4. Phytotoxicity assays
4.1. Garlic germination study
Phytotoxic effects on roots and leaves of EOs are shown in Table 4. NPEOs were considered those that inhibit the growth of roots and leaves by less than 50%. Significant differences were found in the length of roots and leaves when they were exposed to EOs. The lowest inhibitions in radicle and leaves elongation were observed when garlic cloves were treated with An and Ba (15.19% and 30.0% and 22.78% and 29.68%, respectively). The growth of roots and leaves was partially inhibited in treatments with Su. On the other hand, OCom and OMen inhibited completely roots and foliar growth, presuming toxic effects on garlic. Some terpenes usually show a suppressing effect on germination and seedling growth. The toxic effect of OCom and OMen can be attributed to their main components, thymol and carvacrol, which have been documented as potential herbicides against various plant species (Kordali et al., 2008; Pérez-Vásquez et al., 2008).