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Determining the competitive ability of bean cultivars and the economic damage level (EDL) caused by alexandergrass is important for the implementation of integrated weed management. This work aimed to evaluate the interference of alexandergrass and determine the level of economic damage when it competes with seven carioca-type bean cultivars. The experiment was conducted in a completely randomized experimental design, with treatments consisting of the carioca bean varieties IAC Imperador, IPR Curió, ANFC9, IAC Milênio, IPR Tangará, IPR Sabiá, and BRS Pérola and 12 alexandergrass densities for each cultivar, ranging from 0 to 560 plants m−2. Plant density, leaf area, soil cover, and shoot dry matter of alexandergrass were evaluated 35 d after emergence. The variables alexandergrass plant density, grain productivity, control costs, bean price, and herbicide efficiency were used to estimate EDL. The cultivars ANFC9, IAC Milênio, and IPR Tangará were the most competitive, and IAC Imperador, IPR Curió, IPR Sabiá, and BRS Pérola the least competitive against alexandergrass. The highest EDL values were observed in the cultivars ANFC9, IAC Milênio and IPR Tangará, which ranged between 3.80 and 15.70 plants m−2 of alexandergrass. The cultivars IAC Imperador, IPR Curió, IPR Sabiá, and BRS Pérola showed the lowest economic damage with 1.10 to 5.60 plants m−2 of alexandergrass.

Among the factors that affect potato productivity, the interference caused by weeds stands out as they may compete with the crop, release allelopathic substances to soil and host insects and diseases. Therefore, the objective of this work was to assess the competitive ability of white (Aghata) and pink (Asterix) potato cultivars when infested by Alexandergrass (Urochloa plantaginea) or wild poinsettia (Euphorbia heteroplylla). The experiment was carried out into greenhouse in randomized blocks design, with four replications. A single potato plant faced competition by either Alexandergrass or wild poinsettia, ranging from 0 to 64 plants per plot. Fifty days after seedling transplanting, variables related to the morphophysiology of potato cultivars and weeds were assessed. Potatoes have low competitive ability with both weed species, with wild poinsettia being the most aggressive in reducing the accumulation rates of leaf area and aboveground dry mass. Potato photosynthetic rate is negatively influenced by the presence of both weeds. Internal CO2 concentration, stomatal conductance, carboxylation efficiency and transpiration rates of potato varied depending on weed species and density. Morphological parameters are reduced when potato competed with Alexandergrass or wild poinsettia; however the physiological parameters are most sharply affected when under competition with wild poinsettia. [ABSTRACT FROM AUTHOR]

This study assessed the nitrogen nutrition index, morphogenic characteristics and tiller structure of Alexandergrass (Urochloa plantaginea (LINK) Hitch) pasture submitted to different nitrogen (N) levels (zero, 150 or 300 kg ha-1 of N). The experimental design was entirely randomized with repeated measures arrangement. The experimental animals were Angus heifers under rotational stocking grazing method. The number of animals was variable to keep 30±5 cm post-grazing sward height. Nitrogen nutrition index increased linearly according N levels (Ŷ = 59.8 + 0.1216N; P < 0.0001; r²=0.53). The leaf appearance rate adjusted to a positive linear regression model according the thermal sum (TS) with zero of N (Ŷ0N = 0.0077 + 0.0000087TS; P = 0.0308; r² = 0.72) and 150 kg ha-1 of N (Ŷ150N = 0.0020 + 0.000021 TS; P = 0.0022; r² = 0.92). The use of 300 kg ha-1 of N did not alter the leaf appearance rate (0.0124 leaf degree-days-1). The use of up to 300 kg ha-1 of N increases the Alexandergrass nitrogen content. The leaf appearance rate in Alexandergrass is modified using N while the morphogenic characteristics leaf expansion, stem expansion, phyllochron, leaf lifespan, leaf elongation duration and tiller structure are not altered by N utilization. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

O estudo da densidade de semeadura do feijoeiro e do nível de dano econômico (NDE) ocasionado pelo papuã (Urochloa plantaginea) são ferramentas importantes para a adoção do manejo integrado dessa planta daninha e, assim, produzir um alimento com maior qualidade e menor resíduo de agrotóxico. Diante disso, objetivou-se com o trabalho avaliar a interferência e o nível de dano econômico do papuã em competição com o feijoeiro, estimados em função de densidades de semeadura da cultura e da planta daninha. Os tratamentos foram compostos por densidades do feijoeiro, cultivar IPR Uirapuru (140.000, 180.000, 220.000 e 260.000 plantas ha-1) e do papuã que variaram de 0 até o máximo de 104 plantas m-2. O experimento foi implantado em um Latossolo Vermelho Aluminoférrico típico na área experimental da Universidade Federal da Fronteira Sul, campus Erechim/RS, em 31/10/2016. Para descrever a relação entre a perda de produtividade de grãos do feijoeiro e as variáveis explicativas; densidade de plantas (DP), cobertura do solo (CS), área foliar (AF) e massa seca da parte aérea (MS), usou-se o modelo da hipérbole retangular. As variáveis CS e DP podem ser usadas em substituição a AF e a MS para estimar as perdas de produtividades de grãos do foeijoeiro. A densidade de 260.000 plantas ha-1 do feijoeiro apresentou maior competitividade com o papuã e os maiores valores de NDEs, justificando a adoção de medidas de controle da planta daninha em densidades mais elevadas.

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O controle de plantas daninhas infestantes na soja torna-se prática importante para evitar perdas na produtividade de grãos. Diante disso, objetivou-se avaliar a seletividade e a eficácia de herbicidas pré-emergentes associados ou não ao glyphosate aplicado em pós-emergência da cultivar de soja DM 57i52. O experimento foi conduzido em delineamento de blocos casualizados, com quatro repetições. Foram testados 15 tratamentos consistindo no uso de três doses de cada mistura comercial dos herbicidas pré-emergentes, imazethapyr+flumioxazin e sulfentrazone+diuron, associadas ou não ao glyphosate aplicado em pós-emergência. Em paralelo foram conduzidas duas testemunhas, capinada e infestada. As misturas formuladas dos herbicidas imazethapyr+flumioxazin e sulfentrazone+diuron demonstraram ser seletivas à soja. A mistura de imazethapyr+flumioxazin apresentou maior eficiência no controle de papuã e da guanxuma. O uso de herbicidas pré-emergentes associados ao glyphosate aplicado em pós-emergência favoreceu o aumento da produtividade de grãos da soja.

Among the weed species infesting soybean, Alexandergrass (Urochloa plantaginea) is highlighted as one of the most competitive. The objective of this work was to determine the periods of interference of Alexandergrass, and is effects, on morphophysiology and yield components of soybean. Treatments were pooled into two groups: the group "convivence" comprised soybean growing among Alexandergrass for increasing periods: 0, 7, 14, 21, 28, 35 and 42 days after emergence (DAE), as well as along all the crop cycle. The "control" group comprised soybean free from competition for the same time lapses. Forty-two DAE, soybean morphophysiology was assessed. There was no effect of the time lpse of Alexandergrass "control" or "convivence" on soybean physiological performance. Plant height, stem diameter, plant dry mass, leaf area and grain yield components of soybean were, however, affected by Alexandergrass. The critical period of interference prevention comprises 26-41 DAE; the period prior to interference is 26 DAE; and the total period of interference prevention is 41 DAE. [ABSTRACT FROM AUTHOR]

ABSTRACT This study was carried out to evaluate the effect of nitrogen fertilization on tillering dynamics of Alexandergrass (Urochloa plantaginea (Link) Hitch) grazed by beef heifers in a rotational stocking grazing method. The experiment was conducted in a completely randomized design following a repeated measure arrangement, three levels of nitrogen (Zero, 150 and 300kg ha-1) and two area repetition. The classification of tillers into categories (basal and axillary) showed a greater number of basal tillers, due to their higher appearance rate, in the absence of nitrogen fertilization. Nitrogen fertilization promoted higher axillary tiller density. The use of nitrogen promotes the renewal of axillary tillers of Alexandergrass, without compromising the stability of the tiller population.

ABSTRACT: The objective of this work was to evaluate the interference and to determine the level of economic damage (NDE) of the weed when infesting the corn crop. Treatments were composed by corn densities (2.60, 3.10, 3.65, 4.00 and 4.80 plants m-1) and 10 Alexandergrass populations for each crop seeding density. The population of plants, leaf area, soil cover and shoot dry mass of Alexandergrass were evaluated as indicator of infestation. Shoot dry mass of Alexandergrass presents better adjustment to the model of rectangular hyperbole, and losses of grain yield due to interference of the weed were satisfactorily estimated by this model. Corn sowing densities of 2.60; 3.10 and 3.65 plants m-1 in average, were more competitive of all evaluated variables in the presence of Alexandergrass. Corn densities of 2.60; 3.10 and 3.65 plants m-1 increase the level of economic damage, justifying the adoption of control measures of Alexandergrass when in higher populations. NDE values ranged from 1.58 to 9.37 plants m-2 at the densities of 4.00 and 4.80 maize plants m-1, which were less competitive with Alexandergrass.

This paper aimed to elucidate the behavior of Urochloa plantaginea biotype with differential physiological characteristics, which allows a better growth and development in a flooded environment. A completely randomized experimental design was used 2x3, being the factors: populations of Urochloa plantaginea (lowlands and highlands) and soil water conditions (50% and 100% of soil water retention capacity (CRA); water depth 5 cm). Responses related to photosynthetic parameters and lipid peroxidation were verified 24h and 192h after the onset of water conditions. Morphology-related variables were measured at the end of the plant cycle. The lowland biotype compared to the highland biotype showed superior morphophysiological characteristics under soil flooding. It can be emphasized, higher water use efficiency (about 30%), higher plant height, lower aerial part lipid peroxidation and higher aerial part dry matter increment. In addition, the lowland biotype was shown not to vary photosynthetic parameters A, Gs, Ci, E, USA and A/Ci when exposed to the water depth 5 cm, compared with the 100% CRA condition. Both populations survived and ended their cycle producing seeds. Thus, a possible adaptive process of the population to the flooded environment is evidenced. [ABSTRACT FROM AUTHOR]

Our work was carried out to evaluate forage intake, feeding behavior and displacement patterns of beef heifers fed exclusively on pasture or receiving oat grain, either daily (“frequent”) or from Monday to Friday (“infrequent”), in two phenological stages of Alexandergrass (Urochloa plantaginea Link.): “Vegetative” and “Reproductive”. The grazing method was continuous, with a variable number of animals. The experimental design was completely randomized with measures repeated in time with three feeding frequencies and two phenological stages. Forage intake was estimated using the chromic oxide technique as an indicator of fecal output. Heifers on exclusive Alexandergrass pasture and frequently supplemented had higher forage intake of dry matter (DM, 2.91 kg DM 100 kg BW-1) than those that were infrequently supplemented (2.00 kg DM 100 kg BW-1). Forage intake was greater in the “Vegetative” stage. The use of feeding stations is modified in response to supplementation frequency and phenological stages of Alexandergrass. Bite mass was higher for daily supplemented heifers, and these animals spent less time grazing. Also, bite mass was the item that best explained DM total ingestion. Bite mass and grazing time were similar throughout the phenological stages, whereas bite rate decreased in the reproductive stage. Feeding behavior and forage intake responses of beef heifers were influenced by supplementation frequency and phenological stages of Alexandergrass.

The aim of this experiment was to identify grazing height targets for Alexandergrass pastures under continuous stocking in integrated crop-livestock system (ICLS). For this purpose, twelve pastures were cultivated into an ICLS area, and maintained at 10, 20, 30, or 40 cm using grazing goats. The following variables were analyzed: leaf and herbage mass, accumulation rate, and allowance; leaf:stem ratio; chemical composition of hand-plucked samples; stocking rate; average daily gain and gain per area. The data were submitted to regression and correlation analysis. Significance was set at 5% (P≤0.05). The main results were: i) herbage and leaf lamina mass increased linearly with grazing height, and pastures maintained at 20 cm already presented the minimum amount recommended for soil cover in ICLS; ii) animal performance achieved an upper asymptotic plateau in pastures maintained around 30-40 cm and it was highly correlated with both grazing height and forage availability (mass and allowance). Alexandergrass pastures under continuous stocking in ICLS should be maintained between 30-40 cm to improve both cover crop biomass and animal performance. [ABSTRACT FROM AUTHOR]

Objetivou-se avaliar os possíveis efeitos da convivência de plantas de Pinus elliottii com diferentes densidades de plantas de Ipomoea grandifolia, Urochloa plantagineae Urochloa humidicola. O delineamento experimental adotado foi inteiramente casualisado, com quatro repetições; cada parcela constou de um vaso de 60 L de capacidade. As quantidades de plantas daninhas mantidas no vaso foram 0, 20, 40, 80 e 160 plantas m-2 em competição com uma planta de pinus. Avaliou-se após 210 dias de convivência os seguintes parâmetros: incremento em altura e diâmetro e, massa seca das plantas de pinus e das plantas daninhas. Para todos os parâmetros as plantas daninhas influenciaram o desenvolvimento das plantas de P. elliottii sendo maior a redução do crescimento de acordo com o aumento da densidade das plantas daninhas, para todas as espécies. A maior redução da massa seca em plantas de P. elliottii foi de 84,5%, em convivência com U. humidicola, e do incremento da altura e diâmetro foi de 81,5% e de 86,7%, respectivamente, quando em convivência com U. plantaginea.

The lack of registered herbicides for weed control in sweet sorghum has been a limiting production factor. This study aimed at evaluating the selectivity of herbicides in sweet sorghum and weed control efficiency. A randomized blocks design, with four replications, was used. Treatments consisted of sweet sorghum cultivars (BRS 506, BRS 509 and BRS 511) and herbicides applied alone at pre-emergence (atrazine - 1,500 g ha-1; atrazine + s-metolachlor - 1,665 g ha-1 + 1,035 g ha-1; flumioxazin - 50 g ha-1; s-metolachlor - 1,440 g ha-1) and post-emergence (tembotrione - 100.8 g ha-1) and sequentially at pre- and post-emergence (atrazine + s-metolachlor + tembotrione - 1,665 g ha-1 + 1,035 g ha-1 + 100.8 g ha-1; atrazine + tembotrione - 1,500 g ha-1 + 100.8 g ha-1; flumioxazin + tembotrione - 50 g ha-1 + 100.8 g ha-1), plus two controls, one weeded and one unweeded. The phytotoxicity rate to sorghum was 98.0 %, 98.0 % and 100 % for tembotrione; 100 %, 98.7% and 100 % for flumioxazin + tembotrione; 100 %, 100 % and 100 % for s-metolachlor + atrazine + tembotrione; and 98.7 %, 98.7 % and 99.7 % for atrazine + tembotrione, respectively to the BRS 509, BRS 506 and BRS 511 cultivars. Tembotrione, flumioxazin + tembotrione, atrazine + s-metolachlor + tembotrione and atrazine + tembotrione showed a good control rate of Ipomoea indivisa, Digitaria ciliaris and Urochloa plantaginea, but did not present selectivity to the sorghum cultivars. Atrazine, in general, showed higher selectivity to the yield components of the BRS 509 and BRS 506 cultivars.

Analyses in a data set of six experiments (n=436) was performed with the aim of characterizing canopy structure and forage intake patterns of beef heifers grazing on Pearl millet (Pennisetum americanum), Alexandergrass (Urochloa plantaginea) and Coastcross (Cynodon dactylon). Forage and leaf lamina mass were similar among species, 3001.4 and 668.1kg of DM/ha, respectively, while leaf:stem ratio of canopy vertical strata was different. Intake rate (12g DM/minute), bite mass (0.343g DM/bite) and bite rate (36.6bites per minute) were similar in Pearl millet and Alexandergrass. In Pearl millet, neutral detergent fiber content (56.1%) in forage as grazed, grazing time (518.9 minutes/day) and displacement rate (8.8 steps/minute) were lower. Increased grazing time (639 minutes/day) represented the main compensatory mechanism for smaller bite masses (0.234g DM/bite) and reduced intake rates (8.8 grams of DM/minutes) in Coastcross. Bite rate variations happened as a response to constraints imposed by canopy structure. Surface utilization on Alexandergrass and Coastcross was increased by greater number of feeding stations visited and displacement rate. Ingestive behavior components of beef heifers are affected by differences in the canopy structure of Pearl millet, Alexandergrass and Coastcross.

ABSTRACT: The objective of this work was to determine the competitive interaction of sweet sorghum cultivars BRS 506, BRS509, and BRS 511 with biotypes of Alexandergrass and wild poinsettia. The adopted experimental design was the randomized block one, with four replications. Treatments were arranged in a substitution series by proportions of 100:0, 75:25, 50:50, 25:75, and 0:100%, corresponding to 20:0, 15:5, 10:10, 5:15 and 0:20 plant per pot of sweet sorghum (cultivars BRS 506, BRS 509 and BRS 511) withweeds (Alexander grass/wild poinsettia). The leaf area (LA) and dry matter (DM) of sweet sorghum, Alexandergrass and wild poinsettia plants were determined 50 days after emergence. Data about competitive abilities were analysed through the graphical analysis method, constructing diagrams based on yield or relative and total variations. Indices of relative competitiveness, clustering coefficient and aggressiveness were also determined; all of them were relative indices. There was competition for the same environmental resources between sweet sorghum cultivars and weeds, with mutual injury to the species involved in the community. Wild poinsettia and Alexandergrass negatively modified the LA and DM of the crop, demonstrating a greater competitive ability for the resources that are available in the environment. Wild poinsettia was less competitive than sweet sorghum cultivars, while Alexandergrass showed higher competitive ability than them. The highest losses for the LA and DM variables were observed when species were in interspecies competition rather than intraspecies competition.

Objetivou-se com este trabalho avaliar a eficácia e a seletividade de herbicidas aplicados isoladamente ou em mistura de tanque na cultura do milho RR®. O delineamento experimental utilizado foi de blocos casualizados com quatro repetições. Os tratamentos avaliados foram: testemunha infestada, testemunha capinada, glyphosate, glyphosate + [atrazine + simazine], glyphosate + [atrazine + simazine], glyphosate + tembotrione, glyphosate + mesotrione, glyphosate + nicosulfuron, glyphosate + 2,4-D, glyphosate + [atrazine + S-metolachlor], glyphosate + [atrazine + S-metolachlor], glyphosate + S-metolachlor, glufosinate ammonium, [nicosulfuron + mesotrione], glyphosate + [nicosulfuron + mesotrione] e glyphosate + [nicosulfuron + mesotrione] + [atrazine + simazine]. A fitotoxicidade ocasionada pelos herbicidas ao híbrido de milho SYN Supremo VIP3 e o controle de Urochloa plantaginea e de Digitaria ciliaris foram avaliados aos 7, 14, 21 e 28 dias após a aplicação dos tratamentos. Na pré-colheita da cultura, determinou-se o controle das plantas daninhas e, em dez plantas por unidade experimental, foram analisadas as variáveis relacionadas aos componentes de rendimento de grãos, como altura de inserção da espiga, comprimento da espiga, o número de fileiras e de grãos por fileiras e por espigas de milho. Na colheita do milho, avaliou-se a massa de mil grãos e a produtividade de grãos. Observou-se que todos os tratamentos herbicidas ocasionaram baixa fitotoxicidade ao milho, exceto a mistura em tanque aplicada em pós-emergência composta por glyphosate + 2,4-D e glyphosate + mesotrione, que demonstraram as maiores injúrias nas quatro épocas avaliadas. A maioria dos herbicidas mostrou bom controle de D. ciliaris e U. plantaginea, com exceção da mistura de glyphosate + 2,4-D na pré-colheita. A mistura em tanque de glyphosate + [atrazine + simazine] aplicada em pós-emergência demonstrou a maior produtividade de grãos. Conclui-se que, dependendo da associação de herbicidas, ocorre efeito sinérgico tanto para o controle das plantas daninhas como para a fitotoxicidade da cultura, sendo a produtividade de grãos a principal variável influenciada.

The soybean crop has been playing a very important role in the agribusiness worldwide, including in Brazil. Among the pests that cause major problems to the crop are the weeds, because they are responsible by the reduction of the productivity and of the grain quality. On the face of it, this work aimed to evaluate the application of burndown herbicides associated to pre-emerging herbicides to the management of the soybean weeds. The experiment was carried out in the field, in area with no soil cover with fallow during the winter, in the randomized block design, with four replicates. The treatments used were: diuron + sulfentrazone (490 + 245), [glyphosate + (diuron + sulfentrazone) - 1,440 + (420 + 210)], [glyphosate + (diuron + sulfentrazone) - 1,440 + (490 + 245)], glyphosate + 2,4-D (1,440 + 806), glyphosate + diclosulam (1,440 + 25.2), [glyphosate + (imazethapyr + flumioxazin) - 1,440 + (100 + 50)], glyphosate + saflufenacil (1,440 + 35), [ammonium-glufosinate + (diuron + sulfentrazone) - 400 + 490 + 245 g ha-1 de i.a], and two herbicide-free controls, weedy and weed-free. At the 7, 14, 21 and 28 days after the emergency of the crop (DAE) the variables were evaluated, herbicide phytotoxicity on soybean and the weeds control, Digitaria ciliaris and Urochloa plantaginea. In the soybean harvest, the number of pods per plant was determined, the number of grains per pods, the mass of a thousand grains (g) and the grain productivity (kg ha-1). The phytotoxicity caused by herbicides to the soybean it was not over to 8% in all the evaluations realized. The control of the weeds, D. ciliaris and U. plantaginea were over to 90%, highlighting the effect of the pre-emerging herbicides in the maintaining of the control until the evaluation of the 28 DAE. In general, all the treatments involving the herbicides did not cause changes in the components of soybean crop yield, being statistically equal the weed-free control higher than the weedy control. The soybean presented an increase of 859.48% in grain yield when Digitaria ciliaris and of the Urochloa plantaginea was controlled. [ABSTRACT FROM AUTHOR]

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In Southern Brazil, intercropping system between corn and Urochloa is an interesting way to improve soil cover and animal feed after corn harvesting. This study was carried out with the objective to evaluate the effect of herbicides and its doses on corn and Alexandergrass (Urochloa plantaginea) yield, in an intercropped system. The experiment was arranged in a randomized block design, with four replications in a factorial scheme. First factor was composed of four herbicide associations: (1) Atrazine + Oil; (2) Atrazine + Simazine + Oil; (3) Atrazine + Nicosulfuron + Oil; and (4) Atrazine + Mesotrione + Oil. The second factor was composed of three doses of these herbicide combinations: 100%, 75% and 50% of the recommended dose to control Alexandergrass. A control treatment, without herbicide spraying, was evaluated. Corn crop was sowed in no-till system and Alexandergrass established by self-seeding. Herbicide management in corn with Alexandergrass intercropping system is primordial to obtain good grain yields, once corn was highly affected by the forage. Herbicides and doses influenced Alexandergrass forage yield, although, all the managements allow forage availability after corn harvest. The better corn yields in the intercropping, with adequate Alexandergrass forage production, were obtained with 75% of the recommended dose of Mesotrione and Nicosulfuron associations. [ABSTRACT FROM AUTHOR]

Corn stands out among the cultivars because of its high importance in food, animal feed and raw materials for energy production. The quantity and quality of the harvested grain can be reduced, mainly due to inadequate weed management. Nowadays, weed control is accomplished with the use of herbicides as pre‐emergence and postemergence, applied alone or in a tank mix. This study aimed to evaluate the efficiency of the control of weeds and phytotoxicity of the herbicides that were applied in tank mix or isolated in the corn hybrids, Formula TL® and SYN 7B28. Two experiments were conducted: in the 2012/2013 season (Formula TL®) and 2013/2014 season (SYN 7B28). There was a low initial phytotoxicity of all the tested herbicides in the initial evaluation; however, from 14 days after treatment, it was minimal. The weed control of Ipomoea indivisa, Urochloa plantaginea and Euphorbia heterophylla in both experiments was better, in general, when using the tank mixtures of atrazine + simazine + tembotrione and atrazine + simazine + mesotrione, respectively. The application of atrazine + simazine + tembotrione in the SYN 7B28 hybrids provided, with the exception of the thousand‐grain weight, the best expression of grain yield components, combining a low phytotoxicity and best control of the weeds. The Formula TL® hybrid presented the highest mass of a thousand grains and yield with the application of nicosulfuron + tembotrione. The yield average difference of the herbicide treatments and the unweeded control showed an increase of 27.66 and 34.59% in the grain yield of the corn hybrids, Formula TL® and SYN 7B28, respectively. [ABSTRACT FROM AUTHOR]

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The experiment aimed at evaluating leaf biomass flow, intensity and frequency of defoliation of Alexandergrass (Urochloa plantaginea (Link) Hitch) by beef heifers exclusively on pasture or that grazed and received protein salt. A completely randomized experimental design was used with repeated measures over time, two treatments and two area replications, with three Angus test heifers by paddock. Leaf blade intake flow is 18% superior for heifers exclusively on pasture. Grazing intensity (59.8%) is similar when heifers receive protein salt or not. Heifers receiving protein salt reduce by one day the defoliation frequency of tillers. The supply of protein salt for beef heifers grazing Alexandergrass affects the herbivore-plant relationship, decreasing intake flow and leaf blade defoliation frequency.

The aim of this study was to assess the Nitrogen Nutrition Index (NNI) of an Urochloa plantaginea pasture submitted to different nitrogen (N) levels and forage mass (FM) through dilution curve model. The experimental design was a random block with six treatments in a factorial scheme. The treatments combination consisted of three nitrogen levels (0, 200 and 400 kg ha-1 of N) and two forage mass (low mass at 2,000 kg ha-1 of DM and high mass at 3,600 kg ha-1 of DM) in a continuous stocking rate grazing method. Urochloa plantaginea forage production was higher at the nitrogen intermediate level (200 kg ha-1 of N), being 31% superior than treatment without nitrogen, which showed unsatisfactory nitrogen nutritional index and due to it, limited forage growth. This fact was not observed at the 400 kg ha-1 of N, where nitrogen luxury consumption occurred showed by the satisfactory levels of this nutrient in the plant tissue. Nitrogen dilution curve allows the diagnosis of the plants nutritional status.

This study evaluated the influences of nitrogen fertilizer and energy supplementation cattle on the growth performance of beef cattle. This study was conducted at the Federal University of Technology of Paraná, Dois Vizinhos through continuous grazing on 6.3 ha, divided into nine paddocks. The treatments were: Alexander grass +100 kg ha of N (N100); Alexander grass + 100 kg ha of N + 0.5 kg per 100 kg of weight live supplementation of wheat bran (N100S); and Alexander grass +200 kg ha of N (N200), with an average herbage allowance of 10% for all treatments. Crossbred and non-castrated steers with an average weight of 276 ± 41 kg were used for 107 days. The crude protein from entire plant differed ( P < 0.05) between treatments, with the greater value (14.8%) occurring in the N200, and the lesser value (13.3%) occurring in the N100S. The herbage accumulation rate was greater ( P < 0.05) in the N200 (55.7 DM ha d) than that in the N100S and N100 (40.0 and 39.7 kg DM ha d, respectively). The N100S produced greater ( P < 0.05) average daily weight gains (0.815 kg animal day) than did the N200 (0.685 kg animal day) and N100 treatments (0.727 kg animal day). [ABSTRACT FROM AUTHOR]

Plants compete for several resources on soil, including water, light and nutrients which can affect crop yield and also weeds growth. Under the hypothesis that in different densities and weed communities, crops and weeds undergo changes in their nutritional contents of macro and micronutrients, the aim of this study was to quantify the nutritional contents of bean plants and weeds cultivated in increasing densities (0, 74, 147, 221 and 295 plants m-2) and the effect of the association of plants (isolated bean, bean + Urochloa plantaginea, bean + Bidens pilosa and bean + Urochloa plantaginea + Bidens pilosa). The contents of macro and micronutrients were evaluated. The increase in plant density promoted a decrease in the total chlorophyll content of bean plants and weeds, as well as a decrease in macronutrients (K and P) and micronutrients (Zn, Fe, Mn and Cu). In the arrangement where the greatest number of species were cultivated simultaneously and in increasing densities, a greater reduction in total chlorophyll content and in macro and micronutrient contents of the three species (crops and weeds) were observed. [ABSTRACT FROM AUTHOR]

Os objetivos do presente trabalho foram estimar níveis críticos de dano de papuã (Urochloa plantaginea) em feijão-comum, em situações onde a planta daninha foi manejada precocemente e ocorreu reinfestação, e avaliar as alterações que sofre em decorrência de cultivares de feijão-comum e variáveis explicativas da infestação. Foram realizados dois experimentos em campo, em Eldorado do Sul, RS, sendo um com o cultivar UFT-06 (grupo Carioca) e o outro com o cultivar IPR Graúna (grupo Preto). Os níveis de infestação de papuã foram obtidos com quatro herbicidas residuais, aplicados em duas doses cada, mais testemunhas com e sem controle de papuã. A densidade, massa fresca e massa seca do papuã foram avaliadas no início e no final do período crítico de prevenção da interferência, e o rendimento de grãos da cultura foi avaliado por ocasião da colheita. O nível crítico de dano de papuã não teve valor elevado nessa situação (0,4 a 0,7%); todavia, pode haver benefício em controlá-lo de acordo com a infestação e o custo de controle. O nível crítico de dano foi sempre maior para o cultivar IPR Graúna, em relação ao UTF-06. A densidade e as massas fresca e seca das plantas de papuã explicaram adequadamente a perda de produção de feijão-comum pelo modelo de regressão não linear da hipérbole retangular.

The experiment was carried out to evaluate forage intake, performance and ingestive behavior of beef heifers. Productive, structural and chemical characteristics of the pasture were also evaluated. The experimental design was completely randomized in a 3 × 2 factorial arrangement, with three pasture systems (Alexandergrass [Urochloa plantaginea Link.] with and without supplement to heifers and Coastcross [Cynodon dactylon (L.) Pers.]) and two phenological stages: vegetative and flowering. The grazing method was put-and-take stocking. Grazing, ruminating and idle activities, feeding stations, displacement patterns, bite mass and bite rate were evaluated. The forage intake was estimated using chromic oxide as an indicator of fecal output. The heifers modified the use of feeding stations and displacement patterns between phenological stages and pasture systems. Heifers consumed more forage in the vegetative stage (2.81% of body weight in dry matter) than in the flowering stage (1.92% of body weight in dry matter). Average daily gain, body condition and stocking rate were similar for heifers in the evaluated systems. Beef heifers receiving protein supplement on Alexandergrass pasture consumed more forage than heifers fed Coastcross exclusively. Regardless of the species, no difference was observed when the heifers were exclusively on pasture. Pasture systems on Alexandergrass or Coastcross provide suitable nutrient intake for heifers to be mated at 18 months of age.

Foram estudados o desempenho, o comportamento e a ingestão de forragem por novilhas de corte em pastagem de milheto (Pennisetum americanum (L.) Leeke) e papuã (Urochloa plantaginea) no período de janeiro a abril de 2008. Foi utilizado o método de pastejo contínuo com número variável de animais. A ingestão de forragem foi estimada nos estádios vegetativo e reprodutivo das forrageiras usando o óxido de cromo como indicador da produção fecal. As avaliações de comportamento foram feitas por meio de observação visual, em quatro períodos contínuos de 24 horas. Os valores médios de massa de forragem, oferta de forragem e oferta de lâminas foliares foram de 3.927 kg/ha de MS, 14,6 kg de MS/100 kg de peso corporal (PC) e 3,36 kg de MS/100 kg de PC, respectivamente. As variáveis do pasto, o desempenho animal, o comportamento ingestivo e a ingestão de forragem foram semelhantes entre milheto e papuã. As variáveis da forragem, desempenho animal e tempos de pastejo, ócio e ruminação e número de bocados por dia apresentaram variação ao longo dos dias de utilização da pastagem. A ingestão de forragem foi de 2,49% do peso corporal e não variou conforme o estádio fenológico. Em áreas infestadas com papuã, sua utilização em pastejo proporciona desempenho semelhante ao obtido com milheto.It was studied performance, behavior and forage ingestion by beef heifers on pearl millet (Pennisetum americanum (L.) Leeke) and Alexander grass (Urochloa plantaginea) pastures from January to April 2008. The continuous grazing method with a variable number of animals was used. Forage ingestion was estimated during vegetative and reproductive stage of forage plants using chromic oxide as fecal production marker. Evaluations of behavior were carried out by visual observation in four 24-hour continuous periods. Mean values of forage mass, forage offer and leaf blade offer were 3,927 kg/ha of DM, 14.6 kg of DM/100 kg BW and 3.36 kg of DM/100 kg BW, respectively. The variables of the pasture, animal performance, ingestive behavior and forage intake were similar for pearl millet and alexander grass. Variables of forage, animal performance and grazing times, idle and rumination and number of bites per day showed variation over days of pasture utilization. Forage ingestion was 2.49% of the body weight and it did not vary according to phenological stage. Use of sites infested with alexander grass as pastures provides performance similar to the one obtained with pearl millet.

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Copyright of Acta Scientiarum: Animal Sciences is the property of Universidade Estadual de Maringa and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Inflorescence development in Panicum maximum and Urochloa plantaginea was comparatively studied with scanning electron and light microscopy to test the transfer of P. maximum to Urochloa and to look for developmental features applicable to future cladistic studies of the phosphoenol pyruvate carboxykinase (PCK) subtype of C4 photosynthesis clade (P. maximum and some species of Brachiaria, Chaetium, Eriochloa, Melinis, and Urochloa). Eleven developmental features not discernable in the mature inflorescence were found: direction of branch differentiation; origins of primary branches; apical vs. intercalary development of the main axis; direction of spikelet differentiation; direction of glume, lemma and palea differentiation; position of the lower glume (in some cases); size of the floret meristem; pattern of distal floret development; pattern of gynoecium abortion; differential pollen development between proximal and distal floret; and glume elongation. Inflorescence homologies between P. maximum and U. plantaginea are also clarified. Panicum maximum and U. plantaginea differ not only in their mature inflorescence structure but also in eight fundamental developmental features that exclude P. maximum from Urochloa. The following developmental events are related to sex expression: size of floret meristem, gynoecium abortion, pollen development delay in the proximal floret, glume elongation and basipetal floret maturation at anthesis. [ABSTRACT FROM AUTHOR]