3.4. Defense-related enzymes activities
PAL activity in control fruit increased within the first 6 d of storage followed thereafter by a slight decline (Fig. 2A). The trend of PAL activity in NO-treated fruit paralleled that of control fruit, but activity was significantly higher than that of control fruit with the exception of initial 2 d (Fig. 2A). C4H activity in control increased within the first 2 d of storage, declined slightly over the next 2 d, and then increased through the end of storage (Fig. 2B). C4H activity in NO-treated fruit exhibited a gradual increase and from 6 to 10 d of storage was markedly higher than that observed in control fruit (Fig. 2B).