The co-occurrences of biotic and abiotic factor stresses were studied on winter wheat cv. “Tonacja”. In the first experiment the controlled infestation by Fusarium spp. and water stress were applied, and in the second experiment Fusarium spp. and various light intensities were given to winter wheat plants. The objective of this study was to determine how wheat’s emission of volatile organic compounds (VOCs) depends on the biotic/abiotic factors.
In the first experiment, nine VOCs were indicated as a result of Fusarium spp. infestation; three of the terpenoids (linalool, β-caryophyllene and β-farnesene) and six green leaf volatiles (GLVs) ((Z)-3-hexenal, (E)-2-hexenal, (Z)-3-hexen-1-ol, (E)-2-hexen-1-ol, 1-hexyl acetate, and (Z)-3-hexen-1-yl acetate). Total amount of VOCs emitted by wheat reached 4-610 ng·h^-1 plant d. wt^-1. Control plants (not infested) released a significantly lower amount of volatiles than diseased. Water regimes, established as the plant available water capacity (PAWC), range from 40 to 80%, caused the increasing emission of VOCs by diseased plants. Wheat that suffered from water stress (40% PAWC) emitted the greatest amount of GLVs of all control plants. Meanwhile, diseased wheat at drought also emitted terpenoids.
In the second experiment ten compounds were indicated (linalool, β-caryophyllene, benzyl acetate and (Z)-ocimene and six GLVs listed in the first experiment) as a result of Fusarium infestation in various light conditions. As light intensity increased from 65 to 295 μmol·m-²·s^-1, the diseased wheat plants produced from 27 to 337 ng·h^-1 plant d. wt^-1 of terpenoids and from 20 to 1,008 ng·h^-1 plant d. wt^-1 of GLVs. Diseased plants subjected to the highest light intensity (295 μmol·m^-2·s^-1) released 45-fold more VOCs than control plants. This can suggest that stress caused by Fusarium spp. at higher light intensity multiplied the production of VOCs by wheat.