Little is known of the physiological and biochemical mechanisms underlying competitive interactions between alien invasive grasses and native taxa, and how these are affected by resource supply. Consequently, this study compared photosystem II (PS II) function, photosynthetic gas and water exchange, enzyme and pigment concentrations, flowering and biomass accumulation in an indigenous geophyte, Tritonia crocata (L.) Ker. Gawl., grown in monoculture and admixed with the alien grass, Lolium multiflorum Lam., at different levels of water and nutrient supply. Diminished stomatal conductances were the primary cause of reduced net C02 assimilation rates, and consequent biomass accumulation in T. crocata admixed with L. multiflorum at all levels of water and nutrient supply with one exception. These corresponded with decreased soil water contents induced presumably by more efficient competition for water by L. multiflorum, whose biomass was inversely correlated with soil water content. Biochemical impairments to photosynthesis were also apparent in T. crocata admixed with L. multiflorum at low levels of water and nutrient supply. These included a decline in the density of working photosystems (reaction center per chlorophyll RC/ABS), which corresponded with a decreased leaf chlorophyll a content and a decreased efficiency of conversion of excitation energy to electron transport (¥0 / l-^o), pointing to a reduction in electron transport capacity beyond QA~, a decline in apparent carboxylation efficiency and Rubisco content. At low nutrient levels but high water supply, non-stomatal induced biochemical impairments to photosynthesis (decreased RC/ABS, chlorophyll a and Rubisco content) were apparent in T. crocata admixed with L. multiflorum. These attributed to a reallocation of fixed carbohydrate reserves to floral production which increased significantly in T. crocata under these conditions only and associated with a corresponding reduction in the mass of its underground storage organ (bulb). The results of this study did not support the hypothesis that under conditions of low water and low nutrient supply invasive annual grasses would have a lesser impact on the growth and physiology of native geophytes than under resource enriched conditions that favor growth of these grasses. Unresolved is whether resource limitation and allelopathic mechanisms functioned simultaneously in the inhibition of the native geophyte by the alien grass. / Thesis (M. Environmental Science (Ecological Remediation and Sustainable Utilisation))--North-West University, Potchefstroom Campus, 2008.

Little is known of the physiological and biochemical mechanisms underlying competitive interactions between alien invasive grasses and native taxa, and how these are affected by resource supply. Consequently, this study compared photosystem II (PS II) function, photosynthetic gas and water exchange, enzyme and pigment concentrations, flowering and biomass accumulation in an indigenous geophyte, Tritonia crocata (L.) Ker. Gawl., grown in monoculture and admixed with the alien grass, Lolium multiflorum Lam., at different levels of water and nutrient supply. Diminished stomatal conductances were the primary cause of reduced net C02 assimilation rates, and consequent biomass accumulation in T. crocata admixed with L. multiflorum at all levels of water and nutrient supply with one exception. These corresponded with decreased soil water contents induced presumably by more efficient competition for water by L. multiflorum, whose biomass was inversely correlated with soil water content. Biochemical impairments to photosynthesis were also apparent in T. crocata admixed with L. multiflorum at low levels of water and nutrient supply. These included a decline in the density of working photosystems (reaction center per chlorophyll RC/ABS), which corresponded with a decreased leaf chlorophyll a content and a decreased efficiency of conversion of excitation energy to electron transport (¥0 / l-^o), pointing to a reduction in electron transport capacity beyond QA~, a decline in apparent carboxylation efficiency and Rubisco content. At low nutrient levels but high water supply, non-stomatal induced biochemical impairments to photosynthesis (decreased RC/ABS, chlorophyll a and Rubisco content) were apparent in T. crocata admixed with L. multiflorum. These attributed to a reallocation of fixed carbohydrate reserves to floral production which increased significantly in T. crocata under these conditions only and associated with a corresponding reduction in the mass of its underground storage organ (bulb). The results of this study did not support the hypothesis that under conditions of low water and low nutrient supply invasive annual grasses would have a lesser impact on the growth and physiology of native geophytes than under resource enriched conditions that favor growth of these grasses. Unresolved is whether resource limitation and allelopathic mechanisms functioned simultaneously in the inhibition of the native geophyte by the alien grass. / Thesis (M. Environmental Science (Ecological Remediation and Sustainable Utilisation))--North-West University, Potchefstroom Campus, 2008.

The primary objective of this study was to increase net farm income in the Highland Sourveld of Natal by developing pasture based fat lamb production systems. Secondary objectives included (a) determination of the most suitable pasture species or species mixture; (b) determination of the optimum level of N fertilization; (c) establishment of biological and economic optimum stocking rates; (d) projection of expected profit and (e) verification of proposals on a farm scale. Midmar Italian ryegrass was compared to selected legumes alone, and in mixtures with ryegrass in a small plot trial conducted over two years at a 3- and 6-week harvesting frequency under irrigation. Ryegrass in combination with red and white clover provided the highest yields for both harvesting intervals in both years. When this pasture was subsequently compared to ryegrass alone under grazing, no significant difference could be detected in lamb gains at 20 and 28 ewe-lamb units/ha, but at 36 ewe-lamb units/ha the lambs on ryegrass started losing weight at 30 kg, while those on ryegrass + clover continued to gain until a market weight of 40 kg was achieved. In a small plot trial little response was detected to added N above 175 kg N/ha on ryegrass + clover, and under grazing, no significant difference was observed between 275; 375 and 4,75 kg N/ha over two single year periods. Relationships between average daily gain (ADG) and stocking rate, ADG and disc meter height, and stocking rate and disc meter height were mostly well described by linear functions. Expected pre-weaning AOG was 150 g higher (p ≤ 0,01) than post-weaning ADG (100 g) in the first year, and a similar difference was observed in the second year. For the period common to all stocking rates an average maximum gain/ha of 824 kg was achieved at a stocking rate of 33,5 lambs/ha and a disc meter height of 4,5 cm. By lambing in April, lambs could be marketed in September at 40 kg and more weaned lambs could be grazed on the pasture and marketed in December, leading to an expected gain/ha of 1400 to 2200 kg, and expected profit/ha of R 1254 to R 2771, depending on stocking rate. When evaluated under farm conditions, this system produced 2060 kg live weight/ha and a profit of R 3206/ha. It is concluded from the present study that the fat lamb production system based on irrigated ryegrass + clover pastures can be recommended with confidence to farmers in the Highland Sourveld of Natal. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1986.

Four grazing trials to characterise cultivated pastures, in terms of beef production, were conducted in Bioclimate 3 of Natal. Dual purpose and British beef type cows were run on kikuyu at stocking rates from 2,81 to 7,30 cows plus calves per ha. During the eight seasons of the trial the seasonal rainfall varied from 580 to 933 mm. There was a positive linear relationship between rainfall and pasture yield with maximum yield of kikuyu being recorded during February - March. Stocking rate affected pasture yields only during favourable rainfall seasons. Crude protein (CP) and crude fibre (CF) of kikuyu fluctuated markedly within and between seasons. However, CP increased and CF decreased as stocking rate increased. There were significant relationships between stocking rate and (a) calf performance, (b) calf livemass gain, (c) period required to attain maximum mass, (d) period on pasture for the cows, and (e) cow mass change: Weaners were run on irrigated Italian ryegrass at 5, 7 and 9 weaners per ha for four seasons. Stocking rate had little effect on the growth pattern of the pasture but affected dry matter yields. Reducing the stocking rate resulted in increased pasture yields and CF content but reduced CP levels of material on offer. Steers exhibited higher gains than heifers but lower carcass grades and stocking rates for maximum gain per ha (SRmax). Livemass gains of 1315 and 1224 kg per ha can be expected at SRmax of 6,85 and 9,54 for steers and heifers respectively. Yearling heifers run at four stocking rates on kikuyu for one season showed a negative linear relationship between stocking rate and gain and a positive linear relationship between pasture height and gain. A SRmax of 8,85 allows for a livemass gain of 1 040 kg per ha. The effect of feeding concentrates on foggaged kikuyu was evaluated. Foggaged kikuyu can be used as a source of roughage for fattening steers. However, as the steers became adapted to the concentrate the intake of kikuyu declined from 39 to 19% of their daily intake. Regressions derived from the characterisation trials allow for developing beef systems for different situations. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1985.

Submitted by ANDREÍSA FLORES BRAGA null (andreisaflores@hotmail.com) on 2016-09-30T14:29:28Z No. of bitstreams: 1 Braga, A.F. - Dissertação.pdf: 1061732 bytes, checksum: 492706c85f5f6005ecd7d464a2fa4a01 (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-10-04T13:48:30Z (GMT) No. of bitstreams: 1 braga_af_me_jabo.pdf: 1061732 bytes, checksum: 492706c85f5f6005ecd7d464a2fa4a01 (MD5) / Made available in DSpace on 2016-10-04T13:48:30Z (GMT). No. of bitstreams: 1 braga_af_me_jabo.pdf: 1061732 bytes, checksum: 492706c85f5f6005ecd7d464a2fa4a01 (MD5) Previous issue date: 2016-08-05 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O uso repetitivo de herbicidas com mesmo mecanismo de ação tem ocasionado a seleção de plantas daninhas resistentes, e o azevém se destaca pela resistência ao glyphosate. Tendo em vista sua ocorrência em eucaliptais, cultura na qual se usa o glyphosate, torna-se necessário estudar sua interferência. Sendo assim, objetivou-se avaliar o efeito de densidades (0, 10, 20, 30 e 50 plantas m-2) de dois biótipos de Lolium multiflorum (resistente e suscetível ao glyphosate) em mudas de dois clones de Eucalyptus. x urograndis (I-144 e 1407). O delineamento experimental adotado foi em blocos casualizados com quatro repetições, seguindo um esquema fatorial 2x5 para cada clone. Aos 0, 14, 28, 42, 56 e 70 dias após o transplante (DAT), foram avaliados nos clones a altura e diâmetro, e aos 70 DAT, área foliar e biomassa seca de parte aérea do eucalipto e do azevém. Não houve interação entre os fatores biótipos e densidades para os clones, mas todas as características foram afetadas pelos fatores isoladamente. O aumento das densidades do azevém reduziu todas as características avaliadas nos clones, sendo que a área foliar foi a mais afetada. O biótipo resistente foi menos agressivo, sendo assim, a densidade de azevém resistente tolerável pela cultura pode ser maior do que a de azevém suscetível. / Repetitive use of herbicides with the same mechanism of action has led to the selection of resistant weeds and ryegrass stands for resistance to glyphosate. In view of its occurrence in eucalyptus plantations, culture in which glyphosate is used, it is necessary to study its interference. Thus, this study aimed to evaluate the effect of densities (0, 10, 20, 30 and 50 plants m-2) of two Lolium multiflorum biotypes (susceptible and resistant to glyphosate) in saplings of two Eucalyptus. x urograndis clones (I-144 and 1407). The experimental design was a randomized block with four replications, following a 2x5 factorial arrangement for each clone. At 0, 14, 28, 42, 56 and 70 days after transplanting (DAT) were evaluated in clones their height and diameter, and at 70 DAT, leaf area and dry biomass of the aerial part of eucalypt and ryegrass. There was no interaction between the factors biotypeand density for both clones, but all the features were affected by each of the factors alone. The increase in ryegrass densities reduced all characteristics evaluated in the clones, being leaf area the most affected one. The resistant biotype was less aggressive thus resistant ryegrass density tolerable for the culture may be higher than the susceptible ryegrass density.

Submitted by Arthur Arrobas Martins Barroso null (arthuragro07@hotmail.com) on 2017-09-06T14:00:26Z No. of bitstreams: 1 Tese_Arthur_Arrobas_Martins _Barroso.pdf: 1551513 bytes, checksum: 9d065640a6416beb7443eb7e6ad2dd94 (MD5) / Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-09-06T16:52:44Z (GMT) No. of bitstreams: 1 barroso_aam_dr_jabo.pdf: 1551513 bytes, checksum: 9d065640a6416beb7443eb7e6ad2dd94 (MD5) / Made available in DSpace on 2017-09-06T16:52:44Z (GMT). No. of bitstreams: 1 barroso_aam_dr_jabo.pdf: 1551513 bytes, checksum: 9d065640a6416beb7443eb7e6ad2dd94 (MD5) Previous issue date: 2017-07-18 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / As culturas agrícolas estão sujeitas a conviver com plantas daninhas que podem, em determinadas situações, reduzir seu potencial genético de produção, causando prejuízos. Na maioria das vezes, devido à praticidade e ao custo, essas plantas são controladas pela aplicação de herbicidas, o que se denomina de controle químico. Dentre os produtos utilizados, está o glyphosate, que nos últimos anos vem sendo usado de maneira repetitiva devido à presença quase que exclusiva de culturas tolerantes a esse herbicida, como a soja, o algodão e o milho. Com isso, a utilização desse herbicida vem selecionando, nos últimos anos, plantas que apresentam adaptações para resistir a sua ação, dentre elas o azevém e o capim-pé-de-galinha. A resistência pode ser causada por diferentes mecanismos, envolvendo ou não a enzima-alvo de atuação do herbicida. Para o glyphosate, essa enzima é a 5-enolpiruvilshiquimato-3-fosfato, e essa pode apresentar mutações simples ou duplas. Essas mutações, além de afetar a tolerância da planta ao herbicida, podem modificar a fisiologia e o metabolismo da espécie, tornando-a mais ou menos adaptada ecologicamente, o que é denominado de fitness. Este trabalho teve por objetivo estudar os impactos da resistência ao glyphosate nas duas espécies supracitadas. Em um primeiro trabalho, plantas de azevém resistentes ao glyphosate foram comparadas a plantas suscetíveis quanto a seu perfil metabólico e proteico antes e após a aplicação do herbicida. As plantas suscetíveis apresentaram maiores níveis de aminoácidos produzidos derivado da rota do ácido chiquímico e menores teores de glyphosate em suas folhas, 72 horas após a aplicação do herbicida. Observou-se que as plantas suscetíveis apresentaram maior desenvolvimento, maior expressão de proteínas ligadas ao sistema fotossintético do azevém e expressão diferencial de proteínas ligadas à defesa vegetal contra estresses, ausentes nas plantas resistentes. Após a aplicação do herbicida, as plantas suscetíveis morreram, e as resistentes sobreviveram, passando a expressar, também, a enzima EPSPS sintase, sendo esse um dos mecanismos de resistência encontrados para a espécie. Em um segundo trabalho, avaliaram-se, em dois experimentos, os impactos da resistência ao glyphosate, causados por mutações simples ou duplas, no capim-pé-de-galinha, e seus efeitos na cultura da soja. O desenvolvimento e a fecundidade do capim-pé-de-galinha são pouco afetados pela mutação simples na posição 106 da enzima EPSPS, na ausência do glyphosate. Por outro lado, a mutação dupla da enzima nas posições 102 e 106 gera elevados custos no desenvolvimento e na reprodução das plantas. Quando se aplica o herbicida, a situação inverte-se. Plantas com a presença de uma mutação passam a sofrer intoxicação com o herbicida, chegando, inclusive, a morrer, enquanto se observa sobrevivência total de plantas com duplas mutações. Quando em convivência com a soja, na ausência do herbicida, tem-se a cultura mais afetada pela convivência com os genótipos suscetíveis e com uma única mutação. Na presença do herbicida, nas condições observadas, a interferência das plantas de capim-pé-de-galinha foi reduzida. / Crops are subject to live with spontaneous plants that may in certain situations reduce their genetic potential of production, causing losses. Most of the time, due to the practicality and cost, these plants are controlled by the application of herbicides, what is called chemical control. Among the products for this control, there is glyphosate, which in recent years has been used repetitively due to the almost exclusive presence of crops tolerant to this herbicide, such as soybean, cotton and corn. The use of this herbicide has been selecting, therefore in the last years plants that present adaptations to resist its application, among them Italian ryegrass and goosegrass. The resistance can be caused by different mechanisms, involving or not the target enzyme of action of the herbicide. For glyphosate, this enzyme is 5-enolpyruvyl-silicon-3-phosphate and it may present single or double mutations. These mutations, in addition to affecting the tolerance of the plant to the herbicide, can modify the physiology and metabolism of the species, making it more or less ecologically adapted, which is called fitness. The objective of this work was to study the impacts of glyphosate resistance on the two species mentioned above. In a first work, glyphosate resistant Italian ryegrass plants were compared to susceptible plants for their metabolic and protein profile before and after herbicide application. Susceptible plants showed higher levels of amino acids produced from the shikimic acid route and lower levels of glyphosate in their leaves 72 hours after the application of the herbicide. It was observed that the susceptible plants presented greater development, proteins linked to the greater ryegrass physiology expressed and differential expression of proteins bound to vegetal defense against stresses, absent in resistant plants. After the application of the herbicide, the susceptible plants died, and the resistant ones continued their normal physiology and start expressing the EPSPS synthase enzyme, being this one of the mechanisms of resistance found for the species. In a second work, the impacts of resistance to glyphosate, caused by single or double mutations in goosegrass and its effects on soybean crop, were evaluated in two experiments. The development and fecundity of goosegrass is little affected by simple mutation at position 106 of the EPSPS enzyme in the absence of glyphosate. On the other hand, the double mutation of the enzyme at positions 102 and 106, generates high costs in the development and reproduction of plants. When the herbicide is applied, the situation reverses. Plants with the presence of a mutation begin to present phytointoxication with the herbicide. When living with soybeans, in the absence of the herbicide, the culture is most affected by the coexistence with the susceptible genotypes and genotype with a single mutation. In the presence of the herbicide, under the conditions observed, the interference of goosegrass plants was reduced. / CNPq: 140943/2014-5

Submitted by Gabriela Lopes (gmachadolopesufpel@gmail.com) on 2016-09-13T17:43:22Z No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertação.pdf: 594620 bytes, checksum: f2b0642b05c911dff9dba034e3e9d4cd (MD5) / Made available in DSpace on 2016-09-13T17:43:22Z (GMT). No. of bitstreams: 2 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Dissertação.pdf: 594620 bytes, checksum: f2b0642b05c911dff9dba034e3e9d4cd (MD5) Previous issue date: 2015-07-07 / Sem bolsa / O objetivo do estudo foi avaliar a produção de forragem, palhada e sementes do azevém anual (Lolium multiflorum Lam.) de ciclo longo (BRS Estações) submetido a diferentes freqüências de desfolha. Foram realizados seis cortes (desfolhas) com quantidade média colhida por corte de 2.039,9kg MS ha-1 com duração do ciclo produtivo de 216 dias ou 2.161,55 GD. O aumento da colheita de forragem foi linear em função do tempo com predomínio de lâminas foliares até o quinto corte. O último corte foi efetuado em final de novembro com uma colheita de 559 kg ha-1 de MS de folhas vivas. A produção total de forragem foi de 15,5 t MS ha- 1 . Máxima colheita de sementes (1.423 kg ha-1) ainda com a execução de três colheitas de forragem (8.178 kg MS ha-1). No entanto, à medida que a execução do corte da forragem avançou no tempo, a partir de 1.000 GD, ocorreu uma queda assintótica no rendimento de sementes. O crescimento das plantas sem a intervenção da desfolha resultou na maior palhada ao final do ciclo da cultura (12,2 t de MS ha-1). Todavia, conforme a utilização da pastagem ao longo do tempo ocorreu uma redução linear da palhada, com valor mínimo, resultante de seis utilizações da pastagem, de 1.688 kg MS ha-1. O máximo número de cortes propicia elevada colheita de forragem com elevada participação de folhas. A execução de três desfolhas não afeta a produção de sementes e possibilita elevada colheita de folhas e a manutenção de significativa palhada ao final do ciclo produtivo da cultura. / The purpose of this study was to evaluate the production of fodder, straw and seeds of a variety annual ryegrass (Lolium multiflorum Lam.) long cycle (BRS Estações) submitted many numbers of defoliation. The variety allowed six cuts (defoliation) with average amount harvested by defoliation 2.039,9kg DM ha-1 with the productive cycle duration of 216 days or 2.161,55 DD. The increase in fodder harvest was linear in relation to time with predominance of leaf blades until the fifth cut. The last cut was made in late November and also made possible the harvest 559 kg of DM ha-1 fresh leaves. The total fodder production was 15,5t DM ha-1. It was possible to obtain the highest seed harvest (1.423 kg ha-1) and by performing three fodder harvest (8.178kg DM ha-1). Nonetheless, as fodder cut running forward in time from, 1.000 DD, there was an asymptotic fall in yield seeds. Plant growth without defoliation intervention resulted in the largest straw at the end of the crop cycle (12,2 t de DM ha-1). However, as the use of grazing over time there was a linear decrease of the straw, with minimum value, resulting from six grazing uses of 1.688 kg DM ha- 1 . The maximum number of cuts provides raised fodder harvest with raised leaves participation. The execution of three defoliation does not affect seed production and enables high leaf harvest and the maintenance of significantly straw at the end of productive cycle of the crop

Submitted by Marcos Anselmo (marcos.anselmo@unipampa.edu.br) on 2016-09-23T20:43:47Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) FABIANE QUEVEDO DA ROSA.pdf: 623070 bytes, checksum: d6e7ed987a04d5ad296d7f91b6123a7d (MD5) / Approved for entry into archive by Marcos Anselmo (marcos.anselmo@unipampa.edu.br) on 2016-09-23T20:44:00Z (GMT) No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) FABIANE QUEVEDO DA ROSA.pdf: 623070 bytes, checksum: d6e7ed987a04d5ad296d7f91b6123a7d (MD5) / Made available in DSpace on 2016-09-23T20:44:00Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) FABIANE QUEVEDO DA ROSA.pdf: 623070 bytes, checksum: d6e7ed987a04d5ad296d7f91b6123a7d (MD5) Previous issue date: 2016-08-26 / Com o objetivo de avaliar a proteína bruta fecal como indicador de consumo e digestibilidade de bovinos alimentados com pastagem nativa situada no Bioma Pampa e inclusões de azevém e avaliar a qualidade nutricional dessas pastagens foram realizados dois experimentos em gaiolas de metabolismo. No experimento I, os animais recebiam diferentes níveis de oferta de pastagem nativa onde os tratamentos consistiam em níveis de1,5 e 2,25% do peso vivo de matéria seca e um nível ad libitum, com pelo menos 20% de sobras diárias onde foram realizados seis períodos experimentais, O experimento II consistia em diferentes níveis de inclusão de azevém na dieta de bovinos alimentados com campo nativo, os tratamentos eram 33%, 66% e 100% de azevém em substituição ao campo nativo, em dois períodos experimentias. Os experimentos foram realizados em delineamento inteiramente casualizado com 3 tratamentos e 2 repetições por tratamento em cada período. Os períodos experimentais consistiram de 10 dias de adaptação e 5 dias de coletas, durante o período de coletas foram amostradas as sobras do cocho, a forragem ofertada e ainda a produção total de fezes a cada 24 horas. Realizou-se as medidas de produção fecal, concentração de componentes fecais, consumo de nutrientes e digestibilidade dos componentes da dieta. No capítulo I foram traçadas relações entre digestibilidade e a concentração da proteína bruta fecal (PBf), sendo testados dois modelos não lineares, o exponencial e o hiperbólico gerando as equações de digestibilidade da matéria orgânica(DMO) = 0,709-9,506* exp(-0,041*PBf) com R2 0,61 e DMO = 0,942-38,619/PBf (R2 0,62), respectivamente. A relação de consumo de matéria orgânica (CMO) com a quantidade de PBf, possui comportamento linear, foi então realizada a análise de stepwise para saber quais outras variávies poderiam explicar melhor o modelo junto com a PBf gerando uma equação CMO = -6724,30 + 39*PBf + 2,55*FDNf + 11591,44*DMO com R2 0,95. Determinou-se a relação da proteína bruta (PB) da dieta (g/kg MO) x PBfecal (g/kg MO), PB dieta = 1,346x - 47,63 R² = 0,931 (modelo linear). No capítulo II, foram testados dois modelos para todas as relações traçadas no experimento II, um modelo linear e um modelo quadrático, as relações foram consumo de matéria orgânica (CMO (g/UTM)) x digestibilidade da fibra em detergente neutro (DFDN), DMO x CMO (g/UTM), DMO x CMO (g/dia), consumo de folhas (g/UTM) x DMO e CMO (g/UTM) x relação proteína/energia. As relações que não foram estatisticamente significativas para nenhum modelo foram CMO (g/UTM) x relação proteína/energia e consumo de folhas (g/UTM) x DMO. Após essas relações, verificou-se que a PBf tem um bom potencial para a estimativa de consumo e a digestibilidade por bovinos alimentados com pastagens nativas ou associadas a forragem cultivada como o azevém anual, mas estes parâmetros também são afetados por diferentes variáveis. / In order to evaluate the fecal crude protein as intake and digestibility marker of cattle fed with natural pasture from Pampa Biome and annual ryegrass inclusions and evaluate the nutritional quality of these pastures it was conducted two experiments in metabolic cages. In the first experiment, the animals received different native pasture offer levels where treatments consisted of 1.5 and 2.25% of the live weight of dry matter and ad libitum with at least 20% of daily leftovers which were carried out six experimental periods. The second experiment consisted of annual ryegrass inclusion levels in the diet of cattle fed with natural pasture, the treatments were 33%, 66% and 100% of ryegrass to replace the native pasture in two experimental periods. The experiments were carried out in a completely randomized design with 3 treatments and 2 replicates per treatment in each period. The experimental period consisted of 10 days of adaptation and 5 days of collection during the period of the trough collects the forage offered have been sampled, the leftovers and also the total fecal production in each 24 hours. It was measured the fecal productions, concentration of faecal components, nutrient intake and digestibility of diet components. In the Chapter I were study the relationship between digestibility and fecal concentration of crude protein (CPf), being tested exponential and hyperbolic equations generating the digestibility of organic matter (OMD) = 0.709 - 9.506 * exp (- 0.041 * CPf) with R2 = 0.61 and OMD =0.942 - 38.619 / CPf (R2 0.62), respectively. The ratio of organic matter intake (OMI) with the amount of CPf, has a linear relation, it was then carried out stepwise analysis to find out what other variables could explain better the model along with the CPf generating a equation OMI = -6724.30 + 0,998 * CPf + 2.55 * NDFf + 11591.44 * OMD with R2= 0.95. It was determined the ratio of crude protein (CP) of the diet (g/kg of OM) x CPf (g/kg of OM), CPdiet = 1,346*CPf - 47.63 R² = 0.931 (linear model). In the Chapter II were tested two models for all relationships outlined in experiment II, a linear model and a quadratic model, relations were organic matter intake (OMI) x digestibility of neutral detergent fiber (DNDF), OMD x OMI, leaves intake x OMD and OMI x protein/energy ratio. The relationships that were not statistically significant for either model were OMI x protein/energy and leaves intake x OMD. After these relationships, it was found that the CPf has a good potential to estimate intake and digestibility in cattle fed native pastures or associated with annual ryegrass, but these parameters are also affected by different variables.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The forage intake was evaluated in beef heifers at grazing exclusive ryegrass (Lolium multiflorum Lam.) or receiving rice bran, with and without ionophore. We used the method of continuous grazing with variable number of animals. Rice bran in the proportion of 0.80% of body weight, was administered daily at 14 hours and showed levels of 13.80% crude protein (CP), 25.79% of neutral detergent fiber (NDF) and 12.45% ether extract (EE). The experimental design was completely randomized with repeated measures over time.Was used chromic oxide as a fecal production indicator. The dry matter intake was estimated using the technique of chromium oxide as an indicator of fecal output. The beef heifers grazing exclusively on pasture intake had a similar those receiving rice bran with or without monensin (2.63% of the BW in DM). The highest total dry matter intake was observed in heifers remained in ryegrass and received rice bran with addition of ionophore (3.42% of the BW in DM), intermediate in heifers that received rice bran (3.26% of the BW in DM) and remained lower in heifers grazing ryegrass (2.82% of the BW in DM). Average daily gain was higher for beef heifers receiving ionophore added to rice bran. The stocking rate was similar between food systems tested. / O consumo de forragem foi avaliado em novilhas de corte exclusivamente em pastagem de azevém (Lolium multiflorum Lam.) ou recebendo farelo de arroz integral, com e sem ionóforo. Foi utilizado o método de pastejo contínuo com número variável de animais. O farelo de arroz, na proporção de 0,80% do peso corporal,foi ministrado diariamente às 14 horas e apresentou teores de 13,80% de proteína bruta (PB), 25,79% de fibra em detergente neutro (FDN) e 12,45% de extrato etéreo (EE). O delineamento experimental foi o inteiramente casualizado, com medidas repetidas no tempo e foram estudadas variáveis do pasto e dos animais. O consumo de matéria seca foi estimado por meio de técnica do óxido de cromo como indicador da produção fecal. As novilhas exclusivamente em pastejo tiveram um consumo de pasto semelhante as que receberam farelo de arroz integral com ou sem monensina (2,63% do PC em MS). O maior consumo de matéria seca total foi observado nas novilhas que permaneceram em azevém e receberam farelo de arroz integral com adição de ionóforo (3,42% do PC em MS), intermediário nas novilhas que receberam farelo de arroz integral (3,26% do PC em MS) e inferior nas novilhas que permaneceram em pastagem de azevém (2,82% do PC em MS). O ganho médio diário foi superior para novilhas que receberam ionóforo adicionado ao farelo de arroz integral. A taxa de lotação foi semelhante entre os sistemas alimentares testados.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / New genotypes of ryegrass of other localities and with desirable characteristics are being commercialized as tool to reach better zoothenic performance indices. However, research must be carried through on its potentiality in the place to be implanted, searching to prevent problems in the growth and development of these fodder plants, compromising potential biomass yield. Thus, the objectives of this study for the cultivated genotypes of azevém at different times of sowings had been (1) was to estimate lower base temperature, it was also possible to investigate may have seasonal production; (2) to evaluate morphogenetic variables on three types of culms (main culm, first order tiller T1, and first order tiller T2) (3) productivity dry matter seed yield of the ryegrass of dual-purpose submitted. The experimental desing was a split-plot complete randomized block, with four block and treatments arranged in a three-factor (3x2x4) desing: three types of culms (main culm, first order tiller T1, and first order tiller T2), two genotypes (Comum and Advance) and four sowing dates (11/05, 07/06, 05/07 and 09/08/2007). The experimental desing was randomized block, and five ryegrass genotypes: three diploid (Comum, Fepagro São Gabriel, and LE 284 and two tetraploid (Avance and INIA Titán), the combination of number of cuts (from one at four), and five sowing dates (05/11, 06/07, 07/05, 08/09 and 09/01/2007). Values of Tb varied from 7.0 to 8.5ºC for the diploid genotypes and from 9.0 to 10.6ºC for the tetraploid genotypes, depending upon the method. Diploid ryegrass germoplasm have no risk of seasonal decrease in forage production, whereas tetraploids, mainly Avance, may have their growth and development decreased from June to August in Santa Maria because of minimum air temperature. The genotype Advance had the greatest accumulate leaf number and leaf appearance rate and the phyllochron were not different between the two genotypes. Main culm had the greatest leaf or final number and leaf appearance rate and the lowest phyllochron compared to tillers. Later sowing dates led to lower leaf blade elongation rate, final leaf number and leaf appearance rate and greater phyllochron. In all cuts and sowing dates, the leaves proportion was found to be higher in the tetraploids genotypes than in the diploids. The increase of cut number increased total dry matter yield and decreased seed yield, in all sowing dates and genotypes. Generally, the number of spike was small in tetraploids genotypes, bust the length of spike and seed, number and length of seed of spikelets and spacing between spikelets were larger. / Novos genótipos de azevém de outras localidades e com características desejáveis estão sendo comercializados como ferramenta para atingir melhores índices zootécnicos. Entretanto, devem ser realizadas pesquisas sobre sua potencialidade no local a ser implantado, buscando evitar problemas no crescimento e desenvolvimento dessas forragens, comprometendo produtividades. Assim, os objetivos deste estudo para os genótipos de azevém cultivados em diferentes épocas de semeaduras foram: (1) estimar a temperatura base e verificar se existe estacionalidade de produção; (2) estudar a morfogênese em três tipos de colmos (colmo principal e perfilhos de primeira ordem T1 e T2); (3) avaliar a produtividade da matéria seca da forragem e dos componentes do rendimento das sementes para o duplopropósito. O delineamento experimental adotado foi o blocos ao acaso. Foram utilizados cinco genótipos de azevém, três diplóides Comum, Fepagro São Gabriel e LE 284, e dois tetraplóides Avance e INIA Titán. Antes do diferimento para produção de sementes foram realizados cortes (variando de um até quatro cortes). Os genótipos foram cultivados em cinco épocas de semeadura (11/05, 07/06, 05/07, e 09/08 e 01/09/2007). A temperatura base inferior (Tb) para os genótipos diplóides de azevém foram menores, variam entre 7,0 a 8,5°C, que as dos tetraplóides, que variam de 9,0 a 10,6°C. As pastagens com genótipos diplóides de azevém não possuem riscos de estacionalidade de produção, mas com os tetraplóides, com destaque para o Avance, poderão ter seu crescimento e desenvolvimento reduzidos nos meses de junho a agosto em Santa Maria em função das temperaturas mínimas do ar. Os genótipos de azevém apresentaram taxa de surgimento de folhas e filocrono similares, mas o tetraplóide Avance em relação ao diplóide Comum possui maior número final de folhas e taxa de alongamento de folhas. O colmo principal de todos os genótipos possui maior número de final de folhas e menor filocrono em relação aos perfilhos. O avanço na época de semeadura determina menor taxa de alongamento de folhas, número final de folhas e taxa de surgimento de folhas e maior filocrono. Os genótipos tetraplóides de azevém apresentam maior proporção de folhas em todos os cortes e épocas de semeadura em relação aos diplóides. A realização de mais cortes nas pastagens dos genótipos diplóides e tetraplóides promovem maior matéria seca total e menor rendimento de sementes para todas as épocas de semeadura. De maneira geral, os genótipos tetraplóides caracterizam-se por apresentar menor número de espigas, e maior comprimento de espiga e sementes, número e comprimento de espigueta e espaçamento entre espigueta em relação aos diplóides.