Use of Raman spectroscopy for determining the effects of herbicides on the carotenoid content in Chenopodium album and Abutilon theophrasti leaves

Raman spectroscopy has so far proved to be a suitable method for the analysis of carotenoids in a wide range of plant samples. This study aimed to determine whether the influence of mesotrione on the changes in carotenoid content of leaves in treated weed species Chenopodium album and Abutilon theophrasti can be detected using Raman spectroscopy. When the plants reached the targeted growth stages (C. album: 4 leaves, A. theophrasti: 2 leaves), Skaut herbicide (a.i. mesotrione 480 g l-1, SC) was applied in the amount of 120 g a.i. ha-1 in the tank mix with the adjuvant Alteox wet 40 (a.i. mineral oil (500 g L-1) + polyoxy alcohol (500 g L-1)), in the amount of 1 L ha-1. Leaf analysis, using Raman spectroscopy, was performed four times: on the 1st, 2nd, 3rd, and 7th day after the application of mesotrione. The intensity of the bands in the obtained Raman spectra, at positions 1007, 1155, and 1522 cm-1 in untreated and treated plants was analysed to determine the relative carotenoid content. The obtained results have shown that changes in the relative carotenoid content in the leaves of treated C. album plants can be detected as early as 3 days after the application of mesotrione, compared to the leaves of untreated plants of the same age. Meanwhile, a statistically significant difference for the same parameter in the leaves of treated A. theophrasti plants was evident at a later stage than in C. album, on the 7th day after the application of mesotrione. Consequently, this study has confirmed that Raman spectroscopy can be used as an adequate method for the rapid detection of the effect of herbicides on the content of carotenoids in the leaves of treated weed species.