This research examined the mechanisms by which temperature, water availability and nitrogen (N) affect the dry matter (DM) yield potential of cocksfoot (Dactylis glomerata L.) dominant pastures. The experiment was a split plot design with main plots of fully irrigated (I) or dryland (D), sub-plots of N fertiliser at 800 kg N/ha in 2003/04; and 1600 kg N/ha in 2004/05 (+N) or 0 kg N/ha (-N). The potential environmental yield of an established 8 year old cocksfoot dominant pasture was 21.9 t DM/ha/y from I+N pastures compared with 9.8 t DM/ha by I-N pastures and 15.1 t DM/ha/y by D+N pastures. The lowest yields were from dryland pastures with no N which produced 7.5 t DM/ha/y in 2003/03 and 5.0 t DM/ha/y in 2004/05. The effect of seasonal temperatures on the DM production, when periods of water stress were excluded, was quantified using thermal time accumulated above a base temperature of 3°C as 7.0 kg DM/°Cd/ha for N fertilised pastures and 3.3 kg DM/°Cd/ha for pastures with no N. The 2.5 t DM/ha difference in yields of D-N pastures in 2003/04 and 2004/05 was the result of the duration, extent and timing of the water stress period. In both years the critical limiting deficit (DL) was calculated as 78 mm from the soil moisture deficit in the 0-0.8 m soil layers. Beyond DL yield decreased at a rate of 1.45%/mm in +N and –N pastures, relative to fully irrigated control pastures. Yields of D+N and D-N pastures were similar during periods of water stress with 0.4±0.1 t/DM/ha produced during the rotation ending 30/12/2003. This was less than from either the I-N (1.2 t DM/ha) or I+N (3.5 t DM/ha) pastures due to the reduction in the amount of photosynthetically active radiation intercepted by the canopies of the dryland pastures. However, in the rotation ending 2/5/2004, after autumn rain alleviated drought conditions, yield of the D+N pasture was 2.1 t DM/ha compared with 1.7 t DM/ha by I+N pastures. The effect of N on yield was described using a nutrition index which showed that as DM yield increased N% in the herbage declined. This is a function of the ratio between metabolic and structural N requirements rather than caused by ontogeny alone. Specific leaf N was determined at two harvests and appeared constant at a given point in time (1.0-1.6 g N/m² leaf). In contrast, specific pseudostem N increased from 0.8-1.0 g N/m² pseudostem at an NNI of 0.4 in –N pastures to 2.6-3.0 g N/m² pseudostem at an NNI of 1.2 in the +N pastures. Differences between the yields of +N and –N pastures were caused by differences in radiation use efficiency (RUE) as determined by the linear relationship (R²=0.76) between RUE and the nitrogen nutrition index (NNI). In this thesis, empirical relationships for the effects of temperature, water availability and N were derived and the physiological mechanisms which underlie these descriptions were identified. These relationships provide clear and simple explanations of the effects of environmental variables on the productivity of cocksfoot based pastures which will enhance understanding of the benefits and limitations of cocksfoot, particularly in dryland farming systems.

Genotypic differences in growth and yield of two common bean (Phaseolus vulgaris L) cultivars to Rhizobium inoculation and management were investigated. In 2003-04, the two bean cultivars (Scylla and T-49) were combined with three inoculant treatments (strains CC 511 and RCR 3644, and a control of no inoculation), two fertiliser levels (0 and 150 kg N ha⁻¹) and two irrigation treatments (irrigated and rainfed). There was no nodulation on either cultivar. To further investigate the symbiotic relationship, 16 rhizobial isolates, including the two used in the first field experiment, were combined with the cultivar Scylla and evaluated in a greenhouse. Subsequently, five Rhizobium isolates were chosen for further field evaluation, based on signs of early nodulation in the greenhouse trial. The second field experiment in 2004-05 combined the five inoculant strains (RCR 3644, UK 2, H 20, PRF 81, PhP 17 and a control) with two bean cultivars (Scylla and T-49). In the greenhouse, nodule number varied from 7 (UK 2) to 347 (H 441) nodules plant⁻¹ at 51 DAS and from 13 (UK 1) to 335 (CIAT 899) nodules plant⁻¹ at 85 DAS. In 2004-05, in the field, nodulation was also variable, ranging between 1 and approximately 70 nodules plant⁻¹, with higher nodules numbers plant⁻¹ being found on cultivar T-49. Of the isolates used in the field, strains H 20, PRF 81 and PhP 17 produced 70, 25 and 12 nodules plant⁻¹ at 70, 40 and 54 DAS respectively. Nodules formed were of various sizes and more than 80 % were pink to dark red in colour denoting the presence of leghaemoglobin and active N fixation. The remaining nodules were either green or white. The importance of selecting an appropriate cultivar for the growing conditions was highlighted in these experiments. Leaf area index, leaf area duration intercepted radiation and final utilisation efficiency were significantly affected by cultivar. In both seasons cv. T-49 reached maturity (dry seed) before Scylla, while unirrigated plants reached green pod maturity seven days before irrigated plants. Plants of cv. Scylla gave a final TDM of 730 g m⁻²; compared to the 530 g m⁻² produced by T-49. The average growth rate was 7.0 and 5.2 g m⁻² day⁻¹ for Scylla and T-49 respectively (2003-04). Plants receiving 150 kg N ha⁻¹ produced 665 g m⁻² TDM which was 12 % more than was produced by unfertilised plants. The application of 150 kg N ha⁻¹ gave an average growth rate of 6.4 g m⁻² day⁻¹ compared to 5.7 g m⁻² day⁻¹ from plants with no N. Inoculation in the field had no significant effect on TDM in both seasons. Temperature affected growth and DM accumulation. Accumulated DM was highly dependent on cumulative intercepted PAR. Air temperatures below the base temperature (10 °C) affected growth in 2004-05, resulting in plants accumulating just 0.24 g DM MJ⁻¹ PAR during early growth. This increased to 2.26 g DM MJ⁻¹ PAR when the temperature was increased above the base temperature. There was a strong relationship between LAI and intercepted PAR. A LAI of 4.0-4.5 was required to intercept 90-95 % of incident solar radiation. Cultivar significantly (p < 0.001) affected radiation use efficiency (RUE). Scylla had a RUE of 1.02 g DM MJ⁻¹ PAR compared to T-49 at 1.18 g DM MJ⁻¹ PAR. Seed yield was significantly (p < 0.001) affected by cultivar and fertiliser application. Cultivar Scylla produced 467 g m⁻² which was 76 % more than T-49, while a 12 % increase in seed yield was observed in N fertilised plants over unfertilised plants. Only cultivar significantly affected HI, while the yield components that had the greatest effect on seed yield were hundred seed weight and pods plant⁻¹. Inoculation significantly (p< 0.05) affected 100 seed weight (2004-05). Plants inoculated with strain H 20 had the highest 100 seed weight at 25.2 g with cv. Scylla producing larger seeds than T-49. The belief that local environmental conditions play a major role on field survival of bacteria, led to the use of PCR methods to identify field nodulating organisms. Amplification of genomic DNA from parent isolates using primers fC and rD generated a single band for each isolate. Isolates were identified to the species level as either Rhizobium or Agrobacterium, using the highly conserved internally transcribed spacer (ITS) region and are known to nodulate common bean. The DNA extracted from the isolates recovered from nodules of field grown beans gave multiple bands with primers fC and rD. Five distinct banding patterns were observed. All of these were different from those of parent isolates. Sequencing of the 16S rRNA demonstrated that nodules of field grown beans in Canterbury were inhabited by Pseudomonads either alone or in association with other root nodulating organisms. The inability to identify the inoculant strains in nodules of field grown beans does not rule out their infection and nodulating function in the cultivars used. The results suggest the possibility of both Rhizobium and Pseudomonads cohabiting in the nodules of field grown beans. The aggressive nature of Pseudomonads on artificial media, possibly out competing the inoculant rhizobia is proposed, leading to the inability to identify the inoculant strain from the nodules of the field grown beans by PCR methods. The need to identify the nodule forming or nodule inhabiting bacteria in the nodules is necessary to classify the importance of these organisms and their economic benefit to agricultural production. This study also underlines the importance of using PCR methods to gain valuable insights into the ecological behaviour of Rhizobium inoculants and nodule inhabiting organisms.

L'étalement de spectre par séquence directe occupe une place prépondérante dans les systèmes de télécommunication utilisant la technique d'accès multiple par répartition de code : ce sont les systèmes dits de troisième génération (3G). En effet, ces systèmes permettent des trafics de données diverses à très hauts débits et l'accès simultané d'un très grand nombre d'utilisateurs. Dans le cadre de la surveillance du spectre radio fréquence, se posent alors les problèmes de la différenciation de ces systèmes et de la reconnaissance automatique des signaux à spectre étalé par séquence directe, sans connaissance a priori sur les systèmes de transmission. C'est dans ce contexte dit non coopératif que se situe le cadre de ce travail. La première phase de l'identification est la détection multi-utilisateurs aveugle des signaux à spectre étalé interférents. Nous avons montré que ces signaux peuvent être détectés grâce à leur effet sur les fluctuations d'estimateurs statistiques. Cette méthode permet également d'estimer les périodes symboles et ainsi d'isoler les groupes de signaux transmis au même débit (c'est-à-dire, les différents systèmes). La seconde phase est la synchronisation dans chaque groupe. Elle consiste à affiner la période symbole obtenue lors de la première phase et, pour chaque signal du groupe, à évaluer de manière précise le début du premier symbole. Nous avons d'abord étendu au cas multi-utilisateurs la technique consistant à maximiser la norme carrée de la matrice de covariance du signal intercepté. La courbe de synchronisation obtenue présente alors des pics, dont le nombre correspond au nombre d'utilisateurs interférents. Toutefois, nous avons montré que certains de ces pics pouvaient être masqués. Partant de ce constat, nous avons développé une méthode originale de synchronisation consistant à maximiser les valeurs propres prépondérantes de la matrice de covariance. Une étude théorique des performances de ces deux techniques, après la synchronisation, prouve la robustesse de la nouvelle méthode. Enfin, une fois les signaux synchronisés, nous avons présenté une méthode d'estimation des séquences d'étalement utilisées à l'émission ainsi que des symboles transmis. Les performances simulées, en terme de taux d'erreurs chip et binaire moyens, confirment les résultats théoriques.

From the Proceedings of the 1973 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - May 4-5, 1973, Tucson, Arizona / A preliminary assessment and ranking of the relative significance of five processes that may contribute to snow removal from ponderosa pine forest canopies was made, including wind erosion of canopy snow, snowslide from the canopy, stemflow, vapor transport from melt water, and vapor transport of canopy snow. The first three represent delayed delivery rather than net water loss. A snow load index was obtained through use of time lapse photography of the study site canopy, while incoming solar radiation and atmospheric processes were monitored. The snow load index was expressed as a ratio of forest canopy area covered with snow to the total canopy area. Results obtained over a 4-day period following a six-hour snowstorm showed that snow removal by snowslide and wind erosion was of significant importance, while vapor transport of melt water and canopy snow, stemflow, and dripping of melt water was of comparatively minor importance.

Based on the considerations presented by the Constitutional Court in the light of a specific case, this article addresses the discussion about the limit of intervention that the employer has to intercept and collect those communications that are protected by the secrecy of the law of the Communications of workers, establishing the possibility of implementing new control mechanisms that suspend any kind of expectation of confidentiality. / A partir de las consideraciones expuestas por el Tribunal Constitucional en atención a un caso en concreto, el presente artículo aborda la discusión sobre el límite de intervención que posee el empleador para interceptar y recaudar aquellas comunicaciones que se encuentran protegidas por el secreto al derecho de las comunicaciones de los trabajadores, estableciendo la posibilidad de implementar nuevos mecanismos de control que suspenden cualquier tipo de expectativa de confidencialidad.

Submitted by Nádja Goes (nmoraissoares@gmail.com) on 2016-08-03T12:27:30Z No. of bitstreams: 1 2015_dis_lvsilva.pdf: 1231278 bytes, checksum: f2c7e3058523d6ccecefab2c7cf93932 (MD5) / Approved for entry into archive by Nádja Goes (nmoraissoares@gmail.com) on 2016-08-03T12:27:44Z (GMT) No. of bitstreams: 1 2015_dis_lvsilva.pdf: 1231278 bytes, checksum: f2c7e3058523d6ccecefab2c7cf93932 (MD5) / Made available in DSpace on 2016-08-03T12:27:44Z (GMT). No. of bitstreams: 1 2015_dis_lvsilva.pdf: 1231278 bytes, checksum: f2c7e3058523d6ccecefab2c7cf93932 (MD5) Previous issue date: 2015 / SILVA, Leane Veras da. Componentes da biomassa e estrutura do capim-aruana sob duas frequências e duas intensidades de desfolhação. 2015. 56 f . : Dissertação (mestrado) - Universidade Federal do Ceará, Centro de Ciências Agrárias, Departamento de Zootecnia, Fortaleza-CE, 2015 / This study evaluated the components of biomass and the canopy structure of aruana grass managed under two frequencies (FD, interception of the photosynthetically active radiation at 85 and 95% incident on the top of the canopy) and two intensities (ID, residual leaf area index of 1.0 and 1.8) of defoliation in a completely randomized design in a 2x2 factorial arrangement with five replications (paddocks). The experiment was conducted at the advanced field of Teaching and Study Center Forage, located in the municipality of Pentecoste, Ceará State. The times of entry and exit of animals were determined using the PAR/LAI Analyzer in Agriculture DECAGON PAR-80 for reading photosynthetically active radiation interception (PARI) and leaf area index (LAI). At the beginning and end of the rest period of each of the five experimental paddocks, the following structural characteristics were evaluated: sward height (cm); height of the first ligule, the oldest below the canopy; grazing horizon and tiller population density. The components of total forage biomass (TFB ha-1 cycle-1) were also quantified at the beginning and end of the rest period, from the collection using two frames of 0.25 m², and sent to the laboratory to separate the components: leaf, stem and dead material. After separation of the TFB components, samples were dried to constant weight in a forced ventilation oven at 55°C to constant weight to estimate the following parameters: total forage biomass (TFB kg ha-1 cycle-1), dead forage biomass (DFB kg ha-1 cycle-1), green forage biomass (GFB kg kg ha-1 cycle-1), green leaf biomass (GLB kg ha-1 cycle-1), green stem biomass (GSB kg ha-1 cycle-1), and green/dead material ratio (GM/DM) and leaf/stem ratio (L/S). The longest rest period was observed in pastures managed with lower rLAI and lower defoliation frequency (95% PARI), with average of 24 days. Biomass components and structural characteristics in the pre-grazing condition were affected (P <0.05) by FD, where the lower defoliation frequency resulted in higher production with considerable contribution of biomass of green stems and dead forage. The pre-grazing height showed a high correlation with the %PARI in the pre-grazing condition (r = 0.9285, P = 0.0001). Pastures managed with lower FD had low L/S, with average of 1.65, while those managed with higher FD, an average of 2.40. With increasing %PARI, we verified higher grazing horizons, with averages of 20.2 and 14.2 cm, for 95 and 85 %PARI, respectively. The components of the residual biomass were affected (P <0.05) by ID, with higher residual forage biomass observed for pastures managed with rLAI of 1.8. Pastures managed with 95x1.8 exhibited higher rGSB ¬and rDFB (P <0.05) compared to the other managements. Pastures managed with 95x1.0 showed an increase in TFB (P <0.05) over successive grazing cycles. Aruana grass supplied to sheep should be managed under 85% PARI frequency and defoliation intensity equal to 1.0 rLAI. / Avaliou-se os componentes da biomassa e a estrutura do dossel em capim-aruana sob duas frequências (FD - níveis de interceptação de 85 e 95% da radiação fotossinteticamente ativa incidente no topo do dossel) e duas intensidades (ID - índices de área foliar residual de 1,0 e 1,8) de desfolhação, em um delineamento inteiramente casualizado, num arranjo fatorial 2x2, com cinco repetições (piquetes). O experimento foi conduzido no campo avançado do Núcleo de Ensino e Estudos em Forragicultura, situado na Fazenda experimental Vale do Curú, localizada no município de Pentecoste-CE. Os momentos de entrada e saída dos animais foram determinados utilizando-se o Analisador PAR/LAI em Agricultura DECAGON PAR-80 para as leituras da interceptação de radiação fotossinteticamente ativa (IRFA) e do índice de área foliar (IAF). Foram avaliadas no início e no final do período de descanso de cada um dos cinco piquetes experimentais, as seguintes características estruturais: altura do pasto; altura da primeira lígula viva, a mais velha abaixo do dossel; horizonte de pastejo e densidade populacional de perfilhos. Os componentes da biomassa de forragem total (BFT) foram quantificados no início e final do período de descanso, a partir da colheita com duas molduras de 0,25 m², sendo encaminhadas ao laboratório para separação dos componentes: folha, colmo e material morto. Após a separação dos componentes da BFT, as amostras foram levadas à estufa de ventilação forçada à 55 °C até peso constante para estimativa das seguintes variáveis: biomassa de forragem total (BFT kg∙ha-1∙ciclo-1), de forragem morta (BFM kg∙ha-1∙ciclo-1 ), de forragem verde (BFV kg∙ha-1∙ciclo-1), de lâmina foliar verde (BLV kg∙ha-1∙ciclo-1), de colmo verde (BCV kg∙ha-1∙ciclo-1), além das relações material vivo/material morto (MV/MM) e folha/colmo (F/C). O maior tempo de descanso foi verificado para os pastos manejados com menor IAFr e menor frequência de desfolhação (95% de IRFA), com média de 24 dias. Os componentes da biomassa e as características estruturais na condição pré-pastejo foram afetados (P<0,05) pelas FDs, onde a menor frequência de desfolhação proporcionou maiores produções, com considerável contribuição de biomassa de colmos verdes e de forragem morta. A altura pré-pastejo apresentou boa correlação com a %IRFA na condição pré-pastejo (r=0,9285; P=0,0001). Pastos manejados com menor FD proporcionaram baixa F/C, com média de 1,65, enquanto pastos manejados com maior FD apresentaram média de 2,40. Com o aumento da %IRFA, foram verificados maiores horizontes de pastejo, com médias de 20,2 e 14,2 cm para as frequências de 95 e 85%IRFA, respectivamente. Os componentes da biomassa residual foram afetados (P<0,05) pelas IDs, com maior biomassa de forragem residual observada para os pastos manejados com IAFr de 1,8. Os pastos manejados com 95x1,8 apresentaram BCVr e BFMr superiores (P<0,05) aos demais manejos. Pastos manejados com 95x1,0 apresentaram incremento (P<0,05) de BFT ao longo de ciclos sucessivos de pastejo. O capim-aruana, para utilização com ovinos, deve ser manejado com frequência de 85% de IRFA e intensidade de desfolhação equivalente a IAFr de 1,0.

Made available in DSpace on 2014-06-11T19:28:22Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-26Bitstream added on 2014-06-13T19:36:49Z : No. of bitstreams: 1 silva_wl_me_jabo.pdf: 738598 bytes, checksum: 3bab2246fd6bc478a66e3929f5f28058 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / A produção de forragem é influenciada pelas estratégias de manejo impostas a ela, desta maneira, as técnicas para identificação do melhor momento para início e término do pastejo, aliadas aos estudos das características morfogênicas e estruturais das plantas, tornam-se úteis para direcionamento do manejo, pois buscam auxiliar no melhor entendimento do crescimento vegetal, e por conseqüência, da produção forrageira. O experimento foi realizado no setor de Forragicultura, em área pertencente à FCAV da UNESP – Jaboticabal no período de dezembro de 2008 a abril de 2009, com o objetivo de avaliar o efeito de índices de área foliar residual (IAFr) sobre as características morfogênicas e estruturais, além do acúmulo de forragem em pastos de Cynodon spp cv Tifton-85 sob regime de lotação rotacionada com ovinos. Os tratamentos foram constituídos por três IAFr, 2,4, 1,6 e 0,8, mantidos por regime de lotação rotacionada com ovinos. O delineamento experimental utilizado foi o de blocos completos casualizados em arranjo de parcelas subdivididas no tempo com sete repetições, totalizando 21 unidades experimentais. Foram avaliadas nas condições de pré e pós-pastejo, as alturas do dossel, os IAF e a massa de forragem, além da taxa de acúmulo de forragem e as características morfogênicas e estruturais dos pastos. No pré e pós-pastejo as alturas médias e o IAF do dossel se comportaram de forma análoga, decrescendo com a diminuição dos IAFr. O maior valor de interceptação luminosa no pós-pastejo (68,19%), foi verificado para o IAFr 2,4 e o menor valor (35,57%) para o IAFr 0,8. A taxa de aparecimento de folhas foi maior para o dossel mantido sob IAFr 0,8 em função da sua menor taxa de alongamento de colmos (0,51 cm/perfilho.dia). Os pastos mantidos sob IAFr 0,8 apresentaram maior densidade populacional de perfilhos. A massa de forragem seca... / The production of forage is influenced by handling strategies imposed on the techniques to identify the best moment for the beginning and ending of grazing, linked to the studies of morphogenetic and structural characteristics of plants, become useful tools for the directing of management for they aim to aid the best understanding of vegetal growth, and as consequence, forage plants. The experiment was conducted at Setor de Forragicultura at Faculdade de Ciências Agrárias e Veterinárias de Jaboticabal, at UNESP – Jaboticabal from December 2008 to April 2009, and aimed to evaluate the effect of residual leaf area index (LAIr) about the morphogenical and structural characteristics, and forage accumulation in pastures of Cynodon spp cv Tifton-85 in a rotational stocking system with sheep. The treatments were constituted by three LAIr, 2,4, 1,6 e 0,8, maintained by rotational stocking with sheep. A complete randomized block design was used arranged in sub-divided parcels with seven replications, totaling 21 experimental units. They were evaluated in pre and post-grazing conditions, the height of the sward, LAI and forage mass, besides the accumulation of forage rate and the morphogenetic and structural characteristics. In the pre and post-grazing, the average height and the LAI of sward, decreasing with the diminishing of LAIr. The biggest value of light interception in post-grazing (68,19%), was verified by LAIr 2,4 and the smallest value (35,57%) for LAIr 0,8. The stem elongation rate (0,51 cm/tiller.day). The grazing maintained by LAIr 0,8 had higher tiller population density. The total dry forage mass was 27,1% superior for LAIr 2,4 regarding to LAIr 0,8 in pre-grazing conditions, being this total production, 72,0% was composed by stem fractions and dead material. The biggest rates of dry matter accumulation were observed with LAIr 2.4, in the second and third grazing cycles... (Complete abstract click electronic access below)

CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior / Avaliou-se as trocas gasosas, o fluxo de biomassa e as caracterÃsticas estruturais do capim-aruana pastejado sob lotaÃÃo rotativa por ovinos Morada Nova submetidos a quatro nÃveis de suplementaÃÃo concentrada (0,0; 0,6; 1,2 e 1,8% do PC), com perÃodo de ocupaÃÃo de quatro dias e descanso quando da interceptaÃÃo de 90% da radiaÃÃo fotossinteticamente ativa (IRFA), num delineamento inteiramente casualizado, num arranjo em parcelas subdivididas, sendo os nÃveis de suplementaÃÃo as parcelas e os ciclos de pastejo as subparcelas. A condiÃÃo de pÃs-pastejo consistiu em um Ãndice de Ãrea foliar de 1,0. Constatou-se efeito linear crescente para a taxa de alongamento das hastes e taxa de aparecimento foliar em funÃÃo dos nÃveis de suplementaÃÃo. As taxas de produÃÃo e acÃmulo de forragem foram incrementadas pelos nÃveis de suplementaÃÃo. As variÃveis das trocas gasosas das folhas recÃm-expandidas: transpiraÃÃo, condutÃncia estomÃtica, taxa de fotossÃntese foliar, mostraram efeito somente de ciclo de pastejo. NÃo houve nenhum efeito significativo sobre as variÃveis das trocas gasosas das folhas emergentes. Os componentes da biomassa pÃs-pastejo registraram efeito significativo da interaÃÃo nÃveis de suplementaÃÃo e ciclos de pastejo para biomassa de forragem verde residual (BFVr), lÃmina foliar verde residual (BLVr), colmo verde residual (BCVr) e relaÃÃo folha:colmo (F_Cr) residual, estas variÃveis, com exceÃÃo da F_Cr apresentaram efeito quadrÃtico nos ciclos dois e trÃs, confirmando o efeito substitutivo, a partir do nÃvel de suplementaÃÃo de 0,86%, com o mÃnimo estimado de 257,53 Kgâha-Ââano-1, para a BLVr. A relaÃÃo material vivo_ material morto residual apresentou efeito linear crescente em funÃÃo dos nÃveis de suplementaÃÃo. A altura do pasto e a densidade populacional de perfilhos residual foram afetadas somente pelos ciclos de pastejo. A biomassa de forragem verde (BFV) e de lÃmina foliar verde (BLV) apresentaram efeito da interaÃÃo nÃveis de suplementaÃÃo e ciclos de pastejo. A BLV registrou efeito quadrÃtico para os ciclos dois e trÃs, onde os maiores valores foram de 1489,47, no nÃvel de 0,62, do segundo ciclo e de 1554,95 Kgâha-Ââano-1no ciclo trÃs com nÃvel de suplementaÃÃo de 0,14 %. As trocas gasosas nÃo sÃo afetadas pelos nÃveis de suplementaÃÃo. As caracterÃsticas morfogÃnicas do pasto de capim-aruana sÃo afetadas linearmente pelos nÃveis crescentes de suplementaÃÃo. Os componentes estruturais do pasto de capim-aruana sÃo afetados pelos nÃveis crescentes de suplementaÃÃo concentrada, registrando efeito substitutivo do suplemento. / This study evaluated the gas exchange, the biomass flow and the structural characteristics of Panicum maximum cv. Aruana grazed by Morada Nova sheep under rotational stocking and supplied with four concentrate supplementation levels (0.0; 0.6; 1.2 and 1.8% body weight), using four day-grazing periods and rest when the interception of 90% of the photosynthetic active radiation (PAR). The experiment was a completely randomized split-plot design with supplementation levels as plots and grazing cycles as subplots. The post-grazing condition consisted of a leaf area index of 1.0. We observed an increasing linear effect for stem elongation rate and leaf appearance rate according to the supplementation levels. The production and accumulation rates of forage also increased according to the supplementation levels. The different grazing cycles affected the variables of gas exchange of the recently expanded leaves, namely transpiration, stomatal conductance, leaf photosynthesis rate. In turn, no significant effect was detected for the gas exchange variables of emergent leaves. Biomass components during the post-grazing period showed a significant effect of the interaction between supplementation levels and grazing cycles for residual green forage biomass (BFVr), residual green leaf biomass (BLVr), residual green stem biomass (BCVr) and residual leaf:stem ratio (F_Cr). All these variables, with the exception of F_Cr, presented a quadratic effect in the cycles two and three, confirming the substitutive effect from the supplementation level of 0.86%, with the minimum estimated at 257.53 Kgâha-Ââyear-1, for BLVr. The ratio between living and senescent material showed an increasing linear response as a function of the supplementation levels. The pasture height and the residual tiller population density were affected only by grazing cycles. Green forage biomass (BFV) and green leaf biomass (BLV) presented a quadratic effect of the supplementation levels and grazing cycles. BLV showed a quadratic effect for the cycles two and three, where the higher values were 1489.47, at the level of 0.62, in the second cycle, and 1554.95 Kgâha-Ââyear-1 in the third cycle with a supplementation level of 0.14%. Gas exchange was not influenced by the supplementation levels. Morphogenetic traits of the aruana grass pasture are linearly affected by increasing levels of supplementation. The structural components of the aruana grass pasture are influenced by the increasing levels of concentrate supplementation, with a substitutive effect of the supplement.

Submitted by (edna.saturno@ufrpe.br) on 2017-03-23T12:40:14Z No. of bitstreams: 1 Bruno Leal Viana.pdf: 1623265 bytes, checksum: 5707cff554bc2506977fb551f2f6b45e (MD5) / Made available in DSpace on 2017-03-23T12:40:14Z (GMT). No. of bitstreams: 1 Bruno Leal Viana.pdf: 1623265 bytes, checksum: 5707cff554bc2506977fb551f2f6b45e (MD5) Previous issue date: 2009-07-27 / The research was conducted at the Experimental Station of the Agronomic Institute of Pernambuco (IPA) located in Itambé, dry rainforest region of Pernambuco. The objective was to estimate the coefficients of repeatability, of determination (R2) and the number of measures needed to predict the real value [using principal component analysis (PCA)] to variable morphophysiological and productive, and the responses dwarf elephant grass pasture under grazing sheep. The experiment was carried out in a randomized block design with five Pennisetum purpureum clones were evaluated: Taiwan A-146 2.27, Taiwan A-146 2.37, Taiwan A-146 2114, Merker Mexico MX 6.31 and Mott. Evaluations were performed during five grazing cycles, from September 2008 to April 2009. Twenty five sheep (42 kg average liveweight) were used in a mobgrazing protocol, leaving the paddock at 30 cm of residual stubble height. The clones were managed under rotational stocking, with 32 days of resting period and three days of grazing period for cycles 1, 2, and 5, and 64 days of resting period and two days ofgrazing period for cycles 3 and 4. Response variables analyzed at pre- and post-grazing included leaf area index, light interception, leaf angle, average sward height, green portion of herbage mass (DM basis). In addition, we estimated net herbage accumulation (ALF), in kg DM ha-1 cycle-1, and net herbage accumulation rate (TALF), in kg DM ha-1 day-1. Data were analyzed by univariate or multivariate analysis of repeated measures over time in the SAS. Means were compared by Tukey test at 5% probability. According to the PCA, for the variables LAI and LI in cycles of shorter period of regrowth, and height of plants in the cycles of higher period of rest is needed only one measurement (R2=0.80), classifying them among the characteristics evaluatedas the easiest prediction in elephant grass clones. Assessments for NHA and NHAR size of dwarf elephant grass, under grazing, need long experimental periods. / Esta pesquisa foi realizada na Estação Experimental do Instituto Agronômico de Pernambuco (IPA), no município de Itambé, Zona da Mata Seca de Pernambuco, com o objetivo de estimar os coeficientes de repetibilidade, de determinação (R2) e o número mínimo de medições necessárias para predizer o valor real [pela análise dos componentes principais (ACP)] para variáveis morfofisiológicas e produtivas, bem como as respostas dos pastos de capim elefante de porte baixo sob o pastejo de ovinos. O experimento foi conduzido no delineamento em blocos casualizados, com cinco clones de Pennisetum purpureum (Taiwan A-146 2.27, Taiwan A-146 2.37, Taiwan-146 2.114, Merker México MX 6.31, e Mott). As avaliações foram realizadas em cinco ciclos de pastejo, compreendidos entre os meses de setembro de 2008 a abril de 2009. Foram utilizados 25 ovinos, com peso médio de 42 kg, como animais pastejadores em “mobgrazing”, buscando-se a altura de 30 cm de resíduo pós-pastejo. Os clones foram manejados sob lotação intermitente, sendo 32 dias de descanso e três de pastejo para os ciclos 1, 2 e 5 e 64 dias de descanso e dois de pastejo para os ciclos 3 e 4. As variáveisanalisadas foram índice de área foliar, interceptação luminosa, ângulos foliares médios realizados, alturas médias do dossel e massa de forragem seca verde (MSV), no pré e pós pastejo. Foram estimados ainda o acúmulo líquido de forragem (ALF), em kg MS ha-1 ciclo-1 e a taxa de acúmulo líquido de forragem (TALF), em kg MS ha-1 dia-1. Os dados foram analisados por meio de análise univariada ou multivariada de medidas repetidas no tempo no SAS. Para comparação das médias foi utilizado o teste de Tukey a 5% de probabilidade. De acordo com a ACP, para as variáveis IAF e IL nos ciclos de menor período de rebrota, e altura média de plantas nos ciclos de maior período de descanso é necessário apenas uma medição (R2=0,80), classificando-as entre às características avaliadas como as de mais fácil predição em clones de capim elefante. Avaliações de ALF e de TALF para capim elefante de porte baixo, sob pastejo, necessitam de períodos experimentais mais longos.

Deforestation of the Brazilian savanna (Cerrado) region has caused major changes in hydrological processes. These changes in water balance and soil erosion are still poorly understood, but are important for making land management decisions in this region. Therefore, it is necessary to understand the magnitudes of hydrological processes and soil erosion changes on local, regional and continental scales, and the consequences that are generated. The main objective of the study presented in this doctoral thesis was to better understand the mechanism of hydrological processes and soil erosion in the Cerrado. To achieve that, I worked with different scales (hillslope, watershed and continental) and using data from experimental field, laboratory, and remote sensing. The literature review reveals that the annual rainfall erosivity in Brazil ranges from 1672 to 22,452 MJ mm ha-1 h-1 yr-1. The smallest values are found in the northeastern region, and the largest in the north and the southeastern region. I found that the canopy interception may range from 4 to 20% of gross precipitation and stemflow around 1% of gross precipitation in the cerrado. The average runoff coefficient was less than 1% in the plots under cerrado and that the deforestation has the potential to increase up to 20 fold the runoff coefficient value. The results indicate that the Curve Number method was not suitable to estimate runoff under undisturbed Cerrado, bare soil (hydrologic soil group A), pasture, and millet. Therefore, in these cases the curve number is inappropriate and the runoff is more aptly modeled by the equation Q = CP, where C is the runoff coefficient. The water balance from the remote sensing data across the Brazilian Cerrado indicates that the main source of uncertainty in the estimated runoff arises from errors in the TRMM precipitation data. The water storage change computed as a residual of the water budget equation using remote sensing data (TRMM and MOD16) and measured discharge data shows a significant correlation with terrestrial water storage change obtained from the GRACE data. The results show that the GRACE data may provide a satisfactory representation of water storage change for large areas in the Cerrado. The average annual soil loss in the plots under bare soil and cerrado were 15.25 t ha-1 yr-1 and 0.17 t ha-1 yr-1, respectively. The Universal Soil Loss Equation cover and management factor (C-factor) for the plots under native cerrado vegetation was 0.013. The results showed that the surface runoff, soil erosion and C-factor for the undisturbed Cerrado changes between seasons. The greatest C-factor values were found in the summer and fall. The results found in this doctoral thesis provide benchmark values of the water balance components and soil erosion in the Brazilian Cerrado that will be useful to evaluate past and future land cover and land use changes for this region. In addition, I conclude that the remote sensing data are useful to evaluate the water balance components over Cerrado regions, identify dry periods, and assess changes in water balance due to land cover and land use change. / O desmatamento nas regiões de Cerrado tem causado intensas mudanças nos processos hidrológicos. Essas mudanças no balanço hídrico e erosão do solo são ainda pouco entendidas, apesar de fundamentais na tomada de decisão de uso e manejo do solo nesta região. Portanto, torna-se necessário compreender a magnitude das mudanças nos processos hidrológicos e de erosão do solo, em escalas locais, regionais e continentais, e as consequências dessas mudanças. O principal objetivo do estudo apresentado nesta tese de doutorado foi de melhor entender os mecanismos dos processos hidrológicos e de erosão do solo no Cerrado Brasileiro. Para tanto, utilizou-se diferentes escalas de trabalho (vertentes, bacias hidrográficas e continental) e usando dados experimentais in situ, de laboratório e a partir de sensoriamento remoto. O estudo de revisão de literatura indica que a erosividade da chuva no Brasil varia de 1672 to 22,452 MJ mm ha-1 h-1 yr-1. Os menores valores encontram-se na região nordeste e os maiores nas regiões norte e sudeste do Brasil. Verificou-se que os valores de interceptação da chuva variam de 4 a 20% e o escoamento pelo tronco aproximadamente 1% da precipital total no cerrado. O coeficiente de escoamento superficial foi menor que 1% nas parcelas de cerrado e o desmatamento tem o potencial de aumentar em até 20 vezes esse valor. Os resultados indicam que o método Curve Number não foi adequado para estimar o escoamento superficial nas áreas de cerrado, solo exposto (grupo hidrológico do solo A), pastagem e milheto. Portanto, nesses casos o uso do CN é inadequado e o escoamento superficial é melhor estimado a partir da equação Q = CP, onde C é o coeficiente de escoamento superficial. O balanço hídrico a partir de dados de sensoriamento remoto para todo o Cerrado Brasileiro indica que a principal fonte de incerteza na estimativa do escoamento superficial ocorre nos dados de precipitação do TRMM. A variação de água na superfície terrestre calculada como o residual da equação do balanço hídrico usando dados de sensoriamento remoto (TRMM e MOD16) e valores observados de vazão mostram uma correlação significativa com os valores de variação de água na superfície terrestre provenientes dos dados do GRACE. Os dados do GRACE podem representar satisfatoriamente a variação de água na superfície terrestre para extensas regiões do Cerrado. A média anual de perda de solo nas parcelas de solo exposto e cerrado foram de 15.25 t ha-1 yr-1 and 0.17 t ha-1 yr-1, respectivamente. O fator uso e manejo do solo (fator C) da Universal Soil Loss Equation para o cerrado foi de 0.013. Os resultados mostraram que o escoamento superficial, erosão do solo e o fator C na área de cerrado variam de acordo com as estações. Os maiores valores do fator C foram encontrados no verão e outono. Os resultados encontrados nesta tese de doutorado fornecem valores de referência sobre os componentes do balanço hídrico e erosão do solo no Cerrado, que podem ser úteis para avaliar o uso e cobertura do solo atual e futuro. Além disso, conclui-se que os dados de sensoriamento remoto apresentam resultados satisfatórios para avaliar os componentes do balanço hídrico no Cerrado, identificar os períodos de seca e avaliar as alterações no balanço hídrico devido à mudanças de uso e cobertura do solo.