University of Tabriz Journal of Agricultural Science and Sustainable Production 2476-4310 33 1 2023 04 21 Evaluation of competitive ability for three rice (Oryza sativa L.) cultivars in different barnyard grass (Echinochloa crus-galli L.) densities Evaluation of competitive ability for three rice (Oryza sativa L.) cultivars in different barnyard grass (Echinochloa crus-galli L.) densities 319 329 16197 10.22034/saps.2023.46271.2686 FA Mehdi Alizadeh Afrozi Graduated Student, Department of Agronomy, Sari University of Agricultural Sciences and Natural Resources, Sari, Iran Rahmat Abbasi عضو هیات علمی Seyyed Yousef Mousavi Toghani Educational Expert., Department of Agronomy, Sari University of Agricultural Sciences and Natural Resources, Sari, Iran. Journal Article 2021 05 29 This study was performed to investigate the response of three rice cultivars in competition with barnyard grass densities and to select a suitable cultivar with the ability to more competitive. The experiment was conducted as a factorial arrangement based on randomized complete block design (RCBD) with three replications in Babol, Iran, in 2018. Factors included rice cultivar (Tarom Hashemi, Fajr, and Neda) and barnyard grass density (0, 10, 20, 30, and 40 plants m-2). The results showed that the Biomass of barnyard grass and rice yield were affected only by the simple effects of rice cultivar and barnyard grass density. The Biomass of barnyard grass in Fajr and Neda cultivars compared to the Tarom Hashemi cultivar decreased by 28 and 35%, respectively. The amount of barnyard grass biomass increased by 18, 49 and 67% at densities of 20, 30 and 40 plants compared to the density of 10 plants m-2 of barnyard grass. The highest and lowest rice grain yield was obtained in Neda (779 g m-2) and Tarom Hashemi (297 g m-2) cultivars, respectively. The amount of increase in rice grain yield in Fajr and Neda varieties compared to Tarom Hashemi cultivar was 133 and 162%, respectively. Also, grain yield decreased up to 2, 7, 12, and 24%, respectively, at 10, 20, 30, and 40 barnyard grass m-2 with 493 g m-2. This study was performed to investigate the response of three rice cultivars in competition with barnyard grass densities and to select a suitable cultivar with the ability to more competitive. The experiment was conducted as a factorial arrangement based on randomized complete block design (RCBD) with three replications in Babol, Iran, in 2018. Factors included rice cultivar (Tarom Hashemi, Fajr, and Neda) and barnyard grass density (0, 10, 20, 30, and 40 plants m-2). The results showed that the Biomass of barnyard grass and rice yield were affected only by the simple effects of rice cultivar and barnyard grass density. The Biomass of barnyard grass in Fajr and Neda cultivars compared to the Tarom Hashemi cultivar decreased by 28 and 35%, respectively. The amount of barnyard grass biomass increased by 18, 49 and 67% at densities of 20, 30 and 40 plants compared to the density of 10 plants m-2 of barnyard grass. The highest and lowest rice grain yield was obtained in Neda (779 g m-2) and Tarom Hashemi (297 g m-2) cultivars, respectively. The amount of increase in rice grain yield in Fajr and Neda varieties compared to Tarom Hashemi cultivar was 133 and 162%, respectively. Also, grain yield decreased up to 2, 7, 12, and 24%, respectively, at 10, 20, 30, and 40 barnyard grass m-2 with 493 g m-2. https://sustainagriculture.tabrizu.ac.ir/article_16197_ea7ea156a308d9212a547497b0ffd195.pdf