ABSTRACT New technologies developed to control weeds in crops have flourished in recent years. Therefore, the objective of this work was to study the competitive ability of maize hybrids 2B433 (Enlist®), Pioneer 30F53 (VYHR®), and 13K288 PWE (Enlist®) and a conventional (non-transgenic) variety with a distinct biotechnological background when competing against wild poinsettia (Euphorbia heterophylla) and Alexandergrass (Urochloa plantaginea). Crops and competitors were studied in distinct plant proportions: 20:0, 15:5, 10:10, 5:15 and 0:20 plants per pot or 100:0, 75:25, 50:50, 25:75, and 0:100% (crop:weed) in replacement series experiments. Fifty days after emergence, the leaf area and aboveground dry mass were measured. Concomitantly, the photosynthetic and carboxylation efficiency and CO2 concentration were assessed in the leaf mesophyll. Maize hybrid 2B433 (Enlist®) showed better physiological and morphological performance compared to the conventional variety, and hybrids 13K288 PWE (Enlist®) and 30F53 (VYHR®) showed better performance when competing with wild poinsettia or Alexandergrass. The increased competitive ability seems to be due to the greater leaf area and aboveground dry mass reported for 2B433 (Enlist®). Therefore, the competitive ability presented by the hybrids was distinct, and we found no evidence that the transgenic event present in these hybrids affected their competitive ability. years Therefore B 2B43 Enlist®, Enlist Enlist® , F 30F5 VYHR®, VYHR VYHR® K 13K28 (Enlist® nontransgenic non (non-transgenic Euphorbia heterophylla Urochloa plantaginea. plantaginea . plantaginea) proportions 200, 200 20 0, 0 20:0 155, 155 15 5, 5 15:5 1010, 1010 10 10, 10:10 515 5:1 020 0:2 1000, 1000 100 100:0 7525, 7525 75 25, 25 75:25 5050, 5050 50 50, 50:50 2575, 2575 75, 25:75 0100% 0100 100% 0:100 cropweed crop weed (crop:weed experiments emergence measured Concomitantly CO mesophyll (VYHR® Enlist®. 2B4 30F 13K2 (Enlist 2 20: 1 15: 101 10:1 51 5: 02 0: 100: 752 7 75:2 505 50:5 257 25:7 010 0:10 (VYHR 2B 13K 10: 75: 50: 25: 01 0:1

RESUMO Novas tecnologias desenvolvidas para controlar plantas daninhas nas lavouras surgiram nos últimos anos. Diante disso objetivou-se com o trabalho estudar a habilidade competitiva dos híbridos de milho 2B433 (Enlist®), Pioneer 30F53 (VYHR®), 13K288 PWE (Enlist®) e uma variedade convencional (não transgênica), com antecedentes biotecnológicos distintos, ao competir com leiteiro (Euphorbia heterophylla) e papuã (Urochloa plantaginea). O milho e os competidores foram estudados em diferentes proporções de plantas: 20:0; 15:5; 10:10; 5:15 e 0:20 plantas vaso-1 ou 100:0; 75:25; 50:50; 25:75 e 0:100% (cultura: planta daninha) em experimentos de série substitutiva. Aos 50 dias após a emergência das espécies foi determinado a eficiência fotossintética e de carboxilação, a concentração de CO2 no mesofilo foliar, além da área foliar e a massa seca da parte aérea das plantas. O milho híbrido 2B433 (Enlist®) apresentou melhor desempenho fisiológico e morfológico em relação à variedade convencional, e os híbridos 13K288 PWE (Enlist®) e 30F53 (VYHR®) quando em competição com leiteiro e papuã. O aumento da capacidade competitiva parece ser devido à maior área foliar e massa seca da parte aérea relatada para 2B433 (Enlist®). A capacidade competitiva apresentada pelos híbridos é distinta não se encontrando evidências de que o evento transgênico presente na cultura esteja afetando a habilidade competitiva. anos objetivouse objetivou B 2B43 Enlist®, Enlist Enlist® , F 30F5 VYHR®, VYHR VYHR® K 13K28 (Enlist® transgênica, transgênica transgênica) distintos Euphorbia heterophylla Urochloa plantaginea. plantaginea . plantaginea) 200 20 0 20:0 155 15 5 15:5 1010 10 10:10 515 5:1 020 0:2 vaso1 vaso 1 vaso- 1000 100 100:0 7525 75 25 75:25 5050 50:50 2575 25:7 0100% 0100 100% 0:100 (cultura daninha substitutiva carboxilação CO (VYHR® Enlist®. 2B4 30F 13K2 (Enlist 2 20: 15: 101 10:1 51 5: 02 0: 100: 752 7 75:2 505 50:5 257 25: 010 0:10 (VYHR 2B 13K 10: 75: 50: 01 0:1

RESUMO O estudo das interações competitivas entre espécies cultivadas e não cultivadas pode ser uma ferramenta importante no manejo integrado de plantas daninhas. O objetivo deste trabalho foi avaliar a habilidade competitiva de híbridos de milho na presença do picão-preto, testando-se diferentes proporções de plantas nas associações. Tanto para os híbridos de milho (Dekalb 230 PRO3, Pioneer 30F53 VYH, Brevant 2B433 PW e Syngenta 505 VIP3) quanto para o picão-preto, a densidade final foi de 20 indivíduos vaso-1, determinada em experimentos preliminares. Após foram instalados ensaios em série de substituição, nas diferentes combinações das espécies, variando-se as proporções relativas (100:0, 75:25, 50:50, 25:75 e 0:100%). A análise da competitividade das espécies foi efetuada por meio de diagramas aplicados a experimentos substitutivos e pelos índices de competitividade relativa. Os híbridos de milho apresentaram menor perda ao reduzirem as variáveis morfológicas do picão-preto e demonstraram superioridade na habilidade competitiva em relação a planta daninha. Ocorreu competição entre os híbridos de milho na presença do picãopreto, sendo afetados negativamente, independentemente da proporção de plantas, provocando reduções na estatura de plantas, diâmetro de caule, área foliar e massa seca. Observou-se redução média de 10 e 86% da MS dos híbridos de milho e da planta daninha, respectivamente ao se comparar a ausência de competição com qualquer das densidades associadas, sendo a competição intraespecífica mais prejudicial do que a interespecífica. Os híbridos de milho e o picão-preto competem pelos mesmos recursos do meio, sendo a cultura mais competitiva do que a planta daninha. daninhas picãopreto picão preto, preto testandose testando associações Dekalb 23 PRO3 PRO F 30F5 VYH B 2B43 50 VIP3 VIP 2 vaso1, vaso1 vaso 1, 1 vaso-1 preliminares substituição variandose variando 1000, 1000 100 0, 0 (100:0 7525, 7525 75 25, 25 75:25 5050, 5050 50, 50:50 2575 25:7 0100%. 0100 100% . 0:100%) relativa daninha negativamente caule seca Observouse Observou 86 associadas interespecífica 30F 2B4 5 vaso- (100: 752 7 75:2 50:5 257 25: 0100% 010 0:100% 8 2B (100 75: 50: 01 0:100 (10 0:10 (1 0:1 ( 0:

ABSTRACT The study of competitive interactions between crops and weeds can be an important tool in integrated weed management. The objective of this work was to evaluate the competitive ability of maize hybrids in the presence of hairy beggarticks, testing different proportions of plants in the associations. For maize hybrids (Dekalb 230 PRO3, Pioneer 30F53 VYH, Brevant 2B433 PW, and Syngenta 505 VIP3) and for hairy beggarticks, the final density was 20 individuals pot-1, which was determined in preliminary experiments. Experiments were carried out on a substitutive series, on different combinations of the species, varying the relative proportions (100:0, 75:25, 50:50, 25:75, and 0:100%). The analysis of species competitiveness was performed using diagrams applied to the substitutive experiments and relative competitiveness indices. The maize hybrids showed less loss when reducing the morphological variables of the hairy beggarticks and demonstrated superiority in competitive ability in relation to the weed. Competition occurred between maize hybrids in the presence of hairy beggarticks, being negatively affected, regardless of the proportion of plants, causing reductions in plant height, stem diameter, leaf area, and dry mass. An average reduction of 10% and 86% of the MS of maize hybrids and weed was observed, respectively, when comparing the absence of competition with any associated densities, intraspecific competition being more harmful than interspecific. Maize hybrids and hairy beggarticks compete for the same environmental resources, with the crop being more competitive than the competitor. management associations Dekalb 23 PRO3 PRO F 30F5 VYH B 2B43 PW 50 VIP3 VIP 2 pot1, pot1 pot 1, 1 pot-1 series 1000, 1000 100 0, 0 (100:0 7525, 7525 75 25, 25 75:25 5050, 5050 50, 50:50 2575, 2575 75, 25:75 0100%. 0100 100% . 0:100%) indices affected height diameter area mass 10 86 observed respectively densities interspecific resources competitor 30F 2B4 5 pot- (100: 752 7 75:2 50:5 257 25:7 0100% 010 0:100% 8 2B (100 75: 50: 25: 01 0:100 (10 0:10 (1 0:1 ( 0:

Resumen El objetivo de este estudio fue evaluar la interferencia y determinar el nivel de daño económico (NDE) de escoba dura infestando diferentes cultivares de soja. Los tratamientos fueron cultivares de soja (NS 6909, NA 5909, DM 5958, Brasmax ELITE, Brasmax LANÇA y SYN 13561) y las densidades de escoba dura (0, 2, 3, 4, 9, 15, 16, 23, 22 y 58; 0, 2, 3, 3, 6, 6, 10, 11, 18 y 47; 0, 3, 4, 7, 8, 10, 11, 13, 15 y 24; 0, 1, 4, 6, 12, 18, 19, 31, 44 y 50; 0, 4, 5, 6, 9, 13, 17, 20, 20 y 47; e 0, 2, 3, 5, 9, 11, 15, 18, 29 y 30 plantas m-2), respectivamente, para cada cultivar. Los cultivares NS 6909, NA 5909 y Brasmax Lança son más competitivos que DM 5958, Brasmax Elite y SYN 13561. Los valores de NDE varían de 0,55 a 0,95 plantas m-2 para los cultivares NS 6909, NA 5909 y Brasmax Lança, que mostraron mejor competitividad. Los valores más bajos de NDE varían de 0,26 a 0,61 plantas m-2 para los cultivares DM 5958, Brasmax Elite y SYN 13561, los cuales mostraron menor competitividad con la maleza.

Abstract This study aimed to assess the interference and threshold level (TL) of Sida rhombifolia, the arrowleaf sida, competing with different soybean cultivars. The treatments comprised different soybean cultivars (NS 6909, NA 5909, DM 5958, Brasmax ELITE, Brasmax LANÇA, and SYN 13561) and densities of arrowleaf sida plants per square meter (m-2) (0, 2, 3, 4, 9, 15, 16, 23, 22, and 58; 0, 2, 3, 3, 6, 6, 10, 11, 18, and 47; 0, 3, 4, 7, 8, 10, 11, 13, 15, and 24; 0, 1, 4, 6, 12, 18, 19, 31, 44, and 50; 0, 4, 5, 6, 9, 13, 17, 20, 20, and 47; 0, 2, 3, 5, 9, 11, 15, 18, 29, and 30, respectively) for each cultivar. Cultivars NS 6909, NA 5909, and Brasmax Lança were more competitive than DM 5958, Brasmax Elite, and SYN 13561. The TL values varied from 0.55 to 0.95 plants m-2 for cultivars NS 6909, NA 5909, and Brasmax Lança, which exhibited greater competitiveness with arrowleaf sida. The lowest values of TL varied from 0.26 to 0.61 plants m-2 for cultivars DM 5958, Brasmax Elite, and SYN 13561, which had less competitiveness with weed.

ABSTRACT The identification of the application stage and correct dose of 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide is important so that wheat is not harmed. In view of this, the objective of this study was to evaluate the effect of 2,4-D doses applied at different development stages of wheat crop. The experiment was conducted in a randomized block design, arranged in a 4 × 5 factorial scheme, with four replications. In factor A, the application stages (before tillering, tillering, first node and booting) were allocated and the doses of 2,4-D (0, 349, 698, 1047 and 1396 g.ha–1) were allocated in factor B. The variables evaluated were phytotoxicity at 7, 14, 21, 28 and 35 days after application of the treatments (DAT), photosynthetic activity, CO2 internal concentration, stomatal conductance, efficient water use and carboxylation efficiency. The number of spikes·m–2, spike length and number of full and sterile grains were determined in the preharvest. Thousand grain mass, grain yield and hectoliter weight were determined after harvest. The results demonstrate that the herbicide caused phytotoxicity to wheat, being greater in increasing doses and mainly before tillering, causing grain sterility and decreased productivity. The other yield components did not present difference when increasing the dose and application in different stages as well as the physiological variables. The increase of the 2,4-D doses applied before tillering and in the booting stage caused linear decrease in wheat grain yield. 2,4dichlorophenoxyacetic 24dichlorophenoxyacetic dichlorophenoxyacetic 2,4 2 2,4D 24D D (2,4-D harmed crop design scheme replications A 0, 0 (0 349 698 104 139 g.ha–1 gha1 gha g ha 1 B 7 14 21 3 DAT, DAT , (DAT) activity CO concentration conductance efficiency spikesm2 spikesm spikes m spikes·m–2 preharvest mass harvest productivity 4dichlorophenoxyacetic 24 2, 4D ( 34 69 10 13 g.ha– (DAT spikes·m– 6 g.ha spikes·m

RESUMO O uso de glifosato associado com outros herbicidas torna-se uma alternativa importante para o manejo de plantas daninhas infestantes do milho, pois ele aumenta o espectro de controle, minimiza problemas com resistência e tolerância de plantas daninhas ao herbicida. O objetivo deste trabalho foi estudar a eficiência, a seletividade e os efeitos nos componentes de rendimento de grãos do milho resistente ao glifosato pelo uso dessa substância associada ou não a outros herbicidas aplicados em pré- e pós-emergência. O experimento foi instalado em delineamento de blocos ao acaso, com quatros repetições. Os tratamentos consistiram na utilização do glifosato em combinação com os herbicidas: atrazina, [atrazina + simazina], [atrazina + óleo], [atrazina + S-metolacloro], aplicados em pré- e/ou pós-emergência e o [nicosulfuron + mesotriona] somente em pós-emergência, além das testemunhas capinada e infestada. Avaliaram-se as variáveis: fitotoxicidade ao milho, controle de plantas daninhas, altura de inserção de espigas, número de fileiras e de grãos por espiga, peso de mil grãos e a produtividade de grãos. Os herbicidas ocasionaram baixa fitotoxicidade ao milho, inferior a 6%, controle superior a 88, 95 e 95% para papuã, nabo e girassol, respectivamente, e não influenciaram negativamente nos componentes relacionados ao rendimento de grãos da cultura. Os herbicidas testados são seletivos ao híbrido Forseed 2A521 PW e efetivos no controle de papuã, nabo e girassol. O manejo das plantas daninhas com capina ou herbicidas proporcionou aumento de cerca de 43% na produtividade de grãos do híbrido de milho Forseed 2A521 PW. O uso de glifosato em mistura de tanque com herbicidas aplicados em pré- ou pós-emergência incrementou, aproximadamente, 14% a produtividade de grãos de milho.

ABSTRACT The application of glyphosate associated with other herbicides is an important alternative for weed control in maize, to increase control spectrum and to minimize problems with resistance and tolerance from some species to the product. The objective of this work was to evaluate the efficacy, selectivity and effects on the grain yield components of glyphosate-resistant maize as a function of its application, associated or not with other pre- and postemergence herbicides. The design used was randomized blocks with four replications. Treatments consisted in the use of glyphosate combined with the herbicides: atrazine, [atrazine + simazine], [atrazine + oil], [atrazine + S-metolachlor], applied pre- and/or postemergence and [nicosulfuron + mesotrione] only postemergence, plus two controls, one weeded and one infested. The evaluated variables were maize phytotoxicity, weed control, ear insertion height, number of rows per ear, number of grains per row, one thousand grain mass and grain yield. Herbicide treatments caused low phytotoxicity to maize, less than 6%; control greater than 88, 95 and 95% for alexandergrass, turnip and sunflower, respectively, and did not affect grain yield components. The tested herbicides are selective to the hybrid Forseed 2A521 PW and effective in weed control. Weed control with weeding or herbicide increased maize Forseed 2A521 PW yield by 43%. The association of glyphosate with pre- or postemergence herbicides increased maize grain yield by approximately 14%.