Competitive ability of Amaranthus hybridus in coexistence with maize, bean and soybean

This study aimed to evaluate the competitive ability of various maize, bean, and soybean cultivars when coexisting with different densities of Amaranthus hybridus, using a replacement series experiment conducted in completely randomized blocks with four replicates. The competitors included four maize cultivars, four bean cultivars, and two soybean cultivars, all tested against A. hybridus. The replacement series consisted of relative crop-to-A. hybridus ratios of 100:0, 75:25, 50:50, 25:75, and 0:100%, corresponding to 20:0, 15:5, 10:10, 5:15, and 0:20 plants per pot, respectively. Competitive ability was assessed using diagrams and relative competitiveness indices. Fifty days after plant emergence, the morphophysiological characteristics of the competing species were determined. Results indicate a negative impact on all species, with both the crop plants (maize, beans, and soybeans) and A. hybridus suffering due to competition for the same environmental resources. Interspecific competition was found to be more detrimental than intraspecific competition. Maize and bean cultivars showed greater competitive ability against A. hybridus, whereas soybeans were more adversely affected by the presence of the competitor.