电激励信号频率对红点病苹果采后电学特性影响

Influence of Frequency of Electric Excitation Signal on Dielectric Property of Fuji Apples with Red-dot Disease

研究了红点病富士苹果采后果实电特性的变化规律,为从电特性角度揭示红点病病害发病的内在机制提供理论参考。运用LCR电子测量仪测定了20℃恒温条件下贮藏70 d的红点病果实在100 Hz、1 kHz、10 kHz、100 kHz和1 MHz频率下复阻抗等电学参数。结果表明,在同一贮藏时间下,随着频率的增加,不论是病果还是正常果其果实的介电常数ε′、复阻抗Z、电抗X和电感L_p值均在减小;果实的Z、X和L_p间存在着显著相关;对100 Hz下以及1、10、100 kHz和1MHz的病果和正常果的Z、X和L_p进行方差分析结果显示,两者差异均不显著(P>0.05),但两者在ε′和损耗因子tanδ上有明显差异(P<0.05)。tanδ和ε′基本可以反映水果的实际品质。

The change of dielectric properties on Fuji apples with red-dot disease stored at constant temperature was investigated,which provides a new theoretical basis for revealing its pathogenetic mechanism at electrical properties.By applying LCR electronic measure instrument,the fruits dielectric properties,which include the impedance,reactance and inductance,were determined at 100 Hz,1,10,100 kHz and 1 MHz at 20℃.The results indicated that the dielectric constant, impedance, reactance and inductance for all fruits decrease with the increase of frequency at the same stored days. Moreover, there was a significantly positive correlation among impedance, reactance and inductance, the value of the loss tangent and dielectric constant is significantly different （P 〈 0.05）, but the value of the impedance, reactance and inductance is not significantly different （P 〉 0.05） between the diseased and normal fruits from 100 Hz to 1 MHz. This research revealed that the loss tangent and dielectric constant could reflect the quality of apples in some extent.