150 research outputs found
Quantitative trait loci analysis for resistance to Cephalosporium stripe, a vascular wilt disease of wheat
Cephalosporium stripe, caused by Cephalosporium
gramineum, can cause severe loss of wheat
(Triticum aestivum L.) yield and grain quality and can be
an important factor limiting adoption of conservation tillage
practices. Selecting for resistance to Cephalosporium
stripe is problematic; however, as optimum conditions for
disease do not occur annually under natural conditions,
inoculum levels can be spatially heterogeneous, and little is
known about the inheritance of resistance. A population of
268 recombinant inbred lines (RILs) derived from a cross
between two wheat cultivars was characterized using field
screening and molecular markers to investigate the inheritance
of resistance to Cephalosporium stripe. Whiteheads
(sterile heads caused by pathogen infection) were measured on each RIL in three field environments under artificially
inoculated conditions. A linkage map for this population
was created based on 204 SSR and DArT markers. A total
of 36 linkage groups were resolved, representing portions
of all chromosomes except for chromosome 1D, which
lacked a sufficient number of polymorphic markers.
Quantitative trait locus (QTL) analysis identified seven
regions associated with resistance to Cephalosporium
stripe, with approximately equal additive effects. Four
QTL derived from the more susceptible parent (Brundage)
and three came from the more resistant parent (Coda), but
the cumulative, additive effect of QTL from Coda was
greater than that of Brundage. Additivity of QTL effects
was confirmed through regression analysis and demonstrates
the advantage of accumulating multiple QTL allelesto achieve high levels of resistanc
Meeting the Challenges Facing Wheat Production The Strategic Research Agenda of the Global Wheat Initiative
Wheat occupies a special role in global food security since, in addition to providing 20% of our carbohydrates and protein, almost 25% of the global production is traded internationally. The importance of wheat for food security was recognised by the Chief Agricultural Scientists of the G20 group of countries when they endorsed the establishment of the Wheat Initiative in 2011. The Wheat Initiative was tasked with supporting the wheat research community by facilitating col-laboration, information and resource sharing and helping to build the capacity to address chal-lenges facing production in an increasingly variable environment. Many countries invest in wheat research. Innovations in wheat breeding and agronomy have delivered enormous gains over the past few decades, with the average global yield increasing from just over 1 tonne per hectare in the early 1960s to around 3.5 tonnes in the past decade. These gains are threatened by climate change, the rapidly rising financial and environmental costs of fertilizer, and pesticides, combined with declines in water availability for irrigation in many regions. The international wheat research community has worked to identify major opportunities to help ensure that global wheat pro-duction can meet demand. The outcomes of these discussions are presented in this paper
Dynamic polarizability of rotating particles in electrorheological fluids
A rotating particle in electrorheological (ER) fluid leads to a displacement
of its polarization charges on the surface which relax towards the external
applied field , resulting in a steady-state polarization at an angle
with respect to . This dynamic effect has shown to affect the ER
fluids properties dramatically. In this paper, we develop a dynamic effective
medium theory (EMT) for a system containing rotating particles of finite volume
fraction. This is a generalization of established EMT to account for the
interactions between many rotating particles. While the theory is valid for
three dimensions, the results in a special two dimensional configuration show
that the system exhibits an off-diagonal polarization response, in addition to
a diagonal polarization response, which resembles the classic Hall effect. The
diagonal response monotonically decreases with an increasing rotational speed,
whereas the off-diagonal response exhibits a maximum at a reduced rotational
angular velocity comparing to the case of isolated rotating
particles. This implies a way of measurement on the interacting relaxation
time. The dependencies of the diagonal and off-diagonal responses on various
factors, such as , the volume fraction, and the dielectric contrast,
are discussed.Comment: 6 pages, 4 figures, accepted to J. Phys. Chem.
A Landau-Squire nanojet
Fluid jets are found in nature at all length scales, from microscopic to
cosmological. Here we report on an electroosmotically driven jet from a single
glass nanopore about 75 nm in radius with a maximum flow rate ~15 pL/s. A novel
anemometry technique allows us to map out the vorticity and velocity fields
that show excellent agreement with the classical Landau-Squire solution of the
Navier Stokes equations for a point jet. We observe a phenomenon that we call
flow rectification: an asymmetry in the flow rate with respect to voltage
reversal. Such a nanojet could potentially find applications in
micromanipulation, nanopatterning, and as a diode in microfluidic circuits.Comment: 20 pages, 4 figure
Relationship between Incidence of Cephalosporium Stripe and Yield Loss in Winter Wheat
Cephalosporium stripe (caused by Cephalosporium gramineum) can be a serious disease of winter wheat (Triticum aestivum L.) in the Pacific Northwest of the USA. Effects of Cephalosporium stripe on yield, test weight, protein, and kernel characteristics were examined using 12 winter wheat varieties in field plots inoculated and not inoculated with the pathogen. Averaged over varieties, inoculation decreased yield, test weight, kernel weight, and kernel diameter; grain protein and the standard deviations of kernel weight and kernel diameter were increased by inoculation. Grain yield of the susceptible check was reduced by as much as 41% with addition of inoculum. The most resistant and the most susceptible varieties performed similarly for yield in the two environments, while varieties with intermediate levels of resistance were sometimes inconsistent. There was a linear relationship between yield and % whiteheads (sterile heads caused by disease) in one environment and a curvilinear relation in the other
Trends in root architecture for historical and contemporary wheat cultivars of Uruguay. [Poster] [Abstract].
Efecto acumulado del pastoreo de cultivos de cobertura: 2. Cobertura de suelo, enmalezamiento y rendimiento de soja. [Resumen].
Optimization of multiple-curve-tube mufflers using neural networks, the boundary element method and GA method
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