Early instrumental Diagnostics of fungal infections in wood
S. R. Loskutov, E. A. Tyutkova, M. A. Plyashechnik, E. A. Petrunina, O. A. Shapchenkova, A. A. Aniskina
V. N. Sukachev Institute of Forest, Russian Academy of Sciences, Siberian Branch Federal Research Center Krasnoyarsk Scientific Center, Russian Academy of Sciences, Siberian Branch, Krasnoyarsk, Russian Federation
Keywords: Scotch pine Pinus sylvestris L. wood, early stage of fungal infestation, FTIR spectroscopy, scanning electron microscopy
Abstract
The changes in the physico-chemical parameters of Scotch pine Pinus sylvestris L. wood were studied at an early stage of a fungal infection development in it using the methods of IR-Fourier spectroscopy and scanning electron microscopy (SEM). Analysis of SEM-images of locally damaged wood showed the presence of hyphae both in the intercellular space and in the lumens of single tracheids. From the comparison of the results of analyses of damaged and healthy wood, a number of parameters of the IR spectra were established - a change in the ratio of the absorption intensity at characteristic frequencies (wave numbers, cm-1) for polymers of wood substance (hemicellulose, cellulose, lignin) and fungi (chitin and glucans) I 1512/898, I 1512/1157, I 1512/894, I 1647/1551, I 1695/1533, I 1620/1564, which allows identifying the presence and degree of exposure to fungal infection on wood. A new version of the assessment of changes in the structure of the wood substance is presented, which consists in a comparative analysis of the second derivatives of the IR absorption spectra of sound and damaged wood. The method significantly improves not only the visualization of changes in the spectra, but also allows to more accurately determine the «addresses» of the impact of a fungal infection on the wood substance by the intensity and frequency of the absorption bands. In addition, it can be used to monitor the appearance of nitrogen-containing compounds because of the presence of fungi. The implemented methodological techniques indicate the possibility of using radial cores in the work for the purpose of conducting their conjugate analysis, «linking» the results of IR-Fourier spectroscopy to the parameters of the annual rings and, in general, to chronologies, as well as correlating them with the morphological and anatomical structure of the annual ring and individual tracheids according to scanning electron microscopy data. The proposed approach to the diagnosis of wood damage at an early stage of the development of a fungal infection is effective, rapid and does not require complex sample preparation
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