Seed-surface disinfection and germination effects of grapefruit seed extract (GSE) on Lactuca sativa seeds

Abstract

It investigated that the seed sterilization and germination effects on Lactuca sativa seeds of two commercially available grapefruit seed extracts (GSEs) from the USA and Brazil. The total bacterial counts in the 0.05% GSE (USA) treatment groups were 0.0 CFU/g for all tested incubation times (1-6 h). All GSE treatments groups (from both the USA and Brazil) showed no or slightly harmful effects on L. sativa seed germination and seedling growth after 24 and 48 h. Additionally, seeds treated with 0.05% GSE showed slightly stronger anti-germination effects and seedling growth inhibition than those treated in a solution of the same concentration but with the pH adjusted to 7.0. We also evaluated the anti-germination effects of naringin, quercetin, and citric acid on L. sativa seeds to identify the active compounds in GSE. We observed no anti-germination effects in the naringin-treated group. In the quercetin-treated group, there was a slight dose-dependent anti-germination effect (0.01-0.1%). In groups treated with 0.01% and 0.05% citric acid (pH 4.79 and 4.03, respectively), no and slight anti-germination effects, respectively, were observed. However, there were strong anti-germination effects among seeds treated with 0.1% citric acid (pH 4.79). We found that 0.05% GSE (from both the USA and Brazil) had strong seed sterilization effects and no anti-germination effects. Together, these results indicate that GSE may be useful as a treatment for seed sterilization without inhibiting seed germination or seedling growth.