Morphophysiological responses of bean cultivars in competition with Conyza bonariensis

Abstract

ABSTRACT Weeds are responsible for large losses in grain quality and quantity of beans produced. Therefore, studies on competition between beans and weeds are important to achieve more efficient crop management while reducing the use of herbicides. Thus, the aim of this work was to evaluate the competitive ability of bean cultivars (BRS Estilo, IPR Urutau, IAC 1850 and IPR Tangará) in the presence of hairy fleabane (Conyza bonariensis) with different proportions of plants in the association. The experiments were conducted in a greenhouse in a randomized block design with four replicates. The treatments were arranged in different proportions of common bean and hairy fleabane plants: 20:00, 15:5, 10:10, 5:15, and 0:20 plants pot-1. The competitive ability of the species was analyzed using diagrams applied in substitution experiments and relative competitive ability indices. Plant height, stem diameter, leaf area, gas exchange and shoot dry matter were measured 40 days after plant emergence. Negative effects were observed for both the crop and hairy fleabane, as both species competed for the same resources available in the environment. Interspecific competition caused greater damage to plant height, stem diameter, leaf area and dry matter of the species than intraspecific competition. Common bean achieved higher photosynthetic rates and water use efficiency in the presence of hairy fleabane. Common bean cultivars have a greater competitive ability against hairy fleabane.