Made available in DSpace on 2014-06-11T19:30:24Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-12-19Bitstream added on 2014-06-13T19:00:28Z : No. of bitstreams: 1 sa_ro_dr_botfca.pdf: 609591 bytes, checksum: fbbd21f4b97ce442e120737b875fffb0 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / O presente trabalho teve como objetivo avaliar 100 progênies de meios irmãos da população de nabo forrageiro (Raphanus sativus L. var. oleiferus Metzg.), cultivar CATI AL 1000 em dois ciclos de seleção entre e dentro de progênies de meios irmãos, para as características: ciclo das plantas, altura das plantas, produtividade de grãos, massa de 1000 grãos, teor de óleo no grão e produtividade de óleo, na Fazenda Experimental São Manuel, no município de São Manuel – SP, no ano de 2004, e na Fazenda Experimental Lageado, no município de Botucatu – SP, no ano de 2005, 2006, e 2007, pertencentes a Faculdade de Ciências Agronômicas – campus de Botucatu – SP, da Universidade Estadual Paulista “Júlio de Mesquita Filho”. Foram avaliadas 100 progênies de meios irmãos de nabo forrageiro cultivar CATI AL 1000, em ensaio de competição, distribuídas em delineamento látice 10x10, parcialmente balanceado, com três repetições. As progênies superiores foram recombinadas e selecionadas no ano agrícola seguinte obtendo um ciclo a cada dois anos. Foram realizados dois ciclos de seleção. Os dados coletados a campo, para todas as características, foram padronizados seguindo a metodologia recomendada, e submetidos a análise de variância e testes de médias. Foram obtidas as correlações entre os caracteres e obtidas as estimativas de parâmetros genéticos. Para todas as características avaliadas, foi identificada a presença de variabilidade genética, decrescendo no segundo ciclo de seleção, entre as progênies de meios irmãos. Foram observados ganhos genéticos de 8,96, 18,47, 93,29, 12,51, e 69,11 %, para as características avaliadas: altura das plantas, massa de 1000 grãos, produção de grãos, teor de óleo do grão, e produtividade de grão, respectivamente. Observou-se correlação negativa e significativa entre produtividade de grãos e teor de óleo... / The purpose of the present research was evaluate100 half-sib progenies of the population of wild radish (Raphanus sativus L. var. Oleiferus Metzg.) Cultivar CATI AL 1000 in two cycles of selection, among and within half-sib progenies for characteristics: cycle of plants, plant height, grain yield, 1000 grain weight, grain oil content and oil yield in the Experimental Farm San Manuel, in Sao Manuel - SP, in 2004, and in the Farm Experimental Lageado, in Botucatu - SP, in 2005, 2006 and 2007, at Faculdade de Ciencias Agronomicas – Botucatu campus - SP, Universidade Estadual Paulista Julio de Mesquita Filho”. In this study, were evaluated 100 half-sib progenies of wild radish cultivar CATI AL 1000, in an essay competition, distributed in a 10x10 lattice, partially balanced, with three replications. The selected progenies were recombined and selected in the following crop year obtaining a cycle every two years. There were two cycles of selection. For all traits, the data collected at the field were patterned according to recommended methodology, and subjected to analysis of variance and multiple comparisons. The correlations between the characters and the estimates of genetic parameters were obtained. For all traits, the presence of genetic variability was identified, decreasing in the second cylce of selection, among the half-sib progenies. Genetic gains of 8.96, 18.47, 93.29, 12.51 were observed, and 69.11% for the characteristics evaluated: plant height, 1000 grain weight, grain yield, oil content of grain, and grain yield, respectively.There was negative correlation between grain yield and grain oil content, plant height and mass of 1000 grains, and positive and significant relationship between grain yield and plant height, also 1000 grain weight and oil content of grain. The genetic parameters values decreased from cycle I to cycle II, but the high magnitudes calculated in the second... (Complete abstract click electronic access below)

Submitted by (edna.saturno@ufrpe.br) on 2017-04-24T14:27:02Z No. of bitstreams: 1 Joelma de Lira Freire.pdf: 571347 bytes, checksum: d2c37ede4ff6420a7cab27e56ccc9240 (MD5) / Made available in DSpace on 2017-04-24T14:27:02Z (GMT). No. of bitstreams: 1 Joelma de Lira Freire.pdf: 571347 bytes, checksum: d2c37ede4ff6420a7cab27e56ccc9240 (MD5) Previous issue date: 2008-02-27 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The objective of this experiment was to evaluate the deposition, chemical composition, and decomposition of litter in a sabiá (Mimosa caesalpiniifolia Benth) canopy. The experiment was carried out at the Experimental Station of Itambé-IPA. The evaluation of existing and deposited litter was carried through the period of August of 2006 until July of 2007, every 28 days. Twenty squares with 1m² were used, in random points to each evaluation. The nylon bag technique was used for litter decomposition evaluation, incubating the following litter fractions: just-fallen leaves, “aging” leaves already deposited and in the beginning of the mineralization, and branches. The incubation periods were 0, 4, 8, 16, 32, 64, 100, and 256 days, being the same procedure carried through in 2006 and 2007. Treatments were distributed in randomized block design with five replications. Leaf deposition reached the value of 15,167 kg OM/ha, presenting greater deposition in the rainy period. Leaves represented the greater proportion of litter deposited, with average ratio of 87% of predominance in the majority of the evaluations. Branches and leaves presented average nitrogen concentration of 1.4% and 2. 7%, respectively, demonstrating that leaves were the maincontributors of nutrients via litter. The C/N ratio of leaves was below 30, branches presented C/N ratio between 30 and 40, likely favoring the nitrogen immobilization by ground microorganisms. The relationship between litter deposition and litter accumulation in the last month of evaluation was 0.30 indicating that it presented greater accumulation than deposition. In the decomposition assay, branches presented lesser mineralization than leaves both for total biomass and nitrogen, with leaf and branch decomposition varying with the incubation periods. The decomposition of substrata was influenced by the rainfall amount occurred in the evaluation period. In a general way, it was concluded that the litter component is essential in the process of nutrient recycling in a sabiá canopy, however, the mineralization occurs in relatively slow taxes, being this fact relevant in the reduction of nutrient losses by leaching, contributing for the maintenance of this ecosystem. / O objetivo deste trabalho foi avaliar a deposição, composição química e decomposição de liteira em um bosque de sabiá (Mimosa caesalpiniifolia Benth). O experimento foi realizado na Estação Experimental de Itambé-IPA. A avaliação de liteira existente e depositada foi realizada no período de agosto de 2006 a julho de 2007 a cada 28 dias. Foram utilizados 20 quadrados com 1m2, em pontos aleatórios a cada avaliação. Para avaliação da decomposição de liteira, foram utilizadas bolsas de “nylon”, sendo incubadas as seguintes frações: folhas recém-caídas, folhas senescentes já depositadas e no início da mineralização e ramos. Os tempos de incubação foram 0, 4, 8, 16, 32, 64, 100 e 256 dias, sendo o mesmo procedimento realizado em 2006 e 2007. Os tratamentos foram distribuídos em delineamento de blocos ao acaso com 5 repetições. A deposição de folhas atingiu valor de 15.167 kg MO/ha, tendo maior deposição no período chuvoso. As folhas representaram a maior contribuição na deposição de liteira, com proporção média de 87% predominando na maioria das avaliações. Os ramos e folhas apresentaram teores médios de nitrogênio de 1,4% e 2,7% respectivamente, demonstrando assim que as folhas foram os principais contribuintes de nutrientes da liteira. A relação C/N de folhas ficou abaixo de 30; os ramos apresentaramrelação mais elevada entre 30 e 40, favorecendo assim a imobilização de nitrogênio pelos microorganismos do solo. A relação entre a deposição e o acúmulo de liteira no último mês de avaliação foi de 0,30 indicando assim que houve maior acúmulo do que deposição. No ensaio de decomposição, os ramos apresentaram taxa de mineralização menor que as folhas tanto para biomassa total como para nitrogênio, tendo as decomposições de folhas e ramos variando de acordo com os períodos de incubação. A decomposição dos substratos foi influenciada pela quantidade de chuvas ocorridas ao longo do período de avaliação. De maneira geral, conclui-se que o componente liteira é essencial no processo de reciclagem de nutrientes em um bosque de sabiá, todavia a mineralização ocorre a taxas relativamente lentas, sendo esse fato relevante na redução de perdas de nutrientes por lixiviação, contribuindo para a manutenção desse sistema

Made available in DSpace on 2014-08-20T14:33:13Z (GMT). No. of bitstreams: 1 Tese_Fernando_Pereira_Menezes.pdf: 1767639 bytes, checksum: 91a91729ef261e42fc911c10e823c7d7 (MD5) Previous issue date: 2011-12-15 / The study was conducted in three stages, assessing the species Adesmia latifolia (Spreng.) Vog. with the aim of increasing knowledge of Adesmia responses regarding the most appropriate methods of overcoming seed dormancy, seed inoculation and production and forage quality in relation to climatic factors. The first stage was conducted at the Laboratory of Seeds Analysis FAEM/UFPEL in Pelotas, the other in the CCR/URCAMP in Bage-RS. In the work of scarification were evaluated with thermal and chemical methods to count only 14 days after sowing. Regarding the assessment of inoculant was used the following treatments: control, Bradyrhizobium spp. Rhizobium leguminosarum bv. trifolli (white clover), Rhizobium leguminosarum bv. trifolli (red clover) and Rhizobium loti (birdsfoot trefoil) in a greenhouse. The third study, conducted in the field, we evaluated the production of dry matter and forage quality, protein digestibility and in vitro. In the first work considering the three variables (normal seedlings, hard seeds and dead), the results showed that the method of soaking in hot water was more efficient in breaking dormancy of seeds of Adesmia latifolia, with emphasis on immersion in hot water at 40°C for three minutes, for issues of safety and economy. In the second study produced the highest dry matter were obtained with Bradyrhizobium spp. and Rhizobium loti, respectively, the same happened in relation to the efficiency of inoculation, with the latter being easily accessible shopping. In the third study concluded that the dry matter production is concentrated in october/november with 88% of total annual crude protein and in vitro while maintaining during the cycle with high levels. / O trabalho foi realizado em três etapas, avaliando a espécie Adesmia latifolia (Spreng.) Vog., com o objetivo de ampliar o conhecimento das respostas da Adesmia no que diz respeito a métodos mais adequados de superação de dormência das sementes, inoculação de sementes e produção e qualidade de forragem em relação aos fatores climáticos. A primeira etapa foi realizada no Laboratório de Análise de Sementes da FAEM/UFPEL em Pelotas-RS, as demais no CCR/URCAMP em Bagé-RS. No trabalho de superação de dormência foram avaliados métodos químicos e térmicos com contagem única aos 14 dias após a semeadura. Em relação à avaliação de inoculantes foram utilizados os seguintes tratamentos: testemunha; Bradyrhizobium spp.; Rhizobium leguminosarum bv. trifolli, (trevo branco); Rhizobium leguminosarum bv. trifolli, (trevo vermelho) e Rhizobium loti, (cornichão) em ambiente protegido. Já o terceiro trabalho, realizado a campo, foi avaliado a produção de matéria seca e a qualidade da forragem, proteína bruta e digestibilidade in vitro. No primeiro trabalho considerando-se as três variáveis (plântulas normais, sementes duras e mortas), os resultados permitiram concluir que o método de imersão em água quente foi o mais eficiente na superação de dormência de sementes de Adesmia latifolia, destacando-se a imersão em água quente a 40ºC por três minutos, por aspectos de segurança e economicidade. No segundo trabalho as maiores produções de matéria seca foram obtidas nos tratamentos com Bradyrhizobium spp. e Rhizobium loti respectivamente, o mesmo acontecendo em relação à eficiência do inoculante, sendo esse último de fácil acesso comercial. No terceiro trabalho conclui-se que a produção de matéria seca concentra-se em outubro/novembro com 88% do total anual com a proteína bruta e a digestibilidade in vitro mantendo-se ao longo do ciclo com elevados teores.

The nutritional value of indigenous fodder plants has been reported to be high and constant throughout seasons as compared to grasses. The aim of this study was to evaluate the nutritional value of three tree species of the Combretum family, C. apiculatum, C. molle, C. zeyheri, and two other plant species, Colophospermum mopane and Pelthophorum africanum. This would be achieved through the determination of chemical composition (ash, dry matter (DM), organic matter (OM), CP, acid detergent fibre (ADF), acid detergent lignin (ADL), acid detergent indigestible nitrogen (ADIN), condensed tannins (CT) and ether extract (EE)), rumen degradability and in vitro digestibility of the leaves of these species were determined. The foliage of the tree species were collected in and north of Pretoria. After rinsing a portion of each species' samples, they were freeze-dried, prepared for analyses and stored as fresh samples pending analyses. The in situ analysis was done as blanket analysis over all the seasonal samples of each plant species excluding Mopane. This was done because the leaf materials collected were not enough to conduct a complete trial for each seasonal collection. Therefore sites were not considered for statistical analyses hence species were compared across seasons only. All the plant species exhibited a wider range of the chemical fractions. Their ash concentrations ranged from 30.3 g/kg DM for C. zeyheri to 85.8 g/kg DM forC. molle, NDF 270.3 g/kg DM for C. apiculatum to 410.1 g/kg DM for P africanum, ADF 208.1 g/kg DM P. africanum to 375.2 g/kg DM for C. molle. Their CP ranged from 62.9 g/kg DM for C. molle to 172 g/kg DM for Mopane, CT 65.6 mg sorghum tannin equivalent (STE)/g DM for C. zeyheri to 660.3 mg STE/g DM for Mopane, ADIN ranged from 1.2 g/kg DM for C. apiculatum to 3.3 g/kg DM in C. mopane. The range of some mineral concentrations of all the plants was not as wide as the other fractions. The concentrations of Ca ranged from 7.9 g/kg DM for Mopane to 16 g/kg DM for C. molle, K 1.2 g/kg DM Mopane to 7.8 g/kg DM for C. molle, Mg 1.4 g/kg DM for C. molle to 3.8 g/kg DM for C. apiculatum. The concentrations of Cu ranged from 7.8 mg/kg DM for C. molle to 66 mg/kg DM for C apiculatum, Fe 169 mg/kg DM for Mopane to 435 mg/kg DM for C. zeyheri. The in vitro dry matter digestibility (IVDOM) ranged from 52.6% for Mopane and C. zeyheri to 64.1% for C. apiculatum. The in situ degradability fractions for the Combretum species ranged as follows: soluble fraction was 4.02% for C. apiculatum to 25.4% for C. zeyheri; degradable fraction was 34% for C. zeyheri to 44% for C. apiculatum and the extent of nitrogen (N) degradation was 47% for C. apiculatum to 60% for C. zeyheri. The concentrations of the chemical fractions of all the plants did not show a particular seasonal trend. However significant and insignificant variations were observed. The CP concentrations were almost constant implying a better N supply to animals throughout the seasons. The CT concentrations were not high enough to adversely affect the digestibility of protein. The Combretum species showed reasonable N degradability in situ, C. zeyheri the most degradable. The plant's digestibility values were within the range of browse plants. These results cannot be conclusive on the eventual nutritional value of these plants to the animals. Further studies would be necessary to quantify the availability of the chemical fractions and the foliage's palatability to the animals. / Dissertation (M Inst. Agrar (Animal Production))--University of Pretoria, 2005. / Animal and Wildlife Sciences / unrestricted

Submitted by Ricardo Cedraz Duque Moliterno (ricardo.moliterno@uefs.br) on 2016-08-23T20:42:07Z No. of bitstreams: 1 Tese_ roberta.pdf: 1295963 bytes, checksum: 0d60f7d523d2599d8bf9e13a4722fa8e (MD5) / Made available in DSpace on 2016-08-23T20:42:07Z (GMT). No. of bitstreams: 1 Tese_ roberta.pdf: 1295963 bytes, checksum: 0d60f7d523d2599d8bf9e13a4722fa8e (MD5) Previous issue date: 2016-03-22 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / This study aims to identify promising progenitors and hybrids for crop improvement of the forage watermelon, for this purpose the heterosis, general and specific combination capacities were estimated, in addition, the phenotypic correlation, the path analysis between morphoagronomic and bromatological characteristics were determined. Five progenitors were evaluated; LPG (1), VM (2), MR (3), BGCIA 228 (4) and Jojoba (5) belonging to Embrapa Semi?rido?s BAG, the ten F1?s were obtained from balanced diallel crossing. An augmented design in complete randomized blocks, with tree replications and eight plants per plot was used. The following characteristics were evaluated: FRP, FRN, PP, FRC/DT, CES, PES, TSS, NS, P100S, PFS, PSS, ProdF, CP, NDF, IVDMD, EE and K. Among the genotypes, potentiality for exploitation in crop improvement programs was observed. The choice of elongated fruit took into account the preference of agriculturists, resulting in the selection of all progenitors expressing this feature. The hybrids were obtained and evaluated in order to select the most promising for obtaining superior progenies to their genitors for the evaluated characteristics. Regarding the production, hybrids 1x4 and 4x5 stood out in obtaining more prolific progenies. The heterosis for bromatological characteristics was low, except for K. The general combining ability indicated the potential of the progenitor VM in obtaining progenies with higher CP and EE levels, as well as MR can contribute to increase fruit production. From the specific combining ability, it was verified that the hybrid 1x4 mostly showed FRP, NS, PSS and EE, as the hybrids 2x4, 3x4 and 3x5 displayed FRN, IVDMD and CP, respectively. From the phenotypic correlation, it was observed that the fruit with enhanced FRC/DT will possess greater PES and FRP, however less CP. The ridge path analysis, with PP dependent variable showed positive and low direct effects to the majority of the characteristics, moreover, indicated the reduction in the CP and NDF contents, important characteristics to the forage plants. The path analysis showed that the EE may be used in the selection of progenitors with higher PB levels. This work provides the first information on the pre-improvement of this culture, contributing to the achievement of more productive progenies and composed of higher levels of EE and CP, important elements for increased animal productivity. / Este trabalho objetivou identificar genitores e h?bridos de melancia forrageira promissores para o melhoramento da cultura, para isto foi estimada a heterose, capacidade geral e espec?fica de combina??o, al?m disto, determinou-se a correla??o fenot?pica, a an?lise de trilha entre os caracteres morfoagron?micos e bromatol?gicos.Foram avaliados cinco genitores; LPG (1), VM (2), MR (3), BGCIA 228 (4) e Jojoba (5) pertencentes ao BAG da Embrapa Semi?rido, os dez h?bridos F1?s foram obtidos a partir de cruzamentos dial?licos balanceados.Foi utilizado um delineamento em blocos casualizados completos, com tr?s repeti??es e oito plantas por parcela. Foram avaliadas as seguintes caracter?sticas: FRP, FRN, PP, FRC/DT, CES, PES, TSS, NS, P100S, PFS, PSS, ProdF, PB, FDN, DIVMS, EE e K. Observou-se entre os gen?tipos potencialidade para a explora??o em programas de melhoramento. A escolha de frutos alongados levou em considera??o ? prefer?ncia dos agricultores, resultando na sele??o de todos os genitores que expressam esta caracter?stica. Os h?bridos foram obtidos e avaliados com o intuito de selecionar os mais promissores para a obten??o de prog?nies superiores aos seus pais para as caracter?sticas avaliadas. Em rela??o ? produ??o, os h?bridos 1x4 e 4x5 destacaram-se para obten??o de prog?nies mais profil?ticas. As heteroses para as caracter?sticas bromatol?gicas foram baixas, exceto para K. A capacidade geral de combina??o indicou a potencialidade do genitor VM para obten??o de prog?nies com maiores teores de PB e EE, assim como MR poder? contribuir com aumento da produ??o de frutos. A partir da capacidade espec?fica de combina??o verificou-se que o h?brido 1x4 sobressaiu para FRP, NS, PSS e EE, j? os h?bridos 2x4, 3x4 e 3x5 destacaram-se para FRN, DIVMS e PB, respectivamente. A partir da correla??o fenot?pica observou-se que frutos com maior FRC/DT possuir?o maiores PES e FRP,no entanto menor PB. A an?lise de trilha em crista, com vari?vel dependentePP, apresentou efeitos diretos positivos e baixos para a maioria dos caracteres, al?m disto, indicoua redu??o nos teores de PB e FDN, caracter?sticas importantes para as forrageiras. A an?lise de trilha mostrou-seque o EE pode ser usado na sele??o de progenitores com maiores teores de PB.Este trabalho traz as primeiras informa??es sobre o pr?-melhoramento desta cultura, contribuindo com a obten??o de prog?nies mais produtivas e compostas de maiores teores de EE e PB, elementos importantes para o aumento da produtividade animal.

Die Futterpflanzen Kaukasischer Klee und Futterchicorée wurden als Reinsaat und in Gemenge mit einer Grünlandmischung auf zwei Standorten in Sachsen auf ihre Anbaueignung und ihren Futterwert untersucht. Der Kaukasische Klee überdauert Trockenstressphasen sehr gut, ist absolut winterfest und weist einen teilweise überdurchschnittlichen Gehalt an wertgebenden Inhaltstoffen auf. Dem stehen eine niedrige Keimfähigkeit und schwierige Etablierung eines Pflanzenbestandes mit geringem Ertrag entgegen. Der Kaukasische Klee ist in seiner Anbaueignung stark eingeschränkt und für sächsische Standortbedingungen wenig geeignet. Der Futterchicorée lässt sich leicht etablieren, zeichnet sich durch rasches Massenwachstum aus und überdauert Trockenstress ebenfalls gut. Er ist gekennzeichnet durch einen teilweise überdurchschnittlichen Gehalt an wertgebenden Inhaltsstoffen, seine Nutzungsmöglichkeiten sind aber durch den geringen Trockensubstanzgehalt eingeschränkt. Der Futterchicorée ist zum Anbau als Futterpflanze in Sachsen geeignet, es deuten sich insbesondere Möglichkeiten der Nutzung als Gemengepartner von Grünlandmischungen an.

Thesis (PhD (Forest and Wood Science))—University of Stellenbosch, 2007. / Sustainable livestock production in semi-arid Botswana could be improved through tree planting on-farm to provide much needed protein and shade. Such action can be encouraged if the growth, productivity, nutritional value of trees and their contribution to mass gain of livestock are known.. A study at Malotwana investigated two indigenous species, Acacia galpinii and Faidherbia albida, and two exotic species, Leucaena diversifolia and L. leucocephala, at three spacings in a randomised complete block design replicated five times. The three spacings represented 400, 317 and 241 trees per hectare. The study was conducted over 6.5 years. Indigenous trees were sampled biennially and exotics annually to evaluate crown width, height, stem diameter, stem number and stem volume index. Complete plant harvesting of exotic trees at 2.5, 4.5 and 6.5 years evaluated agroforestry production. Leaves from all four species and pods of exotic species were analysed for chemical composition. Two groups of eight lambs were balanced for mass at selection for an on-farm feeding trial. Browse from exotic trees, comprising a 2:1 ratio of pods to leaves, was fed at 30% as supplement to hay to one group whose mean mass was contrasted with that of the control group fed sorghum bran at 30%. A. galpinii was a promising species, adaptable to planting away from its origin. Its crown width ranged from 5.86 m in high density plots to 6.08 m at low density and was significantly different among stands (p = 0.0406) at 6.5 years. Diameter at breast height (dbh) was significantly different among stands aged 6.5 years (p = 0.0003) and ranged between 10.38 cm at high density to 12.48 cm in low density plots, demonstrating a capacity to provide both shade and poles on-farm. At 4.5 years, F. albida attained a mean height of 4.5 m and 4.5 cm in dbh but suffered 67% mortality during a severe drought. Annual fodder production of 0.647 and 0.996 metric tonnes ha-1 for leaves and pods of L. diversifolia and 1.237 and 1.431 for L. leucocephala was recorded in years of average rainfall. Yields of 0.3 and 0.59 metric tonnes ha-1 were recorded for both species in the driest year. Equally good agroforestry production was obtained from both low and high density stands suggesting that low density plantings, which foster higher plant survival and reduce disease incidence, are best suited to the semi-arid conditions of Botswana. The crude protein of leaves ranged between 16.26 (L. diversifolia) and 25.25% (F. albida). They were highly digestible with more than twice the calcium content livestock require. Crude protein and digestibility measures were significantly different among leaves and varied significantly at different spacings (p<0.0001). Pods of the exotic species contained significantly more protein than the leaves (p<0.0001). Lambs supplemented with browse gained 102.33 g per animal per day while the control group gained 83.95 g. There were significant differences between groups during growth (p<0.05). Growing of A. galpinii, complemented with L. diversifolia and L. leucocephala, can supply short and long term feed, and greatly enhance livestock production while diversifying farm feed sources

En Afrique Sub-Saharienne, les zones humides forment d'importantes zones de pâturages pour bon nombre de pastoralistes. Le régime d'inondation de ces plaines influence leur fonc tionnement et leur productivité. Pour comprendre et maitriser ces régimes, il est donc essentiel d'évaluer l'impact de l'infrastructure hydro-électrique sur les dynamiques d'inondations en aval des barrages. Pourtant, le manque de données disponibles, l'absence de modèles validés et la forte variabilité environnementale rendent cet exercice difficile. Cette thèse contribue à quantifier l'impact du changement des ressources hydriques sur la productivité fourragère des prairies inondables dans le Delta du fleuve Tana, au Kenya. 1/ Les caractéristiques de croissance et la productivité d'une prairie inondable à Echinochloa stagnina (Retz) P. Beauv. ont été déterminées pour différents régimes de fauche, d'irrigation et conditions d'inondations. Ensuite, un modèle de croissance adapté à des Graminées en C4, tropicales et pérennes, de prairies inondables a été développé. Il constitue, à notre connaissance, le premier modèle éco-physiologique adapté à ce type de prairies. 2/ Des processus hydrologiques importants pour le fonctionnement des écosystèmes (étendue, période, durée et fréquence d'inondation) ont été caractérisés grâce à un modèle de bilan hydrologique et à l'utilisation de techniques de télédétection, et cela en dépit de la faible instrumentalisation du bassin, du peu de données topographiques et d'un fort couvert nuageux. 3/ Une analyse préliminaire de l'impact de différents scénarios d'inondations sur la production fourragère a été effectuée en utilisant des indicateurs de services écosystémiques. Cette thèse participe à l'amélioration de nos connaissances des services écosystémiques des zones humides par la construction de modèles et par l'évaluation de scénarios dans une région du monde où ce type de données est rare. / Wetlands are a vital resource for many pastoralists in Sub-Saharan Africa as they provide dry-season grazing zones. As floods are essential for wetland ecosystems, the assessment of water abstraction and hydroelectric infrastructure on downstream flooding dynamics is crucial. Yet, scarce data, environmental variability and the lack of models make this challenging. This research contributes to quantifying the influence of changing water resources on fodder pro- duction of floodplain grasslands in the Tana River Delta, Kenya. 1/ Growth characteristics of floodplain grasslands of Echinochloa stagnina (Retz) P. Beauv. for different flood and manage- ment options were determined and a quantification of their productivity achieved. This kind of data is scarce for floodplain grasslands. A plant growth model adapted to tropical floodplain conditions and perennial C4 grasses was developed, and is the first known physiologically based model for floodplain grasslands. 2/ Hydrological processes of ecological importance (flood extent, timing, duration, frequency) were characterized in a poorly gauged basin using a water-balance model combined with remote-sensing techniques, despite precise knowledge of discharge rates, topography and a high cloud cover. 3/ A preliminary analysis explored different flooding scenarios and their impact on fodder production through the use of simple ecosystem service indicators. This PhD contributes to the repertoire of wetland ecosystem ser- vices by building biophysically based simulation models and exploring possible scenarios in a region of the world and an ecosystem where these type of evaluations are rare.

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New Zealand, having large areas of hilly landscapes, is subject to the risk of soil erosion, and summer and autumn droughts that limit pasture growth, which in turn affects the livestock-based economy. The nitrogen and phosphorus input in fertilisers coupled with livestock excreta and soil disturbance impose a serious threat to downstream water quality. The planting of trees is one option used to decrease soil erosion, increase the quantity of forage and manage runoff. To date, research has mainly focused on wide spaced poplar trees for feed quality and their effects on understorey pasture growth. However, there is increasing interest in the use of densely planted willow and poplar for fodder purpose. The effects of young (< 5 yrs old) willow and poplar planted at close spacing on runoff, soil erosion, growth of understory pasture and nutrient losses have never been studied in New Zealand. Three field trials (two at Crop and Research Unit, Moginie, Manawatu and one at Riverside Farm, Masterton) were conducted between October 2004 and November 2006 that incorporated comparative establishment and growth of densely planted willow and poplar and their effects on soil moisture, runoff, sediment load and nutrient losses from grazed and fertilised farmland. It was concluded that densely planted willow and poplar (3-4 yrs) reduced total nitrogen (TN) and dissolved reactive phosphorus (DRP) by 47 % each and sediment load by 52 %. Young trees reduced surface runoff and soil moisture more as they aged. However, due to their deciduous nature willow and poplar were not effective in reducing surface runoff in winter and early spring. Sheep preferred camping under trees, especially in late spring and summer, and this led to greater deposition of dung and urine under trees than open pasture. Sheep grazing, especially in winter, significantly increased sediment and nutrient loads in runoff water. The N and P fertiliser application increased nutrient load in runoff water well above the threshold level required to initiate algal growth to create eutrophication. Densely planted willow and poplar significantly reduced understorey pasture growth by 23 % and 9 %, respectively, in their second year at Moginie, mainly due to shade, but coupled with soil moisture deficit in summer. The pasture growth in a willow browse block was 52 % of that in open pasture as a result of shade and differences in pasture species composition. Sheep browsing reduced willow leaf area significantly. Willow and poplar survival rates were similar (P > 0.05) after two years of establishment (100 % vs 90.5 %, respectively). However, willow grew faster than poplar in height (1.90 vs 1.35 m), stem diameter (43.5 vs 32.6 mm), canopy diameter (69 vs 34 cm) and number of shoots (8.7 vs 2.3) at the age of two years, respectively. The research clearly demonstrated that densely planted young willow and poplar trees can reduce runoff, sediment load and nutrient losses from farmland to freshwater, but shade and soil moisture can limit pasture growth under trees. It is recommended that willow and poplar should be planted at wide spacing on the whole farm to minimise loss of pasture. Where blocks of trees are necessary, such as willow browse blocks, sheep browsing can be used as a tool to reduce shade to improve pasture growth. Livestock access to riparian strips should be minimal to avoid livestock camping that can have deleterious effects on water quality.