Comparison of hexaploid and tetraploid wheat cultivars in their responses to water stress

We studied the effect of water stress imposed at anthesis and pre-anthesis stages on oxidative stress and antioxidant activity in four wheat cultivars , two hexaploid Triticum aestivum cultivars, drought resistant cv. C 306 an d drought susceptible cv. Hira, and two tetraploid cultivars, T. durum cv. A 9-30-1 and T. dicoccum cv. HW 24. Water stress decreased relative water c ontent (RWC), membrane stability index (MSI), and increased H2O2 and malond ialdehyde (MDA) contents as well as activity of superoxide dismutase (SOD), catalase (Cat) and peroxidase (POX) in all the genotypes at all the stages . Both the tetraploid cultivars showed higher RWC, MSI and SOD activity, an d lower H2O2 and MDA contents under water stress than hexaploid ones. Cat a nd POX activities were highest in C 306.