Allelopathic investigations in the Fraxino angustifoliae-Quercetum robojus ( Jov. et Tomic 1979) forest community with the autumnal truffle (Tuber macrosporum Vitt.)

Abstract

Both the total phenols and phenolic acids (PA) were analyzed in the litter and soil of the mixed Quercus robur-Fraxinus angustifolia forest with the autumnal truffle (Tuber macrosporum Vitt.). These compounds are the main allelopathic products of host plants of ectomycorrhizal fungi. Fresh litter, mostly composed of falling leaves of pedunculate oak (Quercus robur) and ash tree (Fraxinus angustifolia), is rich in bound (12.39 mg/g) as well as free (12.43 mg/g) forms of phenolics. Partially decomposed litter had significantly lower amounts of phenolics. The soil in investigated forest is non-calcareous. This is in disagreement with available literature sources which emphasize that autumnal truffle exclusively grows on calcareous soils. Amounts of both PA and total phenolics decrease with increasing soil depth. The greatest proportion of the truflle's fruit bodies (nearly 30 kg/ha/year) is located in surface (phenolics-rich) soil horizon, so it may be assumed that Tuber macrmporum Vitt. is well adapted to high concentrations of phenolic compounds. The fruit body of autumnal truffle is rich in free (243.6 µg/g) and bound (349 µg/g) phenolics. Considering PA, however, only small amounts of vanillic acid were detected in the truflle.