Brunetto, Leonardo creator Galon, Leandro creator Cavaletti, Daniel Cristian creator Munareto, Janete Denardi creator Castamann, Alfredo creator Perin, Gismael Francisco creator text periodical abstract or summary bl. continuing eng ABSTRACT: The study of interference and the economic damage level (EDL) of weeds in crops allows more rational management measures to be adopted. Given this, it was the aim of this study to determine the competitive ability and EDL of quinoa genotypes in the presence of alexandergrass. Treatments consisted of three quinoa genotypes (Q 1303, Q 1331, and Q 1324), which competed with 12 alexandergrass densities: 0, 16, 36, 40, 44, 52, 60, 84, 280, 532, and 1,036; 0, 8, 28, 32, 48, 52, 60, 72, 84, 820, and 988; and, 0, 8, 36, 44, 48, 60, 68, 80, 84, 120, 756, and 848 plants m-2, respectively. Alexandergrass plants were evaluated for plant density (PD), ground cover (GC), leaf area (LA), and aerial dry mass (ADM). In quinoa, grain yield, control cost, selling price, and control efficiency were determined. The quinoa genotype Q 1331 shows greater competitive ability when compared to Q 1303 and Q 1324. EDL values varied from 1.81 to 11.74 plants m-2 for genotype Q 1331, which was more competitive in the presence of alexandergrass. The lowest EDL values ranged from 1.21 to 8.12 plants m-2, for the genotypes Q 1303 and Q 1324, which have the lowest competitiveness with the competitor.. Key words: Chenopodium quinoa; plant interference; Urochloa plantaginea RESUMO: O estudo da interferência e do nível de dano econômico (NDE) de plantas daninhas em culturas permite adotar medidas de manejo mais racional. Diante disso, objetivou-se com este estudo determinar a habilidade competitiva e o NDE de genótipos de quinoa na presença de papuã. Os tratamentos foram compostos por três genótipos de quinoa (Q 1303, Q 1331 e Q 1324), os quais competiram com 12 densidades de papuã: 0, 16, 36, 40, 40, 44, 52, 60, 84, 280, 532 e 1036; 0, 8, 28, 32, 32, 48, 52, 60, 72, 84, 820 e 988; e 0, 8, 36, 44, 48, 60, 68, 80, 84, 120, 756 e 848 plantas m-2, respectivamente. Nas plantas de papuã foram avaliadas a densidade de plantas (DP), cobertura do solo (CS), área foliar (AF) e massa seca da parte aérea (MS). Na quinoa determinou-se a produtividade de grãos, custo de controle, preço de venda e eficiência de controle. O genótipo de quinoa Q 1331 apresenta maior habilidade competitiva ao ser comparado com o Q 1303 e Q 1324. Os valores de NDE variam de 1,81 a 11,74 plantas m-2 para o genótipo Q 1331, sendo esse mais competitivo na presença do papuã. Os menores valores de NDE variam de 1,21 a 8,12 plantas m-2, para os genótipos Q 1303 e Q 1324, os quais apresentam as menores competitividades com o competidor. Palavras-chave: Chenopodium quinoa; interferência de plantas; Urochloa plantaginea Publicação online; 30 ref.; 3 illus.; Summaries (En, Pt) QUINOA GENÓTIPO COBERTURA DO SOLO ÁREA FOLIAR ERVA DANINHA DANO ECONÔMICO Recife-PE Universidade Federal Rural de Pernambuco 2006 2026-2526 1981-1160 BR2026001565 v. 18(1) p. 1-10; (2023) http://www.agraria.pro.br/ojs32/index.php/RBCA/article/view/v18i1a2543/1503 http://www.agraria.pro.br/ojs32/index.php/RBCA/article/view/v18i1a2543/1503 BR-BrBNA 260612 20260612150023.0 eng