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.

Thesis (MScFor)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: In South Africa fertilizer applications at establishment is a common practice in the forestry industry. Recommendations are based on past research with conventional sources (CV) and as a result there have only been slight improvements in additional plantation production over recent years. The objective of this study was to investigate initial stand responses in terms of leaf are index (LAI), foliar nutrient content, biomass index (BI) and volume growth to the application of controlled release fertilizers (CRF) at re-establishment. Nitrogen (N), phosphorus (P) and potassium (K) were applied in a three way factorial combination to Pinus radiata at planting on a site in the Western Cape. The design was replicated five times across the study area. N (CRF) and P (CV) were applied in a two way factorial combination at planting to two Eucalyptus grandis x urophylla hybrids and Eucalyptus dunnii across three sites, one ex-agricultural and two re-establishment sites, on the Zululand coastal plain and the Midlands region. The design was replicated nine times on each study site. Harvesting residues were burnt on the eucalypt sites prior to establishment and may have had an impact on the responses found. An outbreak of Fusarium circinatum on the P. radiata site resulted in unexpected and extremely variable responses. An attempt to quantify the effect of the disease had limited success. The mean BI of the control treatment reached 25. The best CV and CRF treatments yielded improvements of 42 % and 83 % in BI over the control respectively, with only the CRF treatment difference being significant. Foliar analysis results revealed marginal to deficient concentrations of P and Mg being alleviated by the treatments in question. On the KZN Zululand sites there was a marked response of the hybrids to N with P having an additive effect on volume growth, LAI and foliar N content. Application of 120 g N and 20 g P per tree on the ex-agriculture site produced a volume of 8 m3 ha-1 at one year of age, a significant increase of 118 % and 80 % over the control and best CV treatment respectively. Application of 80 g N and 20 g P per tree, on the re-establishment site, yielded a volume of 24.6 m3 ha-1 at one year which equates to a significant 39 % and insignificant 7 % additional volume at one year over the control and best CV treatment respectively. A non-significant suppressive effect was found with 20 g CV P application only. At the KZN Midlands site, the major early response in height were to P application. Applications of 20 g CV P per tree, resulted in a mean height of 162.6 cm at seven months of age, a significant 28 % higher than the control. There was no significant effect of 80 g CRF N and 20 g CV P per tree respectively. CRF N applications up to 120 g per tree provide additional growth over recommended CV applications on coastal Zululand sites with low organic carbon (OC) content. On the KZN Midlands site with higher OC and clay content, early responses were limited to P fertilization only regardless of the fertilizer source. / AFRIKAANSE OPSOMMING: Dit is algemene praktyk in die Suid Afrikaanse bosbou industrie om kunsmis tydens aanplanting toe te dien. Hierdie aanbeveling is gebasseer op navorsing resultate met konvensionele bronne (CV), gevolglik was slegs ‘n klein toename in bykomende plantasie produksie gemeet die afgelope paar jaar. Die doelwit tydens hierdie studie is om die aanvanklike reaksie van die bome in terme van blaar oppervlak indeks (LAI), blaar-voedingstof inhoud, biomassa indeks (BI) en volume op die toediening van beheerde vrylating kunsmis (CRF) tydens aanplanting vas te stel. Stikstof (N), fosfor (P) en kalium (K) is in drie-ledige kombinasie aan Pinus radiata op ’n plantasie in die Weskaap toegedien. Die ontwerp is vyf keer in die studiegebied herhaal. N en P is in twee-ledige kombinasie aan twee Eucalyptus grandis x urophylla hibriede en Eucalyptus dunnii op drie groeiplekke, een eks-landbou en twee eks-bosbou, op die Zoeloeland kusvlakte en in die Natalse Middellande toegedien. Die ontwerp is nege keer in elke studiegebied herhaal. Oesreste is voor aanplanting op die Eucalyptus groeiplekke verbrand. Die voorkoms van Fusarium circinatum op die P. radiata groeiplek het onverwagte en hoogs uiteenlopende reaksies tot gevolg gehad. ’n Poging om die effek van die siekte te kwantifiseer, was slegs gedeeltelik suksesvol. Die gemiddelde BI van die kontrole behandeling, was 25. Die beste CV en CRF behandeling het onderskeidelik 42 % en 83 % hoër BI as die kontrole groep gehad, waarvan slegs die CRF behandeling beduidend was. Blaarontleding het gewys dat daar marginale of ontoereikende konsentrasies van P en Mg was. In Zoeloeland het die Eucalyptus hibriede ’n beduidende reaksie op N en P getoon met meer volume groei, LAI en N inhoud. Die toediening van 120 g N en 20 g P per boom op die eks-landbou groeiplek het ’n volume van 8 m3 ha-1 op eenjarige ouderdom tot gevolg gehad. Dis beduidend beter met 118 % en 80 % onderskeidelik vir die kontrole en beste CV behandeling. Die toediening van 80 g N en 20 g P per boom op die hervestigde eks-bosbou groeiplek, het ’n volume van 24.6 m3 ha-1 op eenjarige ouderdom tot gevolg gehad. Dit is 39 % beduidend en 7 % onbeduidend addisionele volume op eenjarige ouderdom vir onderskeidelik die kontrole groep en beste CV behandeling. ’n Onbeduidende depressie effek is met die alleen toediening van 20 g CV P gevind. In die Natalse Middellande groeiplek het die toediening van P ‘n vroeë reaksie in hoogte groei veroorsaak. Die toediening van 20 g CV P per boom, het ’n gemiddelde hoogte van 162.6 cm op die ouderdom van sewe maande tot gevolg gehad. Dit is 28 % beduidend hoër as die kontrole. Die toediening van 80 g CRF N en 20 g CV P per boom was onbeduidend. Toedienings van CRF N tot en met 120 g per boom het in die kusgebiede van Zoeloeland met ‘n lae organiese koolstof (OC) inhoud, groter groei as die aanbevole CV toedienings gehad. Die Middellande groeiplek met ’n hoër OC en klei inhoud, was die vroeë reaksie alleenlik beperk tot P bemesting.

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 2016-12-23T13:51:52Z (GMT). No. of bitstreams: 1 Valeria Hollunder Klippel.pdf: 1679011 bytes, checksum: 81fc92fdc0af96774ee580cab6eba66b (MD5) Previous issue date: 2011-07-25 / This study aimed to evaluate different forest restoration methods of a Tableland Forest, by manipulating the floristic composition and silvicultural practices. With this foundation, it was installed in August of 2007, at the Reserva Natural Vale (RNV) in Linhares - ES, an experiment in randomized blocks with 4 treatments and 3 replications (a total of 12 plots): T1 (Control): Only leafcutter ants control; T2: Selective manual mowing, selective chemical weeding, control of ants and species tolerant to the herbicide; T3: Same as treatment 2, but with the planting of Atlantic Forest pioneer species in the spacing of 5 x 5 m, interspersed, in the same spacing, the seeding of Sesbania grandiflora in pits (10 seeds per pit); T4: Same as treatment 2, but with the planting of 54 Atlantic Forest species in the spacing close to 3 x 3 m. From the moment of installation (2007) until the third year of the study (2010) annual inventories were performed in all plots, to study the arboreal vegetation flora and growth. Moreover, at the third year after the experiment implementation, soil samples were also collected at four depths (0-5, 5-10, 10-20 and 20-40 cm) for later chemical analysis; accumulated litter, for studying biomass and nutrient content and level, and leaf area index (LAI). Regarding the soil chemical attributes, only statistic differences were found for the studied treatments in depths of 0-5 cm, where the highest values of Ca, sum of bases and CEC were observed for the treatment 4 and greater Na Saturation Index value to the treatment 1, and 10-20 cm, where the treatment 4 showed higher Ca value. There were no statistical differences in the accumulated litter biomass. The lower C/N was obtained by the treatment 3. This treatment also had the highest leaf area index. The elimination of weed competition acted positively on trees growth. The entrance of individuals and basal area was higher for treatments 3 and 4 / Esse estudo teve como objetivo avaliar diferentes métodos de restauração florestal de uma Floresta de Tabuleiro, pela manipulação da composição florística e práticas silviculturais. Com esta fundamentação foi instalado em agosto do ano de 2007, na Reserva Natural Vale (RNV) em Linhares ES, um experimento em blocos casualizados, com 4 tratamentos e 3 repetições (totalizando 12 parcelas): T1 (Controle): Somente o controle de formigas cortadeiras; T2: Roçada manual seletiva, capina química seletiva, controle de formigas e as espécies tolerantes ao herbicida; T3: Idêntico ao tratamento 2, mas com o plantio de espécies pioneiras da Mata Atlântica no espaçamento de 5 x 5 m, intercalado, no mesmo espaçamento, o semeio de Sesbania grandiflora em covas (10 sementes por cova); T4: Idêntico ao tratamento 2, mas com o plantio de 54 espécies da Mata Atlântica no espaçamento próximo de 3 x 3 m. Desde o momento de instalação (2007) até o terceiro ano de estudo (2010) foram realizados inventários anuais em todas a as parcelas, para estudo da florística e crescimento da vegetação arbórea. Além disso, no terceiro ano após a implantação do experimento, também foram coletadas amostras de solo em quatro profundidades (0 5; 5 10; 10 20 e 20 40 cm) para posterior análise química; serapilheira acumulada, para estudo da biomassa e do teor e conteúdo de nutrientes; e índice de área foliar (IAF). Em relação aos atributos químicos do solo, somente foram encontradas diferenças estatísticas para os tratamentos estudados nas profundidades de 0-5 cm, onde os maiores valores de Ca, soma de bases e CTC foram observados para o tratamento 4 e maior valor do ISNa para o tratamento 1, e de 10-20 cm, onde o tratamento 4 apresentou maior valor de Ca. Não foram observadas diferenças estatísticas para a biomassa da serapilheira acumulada. A menor C/N foi obtida pelo tratamento 3. Esse tratamento também apresentou o maior índice de área foliar. A eliminação da matocompetição atuou positivamente no crescimento da vegetação arbórea. O ingresso de número de indivíduos e de área basal foi superior para os tratamentos 3 e 4.

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.

Le suivi des variables biophysiques à l’échelle globale sur de longues périodes de temps est essentiellepour répondre aux nouveaux enjeux que constituent le changement climatique et la sécurité alimentaire. L’indice foliaire (LAI) est une variable de structure définissant la surface d’interception du rayonnement incident et d’échanges gazeux avec l’atmosphère. Le LAI est donc une variable importante des modèles d’écosystèmes et a d’ailleurs été reconnue comme variable climatique essentielle (ECV). Cette thèse a pour objectif de fournir des estimations globales et continues de LAI à partir d’observations satellitaires en temps quasi-réel en réponse aux besoins des utilisateurs pour fournir des diagnostiques et pronostiques de l’état et du fonctionnement de la végétation. Quelques produits LAI sont déjà disponibles mais montrent des désaccords et des limitations en termes de cohérence et de continuité. Cette thèse a pour objectif de lever ces limitations. Dans un premier temps, on essaiera de mieux définir la nature des estimations de LAI à partir d’observations satellitaires. Puis, différentes méthodes de lissage te bouchage des séries temporelles ont été analysées pour réduire le bruit et les discontinuités principalement liées à la couverture nuageuse. Finalement quelques méthodes d’estimation temps quasi réel ont été évaluées en considérant le niveau de bruit et les données manquantes.Les résultats obtenus dans la première partie de cette thèse montrent que la LAI effectif et bien mieux estimé que la valeur réelle de LAI du fait de l’agrégation des feuilles observée au niveau du couvert. L’utilisation d’observations multidirectionnelles n’améliore que marginalement les performances d’estimation. L’étude montre également que les performances d’estimation optimales sont obtenues quand les solutions sont recherchées à l’intérieur d’une enveloppe définie par l’incertitude associée aux mesures radiométriques. Dans la deuxième partie consacrée à l’amélioration de la continuité et la cohérence des séries temporelles, les méthodes basées sur une fenêtre temporelle locale mais de largeur dépendant du nombre d’observations présentes, et utilisant la climatologie comme information a priori s’avèrent les plus intéressantes autorisant également l’estimation en temps quasi réel. / Monitoring biophysical variables at a global scale over long time periods is vital to address the climatechange and food security challenges. Leaf Area Index (LAI) is a structure variable giving a measure of the canopysurface for radiation interception and canopy-atmosphere interactions. LAI is an important variable in manyecosystem models and it has been recognized as an Essential Climate Variable. This thesis aims to provide globaland continuous estimates of LAI from satellite observations in near-real time according to user requirements to beused for diagnostic and prognostic evaluations of vegetation state and functioning. There are already someavailable LAI products which show however some important discrepancies in terms of magnitude and somelimitations in terms of continuity and consistency. This thesis addresses these important issues. First, the nature ofthe LAI estimated from these satellite observations was investigated to address the existing differences in thedefinition of products. Then, different temporal smoothing and gap filling methods were analyzed to reduce noiseand discontinuities in the time series mainly due to cloud cover. Finally, different methods for near real timeestimation of LAI were evaluated. Such comparison assessment as a function of the level of noise and gaps werelacking for LAI.Results achieved within the first part of the thesis show that the effective LAI is more accurately retrievedfrom satellite data than the actual LAI due to leaf clumping in the canopies. Further, the study has demonstratedthat multi-view observations provide only marginal improvements on LAI retrieval. The study also found that foroptimal retrievals the size of the uncertainty envelope over a set of possible solutions to be approximately equal tothat in the reflectance measurements. The results achieved in the second part of the thesis found the method withlocally adaptive temporal window, depending on amount of available observations and Climatology as backgroundestimation to be more robust to noise and missing data for smoothing, gap-filling and near real time estimationswith satellite time series.

Avec l'augmentation des sécheresses dans les forêts tempérées, la gestion sylvicole envisage de réduire la densité des peuplements adultes pour limiter le déficit hydrique. Cependant, la réduction de la canopée arborée augmente le rayonnement dans le sous-bois et permet le développement de la strate herbacée monopoliste. Nos objectifs étaient de caractériser l'évapotranspiration (ETu) de 4 herbacées monopolistes (Molinia caerulea, Calluna vulgaris, Pteridium aquilinum and Rubus sp.) et de quantifier leur impact sur la teneur en eau du sol (SWC) dans des peuplements de Quercus petraea. L’ETu des quatre herbacées cultivées en pot a été quantifiée en conditions semi-contrôlées caractérisées par deux niveaux d’éclairement relatif et 3 niveaux de SWC. In situ, le SWC, le microclimat et l’ETu de P. aquilinum et M. caerulea ont été mesurés sur 20 dispositifs dans les peuplements forestiers de Q. petraea présentant un gradient croissant de LAI. Chaque dispositif était subdivisé en 2 placettes, l’une était désherbée et l'autre enherbée. M. caerulea et C. vulgaris ont une faible régulation de leur ETu alors que P. aquilinum et Rubus sp. ont une stratégie conservatrice face au stress hydrique. SWC diminue plus rapidement quand le LAI de la strate herbacée augmente, ce qui est directement lié à l’ouverture du couvert arboré avec une valeur seuil de LAI de la strate arborée à 2-3, sous laquelle la contribution de la strate herbacée à l’évapotranspiration du peuplement pourrait compenser la diminution de celle de la strate arborée.Ces résultats montrent la nécessité de considérer la végétation du sous-bois dans la gestion sylvicole notamment lorsque la ressource hydrique est limitante. Ainsi, la réduction de la densité de la strate arborée doit être un compromis entre la réduction de la surface foliaire des arbres pour réduire l’ET, et le maintien d’une densité suffisante de la strate arborée pour limiter la croissance et l'ETu de la végétation du sous-bois. / In the context of ongoing increase of drought in temperate forests, forest managers consider the reduction of stand density to limit soil water depletion. The reduction of tree canopy density increases light below canopy and allows the development of monopolistic understorey vegetation. Our objectives were to characterize the evapotranspiration (ETu) of common understorey plants (Molinia caerulea, Calluna vulgaris, Pteridium aquilinum and Rubus sp.) and to quantify their impacts on soil water content (SWC) in mature oak stands (Quercus petraea).A first experiment was set up in a greenhouse where the 4 understorey species were potted and subjected to 2 levels of light transmittance and 3 levels of SWC. Microclimate and ETu were monitored. A second experiment was carried out on 20 plots (10 with M. caerulea and 10 with P. aquilinum) in oak stands with contrasted LAI. On each plot, two circular areas were set up, one weeded and the other untouched. SWC, microclimate and ETu were monitored.M. caerulea and C. vulgaris are more water spenders, whereas P. aquilinum and Rubus sp. are more water savers under water stress. Soil water depletion was faster with increasing understorey vegetation LAI, which was directly linked to tree canopy opening with a threshold of tree LAI of 2-3 below which the understorey contribution could offset the reduction of tree ET. The experimentations showed that the relative contribution of understory vegetation in the ecosystem water balance is significant, and depends on SWC and on the understorey species identity. These results show the necessity to consider understorey vegetation in forest management when water availability is an issue. Lower tree canopy density could increase the understorey ETu and soil water stress for trees. From a management perspective, thinning should be designed as a compromise between the reduction of tree leaf area to reduce ET, and maintaining sufficient tree canopy to restrict the growth and ETu of understorey vegetation.

Num ecossistema de pastagem a interceptação da luz incidente é o passo inicial de uma seqüência de eventos que resulta na produção de forragem. Vários são os fatores que interferem no processo de interceptação da luz e, dentre eles, os mais expressivos são aqueles relacionados com o índice de área foliar, com as características estruturais e com o arranjo espacial de componentes do dossel forrageiro. O presente experimento teve como objetivo estudar a estrutura do dossel, a interceptação luminosa e o acúmulo de forragem em pastos de Brachiaria brizantha cv. Marandu submetidos a lotação contínua por bovinos de corte. O experimento foi conduzido no Departamento de Zootecnia da USP/ESALQ. Os tratamentos corresponderam a quatro alturas de dossel (10, 20, 30 e 40 cm) mantidas constantes por meio de lotação contínua e taxa de lotação variável. O delineamento experimental foi o de blocos completos casualizados com quatro repetições. As variáveis estudadas foram: índice de área foliar (IAF), ângulo foliar, interceptação de luz, composição botânica/morfológica da forragem, distribuição vertical dos componentes do dossel forrageiro e acúmulo de forragem. A composição da massa de forragem dos pastos não apresentou grande variação entre tratamentos, principalmente no que diz respeito à porcentagem de hastes (27%) e de folhas (21%). A quantidade absoluta e a porcentagem de material morto em relação aos outros componentes morfológicos do dossel aumentaram do verão (30%) até o início da primavera (61%). Quanto maior a altura do dossel, maior foi o deslocamento dos componentes morfológicos ao longo de seu perfil vertical durante o ano. Reduções acentuadas nos valores de IAF dos pastos mantidos a 20 (5,2 para 1,6), 30 (7,0 para 1,5) e 40 cm (7,5 para 2,1) do verão ao início da primavera, respectivamente, não foram acompanhadas por reduções em interceptação luminosa, que se manteve consistentemente acima de 98%. O componente material morto interferiu de foma significativa na interceptação de luz, além de ter apresentado um padrão “dinâmico” de posicionamento no perfil vertical do dossel ao longo do ano. Essa variação na estrutura vertical do dossel foi tão maior quanto mais altos foram mantidos os pastos, e seu efeito sobre os padrões de interceptação luminosa provocou grandes variações na produção de forragem ao longo do ano. De toda a forragem produzida, 65 e praticamente 100% foi acumulada durante o final da primavera e verão nos pastos mantidos a 10 e 40 cm, respectivamente. A produção total de forragem não diferiu entre os pastos mantidos a 10, 20 e 30 cm (aproximadamente 24 ton.ha-1.ano-1), sugerindo haver grande flexibilidade de manejo para essa espécie forrageira. As modificações no sentido vertical e horizontal na estrutura do dossel forrageiro tiveram impacto maior sobre a distribuição estacional do que propriamente sobre a produção total de forragem. / In a pastoral ecossystem the interception of incident radiation is the first step of a sequence of events that results in herbage production. Several are the factors interfering on the light interception process including sward leaf area index, structure and architecture. The objective of this experiment was to study sward struture, light interception and herbage acummulation of Brachiaria brizantha cv. Marandu pastures submitted to continuous stocking by beef cattle. The experiment was carried out at Departamento de Zootecnia, USP/ESALQ. Treatments correspondended to four sward heights (10, 20, 30 and 40 cm) kept constant through continuous stocking and variable stocking rate, allocated to experimental units according to a complete randomized block design with four replications. The response variables evaluated were sward leaf area index (LAI), foliage angle, light interception, botanical and morphological composition and hebarge production. There was no significant change in hebarge mass composition with stems representing 27% and leaves 21% of the sward. Quantity and proportion of dead material relative to the other sward morphological components increased from Summer (30%) to early Spring (61%). The taller the swards, the larger was the shift in the position of the morphological components across the vertical sward profile throughout the year. Significant reductions in LAI values for the 20 cm (5,2 to 1,6), 30 cm (7,0 to 1,5) and 40 cm swards (7,5 to 2,1) from Summer to early Spring were not followed by reduction in light interception, which remained above 98% consistent by through out the year around. The dead material component played an important role on sward light interception, and its placement across the vertical sward profile exhibited a “dynamic” pattern of variation. This variation was more evident in taller swards and affected sward light interception, resulting in varying seasonalities of herbage production. From the total herbage yield, 65 and 100% was produced during late Spring and Summer on the 10 and 40 cm swards, respectively. There was no difference in total herbage production among swards maintained at 10, 20 and 30 cm (24 ton.ha-1.year-1), sugesting that there is a large flexibilitty in grazing management for Brachiaria brizantha cv. Marandu. Modifications in both vertical and horizontal structure of the sward were more effective in changing the seasonal pattern of herbage production than determining herbage yield.

Apesar de muitos estudos dos diferentes métodos de lotação, a definição de estratégias de manejo eficientes geralmente é embasada em respostas de experimentos realizados com cada método individualmente, e não com ambos impostos sob uma mesma base de comparação. Com o objetivo de fundamentar os argumentos existentes, este estudo avaliou os impactos dos métodos de lotação contínua e intermitente impostos sob duas metas de alturas médias em pastagem de capim Convert HD 364, com avaliações da estrutura e das características morfofisiologicas do dossel, assim como do acúmulo (AF) e taxa de acúmulo (TAF) de forragem durante o verão agrótológico. O delineamento experimental utilizado foi o de blocos completos casualizados, com três repetições, seguindo um arranjo fatorial 2 x 3 entre duas metas de altura média de dossel (20 e 30 cm) e três métodos de lotação: 1) lotação contínua (LC) mimetizada, com taxa de lotação variável; 2) lotação intermitente (i.e., pastejo rotativo) com desfolhação leniente (remoção de ~ 40% da altura de dossel no pré-pastejo) (LIDL); e 3) lotação intermitente (i.e., pastejo rotativo) com desfolhação severa (remoção de ~ 60% da altura de dossel no pré-pastejo) (LIDS), respectivamente impostos por amplitudes de ±10, 25 e 40% entorno das metas de altura média de dossel, totalizando 18 unidades experimentais (piquetes) de 200 m2. Pastos manejados sob LC apresentaram maior AF e TAF (7410 kg MS ha-1 e 87 kg MS ha-1 dia-1, respectivamente). A interceptação de luz pelo dossel foi maior nos pastos sob LC (97%) do que naqueles sob LIDL e LIDS (93,7%) quando comparados nas metas de altura média do dossel (20 e 30 cm). No entanto, em pré-pastejo, os pastos sob LIDL e LIDS apresentaram 99% de interceptação de luz pelo dossel. Alterações com o mesmo padrão de respostas foram registradas para as proporções dos componentes da massa de forragem e índice de área foliar (IAF), com incremento significativo das proporções de lâmina foliar e colmos, assim como do IAF, e redução das proporções de material morto à medida que os pastos eram manejados sob menor intensidade em lotação contínua, ou havia o incremento da altura de pré-pastejo em lotação intermitente. Os métodos de lotação e as respectivas metas de altura não afetaram a taxa de fotossíntese de folhas individuais, mas a maior fotossíntese do dossel (69,35 &mu;mol CO2 m-2 s-1) foi obtida nos pastos manejados sob LIDS com meta de altura média de 30 cm. Os pastos manejados sob LC apresentaram taxas de fotossíntese do dossel constantes (47 &mu;mol CO2 m-2 s-1), o que resultou em maiores TAF e AF dentre os métodos de lotação estudados. / In spite of the great number of studies evaluating plant responses to different stocking methods, the definition of more efficient management strategies is generally based on the results of studies evaluating each stocking method separately. With the purpose of substantiating existing arguments, the present study evaluated the impacts of three stocking methods (1 - mimicked continuous stocking with variable stocking rate - CS; 2 - rotational stocking with lenient defoliation - removal of ~40% of pre-grazing canopy height - RSLD; 3 - rotational stocking with severe defoliation - removal of ~60% of pre-grazing canopy height - RSSD, respectively imposed by ±10, 25 and 40% variations) combined in a factorial arrangement with two mean canopy heights (20 and 30 cm) of Mulato II brachiariagrass, on canopy structure, morphophysiological characteristics, forage accumulation (FA) and forage accumulation rate (FAR) during the summer growing season. The experimental design was a randomized complete block with three replications, totaling 18 experimental units (paddocks) of 200 m2. Paddocks in CS treatments presented greater FA and FAR (7410 kg DM ha-1 and 87 kg DM ha-1 d-1, respectively). Canopy light interception was greater for paddocks in CS (97%) than for those in RSLD and RSSD (93.7%) for the two mean canopy heights. However, at pre-grazing, paddocks under RSLD and RSSD presented 99% of canopy light interception. The same response pattern was observed for forage mass composition and for leaf area index (LAI), with significant increases in the proportions of leaves and stems, as well as in LAI, and decreases in the proportions of dead material, as the grazing intensity decreased in CS, or as the pre-grazing height increased in the rotational stocking treatments. Neither the stocking methods, nor the mean canopy heights affected the photosynthesis rates of individual leaves, but the greatest canopy photosynthesis (69.35 &mu;mol CO2 m-2 s-1) was obtained in paddocks under RSSD with mean canopy heights of 30 cm. Paddocks in CS presented constant canopy photosynthesis rates (47 &mu;mol CO2 m-2 s-1), what lead to the greatest FAR and FA among the investigated stocking methods.