scholarly journals Impact of Growth Habit and Architecture Genes on Adaptation and Performance of Bread Wheat

10.5772/67116 ◽  
2017 ◽  
Author(s):  
Thobeka P. Khumalo ◽  
Annelie Barnard ◽  
Lancelot Maphosa ◽  
Toi J. Tsilo
Keyword(s):  
Bread Wheat ◽  
Growth Habit ◽  
And Performance

Initiation, Development and Anatomy of Lignotubers in Some Species of Eucalyptus

1984 ◽  
Vol 32 (4) ◽  
pp. 415 ◽  
Author(s):  
DJ Carr ◽  
R Jahnke ◽  
SGM Carr
Keyword(s):  
Analytical Study ◽  
Growth Habit ◽  
Stem Growth ◽  
Morphological Development ◽  
Alternative Pathways ◽  
Stem Wood ◽  
Initial Survey ◽  
And Performance ◽  
Lateral Fusion ◽  
Taxonomic Groups

An initial survey of the diversity of early lignotuber development in Eucalyptus and an analytical study of the anatomy of young lignotubers and the seedling stem are presented. Studies of the early stages of the morphological development of the lignotuber in 13 species, representative of five taxonomic groups, resulted in the recognition of four modes of lignotuber initiation. The importance to lignotuber formation of the presence of a suite of accessory buds, adaxial to the axillary bud, is emphasized but lignotuber initiation is not in all cases associated with these buds. Lignotuber buds are derived by branching from existing buds, ultimately from the accessory buds of the node. Following its initiation, the possibilities of later morphological development of the lignotuber are discussed. Lignotuber growth may dominate over stem growth and the lignotubers at a node may then fuse laterally to encircle the stem. Stem growth, on the other hand, may dominate over lignotuber growth and the lignotuber then appears to regress. The consequences for the growth habit of the plant of these alternative pathways of development are outlined. The wood of young lignotubers (and that of the swollen hypocotyl) is shown to be different in composition and in the sizes of its elements from that of seedling stem wood; these differences owe their origin to differences in the nature and performance of the cambia of the lignotuber and stem. In lateral fusion of the lignotubers at a node, and their upward and downwards extension over the stem, e.g. over the hypocotyl, stem cambial initials are either progressively lost or, more likely, converted to lignotuber-type initials. The possibility of the reverse process occumng in stem dominance is discussed.

Temporal diversity changes among 198 Nordic bread wheat landraces and cultivars detected by retrotransposon-based S-SAP analysis

2008 ◽  
Vol 6 (02) ◽  
pp. 113-125 ◽  
Author(s):  
Shu-Chin Hysing ◽  
Torbjörn Säll ◽  
Hilde Nybom ◽  
Erland Liljeroth ◽  
Arnulf Merker ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Bread Wheat ◽  
Growth Habit ◽  
Gene Diversity ◽  
Pedigree Information ◽  
Principal Coordinates Analysis ◽  
Subsequent Increase ◽  
Principal Coordinates ◽  
Frequent Exchange ◽  
Wheat Landraces

The sequence-specific amplified polymorphism (S-SAP) method was used to genotype 198 Nordic bread wheat landraces and cultivars from the 19th to the 21st centuries. It was shown that theSukkula-9900-LARD retrotransposon primer was highly suitable for resolving closely related wheat materials. Cluster analysis was generally consistent with pedigree information and revealed a clear separation for growth habit but not for countries. A principal coordinates analysis (PCoA) showed a separation into different time periods (before 1910, 1910–1969 and 1970–2003). These results are consistent with the breeding history and pedigree information, indicating that little hybridization has occurred between winter and spring wheat, in contrast to frequent exchange of germplasm between the Nordic countries. Estimates of gene diversity, the PCoA results, and changes in band frequencies across time indicate that plant breeding has led to substantial genetic shifts in Nordic wheat. Diversity was reduced through selections from landraces during the early 20th century, followed by a period of relatively lower genetic diversity, and a subsequent increase and net gains in diversity from the late 1960s onwards through the use of exotic germplasm. Thus, an anticipated loss of overall genetic diversity was found to be negligible, although allele losses have occurred at specific loci.

Allele variation in loci for adaptive response in Bulgarian wheat cultivars and landraces and its effect on heading date

2011 ◽  
Vol 9 (2) ◽  
pp. 251-255 ◽  
Author(s):  
Stanislav Kolev ◽  
Dimitar Vassilev ◽  
Kostadin Kostov ◽  
Elena Todorovska
Keyword(s):  
Bread Wheat ◽  
Adaptive Response ◽  
Growth Habit ◽  
Heading Date ◽  
Wheat Cultivars ◽  
Allele Composition ◽  
Sensitive Allele ◽  
Allele Variation ◽  
Photoperiod Sensitive ◽  
Winter Growth Habit

Allele composition at the major growth habit (Ppd-D1, Vrn-1, Rht-1 and Rht8) loci was determined in 52 Bulgarian bread wheat cultivars and landraces, using recently developed diagnostic molecular markers. The study showed that Bulgarian wheat germplasm varies for photoperiod, vernalization and height-reducing genes. The photoperiod-sensitive allele (Ppd-D1b) was the most frequent one in the old cultivars and landraces (90.9%), while the photoperiod-insensitive allele (Ppd-D1a) showed the highest frequency in the modern cultivars (96.71%). The alleles conferring winter growth habit (vrn-A1, vrn-B1 and vrn-D1) were more common in both the old (72.7%) and the modern (93.3%) wheat genotypes. The spring allele Vrn-A1c was not detected in Bulgarian germplasm, while the spring allele Vrn-B1 was found only in the old genotypes (13.6%). The semi-dwarfing allele Rht-B1b was observed in several modern cultivars. Seven allele variants were found in the microsatellite locus Xgwm261, closely located to the Rht8 gene. Among them, alleles of 164, 212 and 216 bp length were specific for the old genotypes studied, while alleles of 192 and 202 bp length were specific for the modern ones. The allele combination Rht-B1b//192 or 202 bp allele (Xgwm261 locus)//Ppd-D1a//vrn-A1/vrn–B1/vrn-D1 was detected in most of the early-heading modern cultivars. Our study emphasizes on the plasticity of the adaptive response of bread wheat cultivars sown in Bulgaria, as well as on the effect of variation for major growth habit on some yield and reproductive characteristics.

Towards optimal designs for hedgerow olive orchards

2006 ◽  
Vol 57 (10) ◽  
pp. 1067 ◽  
Author(s):  
David J. Connor
Keyword(s):  
Shoot Growth ◽  
Growth Habit ◽  
Incident Radiation ◽  
Optimal Designs ◽  
Threshold Values ◽  
Row Width ◽  
Key Sites ◽  
And Performance ◽  
Fruit Formation ◽  
Radiation Research

An analysis of row height, row width, canopy slope, and alley width of hedgerow olive orchards was conducted to identify combinations that maximise productivity while allowing access to machinery for management. This objective requires maximising both the interception of incident solar radiation and its distribution over the canopy surface for productivity. For maximum productivity, all foliage must be illuminated above threshold values for the critical step in the shoot growth – floral initiation – flowering – fruit formation – fruit filling reproductive sequence. The key sites for adequate illumination are the bases of the canopy walls. For canopies with row height and alley width combinations that provide threshold illumination at the bases of the canopy walls, the area of productive foliage per unit orchard area is inversely related to row width because incident radiation received by broad canopy tops is better spread at smaller irradiance over more canopy wall. The analysis revealed that canopies of equal productivity can be formed with a range of combinations of height, slope, and alley width, and that optimal combinations are responsive to threshold values in the range 20–30% of incident radiation. Research is required to establish threshold values and the limits to row height and row width consistent with year-to-year production of reproductive shoots. The latter requires attention to cost and performance of machinery, the growth habit of the tree, and its response to pruning.

Transmission Scanning Electron Microscopy and Energy Analysis with the Siemens ELMISKOP 101

1972 ◽  
Vol 30 ◽  
pp. 450-451
Author(s):  
H. M. Thieringer
Keyword(s):  
Objective Lens ◽  
Transmission Microscopy ◽  
Image Recording ◽  
Mode Of Operation ◽  
Scanning Transmission ◽  
Electron Microscopes ◽  
And Performance ◽  
Convergent Beam ◽  
Ray Path ◽  
Beam Diffraction

It has repeatedly been show that with conventional electron microscopes very fine electron probes can be produced, therefore allowing various micro-techniques such as micro recording, X-ray microanalysis and convergent beam diffraction. In this paper the function and performance of an SIEMENS ELMISKOP 101 used as a scanning transmission microscope (STEM) is described. This mode of operation has some advantages over the conventional transmission microscopy (CTEM) especially for the observation of thick specimen, in spite of somewhat longer image recording times.Fig.1 shows schematically the ray path and the additional electronics of an ELMISKOP 101 working as a STEM. With a point-cathode, and using condensor I and the objective lens as a demagnifying system, an electron probe with a half-width ob about 25 Å and a typical current of 5.10-11 amp at 100 kV can be obtained in the back focal plane of the objective lens.

Angular Resolved Electron Spectroscopy with Parallel Recording

1990 ◽  
Vol 48 (2) ◽  
pp. 370-371
Author(s):  
Huang Min ◽  
P.S. Flora ◽  
C.J. Harland ◽  
J.A. Venables
Keyword(s):  
Electron Spectroscopy ◽  
Low Voltage ◽  
Solid Angle ◽  
Detection System ◽  
Voltage Electron ◽  
Cylindrical Mirror ◽  
Inner Radius ◽  
Channel Plate ◽  
And Performance ◽  
Type Detector

A cylindrical mirror analyser (CMA) has been built with a parallel recording detection system. It is being used for angular resolved electron spectroscopy (ARES) within a SEM. The CMA has been optimised for imaging applications; the inner cylinder contains a magnetically focused and scanned, 30kV, SEM electron-optical column. The CMA has a large inner radius (50.8mm) and a large collection solid angle (Ω > 1sterad). An energy resolution (ΔE/E) of 1-2% has been achieved. The design and performance of the combination SEM/CMA instrument has been described previously and the CMA and detector system has been used for low voltage electron spectroscopy. Here we discuss the use of the CMA for ARES and present some preliminary results.The CMA has been designed for an axis-to-ring focus and uses an annular type detector. This detector consists of a channel-plate/YAG/mirror assembly which is optically coupled to either a photomultiplier for spectroscopy or a TV camera for parallel detection.

Novel epoxy/anhydride alternatives for biological electron microscopy: Physical and performance characteristis of embed 812 and LX 112 in combination with NSA/NMA/DMAE

1989 ◽  
Vol 47 ◽  
pp. 1000-1001
Author(s):  
Joe A. Mascorro ◽  
Gerald S. Kirby
Keyword(s):  
Electron Microscopy ◽  
Flow Rate ◽  
Succinic Anhydride ◽  
Volume Flow Rate ◽  
Mass Density ◽  
Uranyl Acetate ◽  
Volume Flow ◽  
Base Resin ◽  
And Performance ◽  
Acid Anhydrides

Embedding media based upon an epoxy resin of choice and the acid anhydrides dodecenyl succinic anhydride (DDSA), nadic methyl anhydride (NMA), and catalyzed by the tertiary amine 2,4,6-Tri(dimethylaminomethyl) phenol (DMP-30) are widely used in biological electron microscopy. These media possess a viscosity character that can impair tissue infiltration, particularly if original Epon 812 is utilized as the base resin. Other resins that are considerably less viscous than Epon 812 now are available as replacements. Likewise, nonenyl succinic anhydride (NSA) and dimethylaminoethanol (DMAE) are more fluid than their counterparts DDSA and DMP- 30 commonly used in earlier formulations. This work utilizes novel epoxy and anhydride combinations in order to produce embedding media with desirable flow rate and viscosity parameters that, in turn, would allow the medium to optimally infiltrate tissues. Specifically, embeding media based on EmBed 812 or LX 112 with NSA (in place of DDSA) and DMAE (replacing DMP-30), with NMA remaining constant, are formulated and offered as alternatives for routine biological work.Individual epoxy resins (Table I) or complete embedding media (Tables II-III) were tested for flow rate and viscosity. The novel media were further examined for their ability to infilftrate tissues, polymerize, sectioning and staining character, as well as strength and stability to the electron beam and column vacuum. For physical comparisons, a volume (9 ml) of either resin or media was aspirated into a capillary viscocimeter oriented vertically. The material was then allowed to flow out freely under the influence of gravity and the flow time necessary for the volume to exit was recored (Col B,C; Tables). In addition, the volume flow rate (ml flowing/second; Col D, Tables) was measured. Viscosity (n) could then be determined by using the Hagen-Poiseville relation for laminar flow, n = c.p/Q, where c = a geometric constant from an instrument calibration with water, p = mass density, and Q = volume flow rate. Mass weight and density of the materials were determined as well (Col F,G; Tables). Infiltration schedules utilized were short (1/2 hr 1:1, 3 hrs full resin), intermediate (1/2 hr 1:1, 6 hrs full resin) , or long (1/2 hr 1:1, 6 hrs full resin) in total time. Polymerization schedules ranging from 15 hrs (overnight) through 24, 36, or 48 hrs were tested. Sections demonstrating gold interference colors were collected on unsupported 200- 300 mesh grids and stained sequentially with uranyl acetate and lead citrate.

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