Development of fast E-nose system for early-stage diagnosis of aphid-stressed tomato plants

Authors: CUI, SHAOQUING - The Ohio State University; INOCENTE, ELVIA A - The Ohio State University; ACOSTA, NURIS - The Ohio State University; KEENER, HAROLD - The Ohio State University; Zhu, Heping; LING, PETER - The Ohio State University

Submitted to: Sensors
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/9/2019
Publication Date: 8/9/2019
Citation: Cui, S., Inocente, E.A., Acosta, N., Keener, H.M., Zhu, H., Ling, P.P. 2019. Development of fast E-nose system for early-stage diagnosis of aphid-stressed tomato plants. Sensors. 19(16):3480. https://doi.org/10.3390/s19163480.
DOI: https://doi.org/10.3390/s19163480

Interpretive Summary: Early detection of infested and infected plants prior to the onset of visual symptoms can assist growers to choose appropriate pest manage strategies to reduce economic and production losses. In this research, an electronic nose system (E-nose) with a set of sensitive sensor array was designed for diagnosing aphid infested tomato plants at early stages. The system was preliminarily tested for its capability to distinguish volatile organic compounds released from aphids-stressed tomato plants from heathy plants at the beginning of infestation under greenhouse conditions. A gas chromatography–mass spectrometry instrument was used to verify the analyses of volatile compounds identified with the E-nose. Test results illustrated that tomato plants infested by aphids released new volatile compounds for combating aphid attacks. These new compounds could be used as the bio-markers for the E-nose to identify infested plants. Further investigations are needed to quantify the new volatile compounds released from different varieties under different growth conditions to improve the E-nose sensitivity and reliability.

Technical Abstract: An electronic nose (E-nose) system equipped with a set of sensitive sensor array was developed for a fast diagnosis of aphid infestation at early stages in tomato plants growing in greenhouse. Volatile Organic Compounds (VOCs) of tomato plants with and without aphids were detected by the E-nose system and gas chromatography mass spectrometry (GC-MS), respectively. Sensor performances with fast sensor responses and high sensitivity were observed using the developed E-nose system. An accurate diagnosis of aphids-stressed plants differing from healthy plants was clearly achieved based on Principle Component Analysis (PCA) with the two PCs accounted for 86.7% classification. The changes of VOC profiles for infested tomato plants were quantitatively determined by GC-MS. Results indicated that a group of new VOC bio-markers (linalool, carveol, and nonane 2,2,4,4,6,8,8-heptamethyl-) played info-chemical roles in the tomato-aphids interaction. More importantly, the variation of the concentration of sesquiterpene VOCs (e.g., caryophyllene) and the appearance of new terpene alcohol compounds explained the sensor behaviors during E-nose tests, certificating the reliability and accuracy of the developed E-nose system. The VOCs of tomato plants growing in spring show similar profiles as that of plants growing in winter, except several terpenes of spring plants presenting a slightly higher intensity.