In traditional forage breeding programmes, breeders have spent decades improving the agronomic characteristics of grasses, such as herbage yield, persistence and resistance to diseases, without considering the nutrient requirements of the grazing animal. In an attempt to improve the nutritive value of Italian ryegrass, which is widely utilised for intensive dairy, lamb and beef production in South Africa, Enhancer ryegrass was developed from predominantly Italian types of Lolium multiflorum, with a minor Westerwolds component, by selecting for a higher concentration of total nonstructural carbohydrate (TNC) and lower moisture content than that currently available in commercial cultivars. The nutritional value of Enhancer was compared with Midmar ryegrass in a controlled environment study and in a grazing trial with weaned lambs; and with Dargle ryegrass in a grazing trial with Holstein dairy cows. Neutral detergent fibre, acid detergent fibre, lignin, nitrogenous compounds, mineral content and in vitro digestibility were also investigated as parameters of nutritive value. The anatomical features of Enhancer and Midmar were studied to determine possible structural differences. Weaned lambs grazed Enhancer and Midmar in an eight-paddock rotational grazing system, with 3.5 days spent in each paddock, allowing a 24.5 day regrowth period for the pastures. Holstein dairy cows grazed Enhancer and Dargle which were established on 16 and 19 hectare pastures, respectively. The n-alkane technique was used to estimate dry matter intake (DMI) in both grazing trials. Results from the controlled environment study suggest that the differences in the dry matter and TNC concentration of Enhancer are not positively linked to anti-quality factors associated with forage species, but can be attributed to genetic differences between the two grasses. Despite the significantly higher (P < 0.01) DMI of weaned lambs grazing Midmar compared with Enhancer, the lambs on Enhancer outperformed those on Midmar in terms of liveweight gain and carcass quality. The superior animal performance on Enhancer is likely due to an improvement in the readily digestible energy to protein ratio as a result of its significantly higher (P < 0.001) concentration of TNC compared with Midmar. Milk yield for cows grazing Enhancer in period 1 of the cross-over study was significantly higher (P < 0.05) than for cows grazing Dargle, despite the significantly lower (P < 0.05) DMI of animals on Enhancer. The higher TNC concentration relative to the true protein content of Enhancer would suggest that the protein metabolism in the rumen can be enhanced. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 2003.

Perennial ryegrass is an intensive, temperate pasture grass that responds well to applied fertiliser. The purpose of this project was to study the effects of fertiliser on the productivity and quality of perennial ryegrass in KwaZulu-Natal and how this impacts on animal intake. It was hypothesised that over-application of fertiliser to a perennial ryegrass pasture would negatively affect the quality of the herbage for grazing by dairy cattle and that intake would be affected. Thus the project aimed to assess the effects of applied fertiliser on yield, quality and intake of an established perennial ryegrass pasture. The trial consisted of a set of six separate experiments. Each experiment focused on the interaction between two of the major nutrient elements nitrogen (N), phosphorus (P), potassium (K) and sulphur (S). The experiments (NxP, NxK, NxS, PxK, PxS and KxS) were managed separately to avoid possible transfer of nutrients during grazing, which would result in the contamination of treatments. Each factor had three levels (low, medium and high), giving a total of nine treatments per experiment. Each of the experiments was replicated three times in a randomised block design. Increased fertiliser N application rates increased perennial ryegrass yield with a pattern of diminishing return, where split applications above 40 kg N ha-1 produced smaller increases in yield when compared with the response at lower applications of N. Applied P, K and S did not affect yield, suggesting that even the lowest application levels were sufficient to not limit production. Nitrogen application affected apparent intake, but it is suggested that this is due to the yield effect rather than a direct effect of N on apparent intake. The application of P, K and S did not affect apparent intake. Results from this study showed that the quality of perennial ryegrass herbage, especially in terms of feed value to dairy cows, can be significantly affected by applied fertiliser. The extent of the response was affected by sampling date (i.e. time of year) and this must be taken into account when planning a fertiliser management strategy. This is particularly so with respect to N fertiliser recommendations. Crude protein (CP) content of herbage increased with increasing levels of applied N and the extent of the response was influenced by season. P, K and S did not affect CP concentration in herbage, except in the PxK experiment where increased levels of K lowered herbage CP. Applied N considerably increased the concentration of non-protein nitrogen (NPN) in perennial ryegrass herbage. P and S did not affect NPN levels, whereas applied K decreased NPN content in the iv NxK and PxK experiments. Non-structural carbohydrate (NSC) content of herbage was decreased by applied N but was unaffected by applications of P, K and S. Neither neutral detergent fibre (NDF) nor acid detergent fibre (ADF) was affected by applied fertiliser. In this study herbage P declined and herbage Ca increased with increasing levels of applied N. The addition of fertiliser K resulted in lower herbage Ca values. There was no herbage S response to applied fertiliser in this study. Classification and regression tree (CART) analysis identified the primary determinant of apparent intake in experiments containing N as a factor as the amount of material available to be grazed and that NSC, NPN and ADF are also determinants of apparent intake. Cows do not regulate diet choice within the short-term time frame of a meal. Thus intake is determined by short-term needs rather than by meeting long-term nutrient requirements. Fibre creates physical fill within the rumen, thus restricting intake. High NPN content is associated with high nitrate values. The reduction in intake of herbage with high nitrate content may be due to reduced palatability or to a negative feedback system limiting the intake of nitrate and ammonium. Increased NSC content is associated with increased intake, possibly through the effect of sugar on herbage palatability.

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.

Thesis (M. Sc.)--University of Canterbury, 2007. / Typescript (photocopy). Includes bibliographical references (leaves 107-118). Also available via the World Wide Web.

Thesis (M. Agr. Sc.) -- Lincoln University, 2008. / Also available via the World Wide Web.

Rye grass are common considered optimum grass species for intensive agriculture in area with sufficient rainfall, because they provide a high production of quality forage. Unfortunately, they have lack of resistance to abiotic stresses. With heed to the progress climate change, when these stresses will increase, we are looking for genes from better-adapted species of Festuca. Target features are better use of nitrogen and water to attainment high production of forage, increased tolerance to drought and ability rooting compacted layers of soil. These targets lead to research on growth of roots, which are to fulfil the above written targets in award. Following the research of M. Humphreys we are focused on detailed monitoring root growth of three species xFestulolium and their parent species in the early stages of development in our research. They were tested following grasses: Festuca arundinacea (cv. KORA), Festuca pratensis (cv. PRONELA), Lolium multiflorum (cv. MORAVICE) and xFestulolium (cv. HYKOR, HOSTYN and PRIOR). The chosen the method of cultivation in cylinder with sand in outdoor conditions with fertilization in two doses, corresponding to a total 80 kg N/ha. The experiment was performed in two terms: 21. 5. when 23. 7. 2015 and 21. 9. when 11. 12. 2015. In the first term, growth was limited by high temperatures. In the second term were limiting the contrary low temperatures, especially at the end of vegetation. The evaluated parameters were: maximum depth of rooting, total dry root biomass, total root length, root surface, root volume, the ratio R/S, the dry weight of aboveground biomass, maximum height aboveground biomass, number of tillers, number developed leaves, surfaces of the leaves and root length in individual thickness categories. The length, surface and volume of roots with flat leaves, were evaluated through image analysis scans in program WinRHIZO (Regent Instruments, Canada). In most parameters it was the best Lolium multiflorum MORAVICE with xFestulolium HOSTYN. The differences between them are in most of parameters statistically insignificant (outside the maximum depth of root and flat of leaves, where MORAVICE achieved significantly higher values). Anticipated advantages relating to the growth of strong and deep roots in this experiment did not show. The supposed main reason for the termination of the experiment in the early stage of development.

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