In our study, ethylene production decreased with increasing MeJA concentrations (Fig. 4). Thus, lower germination percentage due to MeJA treatment can be attributed to lower production of ethylene. It is known that MeJA and ABA are able to inhibit the conversion of ACC to ethylene, and this inhibitory effect increased with increasing the concentration of both growth regulators (Bailly et al., 1992).
In conclusion, our data showed that decreased α-amylase activity and/or concentration as well as reduced ethylene production plays significant roles in the physiological and biochemical processes underlying inhibited seed germination and root elongation in maize under conditions of increased MeJA concentrations.