Abstract

Cereal production in Australia is severely impacted by stubble-borne pathogens which can survive multiple seasons within cereal residues (stubble). Microwave radiation may be able to reduce or eliminate the pathogens, but the energy requirements first need defining. Hence, the dielectric properties of wheat and barley stubble with different pathogen loads were investigated at 10%, 15%, 30% and 100% moisture content using an open-ended coaxial probe in a spectral band covering 915, 2450, and 5800 MHz. A significant increase in dielectric constant and loss factor was observed with increasing stubble moisture. The dielectric constant and loss factor were lower in the crown (basal) section of stubble compared with the stem (20 cm from base), due to differences in density. When stubble moisture was 100%, the loss factor of barley was higher than wheat. Infection of stubble by different pathogens did not affect the dielectric properties. Microwave heating could therefore be an effective method to heat cereal stubble to eradicate a range of cereal pathogens, especially at lower frequencies and high moisture content, at which the loss factor is high. This research serves as a starting point to define requirements for further development of effective microwave radiation treatments under field conditions.

摘要

澳大利亚的谷物生产受到茬传播病原体的严重影响，这些病原体可以在谷物残留物（茬）中存活多个季节。微波辐射可能能够减少或消除病原体，但首先需要确定能量需求。因此，使用开放式同轴探头在覆盖 915、2450 和 5800 MHz 的光谱带中研究了具有不同病原体负荷的小麦和大麦茬的介电特性，水分含量为 10%、15%、30% 和 100%。随着留茬水分的增加，观察到介电常数和损耗因数显着增加。由于密度差异，与茎（距基部 20 厘米）相比，茬的冠部（基部）的介电常数和损耗因子较低。当留茬水分为100%时，大麦的损失系数高于小麦。不同病原体感染茬不影响介电性能。因此，微波加热可能是一种有效的加热谷物残茬以根除一系列谷物病原体的方法，尤其是在低频和高水分含量的情况下，在这些情况下损失系数很高。这项研究可作为定义在现场条件下进一步开发有效微波辐射治疗的要求的起点。