Muñoz-Huerta Rafael F, Ortiz-Melendez Antonio de J, Guevara-Gonzalez Ramon G, Torres-Pacheco Irineo, Herrera-Ruiz Gilberto, Contreras-Medina Luis M, Prado-Olivarez Juan, Ocampo-Velazquez Rosalia V
Ingeniería de Biosistemas CA, División de Estudios de Posgrado, Facultad de Ingeniería, Universidad Autónoma de Querétaro, Cerro de las Campanas S/N, 76140 Querétaro, Qro., Mexico.
Departamento de Ingeniería Electrónica, Instituto Tecnológico de Celaya, Av. Tecnológico y García Cubas S/N, 38010 Celaya, Gto., Mexico.
Sensors (Basel). 2014 Jun 27;14(7):11492-503. doi: 10.3390/s140711492.
Nitrogen plays a key role in crop yields. Hence, farmers may apply excessive N fertilizers to crop fields, inducing environmental pollution. Crop N monitoring methods have been developed to improve N fertilizer management, most of them based on leaf or canopy optical-property measurements. However, sensitivity to environmental interference remains an important drawback. Electrical impedance has been applied to determine the physiological and nutritional status of plant tissue, but no studies related to plant-N contents are reported. The objective of this article is to analyze how the electrical impedance response of plants is affected by their N status. Four sets of lettuce (Lactuca sativa L.) with a different N-source concentrations per set were used. Total nitrogen and electrical impedance spectra (in a 1 to 100 kHz frequency range) were measured five times per set, three times every other day. Minimum phase angles of impedance spectra were detected and analyzed, together with the frequency value in which they occurred, and their magnitude at that frequency. High and positive correlation was observed between plant N content and frequency values at minimum phase angle with no significant variations detected between days of measurement. These results suggest that electrical impedance can be sensitive to plant N status.
氮在作物产量中起着关键作用。因此，农民可能会在农田中过量施用氮肥，从而导致环境污染。为了改善氮肥管理，人们已经开发了作物氮监测方法，其中大多数基于叶片或冠层光学特性测量。然而，对环境干扰的敏感性仍然是一个重要的缺点。电阻抗已被用于确定植物组织的生理和营养状况，但尚未有与植物氮含量相关的研究报道。本文的目的是分析植物的电阻抗响应如何受到其氮素状况的影响。使用了四组生菜（Lactuca sativa L.），每组具有不同的氮源浓度。每组测量五次总氮和电阻抗谱（在1至100 kHz频率范围内），每隔一天测量三次。检测并分析了阻抗谱的最小相位角，以及它们出现的频率值和该频率下的幅度。观察到植物氮含量与最小相位角处的频率值之间存在高度正相关，测量天数之间未检测到显著差异。这些结果表明电阻抗可能对植物氮素状况敏感。
