Effects of exogenous application of five antioxidants on vigour, viability, oxidative metabolism and germination enzymes in aged cabbage and lettuce seeds

Ageing induces modifications capable of compromising seed vigour and viability. This study investigated the effects of exogenous application of five antioxidants: ascorbic acid (AA), gallic acid (GA), reduced glutathione (GSH), trolox and glycerol, on physical and biochemical lesions induced by controlled deterioration (CD) in Brassica oleracea (cabbage) and Lactuca sativa (lettuce) seeds. The antioxidants were applied at 0.2, 0.4 and 0.6 mM to fresh seeds and seeds subjected to CD: 75% viability (P75), 50% viability (P50) and 25% viability (P25); deionised water (DW) served as control. Controlled deterioration resulted in more abnormal seedlings production in cabbage than in lettuce seeds. Additionally, CD increased electrical conductivity (EC) and protein carbonylation (PC), lowered antioxidant and germination enzymes activities in both species but increased lipid peroxidation in lettuce seeds only. Exogenous application of antioxidants enhanced seed viability of cabbage at P25 and lettuce at P50 and P25; seedling vigour of fresh, P75 and P25 cabbage; P50 and P25 lettuce seeds. Electrolyte conductivity and lipid peroxidation were reduced by AA, GA, glycerol, GSH and trolox in lettuce seeds, while PC was reduced by GA, glycerol and GSH in both species