基于阻抗和电容的番茄叶片含水率实时监测  

Monitoring of Tomato Leaf Moisture Content Based on Electrical Impedance and Capacitance

作　　者：李晋阳[1] 毛罕平[1] 

机构地区：[1]江苏大学现代农业装备与技术教育部重点实验室,镇江212013

出　　处：《农业机械学报》2016年第5期295-299,351,共6页Transactions of the Chinese Society for Agricultural Machinery

基　　金：'十二五'国家科技支撑计划项目(2014BAD08B03);江苏大学高级人才基金项目(13JDG077);江苏省博士后基金项目(1402076B);江苏高校优势学科建设工程项目(苏政办发[2014]37号)

摘　　要：为降低基于叶片电特性的番茄营养状况实时监测系统中叶片含水率对营养监测准确性的影响,提高营养水平监测模型的精度,提出一种基于叶片阻抗和电容的含水率实时测量方法,利用自制的针状电极设计了一种基于叶片阻抗和电容的4电极含水率监测系统。以不同含水率的番茄叶片为对象,在1×10-6~1 MHz的频率范围内研究了番茄叶片含水率对阻抗的影响规律,提取了叶片含水率的敏感频段,并建立了基于阻抗和电容的各生育期的叶片含水率预测模型,各模型的相关系数均大于0.973,均方根误差均小于5.06%。结果表明：番茄叶片含水率为50.5%~94.4%时,利用频率为3.98 k Hz时叶片阻抗和电容的对数函数可对番茄叶片含水率进行监测。In order to decrease the effect of moisture content on the accuracy of tomato nutrition level in the on-time monitoring system and improve the accuracy of nutrition level prediction model,an on-time measurement method for moisture content based on impedance and capacitance of leaf was proposed.A monitoring system of moisture content with four electrodes was designed. The relationship between electric properties and moisture content of tomato leaves was investigated within a frequency range from1 × 10- 6MHz to 1 MHz. The sensitive frequency of 3. 98 k Hz was obtained. Therefore,an equation was developed that simultaneously satisfies both impedance and capacitance. The new method increased the accuracy of moisture measurement as compared to that obtained by using a single parameter. It is suspected that the variation of tissue structure during the growth process of tomato had the effect on electric properties. Therefore,the experimental samples were divided into four classes depending on four growth stages such as strong seedling stage,flowering stage,fruiting stage and picking stage,the samples were reanalyzed. The linear regression equations with the correlation coefficient of 0. 973 at least and root mean square error（ RMSE） of 5. 06% at most for four growth periods respectively were acquired by the least square method. Results showed that the accuracy of model for four growth stages was further enhanced. When the moisture content of leaves was between 50. 5% and 94. 4%,the logarithmic functions of impedance and capacitance can be used to estimate the moisture content at 3. 98 k Hz.

关 键 词：番茄 叶片 含水率 阻抗 监测 

分 类 号：S24[农业科学—农业电气化与自动化]