Study of physiological traits of grass pea with barely in pure and mixed cropping under dry land and irrigated conditions

In order to evaluate some physiological traits such as activity of antioxidant enzymes (Superoxid-Dismutase, Catalase, Glutathione peroxidase) and production of biomarkers (Malon De Aldeide, Dityrozin, Dihydroxy guanozin), an experiment was carried out in two dry land and irrigated conditions at Zanjan Agricultural Research Center during 2007-200. The experiment using two plants grass pea and barely in pure and mixed cropping was designed as randomized complete blocks with five treatments and four replications. Treatments were as fallows: 1. pure stand of barely 2. pure stand of grass pea 3. ratio of 75% grass pea +25% barely, 50% grass pea +50% barely, 25% grass pea +75% barely. Results showed that production levels of biomarkers (MDA, DI-TY, DG) and enzymes activity (SOD, CAT, GPX) and electrical conductivity (EC) were higher in dry land compared to irrigated condition. The measurement of anti-oxydant enxymes as anti-stress enzymes showed that enzymes activity increased with increasing biomarkers production rate in dry condition. In addition, % nitrogen, relative water content (RWC), chlorophyll content a, b in dry condition were lower than irrigated condition. Higher ratio of grass pea and lower ratio of barley in mixed croppings, there were greater enzymes activity (SOD,CAT,GPX), % nitrogen, RWC, chlorophyll a,b, and lower amount of biomarkers (MDA, DI-TY, DG) and EC. With increasing of ratio legume in mixtures, activity of antioxidant enzymes increased and biomarkers production decreased. One reason for increasing activity of antioxidant enzymes in mixcropping with high ratios of legume was due to rhizobium bacteria and effects of these bacteria in increasing free radical oxygens. Therefore, for nitrogen fixation during nodule formation and elimination oxygen free radicals, activity of antioxidant enzymes increased and, thus biomarkers production decreased.