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Many factors are known to influence crop yields. Thus two of the basic plant growth requirements in the environment, namely, light and heat need be available to crop plants in specified quantities and/or qualities for good crop yields. In normal farm practice these two environmental factors are managed by proper cultural practices of the crops concerned. [...]

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The results of a theoretical and experimental investigation into the drying of wheat and barley in two stages with an intervening rest period are presented. The reduction in drying time, excluding rest period, has been determined in comparison with the conventional continuous drying for various drying requirements. The effect of airflow rate and the temperature difference between grain and air on the reduction in moisture content and the time required to cool the grain during dryeration is also included. The moisture diffusion equation was solved numerically assuming a spherical grain. The variable grid spacing, Crank-Nicolson approximation technique and the Gauss-Seidel iterative procedure was employed. The theoretical predictions were compared with experimental results. The drying and resting was performed on a thin layer at a temperature of 60°C. An automatic micro-computer based system was developed to record and store the experimental data. The results indicate that the moisture redistribution during resting is well advanced after a period of two hours for wheat and one hour for barley. The extent of redistribution was measured by the increase in drying rate observed as the rest period was extended. An optimum moisture content for commencing resting is specified, which is a function of initial, final and equilibrium moisture contents. This optimum was chosen to minimise the actual drying time. There is good agreement between the theoreticaaand experimental predictions. It was found that the incorporation of a surface resistance into the diffusion model improves the description of the experimental results. The results enable a drying strategy to be specified that reduces the actual drying time by as much as 39%. - iv For dryeration experiments, the grains pre-heated to different temperatures were put into a well insulated aluminium cylinder and aerated at various airflow rates. An airflow rate of about 60-120 m3/hr/m3 of grain was found to be optimum. The moisture reduction during cooling was observed to be 0.65 to 0.78% (db) per 10°C temperature difference. It was noticed that moisture reduction also depends on initial moisture content of the grain. The practical implications of two-stage drying are discussed.

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Two slotted two-dimensional spouted bed units with flexible bed dimensions were designed and fabricated. Static vertical pressure of grains (shelled corn, soybean, and wheat) on the air entry slots in the pilot scale unit indicated that the silo theories are not applicable to predict this pressure accurately without including the bed to air inlet aspect ratio, slant angle, and sphericity of grains. A grain quantitative factor accounting for emptying angle of repose and sphericity of particles was proposed and included with the collected data to develop an empirical regression model. / Aerodynamics of grains (shelled corn, soybean, and wheat) were found to be affected by slant angle, spout width, separation distance, length of bed and the bed geometrical similarity. Mathematical models for the design parameters of the spouted beds were developed following the principles of dimensional analysis and similitude. Model predictions agree closely with the data. / The drying rate of shelled corn in the geometrically similar two-dimensional spouted beds with draft plates was found to depend on the bed geometry and operating parameters. The drying characteristics of corn in the investigated spouted beds was found to be of the thin layer type. The performance of dryers was modeled in the form of the Page's equation. Expressions for the model parameters accounting for bed geometry, grain moisture content, and drying conditions were developed. The developed model predictions agree well with the data from both beds.

The potential of grain amaranth production in southwestern Quebec was studied. Twenty-nine cultivars were evaluated in single row plots, and seven in mechanically managed plots. Yields averaged 27 g plant-1 in single row plots, and 649 kg ha-1 in mechanically managed plots. Another set of experiments evaluated different seeding dates, row spacings, seeding rates and nitrogen fertilization rates. Seeding date and nitrogen fertilization affected grain yield in one environment, and seeding rate and row spacing did not affect yield. Grains in all experiments required drying. These experiments suggest that grain amaranth could be cultivated in southwestern Quebec. Oxalate concentration and form were determined in seeds from the cultivar, seeding date and nitrogen fertilization trials, and the effects of cooking on oxalate were evaluated. Fertilization increased oxalate concentration, seeding date had no effects, and cooking increased soluble oxalate. Grain amaranth is high in oxalate, but its absorbability is probably low.

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