Disturbances, such as herbivory and fire are commonplace in savanna ecosystems. The effects of herbivory and fire on growth and defences of adult trees is a much studied filed in plant ecology. However, there are comparatively few studies that have investigated the effects of herbivory and fire on seedling growth, defences and establishment. African Acacia trees are common and widespread, and are suggested to be keystone species in savanna ecosystems. They have been shown to significantly positively increase soil characteristics, such as soil moisture and infiltration, while also increasing spatial heterogeneity of savannas. These trees are distinguishable by their array of physical and chemical defences. Physical defences are either in the form of spines (physiologically costly to produce, thus considered inducible) or prickles (physiologically cheap to produce, thus considered constitutive), while condensed tannins are the most common form of chemical defences. Adult Acacia trees have been shown on several occasions to be highly resilient to disturbance events, primarily due to their large size. However, the effects of herbivory and fire on Acacia seedlings have been little studied despite their apparent importance for our understanding of African savanna ecosystem functioning. In two separate experiments, this thesis aimed to investigate the individual and combined effects of simulated herbivory and fire on the regrowth, defences, and total non-structural carbohydrates (TNC) of the seedlings of several Acacia species, while also testing the Resource Availability Hypothesis (RAH) (14 Acacia species) and the Expanded Growth-Differentiation Balance Hypothesis (GDBH) (three Acacia species). The RAH (Coley, Bryant & Chapin 1985) and the GDBH (Loomis 1932) both assume that arid-adapted (resource-poor) species are slow growing, with low tissue turnover rates. Contrastingly, humid-adapted (resource-rich) species have fast growth rates and thus a high tissue turnover rate. Therefore, arid-adapted species are predicted to invest more carbohydrate reserves in defence after a disturbance event, in order to defend new photosynthetic material. Conversely, humid-adapted (resource-rich) species are predicted to invest carbohydrate reserves into increased growth after a disturbance event, in order to compensate for tissue loss. The first greenhouse experiment found that, in accordance with the RAH, humid-adapted species displayed elevated growth rates compared to arid-adapted species. Overall, defences significantly increased after herbivory, but significantly decreased after fire. Herbivory was also shown to significantly reduce TNC stores in roots more than fire. We found that arid-adapted species did indeed invest more carbohydrate stores (TNC) into defence, and displaying an increase in spine and prickle abundance, spine and prickle length, and condensed tannin concentration. Humid-adapted species displayed an increase in growth rather than in defence, with the majority of species only increasing one defensive trait. Humid-adapted species also displayed significant trade-offs (negative correlations) between new stem growth and defence traits, while arid-adapted species overall did not display any significant trade-offs between stem growth and increased defences. The majority of arid-adapted species also displayed an allometric effect for spine abundance and length, with an increase in one trait led to an increase in the other. Prickles were found to be inducible, despite the assumption that due to low physiological cost, they are no inducible. Herbivory and fire were shown to not be substitutable in their effects on Acacia seedlings in a controlled experimental setting. The second greenhouse experiment tested the Expanded Growth-Differentiation Balance Hypothesis (GDBH) in the seedlings of A. erioloba, A. karroo, and A. nilotica using five levels of nutrient availability. Overall, spine abundance and spine length displayed a unimodal trend in all three species, with spine abundance and spine length being greatest at a nutrient availability of 800 mg/ ℓ. Spine abundance, spine length and condensed tannins increased significantly after herbivory, but were shown to significantly decrease after fire. We found that with an increase in nutrient availability, the growth of stems and roots, along with the production of TNC in roots and stems of all species significantly increased. Our data provide mixed support for the assumptions and predictions of the expanded GDBH. The regrowth of stems and physical defences were consistent with the GDBH. Chemical defences (i.e. condensed tannins) were however, inconsistent with the predictions of the GDBH. We have shown that Acacia seedlings are highly resilient to disturbance events, while the growth responses of Acacia seedlings are underpinned by TNC stores in roots. Simulated herbivory and fire are often substituted for one another in controlled experiments. However, we have shown that the effects of herbivory and fire have significantly different effects on regrowth patterns of Acacia seedlings. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

Fusarium circinatum is a fungal pathogen that has had a serious impact on pine production throughout the world. It attacks most Pinus species including Pinus elliottii, Pinus patula and Pinus radiata. Infections in South Africa (SA) are largely on seedlings, and result in fatal seedling wilt. Accurate and quick detection systems suitable for field use are needed to monitor the spread of the disease and optimize fungicide applications. Detection of F. circinatum is currently based on visual observations of typical symptoms. However, symptoms are not unique to the pathogen and can be caused by other biotic and abiotic stress factors. Nucleic acid-based identification techniques using PCR are available for different fungal species. These are sensitive and accurate, but they are expensive and require skilled biotechnologists to conduct the assays. In this study an enzyme-linked immunosorbent assay (ELISA) was developed to identify F. circinatum in infected seedlings. This optimized ELISA is able to discriminate between F. circinatum and two other fungi that frequently affect pine. This method has advantages over other assays because of its ease of operation and sample preparation, sensitivity and the ability to run multiple tests simultaneously. Mycelium-soluble antigens from Diplodia pinea (=Sphaeropsis sapinea), F. circinatum and F. oxysporum were prepared in nutrient broth. Analysis of these antigens on SDS-PAGE indicated the presence of common antigens between the different fungal pathogens. Some antigens were expressed more by some isolates than by others. Separate groups of chickens were immunised with mycelium-soluble antigens from D. pinea, F. circinatum and F. oxysporum and exo-antigen from F. circinatum prepared in nutrient broth. A 34 kDa protein purified from SDS-PAGE specific for D. pinea was also used for immunisation. Five sets of antibodies were obtained including anti-D. pinea, anti-F. circinatum, anti-F. oxysporum, anti-F. circinatumexo and anti-D. pinea 34 kDa antibodies, respectively. Reactivity of these antibodies was evaluated against antigens prepared in nutrient broth using western blotting and ELISA. Western blot analysis indicated that immuno-dominant antigens for F. circinatum were larger than 34 kDa and their reactivity was not the same between different isolates. Each of the antibodies prepared using mycelium-soluble antigens showed increased reactivity when detecting its own specific pathogen, but cross-reactivity was observed. Anti-D.pineaantibodies showed minimal cross-reactivity with antigens from F. circinatum and F. oxysporum. Anti-F. circinatum antibodies cross-reacted with antigens from F. oxysporum but showed little cross-reactivity with D. pinea antigens. Anti-F. oxysporum antibodies showed more cross-reactivity towards antigens from F. circinatum than those from D. pinea. No reactivity was observed when anti-F. circinatum-exo antigen and anti-D. pinea 34 kDa antibodies were used in immuno-blotting analysis. Evaluation of antibody reactivity using indirect ELISA showed patterns similar to those observed on western blotting, where anti-D. pinea, anti-F. circinatum and anti-F. oxysporum antibodies showed the same cross-reactivity relationships. Anti-F. circinatum and anti-F. oxysporumantibodies showed a significant difference when reacting with antigens isolated from other pathogens including D. pinea, F. circinatum, F. oxysporum, F. solani, F. graminearum and F. culmorum (P = 0.001). No significant difference was observed when the antigens were detected with anti-D. pinea antibodies. Reactivity of anti-F. circinatum-exo and anti-D. pinea34 kDa antibodies was mostly similar to that of non-immune antibodies and showed no significant difference between detection of different antigens. Pine seedlings were artificially infected with the three fungal pathogens using a spore concentration of 1 – 1 x 106conidiaml-1.Infection was monitored using scanning electron microscopy. Results showed increased levels of mycelium growth on the stem and roots of the F. circinatum and F. oxysporum infected seedlings and on the leaves and stem in the case of D. pinea infected seedlings. These plant parts were used in ELISA tests for the detection of antigens. Isolation of antigens from the plant materials involved crushing plant parts in buffer and centrifugation of the suspension. The supernatant obtained was directly used in the assay. ELISA tests prepared in this study were sensitive enough to detect infection caused by 1 conidium ml-1at two weeks post inoculation. A positive reaction for detection of F. circinatum and F. oxysporum was indicated by an ELISA reading above an optical density at 405 nm. The plant material used in ELISA tests were further analysed using PCR. Results indicated that there was no cross-infection between seedlings and served as a confirmation of the disease-causing pathogen. This indicated that cross-reactivity observed was due to other factors such as common epitopes on the major antigens. Use of an ELISA dip-stick or ELISA using these antibodies should provide an easy, fast field test to identify infections of pine, discriminating between F. circinatum, F. oxysporum and D. pinea. / M.Sc.Agric. University of KwaZulu-Natal, Pietermaritzburg 2013.

The structure and composition of savanna vegetation is influenced by resource availability and disturbance. Grasses, a major component of savannas, influence this resource availability by competing directly with trees for light, water and soil nutrient resources. The direct causes of bush encroachment are not always apparent, but are commonly ascribed to overgrazing and consequent decreased grass competition. The interaction, both above and belowground, between tree and grass seedlings and the surrounding grass sward is dependant on many factors, such as soil depth, seedling species and sward composition. These factors, as well as the presence or absence of defoliation, in the form of grazing or fire dictate whether the system will remain in a transition state as savanna or move towards a stable woodland state. The major competitive effects experienced by the tree seedlings were dependant on grass species and nutrient level. A. nilotica was affected by aboveground competition while A. karroo was affected by belowground competition. E. capensis caused the greatest decrease in A. karroo plant biomass. Both E. capensis and H. hirta had large competitive effects on the aboveground biomass of A. nilotica, while S. africanus had the greatest effect on belowground biomass. Increasing nutrient availability resulted in an increase in the competitive effect exerted on A. karroo, while little to no change was seen in the competitive effect exerted on A. nilotica. Soil depth constrained plant size in both tree species. The intensity of belowground interactions on tree biomass was unaffected by soil depth, while aboveground competition had a significant effect on shallow soils. Belowground competition was also of greater importance than aboveground competition in dictating tree seedling height. Grass seedlings growing on all three soil depths differed in mean mass, with E. racemosa having the least mass and T. triandra having the greatest. Simulated grazing by cutting the surrounding sward resulted in biomass increases in all three grass species. Changes in savanna composition and structure are thus likely to be influenced by initial species composition and soil depth and soil nutrient composition. While grazing creates niches for grass seedling establishment, heavy grazing has been observed to increase grass seedling mortality. Encroachment is thus more likely to occur on intensively grazed shallow and deep soils than on medium depth soils. This highlights the importance of ensuring the grass sward remains vigorous by resting and monitoring stocking rates to ensure veld is not over-utilized. It is then possible to maintain some form of tree-grass coexistence at a level where available grazing is not compromised. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2007. / Härtill 5 uppsatser.

Made available in DSpace on 2016-06-02T19:32:07Z (GMT). No. of bitstreams: 1 5200.pdf: 2330287 bytes, checksum: 40cc22959878b0557c657a05a39a2e38 (MD5) Previous issue date: 2013-03-15 / Universidade Federal de Sao Carlos / Due to the high rates of environmental degradation and their consequences to the population, environmental recovery in many areas is an urgent need. Recovering degraded areas may be done by using several techniques alone or in combination. The traditional recovery system by means of seedling planting is expensive and has limited guarantee of germination using no-tillage sowing. Therefore, this study tested the viability of experimentally growing seedlings from seven native tree species without them suffering significant changes, after storing the sprouts in cold chambers for periods ranging from 7 to 28 days. The results showed that it is possible to delay the growing of radicles in seedlings stored in cold chambers (15°C) when compared to seedlings stored in germinator (25°C). In four out of seven species (Marlierea eugeniopsoides, Cordia americana, Cedrela fissilis e Hymenaea courbaril) stored for 14 days in cold chambers, the seedlings survival rates were higher than 77% 60 days after they were seeded in the nursery containers. This survival rate was similar to the rate of seedlings not stored in cold chambers. In three species (Marlierea eugeniopsoides, Luehea grandiflora e Hymenaea courbaril) stored for 21 days the survival rates were higher than 75%. The species Marlierea eugeniopsoides did not show significant survival changes even after storage in cold chamber for 28 days. / As elevadas taxas de degradação ambiental e as consequências deste processo para a população trouxeram à tona a urgência na recuperação ambiental dessas áreas. A restauração de uma área degradada pode ser realizada por meio de diversas técnicas utilizadas isoladamente ou em conjunto. Tendo em vista o elevado custo demonstrado no sistema tradicional de restauração de áreas degradadas, através do plantio de mudas, e às limitações de garantia de germinação de sementes utilizando-se a técnica de semeadura direta, este estudo avaliou se seria possível, experimentalmente, o crescimento e o desenvolvimento de plântulas de sete espécies arbóreas nativas, sem sofrerem alterações significativas, após suas sementes, recém-germinadas, serem armazenadas por períodos que variavam de 7 a 28 dias em câmara fria. Os resultados indicam que é possível retardar o crescimento das radículas de plântulas submetidas ao armazenamento em câmera fria (15 °C), quando comparado com plântulas armazenadas em germinador (25 °C). Das sete espécies estudadas, quatro (Marlierea eugeniopsoides, Cordia americana, Cedrela fissilis e Hymenaea courbaril), apresentaram uma taxa de sobrevivência das plântulas, que permaneceram armazenadas por 14 dias em câmara fria, maior que 77 %, após 60 dias que foram plantadas em tubetes no viveiro, uma taxa de sobrevivência equivalente ao das plântulas não submetidas à câmara fria. Três espécies (Marlierea eugeniopsoides, Luehea grandiflora e Hymenaea courbaril) apresentaram taxas de sobrevivência de suas plântulas submetidas à câmara fria por 21 dias superior a 75%. A espécie Marlierea eugeniopsoides não apresentou variação estatisticamente significativa da taxa de sobrevivência de suas plântulas, mesmo quando armazenadas por 28 dias em câmara fria.

Submitted by Deyse Queiroz (deysequeirozz@hotmail.com) on 2018-06-13T12:15:00Z No. of bitstreams: 1 MARIA DO SOCORRO ROCHA - DISSERTAÇÃO PPGEA 2004..pdf: 12014866 bytes, checksum: e5b21eb998760e2ed7cd6bdeddf94a3e (MD5) / Made available in DSpace on 2018-06-13T12:15:00Z (GMT). No. of bitstreams: 1 MARIA DO SOCORRO ROCHA - DISSERTAÇÃO PPGEA 2004..pdf: 12014866 bytes, checksum: e5b21eb998760e2ed7cd6bdeddf94a3e (MD5) Previous issue date: 2004-11 / A conservação e manipulação dos recursos genéticos vegetais de espécies de valor económico são de fundamental importância para a conservação em banco de germoplasma. Este trabalho teve como objetivo; a) avaliar a crioconservação de sementes de algodão das cultivares BRS-Verde, BRS-200, BRS-187-8H e 6MMocó e b) estudar a indução ao superbrotamento dos nós cotiledonares de plântulas do algodoeiro cultivados in vitro, para as mesmas cultivares supracitadas. Neste trabalho propôs-se inicialmente determinar do teor de água limite para crioconservação (TALC). Para esta determinação as sementes foram imersas ao nitrogénio líquido (-196°C) por cinco dias e após esse período elas forma descongelados e submetidas ao teste de germinação e vigor. Utilizou as armazenagem das sementes a 23°C por 5 dias como testemunha. O delineamento estatístico empregado foi o inteiramente casualizado com arranjo fatorial representado por (quatro cultivares x duas temperaturas x seis teor de água). Na crioconservação utilizou-se um lote de sementes com teor de água limite previamente determinado para as diferentes cultivares, a partir do qual se procedeu ao seu armazenamento em nitrogénio líquido (-196°C) e no vapor do nitrogénio (-170°C), durante 5, 30, 60 e 90 dias. O delineamento experimental utilizado nesta etapa foi o inteiramente casualizado em parcela sub-dividida no tempo, sendo a parcela representas pela interação (quatro cultivares x duas temperaturas de armazenamento) e a sub-parcela pelos quatro períodos de armazenamento. Em cada período de armazenamento, as sementes foram submetidas a testes de germinação e vigor. De acordo com os resultados obtidos póde-se concluir que: a) estudar a determinação do teor de água limite para crioconservação-TALC, durante 5 dias, o teor de água limite para a crioconservação das cultivares BRS-Verde, BRS-200, 6M-Mocó e BRS-187-8H considerando-se a germinação dessas cultivares está entre 6 e 8% (b.u.) e considerando-se o vigor das sementes o TALC é de 6% (b.u.); b) sementes de algodoeiro, das diferentes cultivares podem ser crioconservados em banco de germoplasma nas duas temperaturas, ou seja no vapor a -170°C ou imersa ao nitrogénio líquido a -196°C; c) a crioconservação aumenta o percentual de germinação e vigor das sementes de algodão, devido a essa temperatura a promover uma quebra de dormência pela ação do frio. No Capítulo II propôs-se a indução de superbrotamento, empregando como explante dos nós cotiledonares, plântulas cultivadas in vitro durante 25 dias. Os explantes foram cultivados em tubos de ensaio contendo o meio básico MS, suplementado com citocininas BAP, KIN e TDZ, isolados ou associados em diferentes concentrações. Os tubos de ensaio contendo os explantes foram mantidos em sala de crescimento regulada à temperatura de 28°C, fotoperíodo de 16/8h (claro/escuro) e intensidade luminosa de 50umol.m2.s1 , durante 40 dias os quais foram avaliados por meio do delineamento inteiramente casualizado, com arranjo fatorial de 4x17 (quatro cultivares x dezessete meios), sendo então avaliadas quanto ao número de brotos emitidos e altura de brotos. De acordo com os resultados obtidos póde-se concluir que: O meio MS suplementados com BAP (2,0 mg.L"1) isolado ou associado com KIN (1,0mg.L"1), promoveu uma maior capacidade de regeneração e altura de brotos; b) o meio MS suplementados com BAP (2,5 mg.L"1) estimulou maior altura de brotos;c)o meio MS suplementados com TDZ (1,0 mg.L"1 , 0,50 mg.L"1e 0,25 mg.L"1) afetou a capacidade de regeneração de brotos, obteve formação de calos. / A conservação e manipulação dos recursos genéticos vegetais de espécies de valor económico, são de fundamental importância para a conservação em banco de germoplasma. Este trabalho teve como objetivo: a) avaliar a crioconservação de sementes de algodão das cultivares BRS-Verde, BRS-200- Marrom, BRS-187-8H-Branco e 6 M-Mocó-Branco e b) estudar a indução ao superbrotamento dos nós cotiledonares de plântulas do algodoeiro cultivados in vitro, para as mesmas cultivares supracitadas. Inicialmente, determina-se do teor de água limite para crioconservação (TALC). Para esta determinação, as sementes foram imersas no nitrogénio líquido (-196°C) durante cinco dias e após este período elas foram descongelados e submetidas ao teste de germinação e vigor. Utilizou-se a armazenagem das sementes a 23°C por 5 dias, como testemunha. O delineamento estatístico empregado foi o inteiramente casualizado com arranjo fatorial representado por (quatro cultivares x duas temperaturas x seis teores de água). Na crioconservação utilizou-se um lote de sementes com teor de água limite previamente determinado para as diferentes cultivares, a partir do qual se procedeu ao seu armazenamento em nitrogénio líquido (-196°C) e no vapor do nitrogénio (-170°C), durante 5, 30, 60 e 90 dias. O delineamento experimental usado nesta etapa foi o inteiramente casualizado, em parcela subdividida no tempo, sendo a parcela representada pela interação (quatro cultivares x duas temperaturas de armazenamento) e a subparcela pelos quatro períodos de armazenamento. Em cada período de armazenamento as sementes foram submetidas a testes de germinação e vigor. De acordo com os resultados obtidos concluiu-se que: a) O teor de água limite para crioconservação-TALC, durante 5 dias, para a crioconservação das cultivares BRS-Verde, BRS-200-Marrom, 6MMocó- Branco e BRS-187-8H-Branco, considerando-se a germinação dessas cultivares está entre 6 e 8% (b.u.) e, quanto os vigor das sementes, o TALC foi de 6% (b.u.); b) sementes de algodoeiro das diferentes cultivares podem ser crioconservadas em banco de germoplasma, nas duas temperaturas, ou seja, no vapor a -170°C ou imersa ao nitrogénio líquido a -196°C; c) a crioconservação aumenta o percentual de germinação e vigor das sementes de algodão, em virtude dessa temperatura promover quebra de dormência, pela ação do frio. No Capítulo II propôs-se a indução de superbrotamento, empregando-se como explante nós cotiledonares de plântulas cultivadas in vitro durante 25 dias. Os explantes foram inoculados em tubos de ensaio contendo o meio básico MS, suplementado com citocininas BAP, KIN e TDZ, isolados ou associados a diferentes concentrações. Os tubos de ensaio contendo os explantes foram mantidos em sala de crescimento regulada à temperatura de 28°C, fotoperíodo de 16/8h (claro/escuro) e intensidade luminosa de 50umol.m2.s1 , durante 40 dias, os quais foram avaliados por meio do delineamento inteiramente casualizado, com arranjo fatorial de 4x17 (quatro cultivares x dezessete meios), sendo então avaliadas quanto ao número de brotos emitidos e altura do comprimento de brotos. De acordo com os resultados obtidos pôde-se concluir que: a) o meio MS suplementado com BAP (2,0mg.L~1) isolado ou associado a KIN (1,0mg.L~1), promoveu maior capacidade de regeneração e altura de brotos; b) o meio MS suplementado com BAP(2,5mg.L"1 ) estimulou altura superior de brotos; c) o meio MS suplementado com TDZ (1,0mg.L~1, 0,50mg.L"1 e 0,25mg.L"1) afetou a capacidade de regeneração de brotos e a formação de calos.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The aim of this research was to characterize the development of Casearia sylvestris, Cupania vernalis, Eugenia involucrata, Inga vera, Parapiptadenia rigida and Schinus terebinthifolius in relation to the incidence of frost and the use of different silvicultural practices in altered areas in the South Atlantic Forest Biome. The planting was carried out in Nova Palma, RS, in two riparian areas. In the first experiment, the treatments were distributed in a factorial design (2 x 2) [two types of containers (180 cm3 polypropylene conical tubes and 1.500 cm3 polyethylene bags)], and presence or absence of green manure (Canavalia ensiformis and Vicia sativa)]. In the second experiment, factorial design (3 x 2) was used, considering two types of fertilization and control (chemical fertilization, organic fertilization and absence of fertilization) x soil cover (presence or absence of mulching). In both experiments, survival, morphological attributes (height, steam diameter, tree canopy, shoot dry weight and leaf area) and physiological (chlorophyll a fluorescence, chlorophyll a, chlorophyll b and carotenoid content, acid phosphatase, soluble phosphorus content, superoxide dismutase and hydrogen peroxide) were evaluated. During 2014 winter season, the damage from the impact of frost was assessed through a rating scale ranging from 0 (100% of the leaf area and damaged stem) to 10 (no visual damage). It was also evaluated the potential of growth recover species, characterized as resilience. In addition, soil physical parameters in the experimental and adjacent areas were evaluated at the end of the study, at 720 and 900 days after planting (experiment 1 and 2, respectively). The forest species respond differently to frost incidence. C. sylvestris, E. involucrata, P. rigida and S. terebinthifolius were tolerant to frost and/or showed potential for growth recovery, on the other hand, C. vernalis and I. vera were more sensitive to frost, with high mortality rates and/or no resilience potential. Survival rate was higher than 77%, regardless of the factors tested, except for C. vernalis (61%) and E. involucrata (80%) that showed higher survival when mulching was used on the soil. The species presented higher growth when they were produced in larger containers volume and with introduction of the green manure. In addition, chemical fertilization, through controlled release fertilizer, positively influenced the growth in the field, increasing the development of the seedlings, in order to minimize possible damages due biotic and/or abiotic stresses. The presence of mulching did not show any effect on the growth of all species analyzed. In a complementary way, analysis of the environments in the experimental areas evidenced improvements in the physical quality of the soil, contributing to the return of equilibrium of these ecosystems. / O objetivo dessa pesquisa foi caracterizar o desenvolvimento de Casearia sylvestris, Cupania vernalis, Eugenia involucrata, Inga vera, Parapiptadenia rigida e Schinus terebinthifolius diante da incidência de geadas e utilização de diferentes práticas silviculturais, em áreas alteradas no Sul do Bioma Mata Atlântica. O plantio foi realizado em Nova Palma, RS, em duas áreas ripárias. No primeiro experimento, os tratamentos foram distribuídos em esquema fatorial (2 x 2) [dois tipos de recipiente (tubetes cônicos de polipropileno de 180 cm3 e sacos de polietileno de 1.500 cm3) x presença ou ausência de adubação verde (Canavalia ensiformis e Vicia sativa)]. No segundo experimento, utilizouse fatorial (3 x 2), considerando dois tipos de adubação e testemunha (adubação química, adubação orgânica e ausência de adubação) x cobertura do solo (presença ou ausência de cobertura morta sobre o solo). Em ambos os experimentos foi avaliada a sobrevivência, além de atributos morfológicos (altura, diâmetro do coleto, projeção de copa, matéria seca aérea e área foliar) e fisiológicos (fluorescência da clorofila a, teor de clorofila a, clorofila b e carotenoides, atividade da enzima fosfatase ácida, conteúdo de fósforo solúvel, atividade da enzima superóxido dismutase e conteúdo de peróxido de hidrogênio). No inverno de 2014, evidenciaram-se danos nas espécies devido a incidência de geadas, os quais foram avaliados mediante escala de notas variando de 0 (100% da área foliar e caule danificado) a 10 (ausência de dano visual). Também foi avaliado o potencial de retomada do crescimento das espécies, caracterizado como resiliência. Adicionalmente, foram avaliados no final da pesquisa, aos 720 e 900 dias após plantio (experimento 1 e 2, respectivamente), atributos físicos do solo nas áreas experimentais e área adjacente (campo nativo e área agrícola). Evidenciou-se que as espécies florestais respondem de forma diferenciada a ação da geada. C. sylvestris, E. involucrata, P. rigida e S. terebinthifolius mostraram-se tolerantes à geada e/ou com potencial de retomada do crescimento, no entanto, C. vernalis e I. vera foram consideradas como muito sensíveis à geada, e/ou sem potencial de resiliência. A sobrevivência foi superior a 77%, independente dos fatores testados, exceto para C. vernalis (61%), que juntamente com E. involucrata (80%) apresentaram maior sobrevivência quando utilizada cobertura morta sobre o solo. As espécies apresentaram maior crescimento quando foram produzidas em recipientes de maior volume e diante a introdução da adubação verde na área. Além disso, a adubação química, por meio de fertilizante de liberação controlada, influenciou positivamente o crescimento em campo, potencializando o desenvolvimento das mudas, de forma a minimizar possíveis danos decorrentes de estresses bióticos e/ou abióticos. A presença de cobertura morta não demonstrou efeito sobre o crescimento de todas as espécies analisadas. De forma complementar, a análise dos ambientes nas áreas experimentais evidenciou melhorias na qualidade física do solo, contribuindo para o retorno do equilíbrio desses ecossistemas.

Made available in DSpace on 2016-08-12T19:15:25Z (GMT). No. of bitstreams: 1 JoseRSP_DISSERT.pdf: 2216238 bytes, checksum: bb0f85399b49819b4129cd776754eab1 (MD5) Previous issue date: 2014-02-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Sabiá (Mimosa caesalpiniifolia), jucá (Caesalpinia férrea), craibeira (Tabebuia aurea) e ipê-roxo (Handroanthus impetiginosus) are species from the Caatinga biome, used in reforestation programes and degraded areas recuperation. Planting in the Caatinga requires some attention to traits that depend on previous knowledge of the physiological and ecological characteristics of the plants. The study of the growth of a plant under different environmental conditions offer good hints on the best conditions to cultivate it. The disponibility of light is one of these factors that affect the development of plants, with morphological and physiological changes. This work had the objective of analysing the growth of young plants of the species indiated under differente shading levels, at the Mossoro-RN municipality. The experiment was conduced at the Universidade Federal do Semiarido (UFERSA), under a complete blocks experimental design, and a factorial scheme of 4 X 4 factors, and 8 time split plots, wher the first factor are the four species, the second factor is the four shading levels (0, 30, 50 and 70%), and the time split plots are the evaluation times (0, 21, 42, 63, 84, 105, 126 and 147 day after transplanting). It was evaluated in each time: Plant height (CPA), stem diameter (DC), stem dry mass (MSC), leaves dry mass (MSF), above ground dry mass (MSPA) and leaves area (AF). With was calculated the leaf area ratio (RAF), the specific leaf area (AFE), the absolute growth rate (TCA), the relative growth rate (TCR), and the net assimilatory rate (TAL). The shading levels affected the initial growth of M. caesalpinifolia, C. ferrea, and H. impetiginosus, with the best values for the growth indicators observed at 50% shade, with higher growth rates. The reduction of light disponibility induced higher values of CPA, AF, MSF and MSPA fos M. caesalpinifolia, C. ferrea, and H. impetiginosus. T. aurea presented physiological plasticity to all the shading levels, with similar growth under full sun and shade / Sabiá (Mimosa caesalpiniifolia), jucá (Caesalpinia férrea), craibeira (Tabebuia aurea) e ipê-roxo (Handroanthus impetiginosus) são espécies nativas da Caatinga indicadas para utilização em programas de reflorestamento e recuperação de áreas degradadas. O plantio na Caatinga requer uma série de cuidados que dependem do conhecimento prévio das características fisiológicas e exigências ecológicas das plantas. O estudo do crescimento de uma planta, sob diferentes condições ambientais, oferece um bom indício sobre quais as melhores condições para se cultivar determinada espécie. A disponibilidade de luz é um dos fatores que influenciam o desenvolvimento de mudas, com alterações morfológicas e fisiológicas. Este trabalho teve por objetivo analisar o crescimento de plantas jovens de sabiá, jucá, craibeira e ipê-roxo submetidas a diferentes níveis de sombreamento, no município de Mossoró-RN. O experimento foi conduzido na na Universidade Federal Rural do Semi-Árido, sob delineamento experimental de blocos completos ao acaso em arranjo fatorial 4x4 com 8 parcelas subdivididas no tempo, onde o primeiro fator corresponde a quatro espécies (sabiá, jucá, craibeira e ipê-roxo), o segundo fator corresponde a quatro níveis de sombreamento (0, 30, 50 e 75%) e as parcelas são as épocas de avaliação (0, 21, 42, 63, 84, 105, 126 e 147 dias após o transplantio). Foram avaliados a cada 21 dias, o comprimento da parte aérea (CPA), diâmetro do coleto (DC), massa seca do caule (MSC), folhas (MSF), parte aérea (MSPA) e área foliar (AF). Foram calculadas a razão de área foliar (RAF), área foliar específica (AFE), taxa de crescimento absoluto (TCA), taxa de crescimento relativo (TCR) e taxa assimilatória líquida (TAL). Os níveis de sombreamento afetaram o crescimento inicial do sabiá, jucá e ipê-roxo, com os melhores indicadores de crescimento observados nas mudas mantidas em ambiente sob 50% de sombreamento, culminando com maiores taxas de crescimento. A diminuição da luminosidade induziu o aumento de CPA, AF, MSF e MSPA no sabiá, jucá e ipê-roxo. A craibeira apresentou plasticidade fisiológica para os níveis de sombreamento, com crescimento semelhante na condição de sombra e sol

Made available in DSpace on 2016-08-12T19:15:32Z (GMT). No. of bitstreams: 1 GleidsonBG_DISSERT.pdf: 786514 bytes, checksum: 3ae91ac265c5ddc3749833a77978d949 (MD5) Previous issue date: 2011-02-04 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Due to the broad market prospects for crops in tamarind and pitombeira, it becomes essential the evaluation of methods that permit the propagation on a commercial scale. Considering this, two experiments were organized in a greenhouse, located in the Universidade Federal Rural do Semiárido UFERSA, located in the town of Mossoró, RN, from January 2009 until June 2010, with the objective of determining the best grafting method for the production of seedlings of tamarind and pitombeira. We studied the types of grafting: grafting in top cleft, cleft grafting in the top simple English way , grafting in the top complicated English way , grafting budding side and plate cleft. The design used in the experiments was a randomized complete block with five treatments (grafting types). The experiment with tamarind had seven repetitions; each parcel consisted of 14 seedlings, a total of 98 per treatment, adding 490 in the experiment. Variables were evaluated: percentage of grafting success, shoot length, root length, branch length, number of leaves, number of branches, stem diameter, shoot dry matter, root dry matter, Total matter dry. The data were subjected to analysis of variance and compared through the Tukey test at 5% significance using the software SISVAR. The rates of graft takes were submitted to angular transformation of arcsen √ x/100, and data on the number of branches in √ x + 0.5. In order to promote the statistic, treatment of pimple on board was disregarded, considering that this treatment has zero index of plant take. The grafting methods in top cleft, cleft grafting in the English top grafting complicated and simple English way in the top, are respectively the best methods of grafting for the tamarind. The test was conducted with pitombeira with four replications and each plot was composed of twenty seedlings in a total of 400 seedlings on the experiment, in which was observed zero rate of grafting take / Devido às amplas perspectivas de mercado para as culturas do tamarindeiro e pitombeira, torna-se indispensável a avaliação de métodos que permitam a propagação em escala comercial. Diante disso, foram desenvolvidos dois experimentos em casa de vegetação, localizada no Campus da Universidade Federal Rural do Semiárido UFERSA, situada na cidade de Mossoró-RN, no período de janeiro de 2009 a junho de 2010, com o objetivo de determinar o melhor método de enxertia para a produção de mudas de tamarindeiro e de pitombeira. Foram estudados os tipos de enxertia: garfagem no topo em fenda cheia, garfagem no topo à inglesa simples, garfagem no topo à inglesa complicada, garfagem em fenda lateral e borbulhia em placa. O delineamento utilizado nos experimentos foi o de blocos casualizados, com cinco tratamentos (tipos de enxertia). O experimento com tamarindeiro foi constituído por sete repetições, sendo cada parcela composta por 14 mudas, num total de 98 por tratamento, perfazendo 490 no experimento. Foram avaliadas as variáveis: percentagem de pegamento dos enxertos, comprimento da parte aérea, comprimento do sistema radicular, comprimento de ramos, número de folhas, número de ramos, diâmetro do colo, matéria seca da parte aérea, matéria seca do sistema radicular, matéria seca total. Os dados obtidos foram submetidos à analise de variância e comparados através do teste de Tukey ao nível de 5% de significância utilizando o software SISVAR. Os índices de pegamento dos enxertos foram submetidos à transformação angular do arcsen √x/100, e os dados de número de ramos em √x + 0,5. Para fins da realização da estatística, o tratamento de borbulha em placa foi desconsiderado, tendo em vista que este tratamento apresentou índice zero de pegamento. Os métodos garfagem no topo em fenda cheia, garfagem no topo à inglesa complicada e garfagem no topo à inglesa simples são, respectivamente, os melhores métodos de enxertia para o tamarindeiro. O ensaio com pitombeira foi realizado com quatro repetições sendo cada parcela composta por vinte mudas, num total de 400 mudas no experimento, no qual foi verificado índice zero de pegamento dos enxertos