Early detection of the false root knot nematode (Nacobbus aberrans) infection in greenhouse cultivated tomatoes by infrared spectroscopy

Abstract

Tomato (Solanum lycopersicum L.) is the second most important horticultural crop after potato, one of the main problems in the cultivation of tomato is the presence of phytopathogenic nematodes that cause annual losses of millions of dollars worldwide. For that, a fast and simple way of nematode presence determination is desirable for timely disease control. Infection of tomatoes cultivated in soil inside greenhouses in two consecutive years of cultivation was analyzed by MIR. Leaves of healthy and Nacobbus aberrans nematode-infected tomato plants were evaluated for 112 and 54 days (first and second cultivation year, respectively) by mid infrared (MIR) spectroscopy, and spectral differences were found mainly in the 900-1200 cm−1 region, associated to CO bonds; in this region the behavior of four absorbance peaks were followed in time, finding that the first 20 days after infection was the main ones to determine nematode presence. Phenotypically infected plants had a lower height than control plants from 24 to 55 days post infection.By chemometric analysis applying Principal Component Analysis of the MIR spectra, it was possible to differentiate between healthy from Nacobbus aberrans infected plants since day 3 after infection, which correlated well with the experimental results. This study proved the efficacy of using infrared spectroscopy as a non-destructive tool for early detection of phytoparasitic nematodes in tomato plants.

Keywords

• Chemometrics analysis
• Non-destructive testing
• Tomato disease