OXIDATIVE DEFENSE SYSTEMS IN LEAVES OF 3 EDIBLE HERB SPECIES IN RELATION TO THEIR SENESCENCE RATES

Correlation studies between leaf senescence rates of three edible herb species, watercress (Rorippa nasturtium-aquaticum), parsley (Petrosel ium crispum), and sage (Salvia officinalis L.), and their oxidative de fense systems were conducted with detached leaves under simulated shel f-life storage conditions. The relative order of leaf senescence rate, based on their rate of chlorophyll (Chl) degradation and malondialdeh yde accumulation, was watercress > parsley > sage. However, all three herb species showed high proteolysis rates from the first day of incub ation. Of five oxidative defense systems examined in the three herb sp ecies, only the system of total reducing capacity correlated well with their relative order of Chl degradation and could therefore predict t heir storage potential. The results indicate that each herb species ha s developed specific oxidative defense systems, which may also prevent rapid Chl loss but do not affect proteolysis. It seems, therefore, th at among the various components of the senescence syndrome, Chl breakd own is closely linked to lipid oxidation, while proteolysis seems to p roceed independently of these two senescence-associated processes.