Relative Competitiveness of Protoporphyrinogen Oxidase-Resistant Common Waterhemp (Amaranthus Rudis)

Abstract Research was conducted to determine the competitiveness and fitness of a protoporphyrinogen oxidase (protox)-resistant common waterhemp biotype. Protox-resistant and protox-susceptible biotypes were grown under noncompetitive and competitive arrangements in the greenhouse. In the noncompetitive study, a single plant of each biotype was planted separately in 15-cm-diam pots. Photosynthesis, leaf area, and plant biomass were measured 10, 20, 30, and 40 d after transplanting (DATP). In general, photosynthesis rate and plant biomass were similar between biotypes. However, the protox-resistant biotype had higher leaf area than the susceptible biotype at 20, 30, and 40 DATP. A replacement series study was conducted in the greenhouse to evaluate the relative competitiveness of protox-resistant and protox-susceptible common waterhemp. Photosynthesis, leaf area, plant height, and plant biomass were measured 7, 14, 21, and 28 DATP. Protox-resistant and -susceptible common waterhemp were equally competitive...