Interference of Volunteer Corn on Stress Metabolism and Yield of Dry Beans

Dry bean cultivation after corn favors the occurrence of volunteer corn plants which interfere with the crop and cause yield losses of thy bean. Yield losses resulting from interferences caused by corn may be related to oxidative stress, which in turn, is caused by the higher production of reactive oxygen species (ROS), such as hydrogen peroxide (H2O2). This work aimed to quantify H2O2 contents, and the activity of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) in thy beans under interference with densities of volunteer corn F-2 originated from individual plants and clumps (seven corn plants emerged at the same point). Two experiments were carried out in a randomized blocks design with three replicates in Passo Fundo - RS, Brazil. Enzyme analysis was performed in a laboratory at 21, 35 and 46 days after dry bean emergence (DAE). Corn densities were 0, 0.5, 1, 2, 4, 8 and 12 plants or clumps m(-2). The results show changes in H2O2 levels and in the activity of SOD, CAT, and APX enzymes with the increase of corn densities, in which the highest activity occurred for SOD. The interference of volunteer corn with thy beans alters the stress metabolism of thy bean but does not cause oxidative stress. The yield of dry beans reduced under interference with volunteer corn F-2 but it is higher when the corn was originated from clumps.