The hydraulic architecture of roses (Rosa hybrida)

1991 ◽  
Vol 69 (4) ◽  
pp. 702-710 ◽  
Author(s):  
Alan B. Darlington ◽  
Michael A. Dixon
Keyword(s):  
Large Diameter ◽  
Distal Segment ◽  
Hydraulic Conductance ◽  
Rosa Hybrida ◽  
Abscission Zone ◽  
Conducting System ◽  
Hydraulic Architecture ◽  
A Site ◽  
The Rose ◽  
Structural Aspects

The presence of an abscission zone in the stem of greenhouse roses (Rosa hybrida) between the vegetative and reproductive components was verified. This led to a description of the hydraulic architecture of the rose stem. The structural aspects of the xylem conducting system in stem, abscission zone and peduncle were examined to define their relative roles in the delivery of water via the stem to the transpiring plant surfaces and the extent to which their functional capacity may be influenced by environmental variables such as humidity. The stem exhibited a highly developed xylem with many large-diameter tracheary elements. Contrary to this the distal segment of the peduncle was poorly vascularized. The remainder of the peduncle, which included the abscission zone, was a transition between these two extremes. The abscission zone was a site of reduced hydraulic conductance that was not due to a reduction in the number or size of xylem conduits but to changes in the alignment of the elements. The variable conductances across the abscission zone and peduncle regions may play an important role in floral development and the response of the plant to water stress. Rose plants grown at constantly high humidity (77% RH) did not exhibit significantly different internal anatomical features of the xylem conducting system relative to roses grown in ambient, uncontrolled humidity (30 to 60% RH). Key words: abscission zone, hydraulic conductance, humidity.

Variability in hydraulic architecture and gas exchange of common bean (Phaseolus vulgaris) cultivars under well-watered conditions: interactions with leaf size

1999 ◽  
Vol 26 (2) ◽  
pp. 115 ◽  
Author(s):  
Maurizio Mencuccini ◽  
Jonathan Comstock
Keyword(s):  
Gas Exchange ◽  
Exchange Rates ◽  
Common Bean ◽  
Water Loss ◽  
Leaf Size ◽  
Hydraulic Conductance ◽  
Hydraulic Architecture ◽  
Greenhouse Study ◽  
Whole Plant ◽  
Leaf Level

In a greenhouse study, 12 common bean cultivars from a wide geographical range were compared for their morphological, gas exchange and hydraulic architecture characters. Cultivars bred for cultivation in hot and dry regions had significantly smaller leaves and crowns, but higher stomatal conductances and transpiration rates per unit of leaf area. Short-term variability in gas exchange rates was confirmed using leaf carbon isotope discrimination. A literature survey showed that, although previously unnoticed, the strong inverse coupling between leaf size and gas exchange rates was present in three other studies using the same set of cultivars. Several measures of ‘leaf-specific hydraulic conductance’ (i.e. for the whole plant and for different parts of the xylem pathway) were also linearly related to rates of water loss, suggesting that the coupling between leaf size and gas exchange was mediated by a hydraulic mechanism. It is possible that breeding for high production in hot regions has exerted a selection pressure to increase leaf-level gas exchange rates and leaf cooling. The associated reductions in leaf size may be explained by the need to maintain equilibrium between whole-plant water loss and liquid-phase hydraulic conductance.

scholarly journals New Records for The Solenogaster Proneomenia Sluiteri (Mollusca) from Icelandic Waters and Description of Proneomenia Custodiens sp. n.

2014 ◽  
Vol 35 (2) ◽  
pp. 291-310 ◽  
Author(s):  
Christiane Todt ◽  
Kevin M Kocot
Keyword(s):  
Barents Sea ◽  
Dna Barcode ◽  
Histological Section ◽  
First Record ◽  
Mantle Cavity ◽  
Marine Animals ◽  
A Site ◽  
The Rose ◽  
A New Species ◽  
Icelandic Waters

Abstract During August–September 2011, scientists aboard the R/V Meteor sampled marine animals around Iceland for the IceAGE project (Icelandic marine Animals: Genetics and Ecology). The last sample was taken at a site known as “The Rose Garden” off northeastern Iceland and yielded a large number of two species of Proneomenia (Mollusca, Aplacophora, Solenogastres, Cavibelonia, Proneomeniidae). We examined isolated sclerites, radulae, and histological section series for both species. The first, Proneomenia sluiteri Hubrecht, 1880, was originally described from the Barents Sea. This is the first record of this species in Icelandic waters. However, examination of aplacophoran lots collected during the earlier BIOICE campaign revealed additional Icelandic localities from which this species was collected previously. The second represents a new species of Proneomenia, which, unlike other known representatives of the genus, broods juveniles in the mantle cavity. We provide a formal description, proposing the name Proneomenia custodiens sp. n. Interestingly, the sclerites of brooded juveniles are scales like those found in the putatively plesiomorphic order Pholidoskepia rather than hollow needles like those of the adults of this species. Cytochrome c oxidase subunit I (COI) DNA barcode sequences are provided for both species of Proneomenia.

Production of Bareroot Roses Using Underground Drip Irrigation

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 474a-474
Author(s):  
U.K. Schuch ◽  
J. Karlik ◽  
J.O. Becker
Keyword(s):  
United States ◽  
Drip Irrigation ◽  
Dry Weight ◽  
Growing Season ◽  
The United States ◽  
Rosa Hybrida ◽  
The Other ◽  
Kern County ◽  
Total Dry Weight ◽  
The Rose

The majority of rose producers in Kern County, Calif., use furrow irrigation to produce ≈50% of the rose plants in the United States. Two experiments were conducted to test the feasibility of producing bareroot roses using underground drip irrigation. Three rose (Rosa hybrida) cultivars, `Dr. Huey', `Manetti', and `Pink Simplicity', were used in both experiments. In the first experiment, drip tape was placed at a depth of 10, 20, 30, or 40 cm. After one growing season, plants irrigated with drip tape at 10-cm depth produced less shoot and total dry weight than plants irrigated with tape placed between 20 and 40 cm. `Manetti' was the most vigorous cultivar and produced ≈70% more shoot and total dry weight than the other two cultivars. In the second experiment, the plants of the three cultivars were spaced 15, 20, or 25 cm apart within the row and irrigated with drip tape placed at 20-cm depth. Total dry weight increased linearly with increased spacing of plants within the row. `Manetti' and `Pink Simplicity' produced higher shoot and total dry weight than `Dr. Huey' plants.

scholarly journals Spatiotemporal changes in along-tract profilometry of cerebellar peduncles in cerebellar mutism syndrome

2021 ◽  
Author(s):  
Sebastian M Toescu ◽  
Lisa Bruckert ◽  
Rashad Jabarkheel ◽  
Derek Yecies ◽  
Michael Zhang ◽  
...  
Keyword(s):  
Fractional Anisotropy ◽  
Distal Segment ◽  
Healthy Children ◽  
Superior Cerebellar Peduncle ◽  
Cerebellar Mutism ◽  
Cerebellar Peduncles ◽  
Cerebellar Peduncle ◽  
Specific Alteration ◽  
One Year ◽  
A Site

Cerebellar mutism syndrome, characterised by mutism, emotional lability and cerebellar motor signs, occurs in up to 40% of children following resection of medulloblastoma, the most common malignant posterior fossa tumour of childhood. Its pathophysiology remains unclear, but prior studies have implicated damage to the superior cerebellar peduncles. In this study, the objective was to conduct high-resolution spatial profilometry of the cerebellar peduncles and identify anatomic biomarkers of cerebellar mutism syndrome. Twenty-eight children with medulloblastoma (mean age 8.8, s.d. 3.8 years) underwent diffusion MRI at four timepoints over one year. Forty-nine healthy children (mean age 9.0, s.d. 4.2 years), scanned at a single timepoint, served as age- and sex-matched controls. Automated Fibre Quantification was used to segment cerebellar peduncles and compute fractional anisotropy at 30 nodes along each tract. Thirteen patients developed cerebellar mutism syndrome. Fractional anisotropy was significantly lower in the distal segments of the superior cerebellar peduncle pre-operatively in all patients (p=0.01). Pre-operative changes in fractional anisotropy did not predict cerebellar mutism syndrome. However, post-operative reductions in fractional anisotropy were highly specific to the distal left superior cerebellar peduncle, and were most pronounced at follow-up timepoints (p<0.04), in those that developed cerebellar mutism syndrome compared to patients that did not. High spatial resolution cerebellar profilometry identifies a site-specific alteration of the distal segment of the superior cerebellar peduncle unique to cerebellar mutism syndrome with important surgical implications in the treatment of these devastating tumours of childhood.

Microhabitat and prey size among three species of Rana (Anura: Ranidae) sympatric in eastern Canada

1989 ◽  
Vol 67 (9) ◽  
pp. 2244-2252 ◽  
Author(s):  
Donald F. McAlpine ◽  
Timothy G. Dilworth
Keyword(s):  
Prey Size ◽  
Interspecific Interactions ◽  
Stomach Contents ◽  
Size Analysis ◽  
Eastern Canada ◽  
Leopard Frogs ◽  
Species Pairs ◽  
Prey Length ◽  
A Site ◽  
Structural Aspects

Microhabitat, prey size, and body morphology were examined in sympatric leopard frogs (Rana pipiens), green frogs (R. clamitans), and bullfrogs (R. catesbeiana) at a site in central New Brunswick. Ratios of head widths among species pairs were 1.23 (leopard and green frogs) and 1.51 (bullfrogs and green frogs), suggesting that leopard and green frogs may take prey of similar size. Analysis of stomach contents showed no significant differences in the mean prey sizes selected by leopard and green frogs. Rana sp. figured prominently in the diet of bullfrogs at the study site. Overlap among the species for prey length indicates the potential for competition between green and leopard frogs (Pij = 0.40 versus Pij = 1.41 for green frogs and bullfrogs). Structural aspects of habitat associated with vegetation were most important in discriminating microhabitat. Leopard frogs selected microhabitats that were much more densely vegetated than those of either bullfrogs or green frogs. In water, green frogs occupied sites that were closer to shore, were of lower water temperature, and had a higher vegetation canopy than sites occupied by bullfrogs. On land, green frogs selected microhabitats that were closer to water and less densely vegetated than those of leopard frogs. There was much greater microhabitat separation between leopard and green frogs than between green frogs and bullfrogs. There is some evidence that predation (bullfrogs preying on green frogs) and perhaps past competition (between green frogs and leopard frogs) have contributed to the patterns of resource use described. A number of other potential mechanisms (i.e., species phylogenies, inherent physiological or behavioural constraints acquired independently of interspecific interactions) remain unevaluated.

Hydraulic conductance and tracheid anatomy in six species of extant seed plants

1988 ◽  
Vol 66 (6) ◽  
pp. 1073-1079 ◽  
Author(s):  
Paul J. Schulte ◽  
Arthur C. Gibson
Keyword(s):  
Capillary Flow ◽  
Large Diameter ◽  
Membrane Resistance ◽  
Hydraulic Conductance ◽  
Linear Increase ◽  
Biophysical Model ◽  
Lumen Diameter ◽  
Seed Plants ◽  
Pit Membrane ◽  
Conductance Increase

Hydraulic conductance of tracheids was studied in either petioles or young stems of six species of seed plants having various types of intertracheid pitting. Measured conductances were compared with estimates based on Hagen–Poiseuille flow through ideal capillaries and with predictions from a biophysical model incorporating observed anatomical characteristics of tracheids and intertracheid pits. Conductance of the xylem, expressed as a percentage of the ideal capillary flow prediction, varied from an average of 88% for a species containing only very narrow tracheids to less than 35% for species with large-diameter tracheids. The biophysical model allowed fairly close predictions of conductance for all species except one, where an estimate of the pit membrane resistance could not be experimentally obtained. For individual tracheids, conductance was largely a function of lumen diameter, pit membrane resistivity, and the exposed area of the pit membranes, as determined by pit shape, size, and frequency. For wide tracheids, scalariform-pitted elements showed a linear increase in conductance with an increase in lumen diameter; however, for tracheids with large circular pits, the conductance increase afforded by a wider lumen declines as lumen diameter increases. These model simulations demonstrate the increasing significance of intertracheid pitting in obstructing flow as lumen diameter increases.

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