EFFECTS OF AROMATIC PLANTS ON POTATO STORAGE - SPROUT SUPPRESSION AND ANTIMICROBIAL ACTIVITY

Sprout suppressant properties of the essential oils of Lavandula angustifolia (lavender), Mentha pulegium (mint), Mentha spicata (spearmint), Origanum onites (Turkish oregano), Origanum vulgare ssp. hirtum (Greek oregano), Rosmarinus officinalis (rosemary), and Salvia fruticosa (sage) were assessed. Except for oregano oils, all other essential oils suppressed potato sprout growth. Those of L. angustifolia, Salvia fruticosa and R. officinalis were the most effective. Application of crude herbs, instead of extracted essential oils, lead to comparable results. The inhibition is reversible, thus allowing subsequent normal sprouting of seed potatoes. The essential oils of the above mentioned aromatic plants, as well as those of Coridothymus capitatus (Spanish oregano), Origanum dictamnus (Cretan dittany), and Satureja thymbra, were also found to possess potent antimicrobial activities against Erwinia carotovora strains and bacteria isolated from the surface of potato tubers. The carvacrol-containing essential oils, and particularly that of Greek oregano, had the strongest effect. Use of aromatic plants could be an effective and safe way to prolong the storage life of potato tubers, at the same time protecting them from certain microbial attacks. This holds, in particular, for regions such as the Mediterranean, where prolongation of tuber dormancy needs more drastic and costly measures, because of the high temperatures. As aromatic plants grow natively and in abundance, their use would be cost-effective.