An Analysis of Electrical Impedance Measurements Applied for Plant N Status Estimation in Lettuce (Lactuca sativa)
Rafael F. Muñoz-Huerta,
Antonio de J. Ortiz-Melendez,
Ramon G. Guevara-Gonzalez,
Irineo Torres-Pacheco,
Gilberto Herrera-Ruiz,
Luis M. Contreras-Medina,
Juan Prado-Olivarez,
Rosalia V. Ocampo-Velazquez
Affiliations
Rafael F. Muñoz-Huerta
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
Antonio de J. Ortiz-Melendez
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
Ramon G. Guevara-Gonzalez
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
Irineo Torres-Pacheco
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
Gilberto Herrera-Ruiz
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
Luis M. Contreras-Medina
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
Juan Prado-Olivarez
Departamento de Ingeniería Electrónica, Instituto Tecnológico de Celaya, Av. Tecnológico y García Cubas S/N, 38010 Celaya, Gto., Mexico
Rosalia V. Ocampo-Velazquez
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
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.
