grown to transplant size. These media were composed of various proportions and combinations of Weblite, vermiculite, Jiffy Mix, peat moss and sand. The available moisture, porosity,field capacity and permanent wilting point of these 2b media were determined. This information was compared with the results from the germination and growth study of tomato plants. Weblite was a constituent of the seven best media for germination. Tomato plants grown in media containing vermiculite had the highest dry weights. Chrysanthemum morifolium cv Sunny Mandalay stem cuttings were rooted in six media. These media were composed of various proportions and combinations of sand, peat moss, Weblite, and perlite. Their root system and foliage condition were evaluated 18 days later. Weblite was significantly better in rooting Chrysanthemums than the six other media.Dianthus caroyphyllus cv Caribe stem cuttings were rooted in nine media. These media were composed of various proportions and combinations of sand, peat moss, Weblite. perlite, and vermiculite. Their roots, stem and foliage condition were evaluated 26 days later. The best root system developed in media with vermiculite as its main constituent. / Master of Science
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Mechanisms of dormancy, preharvest sprouting tolerance and how they are influenced by the environment during grain filling and maturation in wheat (Triticum aestivum L.)Biddulph, Thomas Benjamin January 2007 (has links)
[Truncated abstract] Wheat is the main crop in Australia and there are stringent quality requirements. Preharvest sprouting induced by rainfall between maturity and harvest lowers grain quality from premium to feed grades and reduces yield. Wheat production has expanded into the southern Western Australian region where preharvest sprouting occurs in ~1 in 4 seasons and development of more preharvest sprouting tolerant genotypes is required. The main mechanism for improving preharvest sprouting tolerance is grain dormancy. There is genetic variation for dormancy based in the embryo and seed coat but dormancy is complex and is influenced by environmental conditions during grain filling and maturation. Screening and selecting for preharvest sprouting tolerance is problematic and the level of tolerance needed for regions which differ in the level of dormancy they impose, requires clarification. The research presented here aims to answer the underlying question for breeders of how much dormancy is required for preharvest sprouting tolerance in contrasting target environments of the central and coastal wheat belt regions of Western Australia. In the central and coastal wheat belt regions, field trials with modified environments were used to determine the environmental influence on dormancy. Water supply (without directly wetting the grain) and air temperature were modified during grain development in a range of genotypes with different mechanisms of dormancy to determine the influence of environment on dormancy. ... Genotypes with embryo dormancy were consistently the most preharvest sprouting tolerant, even though this dormancy was influenced by the environmental conditions in the different seasons. Pyramiding the embryo component with the specific seed coat component and/or awnless head trait removed some of the environmental variation in preharvest sprouting tolerance, but this was generally considered excessive to the environmental requirements. The methods developed here, of field imposed stresses may provide a valuable tool to further understand the influence of environment on the regulation of dormancy, as different phenotypes can be made with the same genotype. Moisture stress, sudden changes in water supply or high temperatures during the late dough stages influenced dormancy phenotype and should be considered and avoided if possible when selecting locations and running trials for screening for genetic differences in preharvest sprouting tolerance. In the Western Australian context, the embryo component of dormancy appeared to be sufficient and should be adopted as the most important trait for breeding for preharvest sprouting tolerance.
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Development of hard white winter wheats for a hard red winter wheat regionUpadhyay, Madhusudan P. January 1984 (has links)
Call number: LD2668 .T4 1984 U62 / Master of Science
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A study of the effectiveness of homoeopathically prepared dilutions of abscisic acid, molybdenum and allopurinol in inhibiting or promoting the germination of barley seeds (Hordeum vulgare)Evans, Nicole Paula January 2008 (has links)
Dissertation submitted in partial compliance with the requirements for a Masters Degree in Technology: Homoeopathy, Durban University of Technology, 2008. / Introduction
This study investigated the effectiveness of homoeopathic dilutions of abscisic acid
(ABA), molybdenum and allopurinol on inhibiting or promoting the germination of
barley seeds (Hordeum vulgare cv. Stirling, ex Caledon, Western Cape, South
Africa, 1998 harvest). Recent research involving ABA and seed germination has
shown mixed results, with Bruni (2001), finding there to be statistically significant
biological effects, but Couchman (2001) not.
Objective/Aim/Purpose
The purpose of this study was to evaluate the effectiveness of homoeopathic
dilutions of ABA, molybdenum and allopurinol (two substances which have an effect
on ABA metabolism), especially those above the 10-23 level (Avogadro’s dilution
limit), on germination, in light of recent findings.
Abscisic acid, a plant hormone and molybdenum, a trace element, both play an
essential role in inducing dormancy of the seed. Allopurinol, a therapeutic drug, has
also been shown to affect ABA metabolism and therefore seed germination. The
study used all three substances individually and in combination, in homoeopathic
dilutions ranging from 4CH to 200CH potency.
Methodology
There were 7 treatments with 5 potencies per treatment (4CH, 9CH, 15CH, 30CH
and 200CH). Each potency level for each treatment had a control, which meant
there were 5 controls per treatment.
The seeds (distally cut) were placed in 9cm Petri dishes (20 seeds in each), with 5
repetitions, 100 seeds per dilution level with one control of 20 seeds. There were
thus 600 (120 x 5) seeds per treatment and 4200 seeds in total (600 x 7 treatments).
Seeds were germinated in the dark at a constant temperature. Counts were done
every 24 hours for 3 days and the data recorded. The criterion for germination was
radical emergence.
Results
The data was analysed statistically using Univariate Analysis of Variance
(STATISTICA version 6). The results showed statistically significant interaction
between treatments and potencies and a One-Way Anova was then used to analyse
each treatment to determine the effectiveness of each potency. Statistically
significant differences were noted between potencies for each treatment.
From the results it was clear that the most effective treatment for stimulating
germination was the treatment utilizing homoeopathic dilutions of allopurinol.
The most effective treatment for inhibiting germination was the treatment utilizing
ABA in homoeopathic dilutions.
The 30CH (10-60) showed a statistically significant effect on the stimulation of
germination across almost all treatments, whereas the 15CH (10-30) showed a
statistically significant effect in inhibiting germination in most treatments.
Conclusion
It is evident from the results of this study that all the treatments produced distinct
biological effects, whether it be stimulating germination or inhibiting germination in
homoeopathic dilution.
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A comparison between the efficacy of radionically prepared gibberellic acid and homoeopathically prepared gibberellic acid (GHP) on the germination rate and seedling development of barley seedsKleingeld, Gerhard January 2016 (has links)
Submitted in partial compliance with the requirements of the Master’s Degree in Technology: Homoeopathy, Durban University of Technology, Durban, South Africa, 2016. / Aim
The aim of this controlled, experimental study was to compare the biological activity of various homoeopathic potencies of gibberellic acid manufactured radionically (AMS transfer device) and conventionally (GHP) in terms of their respective influence on germination rate and seedling development of barley seeds; all the respective results being contrasted against those produced by the distilled water control.
Methodology
The research was completed by employing quantitative research techniques and followed true experimental design. Homoeopathically (Hahnemannian) prepared gibberellic acid followed the manufacturing guidelines of method 5a involving liquid preparations, as specified in the German Homoeopathic pharmacopoeia (GHP) (Benyunes 2005).
A second radionic ‘equivalent’ version of each of the Hahnemannian potencies was manufactured using the ‘AMS wave transfer’ device. Four sources of data were collected namely, germination count and rate, seedling development (root length), seedling dry mass, and number of seeds with measurable roots. All the data was collected and documented on a data collection sheet using Microsoft Excel. All the data was statistically analysed and subjected to analysis of variance (ANOVA) using GenStat Version 14 (VSN International, UK) at the 5% level of significance. The statistical data was used to produce a comparison between the different remedies and distilled water.
Results
All of the remedy treatment groups (Radionic 200c, Hahnemannian 200cH, Radionic 4c and Hahnemannian 4cH) displayed suppressive effects (to certain extents respectively ) on seed growth and development in comparison to the control group (distilled water). The control group displayed greater seedling development in comparison to all remedy treatment groups which was most evident in the average root lengths and high vigour seed lot root lengths having longer roots than all remedy treatment groups. The control group also displayed a higher number of seeds with measurable roots compared to all the remedy treatment groups in both total number of seeds and in the seeds accounted for in the high vigour lots. This suggests that all Homoeopathic remedies irrespective of potency or manufacture method (Radionic or Hahnemmanian) had similar suppressive effects on root growth and seedling development and this suppressive effect was in turn not evident in the control group.
Conclusion
The experiment results suggest that radionically manufactured homoeopathic remedies (AMS wave transfer device) have similar biological effects (suppressive effects) to the equivalent Hahnemannian manufactured homoeopathic remedies, although further research in this field is necessary to confirm these findings the results from this study are supportive of the use of radionically prepared remedies in homoeopathic practice. / M
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The influence of chemical seed treatment on germination, seedling survival and yield of canolaDe Villiers, Rykie (Rykie Jacoba) 12 1900 (has links)
Thesis (MScAgric)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: The influence of chemical seed treatments on the germination, seedling
survival and yield of canola (cv. Varola 44) was investigated in a series of
incubation studies, glasshouse experiments, as well as field trials in the
canola producing areas in the Western Cape Province.
Incubation experiments were conducted to compare germination and seedling
growth of untreated (control) seed with that of seed treated at different
application rates (0.5, 1.0 and 2.0 times the recommended) of Cruiser® and
SA-combination (which consists of Thiulin® at 0.5g a.i.; Apron® at 0.0815 g
a.i.; Gaucho® at 0.6125 g a.i. and Rovral® at 0.9975 g a.i.). The results
indicated that seed treatment (all rates of SA-combination and highest rate of
Cruiser) delayed germination and seedling growth, especially if the seed was
subjected to the Accelerated Ageing Test.
Glasshouse studies with pasteurised soil at different water contents, seed
sources (storage periods) and planting depths confirmed the phytotoxic
effects of the chemical seed treatments in the absence of soil borne
pathogens. From the results it became clear that extreme water conditions
(very wet or dry) increased the suppressing effect on germination and
seedling growth, but that no phytotoxic reactions occurred in moist (favourable
soil water conditions) soil, regardless of application rate of the chemicals
used, planting depth and seed source. In a second glasshouse experiment
conducted in moist soil (kept at 50% of field water capacity to prevent any
toxic effects) from seven different localities that were naturally infested with pathogens, both chemicals proved to be effective where soil borne pathogens
(Rhizocfonia so/ani and Pythium spp.) occurred. No clear trend could however
be found due to either chemical or application rates used.
Finally, field trials were conducted to study the effect of chemical seed
treatments on the plant populations and yield of canola planted in different
row widths (17 and 34 cm) and seeding rates (3, 5 and 7 kq.ha'). Results
showed that treated seeds produced more plants.rn" and yielded more than
untreated seeds at Roodebloem Experimental Farm, while the highest
seeding rate produced significantly more plants.rn" (Roodebloem and
Langgewens Experimental Farms), but not significantly higher yields than the
lowest seeding rate at the same locality. Although row width did not have an
effect on plant population, yield (Roodebloem 2003) was significantly less at
the wider (34 cm) rows. As in earlier experiments, no consistent differences
between the two chemicals used were found.
These results clearly illustrated both the negative (in the absence of
pathogens) and positive (where soil borne pathogens do occur) effects that
chemical seed treatments may have on the germination, seedling growth and
even yield of canola under local environmental and soil conditions. Because
no significant differences were found between the chemicals used, both
chemicals should be regarded as efficient. More research, especially under
field conditions and with more cultivars, is needed before the registration of a
chemical for seed treatment could be considered. / AFRIKAANSE OPSOMMING: Die invloed van chemiese saadbehandeling op die ontkieming, saailing
oorlewing en opbrengs van canola (cv. Varola 44) is ondersoek in 'n reeks
inkubasie studies, glashuis eksperimente en veldproewe in die canolaproduserende
gebiede in die Wes Kaap Provinsie.
Inkubasie eksperimente is uitgevoer om die ontkieming en saailing groei van
onbehandelde (kontrole) saad te vergelyk met dié van saad wat behandel is
teen verskillende dosisse (0.5, 1.0 en 2.0 keer die aanbevole) van Cruiser®
en SA-kombinasie (wat bestaan uit Thiulin® teen 0.5g a.i.; Apron® teen
0.0815 g a.i.; Gaucho® teen 0.6125 g a.i. en Rovral® teen 0.9975 g a.i.). Die
resultate het aangedui dat saadbehandeling (vir alle dosisse van SAkombinasie
en die hoogste dosis van Cruiser) ontkieming en saailing groei
vertraag, veral wanneer die saad onderwerp was aan die Versnelde
Verouderings Toets. Glashuis studies met gepasteuriseerde grond by
verskillende waterinhoude, saad bronne (stoor periodes) en plantdieptes, het
die fitotoksiese effekte van die chemiese saadbehandelings bevestig in die
afwesigheid van grondgedraagde patogene. Vanuit die resultate het dit
duidelik geword dat ekstreme water toestande (baie nat of droog) die
onderdrukkende effek op ontkieming en saailinggroei verhoog het, maar dat
geen fitotoksiese reaksies plaasgevind het in klam (gunstige grondwater
toestande) grond nie, ongeag die dosisse of chemikalieë gebruik, plantdiepte
en saad bron. In 'n tweede glashuis eksperiment uitgevoer in klam grond
(gehou by 50% van veldwaterkapasiteit om toksiese effekte te voorkom) van sewe lokaliteite wat natuurlik besmet was met patogene, was beide
chemikalië effektief waar grondgedraagde patogene (Rhizoctonia so/ani en
Pythium spp.) voorgekom het. Geen duidelike tendens is egter waargeneem
vir enige van die chemikalieë of dosisse nie.
Laastens is veldproewe uitgevoer om die effek van chemiese
saadbehandelings op plant populasies en opbrengs te bepaal van canola
geplant in verskillende rywydtes (17 en 34 cm) en saaidigthede (3, 5 en 7
kg.ha-1). Resultate het aangedui dat behandelde saad meer plante.rn"
produseer en 'n groter opbrengs lewer as onbehandelde saad by
Roodebloem Eksperimentele Plaas, terwyl die hoogste saaidigtheid
betekenisvol meer plante.m" (Roodebloem en Langgewens Eksperimentele
Plase), maar nie betekenisvol hoër opbrengste gelewer het as die laagste
saaidigtheid by dieselfde lokaliteit nie. AI het rywydte nie 'n effek op plant
populasie gehad nie, was opbrengs (Roodebloem 2003) betekenisvol minder
by die wyer (34 cm) rye. Soos in vroeëre eksperimente is geen konsekwente
verskille tussen die twee chemikalieë gevind nie.
Hierdie resultate illustreer duidelik beide negatiewe (in die afwesigheid van
grondgedraagde patogene) en positiewe (in die aanwesigheid van
grondgedraagde patogene) effekte wat chemiese saadbehandelings op
ontkieming, saailing groei en selfs opbrengs van canola onder plaaslike
omgewings en grondtoestande kan hê. Omdat geen betekenisvolle verskille
tussen die chemikalieë gevind is nie, moet beide chemikalieë as doeltreffend
aanvaar word. Meer navorsing, veralonder veldtoestande en met meer
kultivars, is egter nodig voordat die registrasie van 'n chemiese middel vir
saadbehandeling oorweeg kan word.
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