Plant hormones regulate progression through the different phases of plant development in response to endogenous and environmental cues. Gene expression studies, as well as genetic and molecular analysis of mutants with altered hormonal responses, are two common approaches to elucidate hormone response pathways. This dissertation compares ovary and fruit development...
The effect of planting density and nitrogen (N) fertilization on growth, yield, and N partitioning in young and mature 'Bluecrop' blueberry plants was studied over a two year period. Depleted 15N-ammonium sulfate was applied at different rates and on different dates in a mature planting, and at different rates in...
1-Phenyl-3-(2-Thiazoly1)-2-Thiourea (PTTU), has been reported to
inhibit dopamine-fi-hydroxylase (a copper-containing enzyme involved in
the pathway of biosynthesis of adrenaline in animal systems). In the
present study, PTTU has been shown to have cytokinin activity in the
tobacco bioassay. The cytokinin activity of PTTU suggested that
cytokinin-active N⁶-substituted adenine derivatives might...
To understand the effect of human-induced stresses on forests, there is a need for a method to separate effects of imposed stress from effects of natural climate stress. I developed an approach to predict forest response to climate stress using as indicators stable carbon isotopes in tree foliage and growth-rings....
Two studies used DNA markers to assess their usefulness in germplasm identification and evaluation of genetic stability in four cryopreserved Rubus accessions that were stored for over 10 years in liquid nitrogen. In the first study, 12 robust Simple Sequence Repeat (SSR) markers were developed from two microsatellite-enriched libraries of...
Poplar Bark Storage Proteins (BSP) are important in storing nitrogen (N)
recovered from autumn-senescent leaves, and supply N for spring growth. Plants of
Populus tremula x P. alba were transformed with a poplar BSP antisense cDNA
fused to a double 35S promoter. Regenerated lines were screened for reduced BSP
accumulation...
Container grown pear trees were used to determine the effects of the following factors on the susceptibility to Phytophthora syringae: 1) tree nitrogen (N) status and foliar sprays of urea and copper-EDTA (CuEDTA); 2) dormancy and environmental conditions; 3) wound and wound age; and 4) chemical and biological control measures....
The auxin-resistant diageotropica (dgt) mutant of tomato (Lycopersicon esculentum Mill.) has a pleiotropic phenotype including a lack of lateral roots and reduced gravitropic response, apical dominance, vascular development, and fruit growth. The dgt mutation reduces the auxin sensitivity of only a subset of auxin responses while levels, metabolism, and transport...
The photosynthetic activities, the pigmentation and the chloroplast
membrane polypeptides of several mutants of the green alga, Scenedesmus
obliquus, with complete or limited deficiencies in the light-harvesting
complex of photosystem II are characterized and compared to those of the
normal phenotype.. The principal phenotype examined in this study, K0 -9,...
Pollen development is an important process in male flower development, the timing of which may be correlated with time of pollen shed in hazelnut (Corylus avellana L.). Early to very late blooming cultivars were identified and the relationship of microsporogenesis and microgametogenesis, and time of pollen shed were studied in...
'Gala' is an apple cultivar with a distinctive aroma and flavor. 'Gala' storage season is short in regular atmosphere (RA). Controlled atmosphere (CA) extends 'Gala' storage but volatile production is reduced. 'Gala' odor-active aroma compounds were identified using Osme, a gas chromatography and olfactometry technique. Changes in aroma after RA...
A series of four studies were conducted in Colombia, South America,
in the field and the greenhouse to determine the effect of plant
competition and mulching on carbohydrate and photosynthate distribution
and nitrogen fixation in beans (Phaseolus vulgaris L.).
Mulching beans (determinant growth habit) with rice hulls in the
lowland...
Semidwarfism has been used extensively in row crops and horticulture to promote yield, reduce lodging, and improve harvest index, and it might have similar benefits for trees for short-rotation forestry or energy plantations, reclamation, phytoremediation, or other applications. We studied the effects of the dominant semidwarfism transgenes GA Insensitive (GAI)...
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Plant growth stages are identified as distinct morphological landmarks in a continuous developmental process. The terms
describing these developmental stages record the morphological appearance of the plant at a specific point in its life cycle. The
widely differing morphology of plant species consequently gave rise to heterogeneous vocabularies describing growth...
Restriction of long-distance movement of several potyviruses in Arabidopsis (Arabidopsis thaliana) is controlled by at least three
dominant restricted TEV movement (RTM) genes, named RTM1, RTM2, and RTM3. RTM1 encodes a protein belonging to the
jacalin family, and RTM2 encodes a protein that has similarities to small heat shock proteins....
Transgenic down-regulation of the Pt4CL1 gene family encoding 4-coumarate:coenzyme A ligase (4CL) has been reported as a
means for reducing lignin content in cell walls and increasing overall growth rates, thereby improving feedstock quality for
paper and bioethanol production. Using hybrid poplar (Populus tremula 3 Populus alba), we applied this...
Of 14 transgenic poplar genotypes (Populus tremula × Populus alba) with antisense 4-coumarate:coenzyme A ligase that were grown in the field for 2 years, five that had substantial lignin reductions also had greatly reduced xylem-specific conductivity compared with that of control trees and those transgenic events with small reductions in...
Investigations were conducted to study in detail some biochemical and physiological aspects of ripening in pears. Anjou pears
picked at different degrees of maturity were treated with Ethrel
(2-chloroethane phosphonic acid), 4000 ppm, and ethylene, 500 ppm,
for different lengths of time. Respiration rate was measured twice
daily and changes...
Chlorine – 36 (36Cl) is produced naturally, through neutron activation of stable chlorine during nuclear weapons detonation, or from neutron capture on residual chlorine in graphite piles. It has a half-life of 301,000 years and decays by the means of beta decay with an average energy of 236.33 keV. Due...
Our view of phytoplankton has historically revolved around their inability to
control their location in space. The term phytoplankton itself underscores this
particular difference between phytoplankton and their sessile terrestrial counterparts.
Yet there are other differences between land plants and the phytoplankton that are
perhaps equally important, beyond this sessile-planktonic...
Coffee trees growing in the Kona district of Hawaii
were treated with different concentrations of either BA,
GA3, or Promalin, and pruned at the time of flowering. No
significant differences in the flowering and fruit ripening
pattern were found. High concentrations (100 mg/1) of
growth regulators decreased fruit fresh weight....
The ¹⁴C-uptake method is the most common approach employed for estimating primary production in the ocean. Normalizing ¹⁴C-uptake to chlorophyll a and time yields a value termed the assimilation number, which is thought to reflect phytoplankton physiology. It is often assumed that the measured rate of ¹⁴C-uptake is between net...
Shoot apex senescence is defined as the collective progressive
and deteriorative processes which ultimately terminate the functional
life of the shoot apex. Senescence of shoot apices of Pisum sativum
L. 'Alaska' as measured by cessation of stem elongation was delayed
by removal of flowers and by treatment with gibberellin A₃...
This investigation was undertaken to observe possible changes
in growth substances in Pyrus throughout the dormant period. The
primary objective was to determine if a correlation existed between
growth substance content and the inherent chilling requirement of
seeds and buds.
Samples of whole buds were taken at intervals from the...
In view of the stimulant effects of gibberellic acid on plant
growth, and its interesting modifications of various metabolic products,
it was decided to determine whether this growth regulator
would induce a favorable effect on total alkaloid production, especially
on the antineoplastic alkaloids, of Catharanthus roseus (L.) G. Don
(Vinca...
Cytokinins are plant hormones regulating cell division and differentiation.
Most developmental events from germination, vegetative morphogenesis to seed
and fruit set are influenced by cytokinins. t,ns-Zeatin is the major natural
occurring cytokinin. Its isomer, cis-zeatin, and its derivatives are usually present in
low quantities and have traditionally been considered as...
Many mycorrhizosphere microorganisms can produce
plant growth regulating compounds in vitro. Plant growth
regulating compounds are known to mediate root growth and
development. In reforestation practices, conifer tree
seedling growth and survival are linked to rapid root
growth and development after outplanting. Multifactorial
experiments were conducted to document variations in...
An investigation was undertaken to determine whether
potassium is indeed necessary for the in vivo synthesis of a
specific protein. The effects of univalent cations on the
inductive formation of nitrate reductase and on the level of
activity of representative non-adaptive enzyme are presented.
Cultures of Neurospora crassa were grown...
Objectives:
To evaluate the impact of the ring nematode, Mesocriconema xenoplax on the physiology and productivity of phylloxera-resistant grape rootstocks as a basis for recommending rootstocks in the Pacific Northwest. Specific objectives for 2006:
Spring: Inoculate soil with AMF and M. xenoplax. Plant vines.
Growing season: Monitor plant growth, gas...
Ecological impacts of climate change in the Pacific Northwest may hinge on acclimation to drier summers, highlighting the importance of plant physiological studies in forests. Evaluating dominant forest plant species under old-growth and managed forest conditions is similarly important as timber harvest might change microclimates and alter drought effects on...
Two experimental approaches have been used to investigate the interaction of sterols with respiration in yeast. Cells were tested with an antifungal sterol, azasterol, and a mutant was obtained with an altered sterol composition. Polarographic measurements were done on mitochondria for both experiments. The effects of azasterol on mitochondrial respiration...
Corn oil (CO) and Sterculic foetida oil (SFO) fed rats were
injected with [9, 10-methylene-¹⁴C]sterculic acid. Less than 1%
of the label was expired as carbon dioxide. The majority of the
label was excreted in the urine as short-chain dicarboxylic acids with
an intact cyclopropane ring. The major metabolites for...