Response Of Grains Research Articles

Sensitivity, Fog and Grain Size in Single Emulsions: A New Experimental Approach

AbstractIt is shown that fully developed grains in well-hardened layers of emulsion are of similar size and shape to undeveloped grains. This effect can be used to determine directly the response of grains of different size classes to exposure plus development, and development alone, in dilute layers of emulsions of medium to large grain size.This approach has been used to study the grain size-sensitivity and grain size-fog relations in an emulsion of thin tabular grains having a mean area of 5.9 pm2, and sensitized to three distinct levels with sulphur plus gold, namely, under-, optimally-, and over-sensitized. Major findings were as follows:(a) At optimal and over-sensitization the photon sensitivity is substantially invariant over small to medium grain sizes, but falls at large grain sizes. Thus the latter effect is specific to grain size and is not a property of an emulsion as a whole.(b) The fog fraction increases with increasing grain size, and increases by the same factor at all sizes with increasi...

Response of barley yield and yield components to nitrogen rate under low and high input management systems

Increasing rates of nitrogen (N) fertilization may increase disease and lodging in cereals. As a result, use of high-input management (HIM) systems, which use growth regulators to control lodging and fungicides to control disease, may allow a greater increase in yield due to N fertilization than occurs in conventional low input management (LIM) systems. The study was conducted to determine the influence of two management systems on the response of yield and yield components of barley (Hordeum vulgare L.) to N fertilization and to determine if use of a HIM system was cost-effective under southern Ontario growing conditions. Barley, cv. Leger, was grown at eight rates of N fertilization under either HIM or LIM systems in 10 environments in southern Ontario. The response of grain and straw yield to N rate was not significantly different between management systems; however, the maximum economic yield occurred at a significantly higher N rate under the HIM system (90 kg N ha−1) than under the LIM system (71 kg N ha−1). The number of heads m−2 was higher under the HIM system than under the LIM system whereas the reverse was true for grains head−1. Increased N rate resulted in increased 1000-grain weight under the HIM system but had little influence on 1000-grain weight under the LIM system. Over the duration of the study, the increased revenue obtained under the higher input management system was generally less than the cost of the added inputs used, emphasizing the need for threshold values which producers can use to determine when crop protection inputs are likely to be cost-effective. Key words: Fungicide, growth regulator, seeding rate, nitrogen, barley

The Quantum Sensitivity of an Emulsion and the Size of the Grains Producing the Dye Image in a Coupler Starved Format

AbstractThe quantum sensitivity of an emulsion was determined by studying the effect that the exposure and development have on the size distribution of the halide grains: the method is sometimes referred to as a residual-size-analysis. The emulsion coatings were partially developed initially in a colour developer followed by further development to fully develop the grains, and a combination of electron microscopy and optical microscopy was used to establish the response of grains of different size within the polydisperse emulsion. The study was facilitated for this emulsion of wide size spread by arbitrarily placing the grains in 12 size classes where adjoining classes differ in projective area by √2. The most sensitive grains were among the largest and required on average 12 absorbed photons before 50% were rendered developable, and there was a notable fall-off in quantum sensitivity as the grain size decreased.The response characteristics of grains of different size were used to investigate which grains...

Nitrogen Harvest Index in Oats: Its Repeatability and Association with Adaptation1

The proportion of total plant N that occurs in the grain of cereals is called the nitrogen harvest index (NHI). Twenty oat (Arena sativa L.) cultivars, 10 with high and 10 with low NHI, were used to study the repeatability of NHI measurements over environments and the association of NHI with certain grain and straw yield characteristics, i.e., mean yield, regression response to environments with differing levels of N availability, and stability of that yield response. The NHI values for the oat cultivars were determined at low N (0 kg ha−1) and high N (224 kg−1 in 1979 and 100 kg ha− in 1981). Adaptation to variable soil N was evaluated in 12 environments with varying N availability for 2 yrs. The NHI values were highly consistent across N levels (r=0.72**, significant at the 0.01 probability level) but less so across years (r=0.57**). The NHI values were less consistent across years at low soil N (r=0.18) than at high (r=0.75**). Selection for NHI in the high N environment gave realized heritabilities of 1.01 for high and 0.85 for low NHI lines. The NHI was positively associated with mean grain yield and response of grain yields to environmental productivity, but was inversely related to mean straw yield.

THE EFFECT OF IRRIGATION TIMING ON YIELD AND YIELD COMPONENTS OF WINTER WHEAT

A study was conducted in southwest Kansas to evaluate the effect of limited water applications at critical growth stages on yield and yield components of winter wheat (Triticum aestivum L.). The experiment was a split-plot design. Irrigation treatments were main plots and cultivar × seeding rate combinations were subplots. The irrigation treatments were: Preplant (PP), PP + jointing (JT), PP + flowering (FL), and PP + JT + FL. Two cultivars (Centurk and Newton) were seeded at rates of 22, 45, and 67 kg∙ha−1. The experiment was conducted over a 2-yr period. During the first cropping season grain and straw yields showed a significant (P < 0.05), positive response to irrigation water applications at the JT growth stage, compared to the PP and PP + FL treatments. There was no significant effect of water treatments on heads per square metre, kernels per square metre or kernel weight. The second cropping season resulted in a positive, significant response of straw yields to irrigation treatments, but no significant response of grain. Grain yield response was nullified by greater kernel weight on the treatments that were most limiting in soil water during early reproductive development (PP and PP + FL).Key words: Triticum aestivum L., limited irrigation, moisture stress, seeding rate, kernel number, kernel weight

The interaction of deformation and metamorphism in slates

Abstract The distribution, microchemistry and internal structure of phases present in a slate are reported and used as a basis for a discussion of the interaction between deformation and metamorphism in slates. The study reveals details of the interactions between mechanical and chemical processes involved in slaty cleavage evolution. Evidence for the involvement of mechanical rotation, solution and crystallisation, recrystallisation and metamorphic reactions is presented and amalgamated into a model of cleavage development. The model involves a synchronous variation in the type, location and rate of cleavage evolution processes and a change in the importance of particular processes during the total history. The early stages of cleavage development are dominated by mechanical rotation associated with crenulation and possibly accompanied by grain boundary sliding and solution processes. Later stages of cleavage evolution are more heterogeneous and occur by a complex interaction of deformation and metamorphic growth processes which are concentrated at the interfaces between domains generated earlier in the strain history. The variations in grain chemistry and orientation together with changes in the strain rate (or stress level) are suggested to control the different deformation behaviour of different grains along these strain accommodation zones and to dictate whether grains bend, kink, dissolve, recrystallise or react and undergo growth. Evidence for the involvement of reactions, ranging from ionic exchange to crystallisation from solution, and solid state reordering is presented and the influence of deformation on the location and rates of these reactions discussed. Approximately ten potential reactions are involved in the cleavage evolution of the slate studied. The model presented incorporates these reactions into the deformation processes and accounts for the concentration of phengite and iron-poor chlorites in to one microstructural domain and paragonite, quartz and Fe-rich chlorites into the other domain. Two transformations appear to be fundamental in the slate studied: 1. (1) the transformation of illite to phengite 2. (2) the transformation of Fe-rich chlorite to Fe-poor chlorites, and both can be related to particular responses of grains to the reorientation processes at domain interfaces.