Fig. 3

Effects of sound on the pericarp integrity of maize seeds. a Schematic representation of the samples analyzed. Seeds were placed in water during 8 h in silence (Control, white columns) and then subjected to 10 h of 300 Hz 80 dB at 22 °C in the dark (Sound, black columns) or the same conditions except in silence (Silence, grey columns), and were left germinate in silence at 22 °C in the dark. Germination percentages were measured at 7 days. Radicle protusion was taken as the criterion for germination. b Quantification of the pericarp damages using Fast-green staining. Three types of damage were considered: slight, medium and severe. White columns correspond to initial non-germinated Control seeds, grey columns to Silence treatment controls and black columns to Sound treatment. The results shown represent the mean of 10 independent experiments. Vertical bars indicate standard error. Asterisks indicate significant differences respect to the control (untreated seeds) according to the T test (p < 0.05). c Examples of the types of damages observed in the sound treated maize seeds. Damage was measured by Fast green staining. Slight damage correspond to seeds with small areas of fast green staining in their surface (1). Medium damage correspond to seeds showing large areas of fast green staining (2). Severe damage correspond to seeds showing cracks or severe physical damages (3)