Herbicides were evaluated for control of non-native and invasive plants namely tropical soda apple (TSA) (Solanum viarum), tropical spiderwort or Benghal dayflower (Commelina benghalensis), and Italian ryegrass (Lolium multiflorum) from 2007 to 2012 in greenhouse at Plant Science Research Center, Mississippi State University, Starkville-Mississippi. In TSA study, aminopyralid at 0.88 or 0.12 kg ae/ha, and triclopyr + picloram + 2,4-D at (0.56 + 0.15 + 0.56) kg ae/ha controlled TSA seedlings emergence ranged from 83 to 96% at premergence (PRE), and 1 month after treatments (MAT). All herbicides failed to provide more than 63% control of TSA at 3 and 6 MAT. In Benghal dayflower study, bentazon, bromoxynil, chlorimuron ethyl plus tribenuron methyl, dimethenamid-P, nicosulfuron plus rimsulfuron, primisulfuron-methyl, S-metolachlor plus glyphosate plus mesotrione, and sulfosulfuron provided less than 50% control of Benghal dayflower during 6 weeks of evaluation whereas other herbicides: aminocyclopyrachlor (34-96%) ametryn (2-55%), atrazine (2-68%), diclosulam (12-67%), flumioxazin (59-83%), saflufenacil (24-78%), and sulfentrazone (67-96%) provided variable control of Benghal dayflower. In Italian ryegrass study, 50 seeds of F1 generation of resistant biotype ’49E’ and susceptible biotypes ‘Gulf’ and ‘Marshall’ of Italian ryegrass which were previously grown in mixture were used. Each biotype’s F1 generation responce to imazapyr at 0, 1, and 2% under PRE, early post emergence (EPOST) and late postemergence (LPOST) was evaluated. At PRE, imazapyr at 1 and 2% reduced ‘49E’ seedlings emerged 3 and 18%, respectively, but both rates failed to have any significant impact on fresh biomass weight compared to untreated. At EPOST, survival of ‘49E’ shoots were reduced 3 to 10% by both rate of imazapyr whereas only imazapyr at 1% caused 0.74 to 3.8 % fresh biomass reduction. At LPOST, ‘49E’ shoot survival was reduced 9 to 12% by both rate of imazapyr whereas both rate of imazapyr reduced ‘49E’ fresh biomass 3 to 31%. In all the PRE, EPOST, and LPOST experiments, ‘Gulf’ and ‘Marshall’ were still susceptible to the imazapyr.

Genótipos de azevém (Lolium multiflorum Lam.) diplóides e tetraplóides são cultivados como forrageira na produção animal, no entanto, quando sistemas de produção que envolve o plantio direto são estabelecidos após o cultivo da forrageira é comum a dessecação com o herbicida glyphosate. Portanto, é importante conhecer se existe suscetibilidade diferencial a este herbicida entre os genótipos. Desta forma, foi desenvolvida a presente pesquisa como o objetivo de avaliar o grau de tolerância dos genótipos diplóides e tetraplóides de azevém ao herbicida glyphosate em quatro estádios fenológicos de desenvolvimento. Para isso, foram instalados quatro experimentos, sendo um para cada estádio fenológico do azevém (duas folhas, quatro perfilhos, pré-florescimento e formação de grãos). Os tratamentos consistiram da combinação dos dois genótipos e seis doses do herbicida glyphosate (240; 480; 960; 1.920; 3.840 e 7.680 g e.a. ha-1), e uma testemunha sem aplicação de glyphosate, em delineamento experimental de blocos ao acaso, quatro repetições. Os parâmetros analisados foram porcentagem de controle e fitomassa seca das plantas. Os resultados foram submetidos à análise de variância e em seguida ajustados para modelo de curva de dose-resposta do tipo logística, sendo destes modelos calculados valores de controle correspondestes a 50, 80, 90 e 99%. As conclusões principais obtidas nesta pesquisa foram de que os genótipos de azevém diplóide e tetraplóide apresentam suscetibilidade diferencial ao herbicida glyphosate, sendo o genótipo tetraplóide mais tolerante ao herbicida. O grau diferencial de tolerância, medido pelo fator de tolerância (FT) diferencial entre os genótipos, expresso pelo valor médio dos quatro estádios fenológicos estudados, utilizando como base o controle de 50% das plantas pelo glyphosate foi de 1,6 vezes a dose de glyphosate no genótipo tetraplóide em relação ao genótipo diplóide. Os estádios fenológicos de desenvolvimento das plantas de ambos os genótipos estudados afetam o grau de tolerância ao glyphosate. De maneira geral, em estádios mais avançados de desenvolvimento fenológico dos dois genótipos a suscetibilidade do azevém é menor ao glyphosate, exceto para o estádio de préflorescimento, no qual a planta é mais suscetível que o estádio de quatro perfilhos, quando o parâmetro de análise é a dose necessária para controle de 50% das plantas. O parâmetro de análise de suscetibilidade fitomassa seca das plantas apresentou a mesma tendência diferencial entre os fenótipos diplóides e tetraplóides que o parâmetro porcentagem de controle visual. / Diploid and tetraploid genotypes of Italian ryegrass (Lolium multiflorum Lam.) are cultivated as forage crop for animal production, however, when cropping systems that involve no tillage is established after the forage cultivation it is common the dessecation with the herbicide glyphosate. However, it is important to know if there is differential susceptibility between the genotypes to the herbicide, in four phenological stages of development. Therefore, it was developed this research with the objective of evaluating the degree of tolerance of the diploid and tetraploid genotypes of Italian ryegrass to the herbicide glyphosate. For that, four experiments were installed being one for each of the Italian ryegrass phenological stages (two leaves, four tillers, pre-flowering, and grain formation). The treatments consisted of the combination of the two genotypes and six rates of glyphosate (240; 480; 960; 1.920; 3.840 and 7.680 g a.e. ha-1) and a check plot without glyphosate application, in randomized complete blocks design, four replications. The parameters that were analyzed were control percentage and dry biomass. Results were submitted to analysis of variance and subsequently adjusted to non linear model of logistic dose-response curves, and from these models control values were calculated at 50, 80, 90 and 99%. The main conclusions obtained in this research were that genotypes of Italian ryegrass presented differential susceptibility to the herbicide glyphosate. The differential degree of tolerance, measured by the tolerance factor (TF) between the biotypes, expressed by the mean value of the four development stages studied, using the 50% Italian ryegrass control, was 1.6 times more glyphosate rate for the tetraploid genotype compared to the diploid genotype. The phenological stages of development of both genotypes affected the tolerance degree to glyphosate. In general, the more is the advanced development stages of both biotypes, the lower is the susceptibility of Italian ryegrass to glyphosate, except for the stage of pre-flowering, in which the plant is less susceptible than the stage of four tillers, when the analyzed parameter is the rate necessary to control 50% of the plants. The parameter of analysis of susceptibility plant dry biomass presented the same tendency of differential control between the diploid and tetraploid genotypes than the visual control percentage.

Genótipos de azevém (Lolium multiflorum Lam.) diplóides e tetraplóides são cultivados como forrageira na produção animal, no entanto, quando sistemas de produção que envolve o plantio direto são estabelecidos após o cultivo da forrageira é comum a dessecação com o herbicida glyphosate. Portanto, é importante conhecer se existe suscetibilidade diferencial a este herbicida entre os genótipos. Desta forma, foi desenvolvida a presente pesquisa como o objetivo de avaliar o grau de tolerância dos genótipos diplóides e tetraplóides de azevém ao herbicida glyphosate em quatro estádios fenológicos de desenvolvimento. Para isso, foram instalados quatro experimentos, sendo um para cada estádio fenológico do azevém (duas folhas, quatro perfilhos, pré-florescimento e formação de grãos). Os tratamentos consistiram da combinação dos dois genótipos e seis doses do herbicida glyphosate (240; 480; 960; 1.920; 3.840 e 7.680 g e.a. ha-1), e uma testemunha sem aplicação de glyphosate, em delineamento experimental de blocos ao acaso, quatro repetições. Os parâmetros analisados foram porcentagem de controle e fitomassa seca das plantas. Os resultados foram submetidos à análise de variância e em seguida ajustados para modelo de curva de dose-resposta do tipo logística, sendo destes modelos calculados valores de controle correspondestes a 50, 80, 90 e 99%. As conclusões principais obtidas nesta pesquisa foram de que os genótipos de azevém diplóide e tetraplóide apresentam suscetibilidade diferencial ao herbicida glyphosate, sendo o genótipo tetraplóide mais tolerante ao herbicida. O grau diferencial de tolerância, medido pelo fator de tolerância (FT) diferencial entre os genótipos, expresso pelo valor médio dos quatro estádios fenológicos estudados, utilizando como base o controle de 50% das plantas pelo glyphosate foi de 1,6 vezes a dose de glyphosate no genótipo tetraplóide em relação ao genótipo diplóide. Os estádios fenológicos de desenvolvimento das plantas de ambos os genótipos estudados afetam o grau de tolerância ao glyphosate. De maneira geral, em estádios mais avançados de desenvolvimento fenológico dos dois genótipos a suscetibilidade do azevém é menor ao glyphosate, exceto para o estádio de préflorescimento, no qual a planta é mais suscetível que o estádio de quatro perfilhos, quando o parâmetro de análise é a dose necessária para controle de 50% das plantas. O parâmetro de análise de suscetibilidade fitomassa seca das plantas apresentou a mesma tendência diferencial entre os fenótipos diplóides e tetraplóides que o parâmetro porcentagem de controle visual. / Diploid and tetraploid genotypes of Italian ryegrass (Lolium multiflorum Lam.) are cultivated as forage crop for animal production, however, when cropping systems that involve no tillage is established after the forage cultivation it is common the dessecation with the herbicide glyphosate. However, it is important to know if there is differential susceptibility between the genotypes to the herbicide, in four phenological stages of development. Therefore, it was developed this research with the objective of evaluating the degree of tolerance of the diploid and tetraploid genotypes of Italian ryegrass to the herbicide glyphosate. For that, four experiments were installed being one for each of the Italian ryegrass phenological stages (two leaves, four tillers, pre-flowering, and grain formation). The treatments consisted of the combination of the two genotypes and six rates of glyphosate (240; 480; 960; 1.920; 3.840 and 7.680 g a.e. ha-1) and a check plot without glyphosate application, in randomized complete blocks design, four replications. The parameters that were analyzed were control percentage and dry biomass. Results were submitted to analysis of variance and subsequently adjusted to non linear model of logistic dose-response curves, and from these models control values were calculated at 50, 80, 90 and 99%. The main conclusions obtained in this research were that genotypes of Italian ryegrass presented differential susceptibility to the herbicide glyphosate. The differential degree of tolerance, measured by the tolerance factor (TF) between the biotypes, expressed by the mean value of the four development stages studied, using the 50% Italian ryegrass control, was 1.6 times more glyphosate rate for the tetraploid genotype compared to the diploid genotype. The phenological stages of development of both genotypes affected the tolerance degree to glyphosate. In general, the more is the advanced development stages of both biotypes, the lower is the susceptibility of Italian ryegrass to glyphosate, except for the stage of pre-flowering, in which the plant is less susceptible than the stage of four tillers, when the analyzed parameter is the rate necessary to control 50% of the plants. The parameter of analysis of susceptibility plant dry biomass presented the same tendency of differential control between the diploid and tetraploid genotypes than the visual control percentage.

Master of Science / Department of Agronomy / Randall S. Currie / Mithila Jugulam / Italian ryegrass (Lolium perenne L. ssp. multiflorum (Lam.) Husnot), one of the problem weeds of the US, evolved resistance to multiple herbicides including glyphosate due to selection in Arkansas (AR). Glyphosate is a 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) inhibitor and amplification of EPSPS gene, the molecular target of glyphosate confers resistance to this herbicide in several weed species, including Italian ryegrass from AR. The objective of this study was to determine the expression of EPSPS gene and protein as well as distribution of EPSPS copies on the genome of glyphosate-resistant Italian ryegrass (ARR) using a known susceptible Italian ryegrass (ARS) from AR. EPSPS gene copies and expression of ARR and ARS were determined using quantitative PCR with appropriate endogenous controls. EPSPS protein expression was determined using Western blot analysis. Fluorescence in situ hybridization (FISH) was performed on somatic metaphase chromosomes to determine the location of EPSPS copies. Based on qPCR analysis, ARR plants showed a wide range of 12 to 118 EPSPS copies compared to a single copy in ARS. EPSPS gene expression correlated with the gene copy number in both ARR and ARS. Individuals with high EPSPS copies showed high protein expression in Western blot analysis. FISH analysis showed presence of brighter EPSPS signals, distributed randomly throughout the genome of ARR individuals compared to a faint signal in ARS plants. Random distribution of EPSPS copies was previously reported in glyphosate-resistant Palmer amaranth. Overall, the results of this study will help understand the origin and mechanism of EPSPS gene amplification in Italian ryegrass.

To combat herbicide resistance among weeds, non-herbicide methods of control, such as cover crops, are becoming widely adapted. Experiments were conducted to determine how to effectively establish and manage cover crops in order to suppress tall waterhemp and Italian ryegrass and to assess their overall impact on soybean growth and yield. Various cover crop establishment methods were evaluated, and it was determined that interseeding at the R7 growth stage of soybean was the least effective method for proper cover crop establishment. Biomass data demonstrated that interseeding created the least amountof cover crop biomass, with no differences found among the other establishment methods that included drilling and sowing broadcast. At soybean planting timing, treatments with tillage had greater control of tall waterhemp than those without tillage. Wheat was shown to have the greatest weed suppressive capabilities, largely due to its ability to create high levels of residual biomass. Daikon radish produced the least biomass residue and had the poorest tall waterhemp control. The termination experiment of Elbon rye determined that treatments with rolling could impact soybean emergence and plant height largely due to dense biomass that lay flat onto the soil surface

No description available.

Integrated weed management involves the utilization of weed biology principles to develop effective and economical control strategies. This research involved investigations of herbicide-based weed management programs in potato (<i>Solanum tuberosum</i> L.) and winter wheat (<i>Triticum aestivum</i> L.) as well as investigations of the biological characteristics of smooth pigweed (<i>Amaranthus hybridus</i>), a troublesome species in many crops. Sulfentrazone is an herbicide registered for use in soybean [<i>Glycine max</i> (L.) Merr.] and tobacco (<i>Nicotiana tabacum</i> L.) that may also have potential for use in potato. In field experiments, potato tolerance to preemergence (PRE) applications of sulfentrazone at rates up to 0.21 kg/ha was similar to that from the registered herbicides metribuzin, metolachlor, or metribuzin plus metolachlor PRE. Potato generally did not tolerate sulfentrazone applications to foliage. Sulfentrazone effectively controlled common lambsquarters (<i>Chenopodium album</i> L.) at rates as low as 0.11 kg/ha and also controlled several annual grasses at higher application rates, but was slightly less effective on jimsonweed (<i>Datura stramonium</i> L.) and ineffective on common ragweed (<i>Ambrosia artemisiifolia</i> L.). Potato tuber yield and grade from sulfentrazone PRE applications was similar to yield of potato treated with registered herbicides. Laboratory research was also conducted to determine the mechanism of sulfentrazone selectivity between potato (a tolerant species), common lambsquarters (a sensitive species), and jimsonweed (an intermediate species). After 48 h root exposure to [14C] sulfentrazone, absorption by common lambsquarters was nearly two-fold that of jimsonweed and three-fold that of potato. Both weed species also exhibited nearly a two-fold increase in sulfentrazone translocation from roots to shoots compared to potato. Since the site of action of sulfentrazone, protoporphyrinogen oxidase, is located in shoot tissue, translocation to shoots is essential for sulfentrazone toxicity. Therefore, the proposed primary mechanisms of selectivity between these species are differential root absorption and differential translocation. Experiments were also conducted to investigate the potential of the experimental herbicide AE F130060 03 for Italian ryegrass (<i>Lolium multiflorum</i> Lam.) control in winter wheat. In laboratory research, foliar absorption of AE F130060 03 in Italian ryegrass was at least three times that in wheat. Additionally, herbicide metabolism was greater in wheat, particularly in wheat treated with the herbicide safener AE F107892. In field experiments, AE F130060 03 was as effective as diclofop-methyl for control of diclofop-sensitive Italian ryegrass and more effective than diclofop-methyl and all other herbicides tested for control of diclofop-resistant Italian ryegrass. Although wheat injury from AE F130060 03 was greater than from other herbicides, wheat recovered and yields were not affected. Postemergence AE F130060 03 applications controlled Italian ryegrass from emergence until the end of tillering, but applications made to four- to five-tiller Italian ryegrass resulted in the least amount of new Italian ryegrass emergence following application. To further define the utility of AE F130060 03 in winter wheat, ten wheat cultivars adapted to Virginia were evaluated for tolerance to AE F130060 03. Biomass production between cultivars was not influenced by AE F130060 03 application in the greenhouse, although slight yield decreases due to herbicide application were found in FFR 518, Coker 9663, AgriPro Patton, and VA98W593 under weed-free conditions in the field. Greenhouse, growth chamber, and field experiments were also conducted to investigate growth and seed production of one imidazolinone-susceptible (S) and five -resistant (R1, R2, R3, R4, and R5) smooth pigweed biotypes. Although the S biotype produced more total biomass than four of the five R biotypes, R4 displayed a more rapid growth rate at 3 to 5 wk after planting and a faster germination rate than S and all other R biotypes. Seed production in R4 was similar to S and greater than in all other R biotypes. Early rapid growth in R4 did not translate into increased biomass accumulation compared to S at the conclusion of the experiments. / Ph. D.

Italian ryegrass (Lolium multiflorum Lam.) is a competitive weed in small grain production areas throughout the northwestern and southeastern US. In small grains, Italian ryegrass has generally been controlled with postemergence treatments of diclofop, or diclofop-methyl, a member of the subfamily of the aromatic carboxylic acid family, the aryloxyphenoxypropionates. The first incidence of diclofop resistance in Italian ryegrass was reported in Virginia in 1995. Experiments to characterize diclofop resistance in several Virginia biotypes of Italian ryegrass included the following objectives: (1) evaluation of the presence of diclofop resistance in several Italian ryegrass biotypes collected across Virginia, (2) evaluation of alternative herbicide efficacy for diclofop resistant Italian ryegrass control, and (3) characterization of the aryloxyphenoxypropionate (APP) resistance mechanism in resistant Italian ryegrass biotypes. The response of 32 biotypes to diclofop collected from various locations statewide with varying histories of diclofop applications confirmed diclofop resistance in Virginian Italian ryegrass populations. At 4-times the label-recommended application rate, only 50% of biotypes previously exposed to diclofop in a cropping situation were adequately controlled versus 94% of the biotypes not previously treated with diclofop. Tralkoxydim provided the most effective control of four of the biotypes. No postemergence treatment effectively controlled one biotype previously exposed to diclofop applications. Effective preemergence herbicide treatments for Italian ryegrass control in the greenhouse included acetochlor (two formulations) and flufenacet plus metribuzin. In the field, flufenacet plus metribuzin resulted in excellent Italian ryegrass control, little crop injury, and acceptable barley yields. Acetyl-coenzyme A carboxylase (ACCase) assays and herbicide absorption, translocation, and metabolism studies were conducted to investigate resistant mechanism(s) to two APP herbicides, diclofop and quizalofop. ACCase assays indicated no differences in enzyme activity between the two biotypes of Italian ryegrass evaluated. Furthermore, no significant differences in the specific activity of ACCase were detected between the two biotypes in the absence of diclofop. [14C]Quizalofop-P absorption, translocation, and metabolism did not differ between resistant and susceptible Italian ryegrass biotypes. Lack of a significant biotype effect suggests that differential metabolism does not explain the differential response to diclofop treatments observed in the herbicide dose-plant response experiment. / Ph. D.

Objetivou-se avaliar como diferentes estratégias de manejo do pasto de azevém anual interferem na produção animal, no consumo de forragem e na emissão de metano por ovinos em sistema de integração lavoura-pecuária (SILP) (Capítulo II). Já no Capítulo III objetivou-se avaliar as técnicas dos nalcanos e do nitrogênio fecal na estimativa do consumo de forragem por ovinos em pastos de azevém anual. Os experimentos foram conduzidos nos anos de 2011 e 2012 na Estação Experimental da UFRGS. Foram utilizados ovinos em um SILP de soja e milho no verão, em rotação com azevém anual no inverno. Para ambos os Capítulos (II e III) foram estudados dois métodos de pastoreio (contínuo e rotativo) e duas intensidades de pastejo (moderada e baixa; 2,5 e 5 vezes o potencial de consumo de matéria seca, respectivamente) em um delineamento de blocos casualizados com 3 repetições. Para o Capítulo II, no primeiro experimento os animais experimentais eram cordeiros, enquanto no segundo foram ovelhas em lactação. Os resultados indicaram que o ganho médio diário (GMD) dos cordeiros foi maior (P<0,05) no método de pastoreio continuo que no método de pastoreio rotativo, independente da intensidade de pastejo. O ganho de peso vivo por área (GPV) apresentou a mesma resposta em ambos os experimentos, com maior GPV na intensidade de pastejo moderada (P<0,05). No experimento 1, o consumo de matéria seca (CMS) foi maior para o método de pastoreio continuo, enquanto no experimento 2 não houve diferenças entre métodos e intensidades. As emissões de CH4 diárias por animal não diferiram entre tratamentos em ambos os experimentos (P>0,05), porém, quando expressas em g CH4 kg GPV-1 as emissões foram em média 15,33% maiores (P<0.05) para o método de pastoreio rotativo, independente da intensidade de pastejo. Os resultados afirmam que as emissões de metano por animal não são afetadas pelos tratamentos impostos. Porém, do ponto de vista de sistema o método de pastoreio contínuo o mais eficiente, por apresentar menor emissão de metano por kg de ganho de peso vivo, independente da intensidade de pastejo. Para o Capítulo III, foram utilizados apenas cordeiros. Utilizou-se a metodologia dos n-alcanos e do nitrogênio fecal, por meio de coleta total de fezes com o auxílio de bolsas coletoras. Na avaliação entre os n-alcanos, verificou-se melhores resultados quando utilizando o par C31:C32. Para a metodologia do nitrogênio fecal, as equações propostas por Wang et al. (2009) e por Azevedo (2011) foram as melhores (P<0,05). A técnica do nitrogênio fecal mostrou-se mais acurado do que o uso dos n-alcanos, que superestimou os valores de consumo. / The aim of this study was to evaluate how different management strategies of Italian ryegrass affects animal production, forage intake and methane emissions by sheep in integrated crop-livestock system (ICLS) (Chapter II). In Chapter III, we aimed to evaluate the techniques of n-alkanes and fecal nitrogen in estimating forage intake by sheep grazing on ryegrass. The experiments were conducted in 2011 and 2012 at the UFRGS Experimental Station. The ICLS soybeans and corn crops in summer, in rotation with grazed Italian ryegrass in winter. For both chapters (II and III) two stocking methods (continuous or rotational) and two grazing intensities (moderate and low, 2.5 and 5 times the potential dry matter intake, respectively) were studied in a randomized block design with three replications. In Chapter II, in the first experiment, the experimental animals were lambs, while in the second were lactating ewes. The results indicated that the average daily gain (ADG) of lambs was higher (P<0.05) in the continuous method than in rotational grazing method, regardless of grazing intensity. The live weight gain per area (LWG) showed the same response in both experiments, with higher LWG values in moderate grazing intensity (P<0.05). In experiment I, higher dry matter intake (DMI) values were obtained under continuous grazing, while in experiment II, there no differences between methods and intensities. CH4 emissions per animal and per day did not differ between treatments in both experiments (P>0.05), but when expressed in g CH4 kg-1 LWG emissions were, on average, 15.33% higher (P<0.05) for rotational grazing method, regardless of grazing intensity. Methane emissions per animal were not affected by the treatments applied. However, from system point of view, the continuous grazing method is more efficient, since lower methane emissions per kg of LWG, regardless of grazing intensity, were obtained. In Chapter III, were used only lambs. The methodologies of n-alkanes and fecal nitrogen, were applied through total collection with dung bags. In relation to n-alkanes, better results were obtained when using the pair C31:C32. For the methodology of fecal nitrogen, the equations proposed by Wang et al. (2009) and Azevedo (2011) were the best (P<0.05). The technique of fecal nitrogen proved to be more accurate than the use of n-alkanes, which overestimated the intake.

Objetivou-se avaliar como diferentes estratégias de manejo do pasto de azevém anual interferem na produção animal, no consumo de forragem e na emissão de metano por ovinos em sistema de integração lavoura-pecuária (SILP) (Capítulo II). Já no Capítulo III objetivou-se avaliar as técnicas dos nalcanos e do nitrogênio fecal na estimativa do consumo de forragem por ovinos em pastos de azevém anual. Os experimentos foram conduzidos nos anos de 2011 e 2012 na Estação Experimental da UFRGS. Foram utilizados ovinos em um SILP de soja e milho no verão, em rotação com azevém anual no inverno. Para ambos os Capítulos (II e III) foram estudados dois métodos de pastoreio (contínuo e rotativo) e duas intensidades de pastejo (moderada e baixa; 2,5 e 5 vezes o potencial de consumo de matéria seca, respectivamente) em um delineamento de blocos casualizados com 3 repetições. Para o Capítulo II, no primeiro experimento os animais experimentais eram cordeiros, enquanto no segundo foram ovelhas em lactação. Os resultados indicaram que o ganho médio diário (GMD) dos cordeiros foi maior (P<0,05) no método de pastoreio continuo que no método de pastoreio rotativo, independente da intensidade de pastejo. O ganho de peso vivo por área (GPV) apresentou a mesma resposta em ambos os experimentos, com maior GPV na intensidade de pastejo moderada (P<0,05). No experimento 1, o consumo de matéria seca (CMS) foi maior para o método de pastoreio continuo, enquanto no experimento 2 não houve diferenças entre métodos e intensidades. As emissões de CH4 diárias por animal não diferiram entre tratamentos em ambos os experimentos (P>0,05), porém, quando expressas em g CH4 kg GPV-1 as emissões foram em média 15,33% maiores (P<0.05) para o método de pastoreio rotativo, independente da intensidade de pastejo. Os resultados afirmam que as emissões de metano por animal não são afetadas pelos tratamentos impostos. Porém, do ponto de vista de sistema o método de pastoreio contínuo o mais eficiente, por apresentar menor emissão de metano por kg de ganho de peso vivo, independente da intensidade de pastejo. Para o Capítulo III, foram utilizados apenas cordeiros. Utilizou-se a metodologia dos n-alcanos e do nitrogênio fecal, por meio de coleta total de fezes com o auxílio de bolsas coletoras. Na avaliação entre os n-alcanos, verificou-se melhores resultados quando utilizando o par C31:C32. Para a metodologia do nitrogênio fecal, as equações propostas por Wang et al. (2009) e por Azevedo (2011) foram as melhores (P<0,05). A técnica do nitrogênio fecal mostrou-se mais acurado do que o uso dos n-alcanos, que superestimou os valores de consumo. / The aim of this study was to evaluate how different management strategies of Italian ryegrass affects animal production, forage intake and methane emissions by sheep in integrated crop-livestock system (ICLS) (Chapter II). In Chapter III, we aimed to evaluate the techniques of n-alkanes and fecal nitrogen in estimating forage intake by sheep grazing on ryegrass. The experiments were conducted in 2011 and 2012 at the UFRGS Experimental Station. The ICLS soybeans and corn crops in summer, in rotation with grazed Italian ryegrass in winter. For both chapters (II and III) two stocking methods (continuous or rotational) and two grazing intensities (moderate and low, 2.5 and 5 times the potential dry matter intake, respectively) were studied in a randomized block design with three replications. In Chapter II, in the first experiment, the experimental animals were lambs, while in the second were lactating ewes. The results indicated that the average daily gain (ADG) of lambs was higher (P<0.05) in the continuous method than in rotational grazing method, regardless of grazing intensity. The live weight gain per area (LWG) showed the same response in both experiments, with higher LWG values in moderate grazing intensity (P<0.05). In experiment I, higher dry matter intake (DMI) values were obtained under continuous grazing, while in experiment II, there no differences between methods and intensities. CH4 emissions per animal and per day did not differ between treatments in both experiments (P>0.05), but when expressed in g CH4 kg-1 LWG emissions were, on average, 15.33% higher (P<0.05) for rotational grazing method, regardless of grazing intensity. Methane emissions per animal were not affected by the treatments applied. However, from system point of view, the continuous grazing method is more efficient, since lower methane emissions per kg of LWG, regardless of grazing intensity, were obtained. In Chapter III, were used only lambs. The methodologies of n-alkanes and fecal nitrogen, were applied through total collection with dung bags. In relation to n-alkanes, better results were obtained when using the pair C31:C32. For the methodology of fecal nitrogen, the equations proposed by Wang et al. (2009) and Azevedo (2011) were the best (P<0.05). The technique of fecal nitrogen proved to be more accurate than the use of n-alkanes, which overestimated the intake.