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  • Articles  (121)
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  • Springer  (121)
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  • 1
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    Mathematical programming 61 (1993), S. 197-214 
    ISSN: 1436-4646
    Keywords: Epi-convergence ; epi-distance ; stability ; convex optimization ; approximate solutions ; subgradients ; level sets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract We prove that theε-optimal solutions of convex optimization problems are Lipschitz continuous with respect to data perturbations when these are measured in terms of the epi-distance. A similar property is obtained for the distance between the level sets of extended real valued functions. We also show that these properties imply that theε-subgradient mapping is Lipschitz continuous.
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  • 2
    ISSN: 1572-8900
    Keywords: Chemiluminescence ; oxidation ; stability ; acrylonitrile-butadiene-styrene (ABS) ; ABS/polycarbonate blend
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The thermal oxidative stability of various ABS/PC compounds was studied by means of the chemiluminescence technique. Similarly to pure ABS, Irganox 1076 and Irganox MD 1024 perform as moderate antioxidants in ABS/PC and (ABS/PC + lubricant) blends. Neither Tinuvin 144, Irgaphos 168, nor their mixture affects the durability of the ABS/PC blend. At the same time, (Irgaphos 168 + Tinuvin 144) in combination with Irganoxes was found to provide a noticeable enhancement in durability to the (ABS/PC + lubricant) system. Titanium dioxide pigments by themselves have only a slight influence on the oxidative stability of the ABS/PC blend. Durability of the (ABS/PC + pigment) and (ABS/PC + lubricant) systems was found to be the same and the overall protective effect of Irganox 1076 was similar in both the (ABS/PC + lubricant) and the (ABS/PC + lubricant + pigment) systems. Certain modifiers significantly improve the durability of the ABS/PC compounds, although their function may differ in the systems with and without pigments.
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  • 3
    ISSN: 1572-8900
    Keywords: Chemiluminescence ; oxidation ; stability ; acrylonitrile-butadiene-styrene (ABS)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The influence of lubricants, UV stabilizers, antioxidants, and metal deactivators on the resistance of ABS to thermal oxidation was studied by means of the chemiluminescence technique. Neither of the additives seems to affect significantly the induction period of oxidation. At the same time, the influence of various additives on the oxidation rate constant is remarkably different: the introduction of lubricants and UV stabilizers increases its value, while antioxidants and metal deactivators have the opposite effect. For the particular systems studied durability is decreased in samples containing the lubricant and UV stabilizers and increased in samples stabilized with the antioxidant and metal deactivator.
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  • 4
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    Journal of dynamics and differential equations 5 (1993), S. 625-671 
    ISSN: 1572-9222
    Keywords: Scalar reaction-diffusion equation ; singular perturbation methods ; internal layer ; Neumann layer ; stability ; 35K57 ; 35B25 ; 35B35
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract The multiple existences and their stability properties of stationary solutions with a single transition layer in some scalar reaction-diffusion equation are shown. Each solution is constructed by using classical singular perturbation methods and its stability property is determined by a simple algebraic quantity, say index, appearing in the construction of a solution.
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  • 5
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    Journal of dynamics and differential equations 5 (1993), S. 189-218 
    ISSN: 1572-9222
    Keywords: Equivariant bifurcation ; symmetry ; singularity ; equivariant jets and transversality ; normal forms ; universal unfolding ; stability ; structural stability ; 58F14 ; 58E07 ; 58C27
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract The theoretical machinery from singularity theory introduced by Golubitsky, Stewart, and Schaeffer, to study equivariant bifurcation problems, is completed and expanded while generalized to the multiple parameter context. In this setting the finite determinacy theorems or normal forms, the stability of equivariant bifurcation problems, and the structural stability of the universal unfolding are discussed.
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  • 6
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    Set-valued analysis 1 (1993), S. 393-402 
    ISSN: 1572-932X
    Keywords: Primary: 49J40, 65K10, 47A55, 47H05, 65L20 ; Variational inequality ; perturbation ; unbounded and nonsmooth operators ; convex sets ; Hausdorff distance ; regularization ; monotonicity ; convergence ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract The stability and convergence of the solutions of perturbed and regularized variational inequality to the solutions of the primary (unstable a priori) variational inequality with proper monotone operator are investigated. All the objects of inequality: the operatorA, the right-hand partf and the set of constrains Ω are to be perturbed. At the same time no assumptions of boundedness and smoothness of the operatorA are used. The connection between the parameters of perturbations, which guarantees strong convergence of approximate solutions, is established. It is proved that the existence of the solution to the unperturbed variational inequality is necessary and sufficient condition for convergence of the regularized perturbed inequality solutions.
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  • 7
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    Journal of dynamics and differential equations 5 (1993), S. 105-128 
    ISSN: 1572-9222
    Keywords: Delay system ; stability ; relative variance ; dynamical disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract A new approach to the study of delay systems, applicable to physiological control systems and other systems where little information about the time delays is available, is examined. The method is based on the fact that stability information can be deduced from the statistical properties of the probability distribution that encodes the structure of the time delay. The main statistical variables used are the usual expectation parameter,E, and a modified variance, calledrelative variance and denotedR, that is invariant under time scale changes. Recent work of the author has shown that stability often improves asR increases whileE remains fixed. A four-parameter family of delay models is analysed in this paper, and the (E, R) pair is found to be a reliable indicator of stability over the global parameter domain of the family.
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  • 8
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    Journal of solution chemistry 22 (1993), S. 1151-1158 
    ISSN: 1572-8927
    Keywords: Molecular complexes ; solvent effect ; stability ; solid CT complexes ; nicotine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Interaction of nicotine with tetracyanoethylene and iodine was investigated spectrophotometrically and found to form strong CT complexes (n−π and n-σ*, respectively). The donor site involved in CT interaction is the pyrrolidine nitrogen. The nicotine-I2 complex exists as the ionic structure (nicotine) I+-I 3 − . Formation constants of the CT complexes in various solvents were determined from 10 to 25°C and are discussed in terms of the nature of the electron acceptor and solvent polarity. Solid CT complexes were synthesized and were characterized by microchemical analysis and infrared spectra techniques.
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  • 9
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    Annals of global analysis and geometry 11 (1993), S. 387-395 
    ISSN: 1572-9060
    Keywords: Curvatures of hypersurfaces ; Reilly's inequality ; stability ; 53 A 10 ; 53 C 42
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract We generalize Reilly's inequality for the first eigenvalue of immersed submanifolds ofIR m +1 and the total (squared) mean curvature, to hypersurfaces ofIR m +1 and the first eigenvalue of the higher order curvatures. We apply this to stability problems. We also consider hypersurfaces in hyperbolic space.
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  • 10
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    BIT 33 (1993), S. 332-350 
    ISSN: 1572-9125
    Keywords: AMS(MOS): 65L06 ; Multistep collocation method ; continuous solution ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract This paper describes an implementation of multistep collocation methods, which are applicable to stiff differential problems, singular perturbation problems, and D.A.E.s of index 1 and 2. These methods generalize one-step implicit Runge-Kutta methods as well as multistep one-stage BDF methods. We give numerical comparisons of our code with two representative codes for these methods, RADAU5 and LSODE.
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  • 11
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    Annals of global analysis and geometry 11 (1993), S. 221-235 
    ISSN: 1572-9060
    Keywords: Second variation formula ; Morse index ; stability ; 53C
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Iff is a minimal, isometric immersion of the Riemannian manifoldM of dimensionn in a Riemannian manifold $$\overline M$$ of dimensionm and ifI N is the „differential Jacobi operator” acting on the cross sections of the normal bundleN(M), we obtain some information on the Morse index and on the stability ofM through a detailed geometric analysis of the immersionf obtained when considering the higher fundamental forms off.
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  • 12
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    BIT 33 (1993), S. 74-84 
    ISSN: 1572-9125
    Keywords: 65J10 ; 65M12 ; Analytic semigroup ; Banach space ; rational approximation ; A-acceptable ; A(θ)-acceptable ; stability ; Crank-Nicolson method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract It is shown thatA-acceptable and, more generally,A(θ)-arational approximations of bounded analytic semigroups in Banach space are stable. The result applies, in particular, to the Crank-Nicolson method.
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  • 13
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    BIT 33 (1993), S. 285-303 
    ISSN: 1572-9125
    Keywords: 65L05 ; stiffness ; stability ; pseudospectra
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract It is argued that even for a linear system of ODEs with constant coefficients, stiffness cannot properly be characterized in terms of the eigenvalues of the Jacobian, because stiffness is a transient phenomenon whereas the significance of eigenvalues is asymptotic. Recent theory from the numerical solution of PDEs is adapted to show that a more appropriate characterization can be based upon pseudospectra instead of spectra. Numerical experiments with an adaptive ODE solver illustrate these findings.
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  • 14
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    K-Theory 7 (1993), S. 333-367 
    ISSN: 1573-0514
    Keywords: Locally flat embedding ; pointed Hermitian module ; splitting ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract We prove an existence result for topologically locally flat embeddings of 2-spheres in simply connected 4-manifolds. This topological result is deduced from a splitting theorem for pointed Hermitian modules over a cyclic group ring. A stability result for such modules is also proved. This applies to the isotopy classification of locally flat embeddings.
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  • 15
    ISSN: 1573-0867
    Keywords: animal manure ; leaching ; maize ; nitrification inhibitor ; nitrogen recovery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Field experiments with silage maize during eight years on a sandy soil in The Netherlands, showed that dicyandiamide (DCD) addition to autumn-applied cattle slurry retarded nitrification, thus reducing nitrate losses during winter. Spring-applied slurry without DCD, however, was on average associated with even lower losses and higher maize dry matter yields. Economically optimum supplies of mineral N in the upper 0.6 m soil layer in spring (EOSMN), amounted to 130–220 kg ha−1. Year to year variation of EOSMN could not be attributed to crop demand only. According to balance sheet calculations on control plots, apparent N mineralization between years varied from 0.36 to 0.94 kg ha−1 d−1. On average, forty percent of the soil mineral N (SMN) supply in spring, was lost during the growing season. Hence, the amounts of residual soil mineral N (RSMN) were lower than expected. Multiple regression with SMN in spring, N crop uptake and cumulative rainfall as explanatory variables, could account for 79 percent of the variation in RSMN. Postponement of slurry applications to spring and limiting N inputs to economically optimum rates, were insufficient measures to keep the nitrate concentration in groundwater below the EC level for drinking water.
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  • 16
    ISSN: 1572-9680
    Keywords: Erythrina ; Gliricidia ; alley cropping ; maize ; competition ; nitrogen availability ; Costa Rica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Maize growing next toErythrina hedgerows had 44% lower biomass (p〈0.01) and 35% lower N content (p〈0.1) than maize growing in the middle of the alleys. Maize growing next toGliricidia hedgerows had the same biomass but 56% higher N content (p〈0.1) than maize growing in the middle of the alleys. However these differences did not develop until 2 months after sowing of the maize. Spatial variability in soil nitrogen mineralization and mulch nitrogen release did not explain any of the differences in growth or N uptake of the maize with respect to distance from the trees. It is hypothesized that the slower growth of the maize next to theErythrina trees after 2 months is due to increasing light and/or nutrient competition from the trees as the trees recover from pollarding. The apparent lack of competition fromGlirigidia may be due to different rates of regrowth or different shoot and root architecture. A theoretical model is described demonstrating that if a crop is to take advantage of the higher nutrient availability under alley cropping it must complete the major part of its growth before the trees recover significantly from pollarding, and start competing strongly with the crop.
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  • 17
    ISSN: 1572-9680
    Keywords: alley cropping ; maize ; nitrogen ; organic matter ; soil fertility ; Leucaena leucocephala ; Flemingia congesta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A detailed study of the soil chemical and physical properties in seven-year-old alley cropping trial containingLeucaena leucocephala andFlemingia congesta in Northern Zambia is described. There was a strong correlation between the maize yield and the total amount of nitrogen applied, both from prunings and fertiliser, suggesting that a major reason for the observed benefit from alley cropping, particularly withLeucaena, was due to an improvement in nitrogen supply.Leucaena produced significantly more biomass, and its leaves had higher concentrations of nitrogen, phosphorous and potassium and lower C/N and C/P ratios than did those ofFlemingia. There was also evidence that the trees had a beneficial effect on other soil chemical properties; under the hedgerows, particularly those ofLeucaena, there were higher levels of organic carbon, Mg, K and ECEC, and pH values were also highest. It is suggested that higher levels of organic carbon in the alley crop treatments were responsible for the improvements observed in soil physical properties. Lower bulk density, lower penetration resistance, and a higher infiltration rate and pore volume fraction were measured in the alley crops, although there was no significant change in the soil water release parameters. A deteriorating effect of constant applications of nitrogen fertiliser on soil fertility was observed; as the level of urea application increased, there were significant decreases in Mg, K and pH, increases in Al and soil acidity, and higher penetrometer resistance. These results highlight the urgent need for further research on biological methods of maintaining soil fertility.
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  • 18
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    Journal of nonlinear science 3 (1993), S. 477-539 
    ISSN: 1432-1467
    Keywords: nearly integrable systems ; spectral transform ; attractors ; traveling waves ; stability ; numerical methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Summary In this paper we rigorously show the existence and smoothness inε of traveling wave solutions to a periodic Korteweg-deVries equation with a Kuramoto-Sivashinsky-type perturbation for sufficiently small values of the perturbation parameterε. The shape and the spectral transforms of these traveling waves are calculated perturbatively to first order. A linear stability theory using squared eigenfunction bases related to the spectral theory of the KdV equation is proposed and carried out numerically. Finally, the inverse spectral transform is used to study the transient and asymptotic stages of the dynamics of the solutions.
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  • 19
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    Journal of nonlinear science 3 (1993), S. 307-327 
    ISSN: 1432-1467
    Keywords: bifurcation ; saddle node ; Hopf ; stability ; robustness ; optimization ; numerical methods ; transcritical ; pitchfork ; extended systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Summary Engineering and physical systems are often modeled as nonlinear differential equations with a vector λ of parameters and operated at a stable equilibrium. However, as the parameters λ vary from some nominal value λ0, the stability of the equilibrium can be lost in a saddle-node or Hopf bifurcation. The spatial relation in parameter space of λ0 to the critical set of parameters at which the stable equilibrium bifurcates determines the robustness of the system stability to parameter variations and is important in applications. We propose computing a parameter vector λ* at which the stable equilibrium bifurcates which is locally closest in parameter space to the nominal parameters λ0. Iterative and direct methods for computing these locally closest bifurcations are described. The methods are extensions of standard, one-parameter methods of computing bifurcations and are based on formulas for the normal vector to hypersurfaces of the bifurcation set. Conditions on the hypersurface curvature are given to ensure the local convergence of the iterative method and the regularity of solutions of the direct method. Formulas are derived for the curvature of the saddle node bifurcation set. The methods are extended to transcritical and pitchfork bifurcations and parametrized maps, and the sensitivity to λ0 of the distance to a closest bifurcation is derived. The application of the methods is illustrated by computing the proximity to the closest voltage collapse instability of a simple electric power system.
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  • 20
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    Acta applicandae mathematicae 32 (1993), S. 59-88 
    ISSN: 1572-9036
    Keywords: 47A56 ; 47A55 ; 15A54 ; 35A30 ; 34A30 ; Operator-valued functions ; matrices ; nonself-adjoint operators ; spectrum perturbation ; eigenvalues ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract A survey is presented of estimates for a norm of matrix-valued and operator-valued functions obtained by the author. These estimates improve the Gel'fand-Shilov estimate for regular functions of matrices and Carleman's estimates for resolvents of matrices and compact operators. From the estimates for resolvents, the well-known result for spectrum perturbations of self-adjoint operators is extended to quasi-Hermitian operators. In addition, the classical Schur and Brown's inequalities for eigenvalues of matrices are improved. From estimates for the exponential function (semigroups), bounds for solution norms of nonlinear differential equations are derived. These bounds give the stability criteria which make it possible to avoid the construction of Lyapunov functions in appropriate situations.
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  • 21
    ISSN: 1573-4927
    Keywords: alcohol dehydrogenase ; maize ; Zea mays ; mutation ; cDNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The homodimeric alcohol dehydrogenase gene product of maize (Zea mays L.)Adh1-1S1108 mutation was purified and compared with the parentalAdh1-1S enzyme. The mutant alcohol dehydrogenase activity had pH optima and substrate specificity similar to those of the parental enzyme, but exhibited somewhat increased and decreasedK mvalues for acetaldehyde and NADH, respectively. The mutant enzyme was also markedly less stable than the enzyme from parental tissues to temperatures as low as 50°C. Sequence analysis of a polymerase chain reaction (PCR)-generated cDNA clone revealed a G-to-C mutation at position 406 and a C-to-T mutation at position 974. These would result in residue 103 of each protein subunit being changed from an alanine to a proline and residue 292 being changed from an alanine to a valine. Whether one or both of these changes in primary sequence is responsible for the altered substrate affinities and stability is not yet understood.
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  • 22
    ISSN: 1573-4927
    Keywords: alcohol dehydrogenase ; maize ; Zea mays ; mutation ; cDNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The homodimeric alcohol dehydrogenase gene product of maize (Zea mays L.)Adh1-1S1108 mutation was purified and compared with the parentalAdh1-1S enzyme. The mutant alcohol dehydrogenase activity had pH optima and substrate specificity similar to those of the parental enzyme, but exhibited somewhat increased and decreasedK mvalues for acetaldehyde and NADH, respectively. The mutant enzyme was also markedly less stable than the enzyme from parental tissues to temperatures as low as 50°C. Sequence analysis of a polymerase chain reaction (PCR)-generated cDNA clone revealed a G-to-C mutation at position 406 and a C-to-T mutation at position 974. These would result in residue 103 of each protein subunit being changed from an alanine to a proline and residue 292 being changed from an alanine to a valine. Whether one or both of these changes in primary sequence is responsible for the altered substrate affinities and stability is not yet understood.
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  • 23
    ISSN: 1573-4943
    Keywords: Amino acid sequence ; wheat ; wounding ; plant defence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The amino acid sequence of wheatwin1, a monomeric protein of 125 residues isolated from wheat kernel (variety S. Pastore), is reported. Wheatwin1 is highly homologous (95%) to barwin, a protein from barley seed, which was shown to be related to the C-terminal domain of two proteins encoded by the wound-induced geneswin1 andwin2 in potato and to a protein encoded by the same domain of the hevein gene (hev1) in rubber tree. Similarly to barwin, wheatwin1 contains six cysteine residues all linked in disulfide bridges and the N-terminal residue is pyroglutamate. Moreover, structural studies performed on wheatwin1 andwin1 protein by predictive methods demonstrated that these proteins and barwin are closely related in the secondary structure also. The high level of homology found with the product ofwin1,win2, andhev1 genes strongly suggests that barwin and wheatwin1 play a common role in the mechanism of plant defence.
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  • 24
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    Applied mathematics and mechanics 14 (1993), S. 95-100 
    ISSN: 1573-2754
    Keywords: discrete large-scale systems ; stability ; Liapunov function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Mathematics , Physics
    Notes: Abstract In this paper, we directly use the linear norm Liapunov function to investigate the stability of the linear discrete large-scale systems and obtain some criteria for the asymptotic stability of such a system.
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  • 25
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    Applied mathematics and mechanics 14 (1993), S. 981-982 
    ISSN: 1573-2754
    Keywords: Burgers shock wave ; infinitesimal disturbance ; stability ; asymptotically stable
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Mathematics , Physics
    Notes: Abstract This paper considers the stability of the Burgers shock wave solution with respect to infinitesimal disturbance. It is found that the Burgers shock wave is asymptotically stable in the Liapunov sense.
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  • 26
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    Pharmaceutical research 10 (1993), S. 156-159 
    ISSN: 1573-904X
    Keywords: aspirin ; hydroxypropyl-β-cyclodextrin ; complexation ; stability ; activation energies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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  • 27
    ISSN: 1573-904X
    Keywords: CI-981 ; HMG-CoA reductase inhibitor ; stability ; solubility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The pH dependence of the interconversion kinetics, equilibrium, and solubilities of the lactone and hydroxyacid forms of the HMG-CoA reductase inhibitor, CI-981 ([R-(R*,R*)]-2-(4-fluorophenyl)-β,δ-dihydroxy-5-(l-methylethyl)-3-phenyl-4-[(phenylamino)carbonyl]-lH-pyrrole-l-hepatonic acid), are important considerations when chosing and developing one of the forms of these compounds. Over a pH range of 2.1 to 6.0 and at 30°C, the apparent solubility of the sodium salt of CI-981 (i.e., the hydroxyacid form) increases about 60-fold, from 20.4 µg/mL to 1.23 mg/mL, and the profile yields a pK a for the terminal carboxyl group of 4.46. In contrast, over a pH range of 2.3 to 7.7 and also at 30°C, the apparent solubility of the lactone form of CI-981 varies little, and the mean solubility is 1.34 (±0.53) µg/mL. The kinetics of interconversion and the equilibrium between the hydroxyacid and the lactone forms have been studied as a function of pH, buffer concentration, and temperature at a fixed ionic strength (0.5 M) using a stability-indicating HPLC assay. The acid-catalyzed reaction is reversible, whereas the base-catalyzed reaction can be treated as an irreversible reaction. More specifically, at pH 〈6, an equilibrium favoring the hydroxyacid form is established, whereas at pH 〉6, the equilibrium reaction is no longer detectable and greatly favors the hydroxyacid form. The rate constant for lactone formation, k 1 is well described by specific acid-catalyzed and spontaneous lactonization pathways, whereas the rate constant for lactone hydrolysis (or hydroxyacid formation), k 2, is well described by specific acid-, water-, and specific base-catalyzed pathways.
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  • 28
    ISSN: 1573-904X
    Keywords: emulsions ; stability ; field-flow fractionation ; size distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The combination of sedimentation field-flow fractionation (SedFFF) and photon correlation spectroscopy (PCS) is shown to provide a detailed record of the droplet sizes present in fat emulsions commonly used in parenteral nutrition. The technique presented has been used to record size distribution data for a particular emulsion (Liposyn-II), demonstrating its high stability and lot-to-lot uniformity. The technique is also able to demonstrate how additions of small amounts of electrolytes [0.45% (w/v) NaCl, 0.05% (w/v) CaCl2] tend to destabilize the emulsion, suggesting some caution in the use of total parenteral nutrition (TPN) mixtures. In contrast, a 1:1 mixture with human serum caused no sign of instability in the Liposyn-II. Using the emulsion as a carrier for lipophilic drugs necessitates adding solutions of the drug in nonaqueous solvents, such as DMSO (dimethyl sulfoxide). This solvent's destabilizing effect results in a droplet coalescence that becomes severe after 3–5 days following a 10% (v/v) addition, while a 5% (v/v) addition reaches the same level of coalescence in 10 days.
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  • 29
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    Pharmaceutical research 10 (1993), S. 1174-1180 
    ISSN: 1573-904X
    Keywords: aspartame ; stability ; pH – rate profile ; peptide ester ; hydrolysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The kinetics of demethylation of aspartame and L-phenylalanine methyl ester were studied in aqueous solution at 25°C over the pH range 0.27–11.5. The pseudo-first-order rate constant for aspartame was resolved into individual contributions from methyl ester hydrolysis and diketopiperazine formation. pH – rate profiles were quantitatively described by chemically reasonable kinetic schemes. Aspartame is maximally stable at pH 4 (t 90 = 53 days at 25°C); phe-nylalanine methyl ester, at pH 3. The potentiometrically measured pK a values were pK a1 3.19 and pK a2 7.87 fr aspartame and pKa 7.11 for phenylalanine methyl ester.
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  • 30
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    Pharmaceutical research 10 (1993), S. 1466-1470 
    ISSN: 1573-904X
    Keywords: p-chloro-m-xylenol ; 4-chloro-3,5-dimethylphenol (PCMX) ; radiolabel synthesis ; isotopes ; stability ; reaction kinetics ; in vitro studies
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    Topics: Chemistry and Pharmacology
    Notes: Abstract The synthesis, reaction kinetics, and pH stability of isotopically labeled p-chloro-m-xylenol (PCMX) were evaluated. While base catalysis was more rapid than acid catalysis, the latter allowed the use of a cosolvent for deuterium and tritium labeling using as little as 250 µL labeled water. Both acid and base catalysis were markedly more rapid than that reported previously for the deuteration of PCMX and related phenols. Isotopic labeling occurred only at the 2 and 6 ring positions, ortho to the phenolic group of PCMX. No deuterium loss was observed after storage for 21 days at 37°C over a pH range of 2 – 14. Isotopic loss was observed only below pH 2. The prepared 3H-labeled PCMX had a specific activity of 1.18 mCi/mmol, a radiochemical purity of 99.0%, and a chemical purity exceeding 99.0%, with a high stability during prolonged cold storage.
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  • 31
    ISSN: 1573-904X
    Keywords: α-chymotrypsin ; fatty acid ; insulin ; mixed micelles ; proteolytic degradation ; stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The proteolytic degradation of porcine zinc insulin by α-chymotrypsin was previously found to depend markedly on the state of insulin aggregation (Pharm. Res. 9:864–869, 1992). In this study, the effect of bile salt-unsaturated fatty acid mixed micelles on α-chymotryptic degradation of insulin was further characterized. The incorporation of linoleic acid has greatly accelerated insulin degradation with the apparent first order rate constant being linearly related to the concentration of linoleic acid. At a 10 mM linoleic acid concentration solubilized in 10 mM sodium glycocholate, the proteoly tic degradation rate constant increased by 16 times, which could not be explained solely by the mechanism of insulin oligomer dissociation. Further, this effect is significantly reduced when the free carboxylic group of linoleic acid is methylated. The catalytic role of mixed micelles on chemical degradation of insulin was found to depend on the concentration of linoleic acid incorporated. When solubilized in the form of mixed micelles, linoleic acid chemically catalyzes peptide bond cleavage in a concentration-dependent manner.
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  • 32
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    Plant foods for human nutrition 43 (1993), S. 87-95 
    ISSN: 1573-9104
    Keywords: maize ; bran ; niacin ; thiamin ; pantothenic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The objective of the project was to determine the bioavailability of selected B vitamins (niacin, pantothenic acid and thiamin) to humans from wet and dry milled maize brans which were coarsely or finely ground. Using a double cross-over design, the nine subjects were fed laboratory controlled diets containing unsupplemented bread or bread supplemented with finely ground, wet milled maize bran; coarsely ground, wet milled maize bran; finely ground, dry milled corn bran; or coarsely ground, dry milled maize bran. Subjects made complete collections of urine throughout the study which were analyzed for contents of the test vitamins. Although varying somewhat among vitamins, in general, better apparent bioavailability was achieved with the finely ground, dry milled maize bran than with the other test brans.
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  • 33
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    Colloid & polymer science 271 (1993), S. 793-798 
    ISSN: 1435-1536
    Keywords: Cholesterol colloids ; surfactants ; surface charge ; zeta potential ; stability ; shape ; size ; viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Cholesterol colloids stabilised by Tween 20 (Colloid I), SDS-Et4 NBr (Colloid II), and CTAB-Nac (Colloid III) were prepared. Moving boundary electrophoresis established Colloid III to be positively charged with a zeta potential of 12.2 mV. Addition of 5 mmol dm−3 Na2SO4 and 0.1 mmol dm−3 bilirubin dye (Na-salt) decreased the zeta potential to 9.7 mV and 9.5 mV, respectively, by screening the surface charge of the colloidal particles. Higher concentrations of Na2SO4 and bilirubin (Na-salt) made making electrophoretic measurements difficult, and such a situation was also faced in the case of Colloid II even without external addition of an electrolyte. Addition of several electrolytes revealed that Colloids II and II were coagulated by the neutralisation of their positive charge, but Colloid I was destabilised by salting-out effect. Measured intrinsic viscosity values and electron microscopic measurements supported overall spherical shape of the colloid particles. Colloid II exibited structural viscosity; higher concentration of NaSO4 decreased the viscosities of Colloid II and II by electroviscous effect which helped indirect determination of the electrokinetic potential (23.7 mV) of Colloid II.
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  • 34
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    Plant and soil 155-156 (1993), S. 99-102 
    ISSN: 1573-5036
    Keywords: field bean ; maize ; plasmalemma ATPase ; proton motive force ; retrieval mechanism ; root exudates ; sugar/proton cotransport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The re-uptake of sugars driven by the proton gradient was studied in sugar net-release and net-uptake experiments using roots of intact maize (Zea mays cv. Blizzard) and field bean (Vicia faba L. cv. Alfred) plants. The net release of sugars into the root medium (0.1 mM CaSO4) was stimulated by: the protonophore CCCP (10 μM); the sulfhydryl reagent NEM (300 μM); the specific inhibitor of plasmalemma ATPase vanadate (0.5 mM); and the inhibitor of the glucose carrier phlorizin (2 mM). Net uptake of glucose, fructose and arabinose from 10 μM external concentrations was also inhibited by these substances. Surprisingly fusicoccin, a stimulator of net proton release did not effect net sugar uptake. Medium pH values only influenced sugar net uptake if the pH was above 7. It is concluded that a degradation of the proton gradient across the plasmalemma stimulates net sugar release because of disturbed re-uptake of sugars (in particular glucose) via a proton/sugar cotransport system. Thus, the retention of sugars by root cells not only depends on the plasmalemma permeability but also on the electro-chemical proton gradient. If an electro-chemical proton gradient is established by plasmalemma ATPase activity the re-uptake of sugars by proton/sugar cotransport minimizes the release of sugars into the rhizosphere.
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  • 35
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    Plant and soil 155-156 (1993), S. 87-90 
    ISSN: 1573-5036
    Keywords: amino acids ; maize ; rhizosphere ; root exudates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The aim of the study was to investigate the ability of Zea mays L. roots to regulate the amount of free amino acids present in the rhizosphere. The active uptake of amino acids was shown to conform to Michaelis-Menten kinetics. Comparison of amino acid-N and NO3-N kinetic parameters and soil solution concentrations showed that root uptake of free amino acids from soil may contribute significantly to a plant's N budget. The influx of amino acids also helps to minimize net C/N losses to the soil, and is therefore important in regulating the size of the rhizosphere microbial population. Experimental data and a computer simulation model of amino acid influx/efflux in a sterile solution culture, showed that roots were capable of re-sorping over 90% of the amino acids previously lost into solution as a result of passive diffusion.
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  • 36
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    Plant and soil 155-156 (1993), S. 489-492 
    ISSN: 1573-5036
    Keywords: aluminium ; analog ; boron ; copper ; gallium ; iron ; lanthanum ; manganese ; scandium ; tolerance ; Triticum aestivum ; toxicity ; wheat ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of aluminium (Al), manganese (Mn), zinc (Zn), copper (Cu), boron (B), iron (Fe), gallium (Ga), scandium (Sc) and lanthanum (La) on growth of an Al-tolerant and an Al-sensitive line of wheat (Triticum aestivum L.) were measured in solution culture. The concentrations of nutrients in the basal nutrient solution were (μM) 500 Ca, 100 Mg, 300 K, 600 N (150 NH4, 450 NO3), 600 SO4, 2.5 P, 3 B, 2.5 Fe, 0.5 Zn, 0.5 Mn, 0.1 Cu at a pH of 4.7. The major solution nutrient concentrations were maintained at the nominal concentration with monitoring, frequent additions and weekly renewal. Differentiation in yield between the Al-tolerant and Al-sensitive line only occurred in the presence of Al indicating that, in the long term, none of the other metals tested could be used as an analog for Al. The visual symptoms in the roots of Cu toxicity (in both lines) and Al toxicity (in the sensitive line) were similar. The solution concentration (μM) at which yield of the roots of the tolerant line was reduced by 50% was, in order of increasing tolerance, Cu 0.5, Sc 1.1, La 7.1, Ga 8.6, Al 15, Zn 19, Fe 84, B 490 and Mn 600.
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  • 37
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    Plant and soil 155-156 (1993), S. 529-532 
    ISSN: 1573-5036
    Keywords: chlorsulfuron ; mineral nutrition ; sulfonylurea ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Sulfonylurea herbicides have been found to decrease the uptake and utilization of some nutrients by wheat. This paper reviews the effects of sulfonylureas on nutrient uptake, proposes physiological mechanisms which might explain the effects; and examines the agronomic implications.
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  • 38
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    Plant and soil 155-156 (1993), S. 57-66 
    ISSN: 1573-5036
    Keywords: nitrogen ; wheat ; simulation ; yield-response curve
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Models of the yield responses of crops to applied nutrients are a recent addition to the methods available for making fertilizer recommendations. They have a place in integrating nutrient information with information on other factors which affect yield and its response to added nutrients. This review deals with nitrogen models classified into three groups: those which predict yield-response curves based on empirical factors; those which simulate the yield response from complex simulation models of many processes regulating crop growth and the soil environment; and those which aim to simulate yield and selected processes based on simplified functional relationships which apply to a target region or industry. Three case studies representing the three classes of model are drawn from research on dryland wheat in different parts of Australia. They show examples in which models provide information which is unobtainable from experimental procedures and which provide information useful to farmers in making decisions about fertilizers. Suggestions are made for future developments in crop-nutrient modelling including further comparisons of models, linkage of models with tissue tests, modelling co-limiting nutrients, deciding on the appropriate level of detail within a model and the need for methods for calibrating and testing models on attributes other than yield alone.
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  • 39
    ISSN: 1573-5036
    Keywords: autoradiography ; freeze-cutting ; maize ; P-accumulation ; P-depletion ; phytate-P
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Autoradiographs of soil slices mapping the distribution of phytate-derived33P around the primary root of 6-day-old maize seedlings were used to investigate the uptake of phytate by the root. Analysis of the autoradiographs with a laser densitometer and processing of the data with image analysing software resulted in a resolution of 40 μm. The effect of33P-crossfire was corrected by analysis of the apparent33P-gradient around a phosphate-impermeable teflon tube that was inserted into the labeled soil as a standard. In spite of the high resolution achieved, a significant depletion zone could not be detected when the soil was equilibrated with33P-phytate. However, with33P-inorganic phosphate, 2 concentric zones were obvious. Within the inner zone, P was accumulated by about 20%, while in the outer zone a corresponding depletion of P could be detected. The accumulation zone coincided with the extension of the root hair cylinder, whereas the depleted area was clearly beyond the range of the root hairs.
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  • 40
    ISSN: 1573-5036
    Keywords: carbon partitioning ; CO2 enrichment ; nitrogen mineralization ; nitrogen partitioning ; rhizosphere ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The aim of this work was to examine the response of wheat plants to a doubling of the atmospheric CO2 concentration on: (1) carbon and nitrogen partitioning in the plant; (2) carbon release by the roots; and (3) the subsequent N uptake by the plants. The experiment was performed in controlled laboratory conditions by exposing fast-growing spring wheat plants, during 28 days, to a 14CO2 concentration of 350 or 700 μL L−1 at two levels of soil nitrogen fertilization. Doubling CO2 availability increased total plant production by 34% for both N treatment. In the N-fertilized soil, the CO2 enrichment resulted in an increase in dry mass production of 41% in the shoots and 23% in the roots; without N fertilization this figure was 33% and 37%, respectively. In the N-fertilized soil, the CO2 increase enhanced the total N uptake by 14% and lowered the N concentration in the shoots by 23%. The N concentration in the roots was unchanged. In the N-fertilized soil, doubling CO2 availability increased N uptake by 32% but did not change the N concentrations, in either shoots or roots. The CO2 enrichment increased total root-derived carbon by 12% with N fertilization, and by 24% without N fertilization. Between 85 and 90% of the total root derived-14C came from respiration, leaving only 10 to 15% in the soil as organic 14C. However, when total root-derived 14C was expressed as a function of root dry weight, these differences were only slightly significant. Thus, it appears that the enhanced carbon release from the living roots in response to increased atmospheric CO2, is not due to a modification of the activity of the roots, but is a result of the increased size of the root system. The increase of root dry mass also resulted in a stimulation of the soil N mineralization related to the doubling atmospheric CO2 concentration. The discussion is focused on the interactions between the carbon and nitrogen allocation, especially to the root system, and the implications for the acquisition of nutrients by plants in response to CO2 increase.
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  • 41
    ISSN: 1573-5036
    Keywords: efficiency ratio ; harvest index ; potassium ; Triticum aestivum ; utilization index ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nutrient use-efficiency (NUE) is commonly measured in relation to vegetative growth without regard for economic productivity of crops whose valued product is reproductive. Although vegetative measures can be useful, particularly in forage crops, their validity in the quantification of NUE in grain crops is questionable. This study was undertaken primarily to examine the relationship between vegetative and economic potassium use-efficiency (KUE) in several wheat (T. aestivum) genotypes under conditions of potassium stress. Genotype environment interaction for vegetative KUE was also examined. Vegetative KUE was assessed as shoot fresh weight, efficiency ratio (VKER) and utilization index (VKUI) whereas economic KUE was evaluated as grain weight, total weight and economic efficiency ratio (EKER). Significant genotype-environment interactions for shoot weight, VKER and VKUI were observed. In some instances interaction was associated with crossovers between genotypes indicating that it can affect selection. Correlations between vegetative and economic measures of KUE were generally nonsignificant, but negative and significant for shoot weight of three-week-old plants and grain weight. It appears that if genotypes differ considerably for harvest index and it is not positively correlated with total biomass, vegetative measures of KUE are unreliable as indicators of economic KUE. Therefore, economic rather than vegetative measures should be used to evaluate KUE in crops whose valued product is reproductive. ei]{gnH}{fnMarschner} ei]{gnH.}{fnLambers}
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  • 42
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    Plant and soil 151 (1993), S. 97-104 
    ISSN: 1573-5036
    Keywords: aluminium ; ammonium ; induction ; maize ; nitrate ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Experiments with two maize (Zea mays L.) hybrids were conducted to determine (a) if the inhibition of nitrate uptake by aluminium involved a restriction in the induction (synthesis/assemblage) of nitrate transporters, and (b) if the magnitude of the inhibition was affected by the concurrent presence of ambient ammonium. At pH 4.5, the rate of nitrate uptake from 240 μM NH4NO3 was maximally inhibited by 100 μM aluminium, but there was little measurable effect on the rate of ammonium uptake. Presence of ambient aluminium did not eliminate the characteristic induction pattern of nitrate uptake upon first exposure of nitrogen-depleted seedlings to that ion. Removal of ambient aluminium after six hours of induction resulted in recovery within 30 minutes to rates of nitrate uptake that were similar to those of plants induced in absence of aluminium. Addition of aluminium to plants that had been induced in absence of aluminium rapidly restricted the rate of nitrate uptake to the level of plants that had been induced in the presence of aluminium. The data are interpreted as indicating that aluminium inhibited the activity of nitrate transporters to a greater extent than the induction of those transporters. When aluminium was added at initiation of induction, the effect of ambient ammonium on development of the inhibition by aluminium differed between the two hybrids. The responses indicate a complex interaction between the aluminium and ammonium components of high acidity soils in their influence on nitrate uptake. ei]{gnA C}{fnBorstlap}
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  • 43
    ISSN: 1573-5036
    Keywords: fructans ; NIR ; nitrogen ; non-structural carbohydrates ; rice ; starch ; stress ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Plant shoot samples are frequently analysed to assess if crops require additional nitrogen or mineral elements to maintain satisfactory growth. If plant growth is limited by temperature, water stress, disease, lodging or a mineral deficiency, non-structural carbohydrates (NSC) may be accumulated in, or depleted from, tissues especially those in the lower stems. Plant testing laboratories do not routinely analyse NSC to assist in the identification of plant stress probably because skilled technicians and time are required for the wet chemical determination. In this paper we report that routine determination of NSC is possible using near-infrared reflectance spectroscopy; the errors of determination are comparable with traditional chemical methods. The concentration of NSC in the shoots of rice grown in south eastern Australia ranges from 1.6 to 22.8%, as starch. In the shoots of wheat grown in eastern Australia the range is from 2.4 to 35.2%, as fructans. In both crops the NSC content is highly inversely correlated with the shoot nitrogen content. Based on data from commercial wheat and rice crops we suggest that the ratio between nitrogen and NSC can be used to identify crops in which growth has been limited by a stress other than nitrogen and so are unlikely to show the predicted response to an application of nitrogen fertilizer.
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  • 44
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    Plant and soil 155-156 (1993), S. 45-55 
    ISSN: 1573-5036
    Keywords: compartmentation ; cytoplasm ; 39K NMR ; maize ; nitrogen ; 14N NMR ; 15N NMR ; pea ; phosphorus ; potassium ; 31P NMR ; vacuole
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The cytoplasmic and vacuolar pools of ammonium, inorganic phosphate and potassium can be studied non-invasively in plant tissues using high resolution nuclear magnetic resonance spectroscopy. The techniques that allow these pools to be discriminated in vivo are described and their application to plants is reviewed with reference to the phosphorus, nitrogen and potassium nutrition of root tissues.
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  • 45
    ISSN: 1573-5036
    Keywords: autoradiography ; freeze-cutting ; maize ; P-accumulation ; P-depletion ; phytate-P
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Autoradiographs of soil slices mapping the distribution of phytate-derived 33P around the primary root of 6-day-old maize seedlings were used to investigate the uptake of phytate by the root. Analysis of the autoradiographs with a laser densitometer and processing of the data with image analysing software resulted in a resolution of 40 μm. The effect of 33P-crossfire was corrected by analysis of the apparent 33P-gradient around a phosphate-impermeable teflon tube that was inserted into the labeled soil as a standard. In spite of the high resolution achieved, a significant depletion zone could not be detected when the soil was equilibrated with 33P-phytate. However, with 33P-inorganic phosphate, 2 concentric zones were obvious. Within the inner zone, P was accumulated by about 20%, while in the outer zone a corresponding depletion of P could be detected. The accumulation zone coincided with the extension of the root hair cylinder, whereas the depleted area was clearly beyond the range of the root hairs.
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  • 46
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    Plant and soil 149 (1993), S. 235-243 
    ISSN: 1573-5036
    Keywords: De ; exchangeable K ; K diffusion ; K release ; K utilization ; model calculation ; non-exchangeable K ; root hairs ; sugar beet ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract To predict the contribution of soil K fractions of different mobility to K supply of plants, the kinetics of K release from soil was related to the kinetics of K uptake of young sugar beet and wheat plants. For this purpose K release rates from soil were measured by continuously percolating samples of a luvisol with 0.01 M CaCl2 solution and effective diffusion coefficients, De, were determined. Two soil K fractions of different mobility were obtained. De values of the more mobile ‘exchangeable K’ and the less mobile ‘non-exchangeable’ K fraction were found to be 58.9 × 10−9 and 8.2 × 10−9 cm2 s−1, respectively. In a pot experiment, sugar beet and wheat plants were grown, for 15 days and both root growth and K uptake were measured. K uptake kinetics of both crops was determined in a separate experiment using flowing solution culture. To integrate these data quantitatively, the simulation model of Claassen et al. (1986) was applied. Results show that calculated total K uptake agreed closely with real K uptake of the plants. On this basis, 64 and 79% of the K taken up by wheat and sugar beet plants was derived from the rapidly released ‘exchangeable’ and 21–36% from the less mobile ‘non-exchangeable’ soil K fraction.
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  • 47
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    Plant and soil 151 (1993), S. 211-218 
    ISSN: 1573-5036
    Keywords: amides ; free ammonium ; MSX ; net ammonium uptake inhibition ; total free amino acids ; Triticum aestivum L. ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract When N deficient 10-day-old wheat plants were supplied with 1.5 mol m−3 NH4 +, net NH4 + uptake rapidly decreased during the first 6h, while root free-NH4 + and free amino acids concentration increased. However, after 24 h the NH4 + uptake rate increased again, as the internal NH4 + concentration decreased. When plants were pretreated during 40 h with different external NH4 + concentrations, net uptake measured on 1.0 mol m−3 NH4 + decreased with the increasing ion concentration during the pretreatment. This decrement coincided with both root free-NH4 + and total free amino acids levels. When N-starved and NH4 + fed plants were treated during 0, 3 or 6 h with 1.0 mol m−3 NH4 + in the presence of 1.0 mol m−3 MSX2, net uptake (measured without MSX) decreased with the length of the inhibitor treatment. In both groups, MSX significantly increased root free-NH4 + concentration, while the level of total free amino acids was only increased in N-starved plants. When N-starved plants were externally supplied with 1.0 mol m−3 of different amino acids or amides, net NH4 + uptake was only strongly inhibited in the presence of glutamine or asparagine. It is concluded that rapid changes in the concentration of certain amino acids during NH4 + nutrition might regulate the ion absorption, though at high endogenous levels of free NH4 + net uptake could be suppressed independently of the root concentration of free amino acids.
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  • 48
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    Plant and soil 152 (1993), S. 261-267 
    ISSN: 1573-5036
    Keywords: gravitropism ; growth angle ; maize ; nodal roots ; soil water content ; Zea mays L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The direction of root growth is an important factor that determines the spatial distribution of roots in the soil. The influence of soil water content on the direction of growth of maize nodal roots was studied both in the field and in the greenhouse. In the field experiment, the one plot was regularly irrigated (I-plot) and the other non-irrigated (N-plot). In the greenhouse experiment, three water treatments were conducted on plants grown in pots: continuously wet (CW), early drying (ED), and late drying (LD). The direction of root growth was quantified by the angle from the vertical, measured at 1 cm intervals for 10 cm from the first five internodes. Nodal roots grew more vertically in the N-plot and ED treatment than those in the I-plot and CW treatment. This was due to the decrease of the initial angle and/or the liminal angle. It is therefore thought that two events regulate the growth direction of nodal roots under dry soil conditions: gravitropic bending at root emergence from the stem and the later establishment of the angle of growth. Nodal roots appearing after rewatering in the ED treatment grew in a similar direction as those in the CW treatment. It follows from this that the water content of the surrounding soil has a direct effect on the direction of growth. Nodal roots that emerged in rapidly drying soil in the LD treatment ceased growing after showing negative gravitropism. The possible mechanisms determining the growth direction of nodal roots in drier soils are discussed.
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  • 49
    ISSN: 1573-5036
    Keywords: alfisols ; maize ; mulch quality ; nutrient uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Effects of application of prunings of three woody species (Acioa barteri, Gliricidia sepium and Leucaena leucocephala), maize (Zea mays L.) stover and rice (Oryza sativa L.) straw as mulch on maize were studied on an Alfisol in southern Nigeria in 1990 and 1991. Maize dry matter and grain yield were higher with applications of plant residues and N fertilizer in both years. Addition of Leucaena prunings gave the highest maize grain yield in both years. Compared to the 1990 results, Acioa showed the least grain yield decline among the mulch treatments in 1991. Nutrient uptake was enhanced by applications of plant residues. Leucaena prunings had the highest effect in both years and increased the mean N, P, and Mg uptake by 96%, 84%, and 50%, respectively, over the control. Addition of Acioa prunings increased K and Ca uptake by 59% and 92%, respectively, over the control. ‘High quality’ (low C/N ratio and lignin level) plant residues enhance crop performance through direct nutritional contributions, whereas ‘low quality’ (high C/N ratio and lignin level) plant residues do so through mulching effects on the microclimate. ‘Intermediate quality’ plant residues have no clear effects on crop performance.
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  • 50
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    Plant and soil 154 (1993), S. 133-137 
    ISSN: 1573-5036
    Keywords: ammonium nutrition ; potassium nutrition ; salinity ; Triticum aestivum L. ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Wheat (Triticum aestivum L.) was grown to maturity in a pot experiment in a calcareous silty sand soil. N was applied at two levels as granulated N-P fertilizers, amended or not with nitrification inhibitors (1% and 5% DCD, 1% N-serve). Potassium as KCl was given at three levels of application. P was applied at a uniform rate. Two levels of salinity were obtained by using the soil as such (EC= 0.3 mmho/cm) and by adding NaCl to the same soil (EC=2.4 mmho/cm). 1% DCD and 1% N-serve treatments gave significantly higher wheat grain yields and N-uptake than the other ones. Nitrate content of leachates indicated a prevalent nitrate nutrition in the treatment without nitrification inhibitors. The 5% DCD treatment showed a yield depression. In the lower N level treatments, a significant yield increase, generated by 1% DCD and N-serve was found in the salinized soil as compared to the non-saline soil. Soil salinity reduced N-uptake when nitrification inhibitors were not present. In treatments having the inhibitors, N-uptake was equal or greater in the salinized than in the non saline soil. An enhanced ammonium nutrition increased the P uptake.
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  • 51
    ISSN: 1573-5036
    Keywords: bioavailability ; maize ; myo-inositol ; phosphorus ; phytase ; phytin ; soil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of adding phytase to the root medium of maize plants on the P-availability of added myo-inositol hexaphosphate (phytin) has been studied in pot experiments. When 40 mM phytin-P in nutrient solution was incubated in quartz-sand for 15 days in the absence of plants, 80% of it could be recovered from the solution as soluble organic P. Maize plants growing on this mixture assimilated P from phytin at rates comparable to those from inorganic phosphate (Pi). At a lower addition rate (2 mM phytin-P) only 10% was recovered in the soil solution, and plant growth was severely limited by P. At this low phytin level, the addition of phytase (10 enzyme units per kg sand) increased the plants' dry weight yield by 32%. The relative increases of the Pi concentration in the solution and of the amount of P in the plants were even higher, indicating that the observed growth stimulation was due to an increased rate of phytin hydrolysis. The enzyme-induced growth stimulation was also observed with plants growing in pots filled with soil low in P, when phytin was added. However, on three different soils the addition rates of phytin and phytase necessary for obtaining a significant phytase effect were both about 10 times higher than those required in quartzsand. It is concluded that the P-availability from organic sources can be limited by the rate of their hydrolytic cleavage.
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  • 52
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    Plant and soil 155-156 (1993), S. 247-250 
    ISSN: 1573-5036
    Keywords: rate of Zn desorption ; Vertisols ; wheat ; Zn buffer power ; Zn desorption power ; Zn intensity ; Zn quantity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Since Zn availability to plants growing in a soil is governed by quantity, intensity, buffer power, rate of Zn desorption and diffusion, an improved understanding of a number of these factors in Vertisols would facilitate a more reliable prediction of crop requirements for Zn. The DTPA-extractable Zn, a quantity factor, together with initial Zn desorption rate coefficients, accounted for 80% of the variation in relative dry matter yield of wheat grown to anthesis. In combination with these factors, desorption (buffer) power explained 92% of the variation in Zn concentration in the young mature leaf blade (YMB) of wheat. Thus, the combination of the quantity, rate of Zn desorption and buffer power better predict growth responses of wheat to applied Zn in Vertisols than the commonly-used single extraction with DTPA alone (quantity), which provides only a static measure of Zn availability.
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  • 53
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    Plant and soil 155-156 (1993), S. 305-308 
    ISSN: 1573-5036
    Keywords: boron ; wheat ; Triticum aestivum L. ; uptake ; genotypic variation ; toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The mechanism of boron (B) uptake in wheat was studied using two genotypes with known differences in their ability to accumulate B. Influx and efflux of B was measured in the roots of intact 21 d old plants. Roots grown in 15 μM B, when transferred to solutions containing 1mM B showed a rapid increase in B content for up to 60 min, after which no further increase was evident up to 4 h. No genotypic difference in B influx was apparent over these time periods. Roots grown in 1mM B for 7 d and then rinsed in B-free solutions quickly lost most of B that they contained within 1 hour; little further efflux was observed over the following three hours. As with the influx, no genotypic difference in B flux was evident. It is suggested that the lack of genotypic difference in the short-term B fluxes could be due to a masking effect of extracellular B bound in the cell walls of the roots.
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  • 54
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    Plant and soil 155-156 (1993), S. 407-410 
    ISSN: 1573-5036
    Keywords: L. cosentinii ; nutrient recycling ; potassium ; subterranean clover ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The influence of pasture species and pasture/crop rotations on the fate of K fertilizer in the soil profile of a sandplain soil was investigated. Results for Lupinus cosentinii, subterranean clover and a subterranean clover/wheat rotation are presented. Potassium was applied as KCl at six rates up to 150 kg K ha-1 for three years; bicarbonate-extractable K was measured at five depths in the profile (0–100 cm) for four years. The net change in available K in the top 100 cm of the profile (kg ha-1) was calculated. There was a gradual increase in K down the profile under all species with fertilizer application. The increase was largest for L. cosentinii, which also appeared to redistribute K from below 100 cm to the soil surface. The K residual value on this soil type was higher than expected with most of the fertilizer applied over three years being retained in the top 100 cm.
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  • 55
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    Plant and soil 155-156 (1993), S. 453-456 
    ISSN: 1573-5036
    Keywords: copper deficiency ; cotton ; ELISA ; Gossypium hirsutum ; immunoassay ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Studies were carried out with hydroponically grown wheat and cotton to develop the Cu-requiring protein phenolase as a biomarker of Cu nutrient status. Isozymes of phenolase whose levels were reduced by Cu deficiency were identified by Western blots. A competitive enzyme-linked, immunosorbent assay (ELISA) was developed that could detect as little as 25 ng of phenolase. The ELISA revealed that Cu-sufficient cotton leaves had about 4-fold more phenolase antigen than did Cu-sufficient wheat leaves. In both species, the level of phenolase was reduced by 2- to 5-fold in leaves of Cu-deficient plants. Because the immunoassay for phenolase protein is rapid, inexpensive, and can be carried out with small amounts of leaf material, it has potential as a tool for assessment of the Cu status of crop plants.
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  • 56
    ISSN: 1573-5036
    Keywords: 2,4-dichlorophenoxyacetate ; para-nodule ; Rhizobium trifolii ; structure ; Triticum aestivum L. ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nodular outgrowths (para-nodules or p-nodules) on the roots of wheat (Triticum aestivum L.) cv. Miskle seedlings were induced by treatment with 0.3 and 0.6 mg L-1, 2,4-dichlorophenoxyacetate (2,4-D). When co-inoculated with Rhizobium trifolii strain ATCC 14480, more p-nodules were formed at these levels and p-nodulation occured at 0.1 mg L-1 indicating that inoculation enhances 2,4-D-induced p-nodulation. Similar to lateral roots, the p-nodules arose from the pericycle opposite the phloem tissues and were free from the cortical cells of the parental root at all stages of development. Structurally, the p-nodules exhibited tissue differentiation. They possessed a highly organized central vascular cylinder connected to that of the parent root, an endodermis, a cap, and an apical and lateral meristems. P-nodules formed by 2,4-D treatment alone were irregularly lobed due to uncoordinated activity of the apical meristem, while those in the combined 2,4-D and inoculation treatment were more globose. The results of the present study indicate that the 2,4-D-induced wheat p-nodules are modified lateral roots, the structure of which is enhanced by rhizobial inoculation.
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  • 57
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    Plant and soil 157 (1993), S. 239-245 
    ISSN: 1573-5036
    Keywords: bean ; bulk density ; compaction ; minirhizotron ; root image analysis ; root quantification ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Flexible- and rigid-walled minirhizotron techniques were compared for estimating root length density of 14- to 28-day-old Pinto bean (Phaseolus vulgaris L.) and spring whet (Triticum aestivum L.) plants in soil boxes under controlled environment conditions at three soil bulk densities (1.3, 1.5 and 1.7 g cm−3). The flexible-tube system consisted of bicycle inner tubes inflated inside augered access holes and removed only when measurements were taken. Rigid tubes were constructed of extruded polybutyrate plastic. In both cases tubes were oriented horizontally. Despite similar root densities for wheat and beans based on measurements obtained from soil cores, root densities estimated from both types of minirhizotron were higher in bean than in wheat in uncompacted soil. Estimates of root density by the flexible tube minirhizotron were more closely correlated with soil core image analysis estimates than were those by the rigid minirhizotron system. At high soil bulk density, rigid tube measurements consistently overestimated actual rooting density of both wheat and bean. The relationship between estimated and actual rooting densities in the case of flexible tube measurements was not significantly influenced by soil bulk density. These findings were consistent with the theory that preferential root growth is induced by gaps at the soil-observation tube interface, inherent in the rigid tube technique, and was accentuated under conditions of high soil strength.
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  • 58
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    Euphytica 67 (1993), S. 41-48 
    ISSN: 1573-5060
    Keywords: Aegilops crassa ; hybrid wheat ; PCMS ; photoperiod-sensitive cytoplasmic male sterility ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Triticum aestivum cv. Norin 26 with Aegilops crassa, Ae. juvenalis or Ae. vavilovii cytoplasm (all D2 type) has been studied relative to its photoperiodic response of male sterility and fertility restoration patterns. Alloplasmic lines of ‘Norin 26’ with a D2 type cytoplasm showed almost complete male sterility under long-day conditions (≥15 h), but high male fertility under short-day conditions (≤14.5 h). No significant influence of temperature on reduction in male fertility was observed. Thus, this type of male sterility is called ‘photoperiod-sensitive cytoplasmic male sterility’ (PCMS). The PCMS is expressed in the form of pistillody of stamens. Histological studies revealed that there were incomplete ovule-like structures instead of tapetal cells and pollen grains in the pistillate stamens. The floret differentiation stage of the plant is the stage that is sensitive to photoperiod. The PCMS can be used as a new means for hybrid wheat production, named ‘two-line system’. The PCMS line is maintained and multiplied by self-fertilization under short-day conditions, and hybrid seed can be produced by crossing the PCMS line with a pollinator line under long-day conditions. In contrast to the system of hybrid wheat production using the T. timopheevi cytoplasm, the present system requires only PCMS and pollinator lines.
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  • 59
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    Euphytica 67 (1993), S. 49-57 
    ISSN: 1573-5060
    Keywords: aphid infestation ; bird cherry-oat aphid ; Rhopalosiphum padi ; cereal aphids ; insect resistance ; leaf pubescence ; wheat ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In Hungary the bird cherry-oat aphid (Rhopalosiphum padi L.) is the most frequent aphid species in winter wheat (Triticum aestivum L.). Estimations of infestation by R. padi as well as measurements of grain yield and thousand-kernel mass were carried out in 26 winter wheat genotypes in conditions of naturally infested and not infested (protected) control plots. The experiment was performed in isolated conditions in two field cages covered by nets. The aphids overwintered on wheat and got into cage, extremely quickly multiplied, therefore there was no need to apply any artificial aphid infestation. Highly significant differences were demonstrated among genotypes in infestation severity of R. padi as well as in losses of grain yield and thousand-kernel mass. The most resistant variety ‘GK Zombor’ had 25% infestation, and the most susceptible one ‘GK Lili’ had 79.2%. The reduction of grain yield of the most tolerant genotypes (‘GK Korány’, ‘Downy’, ‘Mv 4’, ‘Jubilejnaja 50’, ‘Mv 8’, ‘GK Kincsö’ and ‘GK Zombor’) was 26–33%, and that of thousand-kernel mass was 23–30%. The most sensitive genotypes (‘GK Lili’, ‘GK Örzse’, ‘GK Koppány’ and ‘Mv 13’) suffered 58–63% losses in yield, and 40–50% in thousand-kernel mass. A close correlation was found between infestation of R. padi in different wheat genotypes and losses of grain yield (r=0.7572, P〈0.001). Also there were tolerance differences among genotypes even within the same level of infestation. The reductions of thousand-kernel mass correlated very closely with the reductions of grain yield (r=0.9212, P〈0.001), that makes screening possible by reductions of thousand-kernel mass. These results have found application in breeding. The leaf pubescence of the varieties studied did not generally influence the infestation by R. padi.
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  • 60
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    Euphytica 70 (1993), S. 35-42 
    ISSN: 1573-5060
    Keywords: biomass ; heritability ; response to selection ; selection ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Biomass (above ground plant parts) yield may be a useful selection trait for yield improvement in wheat (Triticum aestivum L.). This study was conducted to estimate realized heritability of biomass yield and to determine the response to selection for high and low biomass yield in 8 genetically diverse populations of spring wheat under two production systems. Selections were made among the F3 lines. Progenies of the selected lines were evaluated in replicated field tests in the F4 generation under high fertility and low fertility production systems at Rampur, Nepal, in 1991. Fertility level had a significant effect on biomass yield, grain yield, effective tiller number, number of kernels per spike, thousand kernel weight, and harvest index. Selection in the F3 for high and low biomass yield was effective in identifying F4 lines with high and low biomass yield, respectively. Biomass yield differences between high and low selection groups in the F4 generation, expressed as percent of the mean of the low selection group and averaged over the eight populations, were 53.9 and 36.5% higher than the mean of the low selection group under the high and the low fertility production systems, respectively. The corresponding figures for grain yield were 48.8 and 34.9% under the high and the low production systems, respectively. Also, selection for high biomass yield resulted in higher effective tiller number, and number of kernels per spike, but lower harvest index. Realized heritability estimates for biomass yield were greater at high fertility (range 0.49 to 0.85) than at low fertility (range 0.22 to 0.44). Biomass yield showed positive genotypic correlations with grain yield, effective tiller number, and number of kernels per spike but a negative correlation with harvest index. The results indicated that selection for high biomass yield should bring about positive improvements in biomass yield, grain yield, effective tiller number, and number of kernels per spike. The correlation between F3 and F4 generations suggested that biomass yield in the F3 generation was a good predictor of biomass yield and grain yield in the F4 generation. Selection for biomass yield in wheat should be made under the standard production system to obtain a realistic response.
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  • 61
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    Euphytica 70 (1993), S. 105-111 
    ISSN: 1573-5060
    Keywords: maize ; genotype × environment interaction ; stability analysis ; cultivar testing ; YSi statistic ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Genotype × environment (GE) interaction complicates selection of superior genotypes across environments. The main objective of this study was to select maize (Zea mays L.) genotypes via a new yield-stability (YSi) statistic in yield trials conducted in Albania. Another objective was to estimate contribution of environmental index (% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaaiaacaqabeaadaqaaqaaaOqaaiqadIfagaqeaa% aa!3851!\[\bar X\]·j − % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaaiaacaqabeaadaqaaqaaaOqaaiqadIfagaqeaa% aa!3851!\[\bar X\].., where % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaaiaacaqabeaadaqaaqaaaOqaaiqadIfagaqeaa% aa!3851!\[\bar X\]·j is mean of all genotypes in the jth environment and % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGak0dh9WrFfpC0xh9vqqj-hEeeu0xXdbba9frFj0-OqFf% ea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs0dXdbPYxe9vr0-vr% 0-vqpWqaaeaabaGaaiaacaqabeaadaqaaqaaaOqaaiqadIfagaqeaa% aa!3851!\[\bar X\]is mean of all genotypes across all environments), minimum temperature, maximum temperature, preseason rainfall, rainfall during the growing season, and relative humidity to GE interaction by determining heterogeneity (nonadditivity) attributable to each of these environmental factors. In five of eight trials, heterogeneity due to environmental index was significant. Heterogeneity due to the other environmental factors was not significant in any trial. A comparison of δ i 2 (stability-variance statistic derived from total GE interaction) and s i 2 (stability-variance statistic derived from residual GE interaction following removal of heterogeneity due to encovariate) helped identify genotypes that performed stably or unstably because of a linear effect of environmental index. In three of the five trials showing significant heterogeneity due to environmental index, the YSi statistic selected a reduced number of unstable genotypes as compared with selection based solely on yield. However, the circumstances or conditions under which YSi and solely yield-based method select the same or different genotypes are not fully understood.
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  • 62
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    Euphytica 71 (1993), S. 231-238 
    ISSN: 1573-5060
    Keywords: sweet potato ; Ipomoea batatas ; stability ; joint regression analysis ; G x E interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Two experiments, each involving a set of 10 sweet potato clones, were conducted for three years at 4 sites (Ekona, Ebolowa, Nkolbisson, and Bambui Plain) in Cameroon. Data obtained were subjected to analysis of variance to determine the presence of genotype x environment (G x E) interactions, and to regression analysis to assess the performance of clones across anvironments. Environments were assessed in two ways: (i) the mean response of all clones (dependent assessment), and (ii) the average performance of a different set of clones (independent assessment). The first experiment (Expt 1) produced higher yields but had fewer stable clones than the second (Expt 2). The analysis of variance revealed that the clones interacted significantly with environments for all traits. The study has identified high yielding and stable sweet potato clones for distribution to growers in the major areas of cultivation in the tountry. Despite slight differences in numbers of clones judged stable by the various regression indices in the two methods of environmental assessments, the rankings of clones on the basis of their linear regression coefficients were similar. In a developing country like Cameroon, with limited resources and where sophisticated equipment for obtaining physical or biological measures of the environment may be lacking, the mean performance of genotypes may still be the most reliable measure of environment in evaluating the stability of performance of crop cultivars.
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  • 63
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    Euphytica 72 (1993), S. 1-7 
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; wheat ; Puccinia striiformis ; yellow rust ; stripe rust ; genetics ; resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nine Mexican spring bread wheat (Triticum aestivum L.) cultivars derived from CIMMYT germplasm and the U.S. spring wheat cultivar Wheaton were susceptible to the Mexican Puccinia striiformis pathotype 14E14 in seedling growth stage, but displayed different levels of adult plant resistances to the same pathotype when tested in the field. One hundred and eighteen random F2 plant derived F3 and F5 lines from the crosses of these ten adult plant resistant wheats and susceptible cultivar Jupateco 73S were evaluated in the field. The moderate adult plant resistance of Penjamo 62, Lerma Rojo 64, Nacozari 76, Tesia 79, and Wheaton was under monogenic genetic control and was attributed to the adult plant stripe rust resistance gene Yr18. The moderate resistances of Cleopatra 74, Zaragoza 75, and Apache 81 were also monogenic, but gene Yr18 was absent. Pavon 76 carried two partially effective additive genes; and the adult plant resistance of Tonichi 81 was based on additive interaction involving Yr18 and two additional partially effective genes. Tonichi 81 does not carry any seedling resistance gene, however, the adult plant resistance is highly effective worldwide. This resistance, designated as the Yr18 complex, is of a durable nature. The partial adult plant resistance of Pavon 76 has also remained durable in Mexico and other countries where it is grown.
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  • 64
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    Euphytica 72 (1993), S. 87-94 
    ISSN: 1573-5060
    Keywords: Zea mays ; maize ; pollen storage ; pollen grain viability ; pollen enzymes ; pollen physiology ; enzyme cytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Maize pollen quality was investigated after long-term storage both in a refrigerator and in liquid nitrogen by a combination of viability tests and cytochemical methods. Determination of the activities of a number of enzymes involved in important metabolic pathways was carried out. Quinone formation was also studied, as some products of secondary metabolism affect pollen grain viability. One year of pollen storage in liquid nitrogen had little effect on the activities of oxidoreductases and hydrolases and had no significant effect on pollen grain viability evaluated by acetocarmine, neutral red and acridine organe. Only the FCR test showed slightly decreased viability. After one and two years of storage in a refrigerator, pollen grain viability, tested using acetocarmine, neutral red and acridine orange, did not change substantially. Simultaneously the FCR test showed a considerable decrease in pollen grain viability. Long-term storage in a refrigerator resulted in the loss of cytochrome oxidase activity and rise of alcohol dehydrogenase, lactate dehydrogenase, peroxidase and polyphenoloxidase activities as well as of quinone formation.
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  • 65
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    Euphytica 72 (1993), S. 107-113 
    ISSN: 1573-5060
    Keywords: wheat ; Triticum aestivum ; recurrent selection ; resistance to scab ; gene pool ; Taigu male-sterile gene Ms2 ; breeding method ; Gibberella zeae ; Fusarium graminearum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Scab caused by Gibberella zeae Petch., in common wheat, is one of the most severe diseases in China. A source population C0, bred for scab resistance, was developed through three cycles of multiple-parent crossing and intercrossing by means of the dominant male-sterile gene Ta1 (Ms2), according to Wu's scheme. Phenotypic recurrent selection methods for increasing the resistance to scab-infection of spikelets and seeds with the male-sterile plants were carried out simultaneously in Nanjing and Shanghai and at Jianyang, Fujian Province, for three cycles. The generations from C0 to C3 and two check cultivars were evaluated, using a randomized block design, under conditions of an artificially induced epidemic of scab during 1988–1990. The results indicate that there were significant differences in the resistance to scab between these generations. On average, the percentages of diseased spikelets and seeds of the male-fertile plants were reduced by 9% and 10%, respectively. The frequency of resistant plants was distinctly enhanced by recurrent selection. Analysis of variance showed that no significant differences existed between cycles of recurrent selection in agronomic characters such as plant height, spikes per plant, spike length, numbers of spikelets and seeds per spike, weight of seeds per spike and 100-kernel weight, days to heading and to maturity. Except for plant height, most of these traits tended to be slightly improved with improvement of resistance in the gene pool. The variance for resistance in the generations was decreased under selection. Recurrent selection for scab resistance using the dominant male-sterile gene Ta1 (Ms2) was both an effective and feasible breeding method for producing this character in wheat.
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  • 66
    ISSN: 1573-5060
    Keywords: wheat ; Triticum aestivum ; resistance selection ; disease complexes ; pathogen mixtures ; septoria nodorum blotch ; Leptosphaeria nodorum ; septoria tritici blotch ; Mycosphaerella graminicola ; yellow spot ; tan spot ; Drechslera tritici-repentis ; Pyrenophora tritici-repentis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In controlled inoculation studies with Septoria nodorum and Pyrenophora tritici-repentis, estimates of the relative proportion of each pathogen demonstrated differences in the responses of cultivars to pathogen mixtures that were not apparent from measurements of diseased leaf areas. Under field conditions estimates of the relative proportion of S. nodorum, P. tritici-repentis and S. tritici varied between field screening locations in Western Australian but also between lines within locations. Lines with known resistance to P. tritici-repentis and S. tritici, but susceptible to S. nodorum, could not be distinguished from susceptible lines on the basis of leaf area diseased or grain weight depression when S. nodorum was present in the disease complex. Such conditions, while suitable for the selection of combined resistance to these pathogens, were unsuitable for identifying resistance to individual pathogens. As symptoms were similar, the proportion of diseased leaf area sporulating with each pathogen provided a means of measuring the variation in disease development induced on lines varying in resistance. Knowledge of the components of disease and their relative importance were essential in understanding varietal response information under mixed infections of these leaf spot pathogens.
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  • 67
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    Euphytica 73 (1993), S. 199-212 
    ISSN: 1573-5060
    Keywords: wheat ; Triticum spp. ; gene pool ; wide hybridization ; chromosome translocation ; alien gene transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The recent advances in alien gene transfer from distantly-related species into wheat are reviewed in the present paper. The main achievements during the last ten years include the great expansion of the range of wide hybridization and development of new techniques for production and characterization of wheat-alien chromosome translocations. Updated results of wide hybridization since 1983 and comprehensive characterization of wheat-alien translocation lines in our laboratory are compiled. The future outlook for alien gene transfer in wheat is also discussed.
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  • 68
    ISSN: 1573-5060
    Keywords: Russian wheat aphid ; Diuraphis noxia ; wheat ; Triticum aestivum ; monosomic analysis ; resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The Russian wheat aphid, Diuraphis noxia (Mordvilko) (Homoptera: Aphididae), has become an important pest of wheat (Triticum aestivum L.) in the United States. The aphid causes a phytotoxemic reaction in wheat evidenced by local and systemic chlorosis and rolling of infested leaves. Developing resistance in wheat cultivars to D. noxia is an essential factor in controlling the damage caused by this pest. Several sources of genetic resistance to D. noxia have been identified in wheat germplasm. Monosomic analysis of the monogenic resistant T. aestivum accession PI137739 has shown that the gene (Dn1) for resistance is carried on chromosome 7D. It appears that chromosome 7B may carry a second resistance gene for D. noxia that might be a source of minor or complementary gene action for resistance.
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  • 69
    ISSN: 1573-5036
    Keywords: Azospirillum ; inoculation ; nitrogen fixation ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Azosprilla were collected in wheat fields from subtropical and temperate soils of central Nepal at various elevations. Different wheat cultivars responded positively and significantly in grain yield, grain N-yield, and total N-yield in plant shoots to the inoculation with Nepalese isolate Azospirillum 10SW. Nepalese wheat cv. Seto responded significantly better with Azospirillum 10SW than with the Brasilian isolate A. lipoferum Sp 108 st, a strain which was found highly efficient in earlier experiments with German wheat cultivars, especially cv. Turbo. Yield of Turbo was increased by inoculations of both Azospirillum strains too, but it showed no significant differences depending from the inoculum used. The higher efficacy of combining Azospirillum 10SW and Seto, both collected from the same locality, indicates the possibility of improved associations using traditional cultivars and local bacteria. ei]{gnR O D}{fnDixon}
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  • 70
    ISSN: 1573-5036
    Keywords: depth distribution ; irrigation ; nitrogen fertilization ; root biomass ; soil-coring ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Root biomass, root nitrogen content, and root distribution down to 50 cm depth in winter wheat were determined by soil coring on five dates in four different treatments: control (C), drought (D), daily irrigation (I), and daily irrigation and fertilization (IF). The first three treatments received the N fertilizer application as a single dose in spring, whereas in IF daily doses of N were supplied in the irrigation water using a drip-tube system, according to the estimated nutrient demand of the crop. All treatments received 20 g N m−2 year−1. The maximum root biomass (104 g m−2) was reached earliest in IF. On 6 June, root samples were taken down to a depth of 100 cm, and the proportion of deep roots (50–100 cm) was least in I, indicating that it had the shaklowest root system. The root biomass as a fraction of the total plant mass decreased during crop development in all treatments down to about 4% at harvest. The decrease was more rapid in I and C than in D and IF. The higher proportion of roots during spring in D and IF coincided with a low nitrogen concentration in the roots, which was attributed to the restricted water supply and to the relative shortage of nitrogen during early crop development in D and IF, respectively. The dynamics of mass and nitrogen in macroscopic organic debris in the soil suggested that root turnover rates were high. ei]{gnB E}{fnClothier}
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  • 71
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    Plant and soil 152 (1993), S. 187-199 
    ISSN: 1573-5036
    Keywords: aeration ; aerenchyma ; carnation ; cucumber ; gerbera ; maize ; oxygen stress ; oxygen transport ; redox dye ; rice ; rose ; sugar beet ; sweet pepper ; tomato ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The development of gas-filled root porosity in response to temporary low oxygen supply was tested for a range of edible and ornamental crops: rice, maize, wheat, sugar beet, tomato, cucumber, sweet pepper, carnation, gerbera and rose. In a first experiment, the roots of tomato, maize and gerbera had a higher gas-filled root porosity, Ep (% v/v), when grown permanently in a non-aerated instead of aerated solution. The Ep of roots increased during two weeks when half the root system of a young plant was transferred to a non-aerated solution; in older plants this response was not seen. Carnation had a negligible gas-filled porosity in all treatments. In a second experiment, a comparison was made between high (20 kPa) and low (about 2 kPa) O2 partial pressure in a recirculating nutrient solution. Half of the root system was transferred to low O2 at various growth stages. In most species older plants did not increase Ep on exposure to low O2. For tomato, sweet pepper and rose, Ep was normally in the range 3–8% (v/v). Young plants of cucumber, wheat and sugar beet also had an Ep in that range, but in older plants values ranged from 1 to 3%. Transverse root sections examined by light microscopy showed, on average, 60% more intercellular spaces in the root cortex than the measurements of gas-filled porosity, probably because some gaps and spaces in the cortex were not gas-filled. This effect was most pronounced in tomato. A negative pressure in the cortex may be needed for gaps to be gas-filled. An exodermis may increase the effectiveness of gas spaces in the cortex by closing the gas channels and, by offering some resistance to water uptake, allowing a negative pressure head in the cortex which keeps gaps gas-filled. A redox dye method was developed to study the length of root which is effectively supplied with oxygen, as a function of Ep. Results indicated that for every percent Ep the root can remain aerated over at least 1 cm in a non-aerated medium under the conditions of the test.
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  • 72
    ISSN: 1573-5036
    Keywords: cereal root rot ; Rhizoctonia solani ; wheat ; Zn nutrition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract An inverse correlation between plant Zn concentration and the severity of Rhizoctonia root rot, described in an earlier paper, was examined in two experiments in a growth chamber. In the first experiment, wheat (Triticum aestivum cv Songlen) was planted in a Zn deficient soil with and without added Zn, and combined factorially with different inoculum densities of Rhizoctonia solani anastomosis group 8. When Zn was added, the percentage of seminal roots infected with R. solani was significantly lower compared to the treatments without added Zn, showing that low Zn potentiated the disease. A subsequent factorial experiment of four inoculum densities and six Zn levels, (0, 0.01, 0.04, 0.1, 0.4 and 6.0 mg Zn kg−1 soil) was conducted to investigate the Zn effect in more detail. Disease severity was markedly decreased by the higher Zn applications; the disease score dropped sharply between treatments of Zn0.04 and Zn0.1, a difference which was reflected in the plant yield response to Zn. For both experiments the Zn concentrations in shoots were significantly different only among Zn treatments, not among the inoculum treatments. This indicated that inoculum density or disease severity did not reduce Zn concentration in the plant. Thus, disease did not exaggerate Zn deficiency, but rather, Zn sufficiency suppressed disease severity. A potentiating link between Zn nutrition and disease severity is thereby established, although this type of experiment did not indicate the mechanism of the Zn effect.
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  • 73
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    Plant and soil 155-156 (1993), S. 155-158 
    ISSN: 1573-5036
    Keywords: nitrate uptake ; root activity ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A technique was developed to determine the physiological activity of defined sections of seminal roots of wheat grown in sand. Wheat plants were grown for 2 weeks in narrow columns of N-deficient sand to which all other nutrients had been added. The columns were split longitudinally and 15N-labelled nitrate, in an agar medium, supplied to 2 cm sections of root. Shoots and roots were analysed after 24 h to determine the uptake of 15N. Three sections were examined on either the secondary or tertiary seminal root: 1 cm from the seed (basal segment), 35 cm from the seed (middle segment) and 4 cm from the root apex (apical segment). Total uptake was greatest from the basal and middle segments, declining by 50% from the apical segment. However, uptake per unit root length, including exposed sections of lateral roots, was not significantly different along the root.
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  • 74
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    Plant and soil 155-156 (1993), S. 175-178 
    ISSN: 1573-5036
    Keywords: diagnosis ; nutrition ; plants ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Macronutrients accumulate as free ions in all plant organs when supplies are abundant but growth requirements are generally satisfied before high concentrations are attained. Low threshold concentrations are necessary to ensure maximum growth and in wheat leaves these are around 10 mM nitrate, 5 mM phosphate, 0.5 mM sulfate and 130 mM potassium. The measurement of inorganic ion concentrations in leaves has potential as a diagnostic toll and might enable soil nutrient supplies to be more accurately matched with crop needs.
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  • 75
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    Plant and soil 155-156 (1993), S. 313-315 
    ISSN: 1573-5036
    Keywords: anther ; boron deficiency ; fertilization ; grain set failure ; in vitro pollen germination ; pollen ; pollen tube ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Grain set failure in wheat, caused by boron (B) deficiency, is associated with poorly developed pollen and anthers. This paper presents results of a study of the effect of B on pollen viability when it was supplied "internally" through the roots and externally in an agar medium for in vitro germination. There was no major effect of B supply to wheat plants on the number of pollen anther-1 or the percentage of pollen with positive reaction to iodine. Pollen germination in the medium was, however, responsive to both internal and external B supply. When B was not added to the medium, germination was poor, regardless of the level of B supplied to the plant, in both a B deficiency sensitive (SW41) and a B deficiency tolerant (Sonora 64) genotypes. The percentage of germinated pollen and length of the pollen tube increased with increasing medium B. With 20–100 mg H3BO3 L-1 in the medium, the percentage of germinated pollen and length of the pollen tube responded positively to increasing B supply to the plant. No difference was found between sensitive and tolerant genotypes in the effect of B on their pollen viability. On the other hand, without added B in the nutrient solution applied to the plant, grain set was depressed in the B deficiency sensitive SW41 and not in the B deficiency tolerant Sonora 64. A difference in B supply to the germinating pollen in the stigma and style is one possible explanation for this variation in the response to B among wheat genotypes.
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  • 76
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    Plant and soil 155-156 (1993), S. 293-296 
    ISSN: 1573-5036
    Keywords: efficiency ; genotypic differences ; phosphorus ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In an attempt to evaluate whether breeding and selection for high yielding capacity did change the P requirements of modern wheat cultivars, the response of two wheat cultivars to different levels of P supply was investigated. A traditional cultivar ("Peragis") and a modern cultivar ("Cosir") were cultivated in a C-loess low in available P and high in CaCO3 in 120 cm high PVC pots. Shoot and root growth at different developmental stages was compared. The grain yield of the modern cultivar Cosir was higher at limiting and non-limiting P supply and, therefore, this cultivar can be considered as more P-efficient than the traditional cultivar. From the results it can be concluded that the main factors contributing to the higher P efficiency of the modern cultivar are (i) efficient use of assimilates for root growth characteristics which enhance P acquisition: smaller root diameter, and longer root hairs, (ii) efficient remobilization of P from vegetative plant organs to the grains, and (iii) lower P requirement for grain yield formation because of lower ear number per plant but higher grain number per ear.
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  • 77
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    Plant and soil 155-156 (1993), S. 309-312 
    ISSN: 1573-5036
    Keywords: anther ; boron deficiency ; female flower ; fertilization ; grain set failure ; warm areas wheat ; pollen ; pollen germination ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Effects of boron (B) deficiency on reproductive development and grain set in wheat was studied in experiments in a sand culture in which grain set was increased by increasing B supply in the nutrient solution. Early vegetative response was also studied in a solution culture experiment with 5 μM B and without added B. Effects of B deficiency on the male and female part of the wheat flower were studied in a cross fertilization experiment involving B deficient and B sufficient wheat plants. An international trial (the Boron Probe Nursery) was conducted as a collaboration between Chiang Mai University, CIMMYT and National Agricultural Research Systems in various countries, to verify the B response in non-traditional, warm wheat-growing areas. There was a wide genotypic variation in reproductive responses to B among the eight wheat genotypes studied. In sand culture with low B (0.2 μM), grain set index ranged from 9.5% in SW41 to 94.5% in Fang 60; with high B (10 μM) it was ≥90% in all genotypes. Early vegetative response to B was measured in the length of the youngest emerged blade at 12 days after sowing. Without added B the length of the leaf blade relative to that with 5 μM B ranged from 0.82 to 0.92. This indicates some variation in vegetative response to B among the genotpes. However, there was no relationship between vegetative and reproductive responses to B of the wheat genotypes. Fertility of both the male and female part of the wheat flower appears to be affected by B deficiency. Ears from B deficient plants that were bagged to prevent cross fertilization set no grain. Cross pollination of B deficient female flowers with pollen from B sufficient plants resulted in only 28% grain set, compared with 94% percent from manual crossing of B sufficient pollen on B sufficient female. Reponses to B application of SW41 and other sensitive genotypes at field sites of the first international Boron Probe Nursery (1990/91) confirmed that B deficiency can be a major cause of grain set failure in wheat in warm areas.
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  • 78
    ISSN: 1573-5036
    Keywords: 2,4-dichlorophenoxyacetate ; para-nodule ; Rhizobium trifolii ; structure ; Triticum aestivum L. ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nodular outgrowths (para-nodules orp-nodules) on the roots of wheat (Triticum aestivum L.) cv. Miskle seedlings were induced by treatment with 0.3 and 0.6 mg L-1, 2,4-dichlorophenoxyacetate (2,4-D). When co-inoculated withRhizobium trifolii strain ATCC 14480, morep-nodules were formed at these levels andp-nodulation occured at 0.1 mg L-1 indicating that inoculation enhances 2,4-D-inducedp-nodulation. Similar to lateral roots, thep-nodules arose from the pericycle opposite the phloem tissues and were free from the cortical cells of the parental root at all stages of development. Structurally, thep-nodules exhibited tissue differentiation. They possessed a highly organized central vascular cylinder connected to that of the parent root, an endodermis, a cap, and an apical and lateral meristems.P-nodules formed by 2,4-D treatment alone were irregularly lobed due to uncoordinated activity of the apical meristem, while those in the combined 2,4-D and inoculation treatment were more globose. The results of the present study indicate that the 2,4-D-induced wheatp-nodules are modified lateral roots, the structure of which is enhanced by rhizobial inoculation.
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  • 79
    ISSN: 1573-5036
    Keywords: adaptation ; maize ; nutrient uptake ; root growth ; root temperature ; shoot base temperature ; shoot growth ; shoot demand per unit of roots ; spring wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of low root zone temperatures (RZT) on nutrient demand for growth and the capacity for nutrient acquisition were compared in maize and wheat growing in nutrient solution. To differentiate between direct temperature effects on nutrient uptake and indirect effects via an altered ratio of shoot to root growth, the plants were grown with their shoot base including apical shoot meristem either within the root zone (low SB), i.e. at RZT (12°, 16°, or 20°C) or, above the root zone (high SB), i.e. at uniformly high air temperature (20°/16° day/night). At low SB, suboptimal RZT reduced shoot growth more than root growth in wheat, whereas the opposite was true in maize. However, in both species the shoot growth rate per unit weight of roots, which was taken as parameter for the shoot demand for mineral nutrients per unit of roots, decreased at low RZT. Accordingly, the concentrations of potassium (K) and phosphorus (P) remained constant or even increased at low RZT despite reduced uptake rates. At high SB, shoot growth at low RZT in both species was higher than at low SB, whereas root growth was not increased. At high SB, the shoot demand per unit of roots was similar for all RZT in wheat, but increased with decreasing RZT in maize. Uptake rates of K at high SB and low RZT adapted to shoot demand within four days, and were even higher in maize than in wheat. Uptake rates of P adapted more slowly to shoot demand in both species, resulting in reduced concentrations of P in the shoot, particularly in maize. In conclusion, the two species did not markedly differ in their physiological capacity for uptake of K and P at low RZT. However, maize had a lower ability than wheat to adapt morphologically to suboptimal RZT by increasing biomass allocation towards the roots. This may cause a greater susceptibility of maize to nutrient deficiency, particularly if the temperatures around the shoot base are high and uptake is limited by nutrient transport processes in the soil towards the roots.
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  • 80
    ISSN: 1573-5036
    Keywords: alley cropping ; C/N ratio ; decomposition ; fertilizer N ; leucaena N ; leucaena residues ; lignin ; maize ; N mineralization ; 15N recovery ; N uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The success of alley cropping depends to a large extent on the efficiency of transfer of nitrogen (N) from the legume hedgerow plants to the non-legume crop. Here the idea is examined that leucaena prunings (residues) can supply enough N to maize plants to significantly reduce the degree of N deficiency. Two experiments on decomposition of leucaena leaf, stem, and petiole and mineralization of N from leucaena residues were conducted in field microplots which received application of either15N-labelled leucaena materials or ammonium sulphate fertilizer. The microplots were installed in alleys formed by leucaena hedgerows spaced 4.5 metres apart and cropped with maize. The decomposition of leucaena leaves, stems and petioles was estimated by several methods. The decomposition ranged from 50–58% with leaves, 25–67% with stems and 38–51% with petioles 20 days after addition. More than 55% of the N was released in 52 days during decomposition of leucaena residues. By 20 days after application of15N-labelled leucaena 3.3–9.4% of the added15N was found in the maize plants, 32.7–49.0% was in the leucaena residues, 36.0–48.0% in the soil and 0.3–21.9% lost (deficit). By 52 days 4.8% of the15N applied in leucaena prunings was taken up by maize, 45.1% was detected in the residues, 24.9% in the soil and 25.2% lost. However, when N fertilizer was applied, 50.2% of the fertilizer N was recovered by maize, 35.5% was retained in the soil and 14.3% apparently lost. There was a marked increase in maize plant dry matter and N uptake in the microplots with addition of leucaena prunings compared with those in the microplots without leucaena added. Most of the15N remaining in the soil profile, derived from leucaena residues, was detected in the top 25 cm soil with less than 2% found below 25 cm. ei]H Lambers
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  • 81
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    Plant and soil 150 (1993), S. 247-253 
    ISSN: 1573-5036
    Keywords: deficiency ; efficiency ; genotypic variation ; sub-soil ; water use ; wheat ; zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of variable Zn supply with depth in a soil profile was examined in two wheat genotypes differing in their Zn efficiency. ‘Gatcher’ (Zn-inefficient) and ‘Excalibur’ (Zn-efficient) were grown in a low Zn soil in pots with two treatment zones. The upper zone (10 cm) was supplied with Zn while Zn was either supplied or withheld from the lower zone (25 cm). In both genotypes, withholding Zn from the lower zone had no effect on root growth in either the upper or lower zones; neither did it affect plant appearance prior to booting. However, withholding Zn from the lower zone delayed head emergence in Gatcher by some 10 d and depressed grain yield by 20%. In Excalibur, Zn treatment had no effect on head emergence or grain yield. In Gatcher, withholding Zn from the lower zone depressed water usage by 12% during a 60 d period preceding maturity. No effect of Zn treatment on water usage was seen in Excalibur. Tissue Zn concentrations closely reflected the lower zone Zn treatments in both genotypes. Irrespective of the Zn treatment, Excalibur had higher Zn concentrations in flag leaves but lower concentrations in grain than Gatcher. In whole shoots, genotypic differences in Zn concentration only occurred when Zn was added to the lower zone; Excalibur having almost twice that of Gatcher. Clearly, if Zn is not supplied to the entire root system there is the potential for impaired root function and plant development, and for reduced grain yield. Approaches to managing this problem are discussed.
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  • 82
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    Plant and soil 154 (1993), S. 179-188 
    ISSN: 1573-5036
    Keywords: ash ; burning ; Côte d'Ivoire ; efficiency of utilization of nutrients ; maize ; nutrient uptake ; residual effects ; shifting cultivation ; Taï National Park ; upland rice ; weed growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract At two sites, one with a 4-year-old (4-Y) secondary vegetation and the other with a 20-year-old (20-Y) vegetation, the influence of burning slashed vegetation on crop performance was studied during three seasons. In the first season after clearing, also the influence on weed growth was studied. At both sites, burning significantly decreased the number of weed seedlings. The lowest number of seedlings was found on the burnt plots of the 20-Y site. Burning increased yield and nutrient uptake significantly in the first and second season after clearing. In the third season after burning, only at the 4-Y site a significantly higher yield and nutrient uptake were found. At the 20-Y site the effect had disappeared. Calculations of efficiency of utilization of absorbed N, P and K indicated that P was the least available nutrient, also after burning. At both sites three consecutive crops absorbed approximately 40% of P applied in ash, while the cumulative recovery of K was at least 36% at the 4-Y site and at least 59% at the 20-Y site. On non-burnt plots, yields were not lower in the third season than in the first season after clearing, thus indicating that the inherent soil fertility did not decrease. Hence, yield decline on the burnt plots could be ascribed to ash depletion. It was concluded that in the local shifting cultivation system, the combination of ash depletion and infestation of weeds are the main reasons for abandoning the fields.
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  • 83
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    Plant and soil 153 (1993), S. 287-293 
    ISSN: 1573-5036
    Keywords: grain protein concentration ; grain yield ; nitrogen ; tritordeum ; triticale ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The new species of cereal × Tritordeum Ascherson et Graebner (Hordeum chilense Roem. et Shultz × Triticum ssp.) has a grain protein concentration (GPC) of up to 25%. The relationship between GPC and yield, and the factors responsible for the high GPC of tritordeum were examined and compared in field experiments. Three experimental tritordeum lines, two early and a later released (recombined and secondary tritordeums) were compared to wheat (cv. Cajeme) and triticale cultivars (cv. Trujillo). GPC's were 19%–22% for recombined tritordeums, 16% for the secondary tritordeum, 12–15% for wheats and 11% for triticale. Grain yields of the recombined and secondary tridordeum were 17–33% and 45–57% that of the wheats and triticale, respectively. Reducing grain sink size by spikelet removal resulted in an increased GPC of remaining grains. Considering all species together there were a strong inverse relationship between GPC and grain yield (GY) per main ear (GPC=26−4.76 ln GY; r2=0.82). In another experiment, frost damage to an early sown treatment of wheat reduced sink size. Harvest index (HI) of early sown wheat was reduced from 0.45 to 0.19, values comparable to that of tritordeum. Having similar HI, the GPC of the early sown wheat was the same as an early sown tritordeum (around 18%). Data for total N uptake and the N concentration of plant tissue during the growing season indicated that enhanced N uptake and remobilisation were not responsible for tritordeum's high GPC. These results suggest that the high GPC of the early lines of tritordeum is a consequence of the small grain yield concentrating the grain protein.
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  • 84
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    Journal of chemical ecology 19 (1993), S. 2453-2461 
    ISSN: 1573-1561
    Keywords: DIMBOA ; MBOA ; DIM2BOA ; M2BOA ; 2-amino-7-methoxy-3H-phenoxazin-3-one ; 2-amino-4,6,7-trimethoxy-3H-phenoxazin-3-one ; corn ; wheat ; soil microbial transformation ; phytotoxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The defensive cyclic hydroxamates 7-methoxy-2,4-dihydroxy-1,4(2H)-benzoxazin-3-one (DIMBOA) and 7,8-dimethoxy-2,4-dihydroxy-1,4(2H)-benzoxazin-3-one (DIM2BOA) of wheat and corn are transformed in nonsterile soil, via 6-methoxy-2(3H)-benzoxazolone (MBOA) and 6,7-dimethoxy-2(3H)-benzoxazolone (M2BOA) respectively, into 2-amino-7-methoxy-3H-phenoxazin-3-one and 2-amino-4,6,7-trimethoxy-3H-phenoxazin-3-one. The soil transformation is similar of that undergone by the rye metabolite 2(3H)-benzoxazolone (BOA) into 2-amino-3H-phenoxazin-3-one. The transformations to phenoxazinones are not observed in sterile soil. The 2-amino-3H-phenoxazin-3-one inhibits barnyard grass radicle elongation, but the methoxylated aminophenoxazinones are not significantly inhibitory.
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  • 85
    ISSN: 1573-0867
    Keywords: leucaena ; maize ; 15N recovery ; residual15N
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Legume residues have been credited with supplying mineral nitrogen (N) to the associated cereal crop and improving soil fertility in the long term. Few studies using15N have reported the fate of legume N and fertilizer N in the presence of legume residues in soil-plant systems over periods of two years or longer. A field experiment was conducted in microplots to evaluate: (1) the residual value of the15N added in leucaena residues; (2) the residual value of fertilizer15N applied in the presence of unlabelled leucaena residues in the first year to maize over three subsequent years; and (3) the long-term fate of residual fertilizer and leucaena15N in a leucaena alley cropping system. There was a significant increase in maize production over three subsequent years after addition of leucaena residues. The residual effect of fertilizer N increased maize yield in the second year when N fertilizer was applied at 36 kg N ha−1 in the first year in the presence of leucaena residues. Of the leucaena15N applied in the first year, the second, third and fourth maize crop recovered 2.6%, 1.8% and 1.4%, respectively. The corresponding values for the residual fertilizer15N were 0.7%, 0.4% and 0.3%. About 12–14% of the fertilizer15N added in the first year was found in the 200 cm soil profile over the following three years. This differed from the 38–41% of leucaena15N detected in the soil over the same period. Most of the residual fertilizer and leucaena15N in the soil was immobilized in the top 25 cm with less than 1% leached below 100 cm. More than 36% of the leucaena15N and fertilizer15N added in the first year was apparently lost from the soil-plant system in the first two years. No further loss of the residual leucaena and fertilizer15N was detected after two years.
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  • 86
    ISSN: 1572-9680
    Keywords: intake ; maize ; husk ; leucaena ; goats
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of feeding maize (Zea mays L.) husk and leucaena (Leucaena leucocephala) as a mixture or separately on the voluntary intake of maize husk was studied over a 40-day period. Ten male goats with an average weight of 15 kg were used. The maize husk intake and total dry matter intake for the two feeding methods was about the same. Thus, total dry matter intake was not affected (P〈0.05) by the feeding method. There was also no significant difference (P〈0.05) between the two feeding methods in the digestibility values. The data were considered to indicate that there were no significant differences in the intake of maize husk when fed in a mixture with leucaena or when offered separately but at the same time.
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  • 87
    ISSN: 1572-9680
    Keywords: SCUAF ; computer model ; soil carbon ; soil nitrogen ; miombo ; maize
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract ‘Soil Changes Under Agroforestry’ (SCUAF), a computer model designed to predict changes in erosion, soil carbon and soil nitrogen over time within various agroforestry systems and climatic regimes, was assessed using input data from an undisturbed miombo woodland and an adjacent maize field in Zimbabwe. Predicted changes in soil carbon were in a realistic range for both miombo and maize treatments. However, the accuracy of the model may be a reflection of the detail required in its initialisation. Several problematic relationships were found within the model, in particular inconsistent patterns between nitrogen uptake and plant productivity under complex fertilisation simulations and a lack of attenuation of productivity in the simulation of miombo woodland as it approached maturity.
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  • 88
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    Agroforestry systems 22 (1993), S. 241-258 
    ISSN: 1572-9680
    Keywords: agroforestry ; Inga edulis ; maize ; beans ; statistical analysis ; distributions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Measurements from trees and plants of a BrazilianInga/maize/beans alleycrop experiment were assessed for their distributional properties for three years of the study. Results for the tree data were similar to those found in an earlier study. Results for the crop data demonstrated similarities between the distributions for alleycrops and solecrops, nonnormality shown by positive skewness and peaked distributions. Changes in the distributional shapes were demonstrated from year to year as soil nutrient depletion increased and as climatic variables fluctuated. Variation across the rows in the alley was often of a similar size to variation from plant to plant within the rows. Initial recommendations for analysis of such data are given on the basis of these results.
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  • 89
    ISSN: 1573-5060
    Keywords: wheat ; Puccinia recondita f.sp. tritici ; Triticum aestivum ; slow rusting resistance ; leaf rust ; brown rust ; genetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Forty F6 lines, the two parental lines, and a susceptible check cultivar of wheat (Triticum aestivum L.) were inoculated in the young flag leaf stage with leaf rust (Puccinia recondita f.sp. tritici) and evaluated for latent period, receptivity, and uredinium size in a greenhouse experiment. Genotypic (rg) and phenotypic (rp) correlations between latent period and uredinium size were −0.81 and −0.62, respectively. A negative correlation (rg=−0.50, rp=−0.41) was found between latent period and receptivity and a positive correlation (rg=0.28, rp=0.26) between uredinium size and receptivity was found. Area under the disease progress curve (AUDPC) and final rust severity (FRS) obtained from a subsequent field study with common entries were negatively correlated with latent period and positively correlated with uredinium size. Correlations of receptivity with both AUDPC and FRS were not significant. The distributions of F6 family mean uredinia size and latent period were continuous between slow rusting and fast rusting parents: however, the distribution for receptivity was discrete. Narrow-sense heritability estimates were 63%, 57%, and 47% for uredinium size, latent period, and receptivity, respectively. Estimates of the minimum number of effective factors were three for latent period and three or four for the uredinium size and receptivity. The components are controlled by closely linked genes or due to pleotropic effects of the same gene.
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  • 90
    ISSN: 1573-5060
    Keywords: barley ; Hordeum vulgare ; grain yield ; plot size ; variety trials ; wheat ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A coordinated series of experiments aimed to estimate border effect and intergenotypic competition was carried out on bread wheat and barley in Italy and Germany. The performance of the varieties grown in alternate rows 14–17 cm apart proved to be strictly dependent on the bordering variety. The varieties grown in adjacent plots consisting of eight rows showed significant border effects: the two external rows yielded up to 40% more than the two innermost, and the two 30 cm end hills facing the alleys yielded 29% more than the central part of the plot. Is has been suggested that in variety trials the first 30–40 cm at both ends of each plot should be removed mechanically. In spite of the border effect detected in the outer rows of the plots, the varieties similarly exploited the extra space available at the borders, and the space of 30 cm left between adjacent plots seems to be sufficient to dilute the intergenotypic competition at plot level to an extent only marginally affecting variety performance. In conclusion, grain yield based on whole plot (8 rows, 6–10 m2) appears to provide a good estimate of ‘true yield’, providing that it is based on the actual area of the plot, including the uncropped strip between adjacent plots. By contrast, the reduction of plot size to 1–3 rows is not feasible without introducing considerable bias into the estimation of the yield potential of the varieties.
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  • 91
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    Euphytica 69 (1993), S. 89-94 
    ISSN: 1573-5060
    Keywords: electrophoresis ; glutenins ; alleles ; sedimentation value ; wheat ; quality score ; high molecular weight glutenins ; Triticum aestivum ; Yugoslavia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The high molecular weight (HMW) subunits of glutenin extracted from flour of 36 Yogoslav wheat cultivars were separated by SDS-PAGE to identify their alleles, and the frequency of each allele was calculated. Eleven alleles from the three Glu-loci were recognized, three at the Glu-A1 locus, six at the Glu-B1 locus and two at the Glu-D1 locus. The most frequent allele was “a” (55.5%) from Glu-D1, which controls synthesis of subunits 2+12. The Glu-1 quality score varied from 4 (KG-III/27, KG-75, Morava and KG-101/7) to 10 (Lepenica). The mean Glu-1 quality score of cultivars and lines from Kragujevac was 6.8, for cultivars from Zagreb 7.2, and for cultivars from Novi Sad was 7.9. Most of the genotypes with a quality score of 8 or above, had high sedimentation values (Zeleny test). There were no significant differences in allelic composition at the Glu-1 loci among wheat genotypes from Kragujevac, Novi Sad and Zagreb.
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  • 92
    ISSN: 1573-5060
    Keywords: X Triticosecale ; triticale ; Triticum aestivum ; wheat ; Secale cereale ; rye ; Fusarium spp ; pathogenicity ; head blight ; seedling resistance ; adult plant resistance ; grain yield
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Pathogenicity of 20 isolates of 12 Fusarium species recovered from triticale seed against seedlings of 14 varieties of winter cereals (triticale, wheat, and rye) was tested. The most pathogenic inoculum was a mixture of isolates (a composite isolate) of all the species. The following species were individually the most pathogenic: F. avenaceum, F. culmorum, F. sambucinum var. coeruleum, and F. graminearum. Winter triticale was more resistant to seedling blight than rye but more susceptible than wheat. Also reactions of 31 winter and 12 spring varieties of cereals to head inoculation with a composite isolate of 4 Fusarium spp. (F. avenaceum, F. culmorum, F. graminearum, and F. sambucinum var. coeruleum) was studied. In comparison to other cereals of similar type winter and spring wheat appeared to be the most susceptible while winter rye reaction was comparable to winter triticale. Spring and winter triticale varieties responded to head infection intermediately. There was no significant correlation between seedling and head reactions to infection with Fusarium spp. for winter rye and triticale. For winter wheat a negative trend was found. The above findings imply that screening of cereals at the seedling stage can not be used to predict the resistance to head blight. Nevertheless, resistance at the stage is highly desirable to prevent excessive damage of the crops due to the seedling blight incited by Fusarium spp..
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  • 93
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    Euphytica 71 (1993), S. 107-113 
    ISSN: 1573-5060
    Keywords: Puccinia striiformis ; resistance genes ; stripe rust ; Triticum aestivum ; wheat ; yellow rust
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Carstens V, one of the wheat cultivars used to differentiate races of Puccinia striiformis (stripe rust or yellow rust) in Europe, was crossed with stripe rust susceptible cultivars and cultivars with genes for resistance to the disease to determine the genetic basis of its stripe rust resistance. Seedlings of the parents and F1, F2, and F3 progeny were evaluated for resistance to North American races of P. striiformis. Based on those evaluations, Carstens V has three genes for resistance to North American race CDL-21, two genes for resistance to races CDL-17, CDL-20, and CDL-29, and one gene for resistance to race CDL-27. The genes that confer resistance to race CDL-17 also confer resistance to race CDL-21. The three genes were either dominant or recessive depending upon the race used in the test and the cultivar used in the cross. None of the genes in Carstens V are the same as the genes for resistance in Cappelle Desprez, Chinese 166, Clement, Compair, Heines Peko, Hybrid 46, Minister, Nord Desprez, Triticum spelta album, and Vilmorin 23.
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  • 94
    ISSN: 1573-5060
    Keywords: diallel analysis ; host plant resistance ; Ostrinia nubilalis ; plant breeding ; Zea mays ; maize ; European corn borer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Success in breeding maize resistant to the European corn borer has been limited, with the exception of leaf feeding resistance. The inheritance of resistance to leaf, sheath-collar and ear damage in four maize germplasms and their six F1 crosses was evaluated by diallel analysis. Plants in a completely randomized design were artificially infested at the whorl, anthesis or full silk stage of plant development and were evaluated in the field for insect damage. A damage index based on size, number and location of lesions was calculated for each stage. Stowell's Evergreen (susceptible) had a mean damage index three to six times that of Maiz Amargo (resistant) at the whorl stage and the progeny plants were more resistant than the susceptible parent. Maiz Amargo and its crosses had significantly lower mean indices than Stowell's Evergreen for sheath-collar damage in Year 1 but not Year 2. Zapalote Chico, Maiz Amargo and their cross were significantly less damaged than other genotypes at the full silk stage. Heterosis values indicated an increase in resistance of crosses over the midparent average at all three stages of development. General combining ability (GCA) was highly significant for all types of damage, but specific combining ability was significant only for leaf damage. Based on estimates of GCA, Maiz Amargo was the best source of resistance to leaf and sheath-collar damage and both Zapalote Chico and Maiz Amargo would be good parents for ear damage resistance. Results suggest that resistance at different plant development stages can be combined.
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  • 95
    ISSN: 1573-5060
    Keywords: pattern analysis ; genotype x environment interaction ; grain yield ; mega-environments ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The International Spring Wheat Yield Nursery (ISWYN) has been distributed annually since 1964 and the results provide a base for investigating relationships among locations. Ordination and clustering of locations was conducted using 26 years of grain yield data. Ordination and clusters based on the discrimination of germplasm were compared with ‘mega-environments’, which are groupings of locations defined by CIMMYT on the basis of climatic factors and perceptions of major biotic and abiotic stresses. Discrepancies among mega-environmental groupings, clusters and ordinations may identify locations for which major stresses affecting wheat yield are yet unidentified. Major environmental discriminators were latitude and the presence or absence of stress, although there was little association of locations due to limited moisture availability. We identified two major spring wheat environments, typified as Asian and European, and suggest the mega-environmental classification does not explain all significant associations among locations. Location groupings based on discrimination of germplasm should be considered in parallel to mega-environments on a regular basis and we propose breeding for a base of broadly adapted germplasm to which specific stress tolerances are incorporated.
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  • 96
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    Plant and soil 154 (1993), S. 21-28 
    ISSN: 1573-5036
    Keywords: activity ratio ; ammonium phosphate ; chloride ; maize ; sandy loam ; soil extracts ; sulphate ; superphosphate ; unbalanced nutrition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A new soil testing procedure has been used to demonstrate the effect of an overfertilization by potassium during the preceding years. The total concentration of cations was governed by the amount of soluble anions and the proportion between the different cations was dependent on exchange reactions and is described by activity ratio. High activity ratio between potassium and calcium induced Ca-deficiency, which resulted in a restricted root functioning shown by periodic decreases of nutrient uptake rates and plant growth rate. P-deficiency restricted root growth, but although ammonium phosphate was most effective to increase P-concentration in soil extracts and P-absorption by plants, ordinary superphosphate gave the highest yield and the best utilization of the absorbed phosphorus, magnesium, and calcium.
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  • 97
    ISSN: 1573-5036
    Keywords: Key words ; chromosome translocation ; copper efficiency ; DNA: DNA in situ DNA hybridization ; physical mapping ; phytosiderophores ; rye ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract A 4B/5R wheat-rye translocation line derived from the Danish wheat variety ‘Viking’ was revealed to be highly copper efficient. The chromosomal exchange includes a very small terminal segment of chromosome arm 5RL of rye which was physically mapped by genomic DNA: DNA in situ hybridization and chromosome analysis. The gene for Cu efficiency (Ce) is linked to a dominant hairy neck character from rye (Ha1) and to two rye-specific leaf esterase loci (Est6, Est7), all of which are postulated to map to the distal part of 5RL. Genes coding for mugineic acid synthetase and 3-hydroxymugineic acid synthetase also on chromosome 5R are not included in the 4B/5R translocation and hence map outside the terminal 5R region. These genetic and molecular markers can be useful tools for large-scale screening in wheat breeding programmes.
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  • 98
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    Plant and soil 154 (1993), S. 89-96 
    ISSN: 1573-5036
    Keywords: nitrogen concentration ; nitrogen content ; nitrogen uptake ; Trilicum aestivum L. ; wheat ; water stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nitrogen uptake and distribution in wheat (Triticum aestivum L.) are dependent on environmental conditions and in particular on the water regime. Under Mediterranean conditions, where high water stress at the end of the crop cycle is frequent, nitrogen uptake can be reduced, affecting yield and quality of the grain. To disclose these relations a field experiment was carried out in Central Portugal. Wheat was grown on a clay soil (Vertisol) at three water treatments: rainfed (WO), with 80 mm of irrigation (W1) and with 50 mm and 70 mm irrigations (W2). All treatments received 50 kg ha−1 of N prior to sowing and were top-dressed with 140 kg ha−1 of N, splitted in two applications, Kjeldahl N was determined in green leaves (GL), yellow leaves (YL), stems (ST), chaff (CH) and grain (GR). N uptake after anthesis was 40% of the total in W2, but was not noticeable in the other two treatments. N concentrations in the total above-ground plant dry matter, and in both YL and ST were not very different according to treatment, but water availability increased grain-N concentration. It seems, therefore, that grain protein concentration and N uptake can be substantially increased by late irrigations.
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  • 99
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    Plant and soil 155-156 (1993), S. 457-459 
    ISSN: 1573-5036
    Keywords: copper ; development ; leaf emergence ; nutrient deficiency ; Triticum aestivum ; wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Copper deficiency can delay flowering and plant maturity. However, the effect of copper deficiency on the rate of leaf emergence has not been quantified. We tested the hypothesis that low copper supply decreases the rate of leaf emergence of wheat (Triticum aestivum L. cv Gamenya). Copper foliar sprays are commonly applied to wheat. We examined the response of the rate of leaf emergence to a foliar application of copper sulphate. Wheat was grown in root cooling tanks (20°C) in the glasshouse. Soil copper treatments were applied as solutions of CuSO4.5H2O at three rates: Cu0=no added Cu, Cu400=400 μg Cu per 3 kg pot, and Cu1600=1600 μg Cu per pot. An additional treatment of a foliar spray of CuSO4.5H2O (0.4 mg Cu per plant) was applied to Cu0 and Cu400 plants 45 days after sowing (5.5 leaves on the main stem). Leaves on the main stem were counted and the rate of leaf emergence was estimated from the regression of number of emerged leaves against thermal time (base 0°C). The phyllochron was calculated as 1/rate of emergence. Leaves on Cu0 and Cu400 plants took longer to emerge than on Cu1600 plants, with the phyllochron of Cu1600 plants being 130 compared to 137 for the Cu400 plants and 158 for the Cu0 plants. The foliar application of CuSO4 at the 5–6 leaf stage resulted in a decrease in the phyllochron of the Cu0 plants to 127, but no change in that of the Cu400 plants.
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  • 100
    ISSN: 1573-5036
    Keywords: common bean ; maize ; intercropping ; nitrogen fixation ; 15N isotope ; 15N natural variation ; Rhizobium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Thirty one selected bean lines were evaluated in the field for ability to support N2 fixation when intercropped with maize which received 0, 30 and 60 kg N ha−1 as ammonium sulphate. The amount of fixed N2 was estimated using the natural variation of 15N and wheat as the standard non-fixing crop. Nitrogen as low as 15 kg N ha−1 at sowing suppressed nodule weight and activity (acetylene reduction activity) but not nodule number, suggesting that the main effect of mineral N was on nodule development and function. 15N data revealed a high potential of the bean genotypes to fix N2, with the most promising ones averaging between 50–60% of seed N coming from fixation. Bean lines CNF-480, Puebla-152, Mexico-309, Negro Argel, CNF-178, Venezuela-350 and WBR22-3, WBR22-50 and WBR22-55 were ranked as good fixers.
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