Influence of thyme (Thymus vulgaris L.) and eucalyptus (Eucalyptus globulus Labill.) essential oils on growth, flowering and peroxidase activity of gladiolus

This experiment was done to investigate effect of Thyme (Thymus vulgaris L.) and Eucalyptus (Eucalyptus globulus Labill.)essential oils on gladiolus. Gladiolus is one of the most important ornamental plants whose production is threatened by Fusarium corm rot. Essential oils of Thyme and Eucalyptus are recommended as alternative for chemical fungicides for corms disinfection, but there is not considerable investigation about potential effects of these essential oils on growth and flowering of gladiolus in the greenhouse or field conditions. For this purpose, gladiolus corms were soaked at three concentrations of essential oils of Thyme (1000, 2000 and 3000 ppm) and Eucalyptus (2000, 4000 and 6000 ppm), and distilled water (control) for 14 hours before planting. The results showed that Thyme treatment at 1000 ppm increased the number of leaf and floret, root length, corm and cormlet production, and accelerated flowering. Other treatments delayed the sprouting and flowering time and significantly decreased sprouting percentage, height and number of leaves, root length, and chlorophyll content. Eucalyptus essential oil at concentrations more than 2000 ppm had negative effects ongladiolus, so that corm sprouting and flowering were inhibited at 6000 ppm and 4000 pp, respectively. Peroxidase enzyme activity increased after treatment with both essential oils but with a different trend. The activity of this enzyme in corms treated with thyme remained at a high level during the growth period; however, in corms treated with eucalyptus it was decreased significantly.