Respostas morfofisiológicas e nutricionais de cultivares de feijoeiro em competição com capim-amargoso

Abstract

Studies that explore the competitive interaction between common bean and weeds are important to adopt more efficient management practices in crops and thereby reduce production costs. Therefore, the objective of this study was to evaluate the relative competitive ability of common bean cultivars in the presence of sourgrass (Digitaria insularis) at different plant proportions in the associations. The experiments were conducted in a greenhouse using a randomized complete block design with four replications. The treatments were arranged in proportions of common bean and sourgrass plants: 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. The analysis of species competitiveness was conducted through diagrams applied to substitution experiments, as well as relative competitiveness indices. At 50 days after species emergence, measurements were taken for leaf area, height, shoot dry mass of the plants, gas exchange, and nutrient concentration (nitrogen, phosphorus, potassium, and carbon) in the leaves of the common bean cultivars. Equivalent competition mechanisms and demand for environmental resources were observed between common bean and the weed when in a community. The common bean cultivars BRS Esteio, IPR Uirapuru, IPR Urutau, BRS Estilo, IAC 1850, and IPR Tangará showed similarity in competitive ability when associated with D. insularis. Gas exchange in the common bean was negatively affected by increased competitor plant density. The common bean showed greater relative growth than the weed when in association. Nutrient levels in the common bean were negatively impacted by increased D. insularis plant density. Interspecific competition caused greater damage to morphological, physiological, and nutritional variables of both species compared to intraspecific competition, indicating a basic competition for the same environmental resources between common bean and the weed.