Spelling suggestions: "subject:"needs - devevelopment"" "subject:"needs - agentdevelopment""
1 |
The effect of fruit maturity on seed development in certain xerophytic species of Cucurbita L.Ba-Amer, Mohamed Awadh, 1934- January 1967 (has links)
No description available.
|
2 |
Effect of high temperature on lettuce seed developmentTakahashi, Junji, 1951- January 1988 (has links)
More vegetable seeds are needed for developing countries to produce more vegetables. However, high temperature in these areas limits vegetable seed production. Leaf lettuce (Lactuca sativa L.) was grown in growth chambers at 21°C and exposed to different temperatures (28, 35, 38 and 42°C) for different exposure times (1, 4 and 7 hours) when flowers were at seven stages of development near anthesis.
|
3 |
SEED COATING HISTOLOGY, GERMINATION, DORMANCY AND SEEDLING DROUGHT TOLERANCE OF LEHMANN LOVEGRASS, ERAGROSTIS LEHMANNIANA, NEES.Brauen, Stanton E. (Stanton Elwood), 1932- January 1967 (has links)
No description available.
|
4 |
Effect of hydrophilic gels on seed germination and plant establishmentHenderson, Janet C. January 1984 (has links)
Call number: LD2668 .T4 1984 H46 / Master of Science
|
5 |
Expression of a group 3 LEA protein during maturation of Zea mays L. embryosThomann, Estela B. 30 November 1994 (has links)
Graduation date: 1995
|
6 |
Embryo-independent mobilization of endosperm starch in cereal seedsKonesky, David William January 1990 (has links)
Endosperm mobilization studies in cereal seeds are typically based on the view that α-amylase synthesis in the aleurone tissue is controlled by gibberellins from the germinating embryo. However, α-amylase is often produced by de-embryonated endosperm segments in the absence of added gibberellins. Two specific systems exhibiting this phenomenon were examined; 1) the ability of amino acids to promote α-amylase production in de-embryonated wild oat segments and, 2) autonomous starch hydrolysis (in the absense of exogenous GA₃ or amino acids) in de-embryonated barley endosperm halves.
Specific technical problems were addressed prior to the onset of these studies. Captan (66 μM) controlled fungal contamination in the incubation medium without inhibiting GA₃-induced sugar release, which occurs following seed sterilization in hypochlorite and ethanol. The Nelson-Somogyi reducing sugar assay was not suitable for quantifying sugar levels in incubation solutions containing amino acids as cysteine, cystine, serine, tryptophan and tyrosine interfered with the assay. Absorbance (540 nm) increased as concentrations increased from 0.1 to 1 mM; simultaneous additions of amino acids with glucose resulted in absorbance values higher than glucose alone. MnCl₂ (0.5 mM) inhibited absorbance in the presence of glucose and the amino acids serine, cystine, and tryptophan.
The ability of individual amino acids to promote α-amylase production in wild oat endosperm halves is yet unclear. Although certain amino acids were shown to enhance enzyme production, the level was often quite different between replicated experiments. However,
incubation of endosperm halves in a mixture of 18 amino acids
consistently promoted α-amylase synthesis; enzyme production was further
enhanced if a level of GA₃ (10⁻⁹ M), which was too low to promote α-amylase synthesis alone, was included within the amino acid mixture.
Autonomous endosperm mobilization (AEM) was variable in different barley cultivars. High sugar release correlated well with α-amylase production; the levels were similar among individual cultivars harvested in two different seasons. The onset of AEM was delayed, as the majority of sugar was released in the second day of incubation. AEM was greatly reduced by inhibitors of RNA (6-methyl purine) and protein (cycloheximide) synthesis suggesting that AEM was a result of the de novo synthesis of α-amylase. Incubation conditions greatly affected AEM. Although AEM was high at acidic pH (4.6-5.6), it was greatly reduced at basic pH (7.6-8.6). AEM increased as the temperature was raised to 28°C. Low levels of Ca²⁺ (0.25-0.5 mM) enhanced AEM whereas higher amounts (0.5-1 mM) were inhibitory.
Incubation of wild oat endosperm halves in solutions of
pre-emergence herbicides affected GA₃-induced sugar release to varying
extents when applied at field application levels. Only triallate (22%
reduction) and trifluralin (21% reduction) prevented sugar release (only - 5
at 3x10⁻⁵ M); no inhibition was seen following incubation in EPTC (5xl0⁻⁵, 5xl0⁻⁶ M), metribuzin (5xl0⁻⁶, 1x10⁻⁶M) and oryzalin (3xl0⁻⁵, 3x10⁻⁶M). However, the higher concentrations of each herbicide effectively inhibited the development of wild oat seedlings. / Land and Food Systems, Faculty of / Graduate
|
7 |
The effect of provenance on the response of the recalcitrant seeds of Trichilia dregeana to drying and chilling.Oyerinde, Rebecca Opeyemi. January 2011 (has links)
One of the factors that affect the post-harvest behavior of seeds is provenance. Different
geographical locations are characterised by different environmental conditions, hence,
plant materials harvested from different locations may respond differently to laboratoryinduced
stresses.
The aim of the present study was to assess the role that provenance plays on the degree of
recalcitrance of a single species – a factor that needs to be taken into consideration when
choices are to be made for plant germplasm conservation. In this study, seeds of Trichilia
dregeana, which have been shown to display recalcitrant post-harvest behavior, were
harvested from four locations that were slightly different in climatic conditions: Mtunzini
(MTZN), Durban (DBN), Pietermaritzburg (PMB) and Port Edward (P.ED), all within
the KwaZulu-Natal province of South Africa. Clean seeds, whose aril and seed coat have
been removed, were subjected to different drying and chilling stresses and their responses
to the stresses are examined. Excised embryonic axes of the seeds were also subjected to
flash (very rapid) drying and their responses to the stress are shown.
Although the vegetation of these locations can be categorized as being sub-tropical, the
present study suggests that there may be ‘degrees’ in the sub-tropical nature based on the
rainfall and maximum temperature data. The ‘degree of sub-tropicality’ is suggested to be
in the order MTZN > DBN > P.ED > PMB. Mean seed size assessed as seed length,
width and fresh mass varied significantly across the four regions, with seeds from MTZN
being the smallest and those from P.ED being the largest. The shedding water content of
the embryonic axes of the seeds for 150 min. However, shoot
production, root and shoot length and dry mass accumulation showed that axes of seeds
from MTZN were the most adversely affected by rapid drying while those from PMB
were the least sensitive. When clean whole seeds were dried slowly by burying in silica
gel for 36 h, all seeds of the four provenances still retained more than 50% of their
shedding water. MTZN seeds lost viability completely from the 24 h of slow drying
while seeds from the other three locations retained some viability after 36 h. The order of
survival of slow drying was MTZN < DBN < P.ED = PMB.
Storage of cleaned whole seeds at chilling temperatures (3oC, 6oC and 16oC) caused
increase in the water content of the embryonic axes of the seeds across the four locations.
All seeds of the four provenances had lost more than 50% survival after they had been
stored at 3oC for 10 weeks. Survival was completely lost from the 12th week for MTZN
seeds, from the 14th week for DBN and P.ED seeds and from the 16th week for PMB
seeds. There was no survival recorded for seeds across the four regions at the 18th week.
The seeds were able to tolerate storage at 6oC for a little longer than those stored at 3oC.
Only MTZN seeds completely lost viability at the 18th week; seeds from the other three
locations retained some viability throughout the 18 weeks of storage. Storage at 16oC was
the most tolerable, as all seeds from the four provenances maintained some viability until
the 18th week in storage, with MTZN having the least survival and those from P.ED
having the highest survival.
Phylogenetic analysis of the internal transcribed spacer (ITS) region of the DBN and
PMB samples showed intraspecific levels of genetic variation, and were separated by a
genetic distance of 0.9%, an indicator that differences in storage behavior, chilling and
desiccation sensitivity between seeds obtained from different collection localities may be
genetically based.
This study showed that MTZN seeds were the most sensitive, while seeds from PMB and
P.ED were the most tolerant, to drying and chilling treatments, respectively. The
prevailing climatic conditions may have a bearing on the responses observed in this
study. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2011.
|
8 |
Physiological, biochemical and chemical studies on desiccation tolerance primarily in developing wheat seedsKoshawatana, Chutima. January 1996 (has links) (PDF)
Bibliography: leaves 155-182. Most agricultural crop seeds are 'orthodox' ie. desiccation is a necessary feature of their complete life cycle. Low moisture content lengthens the storage life of orthodox seeds. Recalcitrant seeds, which do not tolerate low moisture content, lose viability in dry storage. The thesis studies the role of sugars in desiccation tolerance in developing seeds and investigates other mechanisms which might be involved in desiccation tolerance and desiccation sensitivity.
|
9 |
Physiological, biochemical and chemical studies on desiccation tolerance primarily in developing wheat seeds / by Chutima Koshawatana.Koshawatana, Chutima January 1996 (has links)
Bibliography: leaves 155-182. / xiv, 182, [10] leaves, [11] leaves of plates : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Most agricultural crop seeds are 'orthodox' ie. desiccation is a necessary feature of their complete life cycle. Low moisture content lengthens the storage life of orthodox seeds. Recalcitrant seeds, which do not tolerate low moisture content, lose viability in dry storage. The thesis studies the role of sugars in desiccation tolerance in developing seeds and investigates other mechanisms which might be involved in desiccation tolerance and desiccation sensitivity. / Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, 1996?
|
10 |
Effects of seed adjuvants on germination and development of onions / Treatment of onion seeds with adjuvantsAllison, Edwin January 2001 (has links)
Thesis (MTech (Agriculture))--Cape Technikon, 2001. / Onion seeds (cultivar Caledon Globe), and soil into which the seedlings were
planted, were treated with various adjuvants including fungicides, a seed
disinfectant and a soil sterilant, as well as soil-applied growth stimulants to
determine the effect of these on germination of seed, the growth of plants and
the storage life of onions obtained. Three sets of germination trials were
undertaken in petri dishes, and sets of seed was also sown in deep seed trays.
A trial planting was made and the crop graded and stored. Seed was also sown
in pots in soil obtained from a commercial undertaking where poor
germination had been obtained. A portion of this soil was pasteurised and a
portion inoculated with Fusarium spp. Growth of these seedlings was then
followed by re-sowing in the same pots using seed of additional cultivars.
|
Page generated in 0.0497 seconds