Antioxidation responses of maize roots and leaves to partial root-zone irrigation

Antioxidation responses of maize roots and leaves to water deficit and rewatering under partial root-zone irrigation (PRI) were investigated using a pot system. Plants were cultured using three irrigation methods, i.e. conventional irrigation (CI), alternate PRI (APRI) and fixed PRI (FPRI) with three different water regimes including W1 (70% field capacity, FC), W2 (50% FC) and W3 (35% FC). Compared to CI, root peroxidases (POD) activity was enhanced in the irrigated root zone of FPRI and both root zones of APRI during mild water deficit. After rewatering, POD activity was increased in the dry root zone under FPRI but reduced in the roots under APRI. Roots in the dry zone and leaves under FPRI remained high superoxide dismutase (SOD) activity after rewatering. In contrast, SOD activity decreased in the roots and leaves under CI and APRI. Malondialdehyde (MDA) contents were increased in leaves and two sub-roots under FPRI during water deficit and remained higher after rewatering compared to those under CI and APRI. MDA contents in the tissues under APRI showed similar levels to those under CI. Compared to CI, APRI showed the same biomass production, achieving significantly higher water use efficiency under mild water deficit. The results suggested that plants under APRI experienced less oxidative stress or damage induced by water deficit.