Response of Antioxidant Systems in Common Bean (Phaseolus vulgaris) Plants to Water Stress

Common bean (Phaseolus vulgaris) is an important food crop that is often subjected to water stress conditions, which can negatively impact growth and yield. Antioxidant systems play a crucial role in plant responses to abiotic stresses, including water stress. In this study the effects of the response of antioxidant systems in broad bean plants to water deficit stresses were investigated. The plants were grown for three weeks in plastic pots containing 3 kg of soil and subjected to different soil moisture levels: 2-fold field capacity (waterlogging), 50% and 75% field capacity (water deficit), and one field capacity as a control. The data obtained revealed that the free phenolic compound in shoots and roots of the tested plants was significantly increased as a result of imposed to the levels of water deficit (75% F.C & 50% F.C) as compared to absolute controls. But in roots the free phenolic compound was significantly decreased especially under waterlogging stress. The hydrogen peroxide concentration of bean plants was significantly increased as a result imposed to decrease the soil moisture content WD and WL stresses. There is a marked and progressive increasing in the production of proline in plants shoots as the soil moisture level decreased, therefore the highest accumulation of proline was recorded in plants subjected to the lowest level of soil moisture content DW (50% FC) of the tested plants compared to absolute controls. Specific activity (Umg-1 protein) of catalase, guaical peroxidase and ascorbate peroxidase were significantly raised under high water deficit (50% FC) and waterlogging (2 FC), whereas SOD specific activity in common bean leaves and roots was unchanged under the LWD and HWD stresses while it was significantly increased under WL stress compared to absolute control. Antioxidant compounds and their enzyme activity are important mechanisms enabling plants to cope with drought.