RESUMO
Bulk nanobubbles, measuring less than 200 nm in water, have shown their salient properties in promoting growth in various species of plants and orthodox seeds, and as potential drug-delivery carriers in medicine. Studies of recalcitrant seeds have reported markedly increased germination rates with gibberellin treatment; however, neither the mechanism promoting germination nor the implication for food safety is well elucidated. In our study, recalcitrant wasabi (Eutrema japonicum) seeds treated with bulk oxygen nanobubbles (BONB) containing K+, Na+, and Cl- (BONB-KNaCl) showed significantly accelerated germination. As germination progressed, 99% of K+ ions in the BONB-KNaCl medium were absorbed by the seeds, whereas Ca2+ ions were released. These results suggest that the germination mechanism involves the action of K+ channels for migration of K+ ions down their concentration gradient and Ca2+ pumps for the movement of Ca2+ ions, the first potential discovery in germination promotion in recalcitrant seeds using nutrient solutions with BONB-KNaCl.
