Conditioning and Germination Control bio-assays of Quercus suber L. acorns under the allelopathic and Residual effects of Volatile Oils and Hydrolates from Aromatic Plants in Northeastern Algeria

Abstract

The present works reported a new technique for conditioning and controlling the germination of healthy Quercus suber L. acorns under the antifungal, allelopathic and residual effects of five volatile oils and their hydrolates obtained by hydrodistillation of plant material and then were subjected to a GC/MS to identify their chemical composition. Monoterpenes were found to be dominant in both oils with amount ranging between 57.59 and 98.88%, followed by sesquitepenes (1.28- 40.07%), whereas ditepenes were found only in Pistacia lentiscus L. volatile oil (15.54%). Pistacia lentiscus L. and Myrtus communis L. volatile oils had the potent antifungal and fungistatic activity where no contamination were registered, a contamination percentage of 10% succeeded by a fungistatic effect was registered in both oils from Calamintha hispidula Boissier and reuter., Lavandula dentata L. and Eucalyptus camaldulensis Dehnh, whereas the control exhibited the weakest antifungal activity with 70% of contamination. Moreover, early germination during storage was more inhibited by volatile oils (10- 20%) than by the control (50%). Hydrolates were less effective than volatile oils in both fungi-infestaion (10- 80%) and germination (50- 90%). The second bio-assay conducted in non allelopathic conditions revealed that acorns previously treated by both volatile oils and hydrolates have resumed their germination with respective increases of 30 to 80% and 10%, respectively. Radicle elongation was, however, more pronounced for Hydrolates (0.13 - 0.62cm) than for volatile oils (0.06- 0.44cm). Owing to the antifungal, fungistatic and stimulating effects observed, the results of this study may help to develop new plant-based biocide for the control of fungi-infestation and early germination limiting the long-term safe storage of acorns.