Interseeding corn and alfalfa allows farmers to replace the low yielding alfalfa establishment year with corn silage, while simultaneously establishing alfalfa. Field experiments were conducted to 1) identify the critical period of weed control (CPWC), 2) analyze the role light plays (upright vs. pendulum corn hybrid light interception) in the CPWC, 3) determine interseeding and weed competition effects on corn-alfalfa yield and quality, and 4) evaluate weed population dynamics. The CPWC was determined to be 303 and 369 GDD for interseeded corn and alfalfa. Duration of weed competition reduced corn silage yield and quality and alfalfa yield; however, it did not reduce alfalfa quality. Weed seed viability decreased in the interseeded system compared to monoculture corn system. In general, interseeding these two crops will result in limited light quantity and changes in light quality; thus, it is important to understand the possible underlying stress mechanisms interseeded corn and alfalfa use to detoxify light stress. Therefore, to further understand the stress experienced by plants in the interseeded system, it is important to: 1) determine reactive oxygen species (ROS) responses in interseeded corn and alfalfa, which was addressed in a greenhouse study evaluating ROS scavenging enzymes including glutathione S-transferase, dehydrascorbate reductase, and superoxide dismutase activity. Overall, ROS scavenging enzyme rates were modified by level and duration of plant competition.
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