Modulation of antioxidant defense system and polyamine catabolism in rice leaves under two planting conditions

Aerobic rice offers an attractive alternative approach over transplanting system as it consumes less water with low labour expenses. Flag leaf of six rice cultivars, viz. PR 120, PR 115, PR 116, Feng Ai Zan, PAU 201 and Punjab Mehak 1 was analysed for antioxidant defence mechanism and polyamine catabolism under the aerobic and the transplanting conditions. Ascorbate peroxidase (APX), guaiacol peroxidase (GPX), catalase (CAT), superoxide dismutase (SOD), diamine oxidase (DAO) and polyamine oxidase (PAO) activities increased gradually from tillering to anthesis stage and then declined towards maturity stage under both planting conditions. Apparently, contents of ascorbic acid, α-tocopherol, proline and polyamines (PAs) also revealed similar trend. The aerobic condition elevated activities of PAO, SOD as well as contents of PAs, lipid peroxide and H2O2 whereas the transplanting condition had higher levels of APX, GPX, CAT and total antioxidant activities and contents of ascorbate, α-tocopherol and proline. C...