Submitted by Erika Demachki (erikademachki@gmail.com) on 2014-10-06T13:52:31Z No. of bitstreams: 2 Dissertação Renata Jardim.pdf: 620239 bytes, checksum: dbbb756833afca246328749e9e3946cf (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2014-10-06T15:44:58Z (GMT) No. of bitstreams: 2 Dissertação Renata Jardim.pdf: 620239 bytes, checksum: dbbb756833afca246328749e9e3946cf (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2014-10-06T15:44:58Z (GMT). No. of bitstreams: 2 Dissertação Renata Jardim.pdf: 620239 bytes, checksum: dbbb756833afca246328749e9e3946cf (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2012-08-15 / This study aimed to evaluate the morphogenetic and structural characteristics of the Brachiaria brizantha cv. Xaraés and Stylosanthes guianensis var. vulgaris cv. Mineirão at Jataí Campus of Federal University of Goiás. The experimental design was the randomized complete block with three planting systems (Xaraés and Estilosantes both single and both intercropped) under three phosphorus levels (low, medium and high - 70, 105 and 140 kg/ha P2O5) applied at sowing with four replications. Data analysis was performed in a split plot model, considering in the plot, the planting system, the block and the evaluation period and at the split plot the dose effect and the interaction between planting system and dose. The means comparison was performed by “t” test at 5% of probability, using SAS® program version 9.0. The phosphorus doses and planting systems did not influence the morphogenetic and structural characteristics of the Brachiaria brizantha cv. Xaraés. The best results of leaf appearance rate, phyllochron, branching elongation rate, leaf enlargement rate, primary branches number, secondary branches number, leaflets length and width for the Stylosanthes guianensis var. vulgaris cv. Mineirão were verified in the single planting system. Independent of the planting system evaluated, the low (70 kg/ha P2O5) and medium (105 kg/ha P2O5) phosphorus doses have provided higher leaf elongation rate and petiole elongation rate for the Mineirão. The higher phosphorus dose (140 kg/ha P2O5) yielded lower elongation petiole rate for the Mineirão in the intercropped system and longer leaflets. / Objetivou-se com este trabalho avaliar as características morfogênicas e estruturais da Brachiaria brizantha cv. Xaraés e do Stylosanthes guianensis var. vulgaris cv. Mineirão no Campus Jataí da Universidade Federal de Goiás. O delineamento utilizado foi o de blocos completos ao acaso, com três arranjos de plantio (Xaraés e Estilosantes solteiros e consorciados) associado a três doses de fósforo (baixa, média e alta - 70, 105 e 140 kg/ha de P2O5) aplicadas na semeadura, com quatro repetições. A análise dos dados foi realizada em parcela subdividida considerando o efeito do arranjo de plantio, bloco e período de avaliação na parcela e efeito da dose e interação de arranjo de plantio e dose na subparcela. A comparação das médias foi realizada pelo teste t a 5% de probabilidade, utilizando o programa SAS® versão 9.0. Arranjos de plantio e doses de fósforo não influenciaram (P>0,05) as características morfogênicas e estruturais da Brachiaria brizantha cv. Xaraés. Por outro lado, influenciaram (P<0,05) as características do estilosantes. Os melhores resultados para taxa de aparecimento de folhas, filocrono, taxa de alongamento de ramificação, taxa de alargamento de folha, número de ramificações primárias, número de ramificações secundárias, comprimento de folíolos e largura de folíolos do Stylosanthes guianensis var. vulgaris cv. Mineirão foram verificados no plantio solteiro. As doses baixa (70 kg/ha de P2O5) e média (105 kg/ha de P2O5) de fósforo proporcionam as maiores taxas de alongamento de folha e de alongamento de pecíolos do estilosantes Mineirão independente do arranjo de plantio avaliado. A dose alta de fósforo (140 kg/ha de P2O5) proporciona menor taxa de alongamento de pecíolos do estilosantes Mineirão no plantio consorciado. A dose alta de fósforo proporcionou maior comprimento de folíolos do estilosantes Mineirão.

Growth polarity in leaves – a final discussion Insights into the growth processes of leaf lamina have come from studies on several species including Arabidopsis, Antirrhinum, tobacco and maize. A feature common to the growth of leaf in these distantly related species is the existence of a pronounced growth gradient in the proximo-distal axis -growth at the tip (distal part) is arrested at an early stage while the basal region (proximal part) continues to grow for the longest duration. This is because the cell division is arrested first at the tip at an early stage of development and the arrest progressively spreads towards the base. Along with the strong proximo-distal growth gradient, a milder growth gradient also exists in the medio-lateral axis, such that the cell division arrest travels slightly faster on the leaf margins imparting an overall convex shape to the arrest front. The temporal and spatial progression of the arrest front has not only been implicated in shaping up of a leaf but is also of paramount importance in the maintenance of a flat surface during leaf growth. Although the patterning mechanisms described above seem to operate during leaf growth in many6 species, the molecular mechanisms governing these processes is still in its infancy. Moreover, patterning of leaf growth has been studied only in a handful of model species and, therefore, the information from the vast body of natural variation remains neglected. Proximo-distal growth patterning by CINCINNATA Mutant leaves with altered rates or shapes of the arrest front progression deviate significantly from the normal shape and overall flat structure. Mutation in the CIN gene in Antirrhinum and its orthologues in Arabidopsis cause buckling of the leaf due to excess cell proliferation, which in turn is caused by a delayed progression of the arrest front. CIN-like genes code for TCP transcription factors and are expressed in a broad zone of a growing leaf somewhat distal to the proliferation zone. Even though several direct and indirect targets of CIN-like genes have been identified in various plant species, their role in regulating leaf maturity and surface curvature has remained unclear. The comparison of global transcription profile of wild type and cincinnata mutant of Antirrhinum showed that the expression of genes involved in either signaling or biosynthesis of the major growth hormones were altered in the mutant. By combining DNA-protein interaction, expression analysis, chromatin immuno-precipitation and RNA in situ hybridization, we show that CIN maintains surface flatness by regulating the signaling or level of major plant hormones in developing leaves. CIN promotes cytokinin signaling by directly binding to and thereby promoting the expression of a cytokinin receptor, AmHK4, in a spatio¬temporal manner. Furthermore, it also seems to affect GA level indirectly in young leaves by regulating the spatio-temporal as well as levels of GA-biosynthetic and GA-degrading enzymes. Thus, CIN seems to accelerate maturity in leaf cells along the tip-to-base direction through its effect on the cytokinin and GA signaling pathways. In addition, CIN suppresses auxin signaling more at the margin than in the centre by establishing a margin-to-medial expression gradient of a homologue of the auxin suppressor IAA3, thereby suppressing excess cell proliferation on the margin. Our results uncover an underlying mechanism in a developing leaf that controls curvature of the leaf surface by promotion of timely exit from cell proliferation in the proximo-distal as well as the medio-lateral axes via multiple hormone pathways. Divergent growth polarities in the proximo-distal axis of leaves The morphogenetic gradient in the proximo-distal axis of a leaf is brought about by the dynamic expression of several heterochronic regulators which can include TCP and GRF classes of transcription factors. Interestingly, many of these transcription factors are also regulated post-transcriptionally by micro RNAs. In case of the studied model species, these factors seem to be associated with basipetal growth. The early arrest in cell proliferation at the tip and continued cell division at the base has served as a paradigm in studying leaf growth and has been used to conceptualize the growth of leaves with different shapes. However, the possibility of the existence of different patterning mechanisms during leaf growth in the highly diverse plant kingdom remains unexplored. Our survey of leaf growth patterns in 75 dicot species reveals the existence of four distinct proximo-distal polarities in growth patterns. Using the law of simple allometry, we also show that the differentially growing regions of leaves bear a constant relationship between them during growth. A combination of cell-size studies, histochemical staining and expression analysis reveals a strong correlation among growth pattern, cell size and the cell proliferation status. The cell size studies also indicate that there is a wide variation in the final cell sizes of leaves and the relative contribution of cell division and cell expansion to the final leaf size can be highly variable. Furthermore, we find that the varying growth patterns are linked to changes in the expression pattern of miR396, which controls the expression pattern of cell division regulatory transcription factors, the GRFs. Mis-expressing miR396 at the base of the young Arabidopsis leaf caused an early exit from cell division while reducing the expression of the miR396 at the tip allowed cell division to continue for a longer duration near the tip. Our results demonstrate that leaves with similar shapes can be differently patterned and that this divergent patterning is linked to the expression differences in the regulatory micro RNA, miR396 In conclusion, this study shows that regulators like CIN maintain surface flatness of the Antirrhinum leaf during growth by promoting timely exit from cell division along the proximo-distal and the medio-lateral axes; and it does so by regulating multiple hormone pathways. Although the basic mechanism of patterned cell division and differentiation seems to be conserved among species, the polarities of growth can vary. The variability in the growth polarities could be brought about by changes in the trans-regulation or cis-regulatory changes in the patterning genes.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Sunflower is an alternative specie to the system of no-tillage and crop rotation. His inclusion in this system provides soil improvements and interruption on cycle of pests and diseases, which are responsible for losses of productivity of the mainly sown crops. In addition to these benefits this specie has characteristics of increased tolerance to drought than traditional crops such as soybean and corn, maintaining satisfactory yields even in dry years considereds. For inclusion in the rotation and maintaining satisfactory yields the knowledge of the best sowing dates is necessary. As the weather has interannual variability, the risk analysis for the sowing dates is required, through a study of probability with a long series of weather data for better definition. This study aims to determine the sowing date of sunflower in which lower severity of alternaria and septoria leaf spots in the RS Central Region occurs. For it has adapted and calibrated an algorithm providing a forecasting system diseases, based on data from leaf wetness duration, air temperature during the leaf wetness period and rain, calculating the accumulated severity values (VSCA) throughout the cycle. In this adaptation and calibration data from six experiments performed at the Department of Plant Science since 2007. Hourly values of weather data from 1968 to 2011 was estimated from the default readings, and use this algorithm were simulated for 14 different dates of sowing spaced in 15 days, beginning on August 1 and ending on February 16 of each year. Due to the interannual variability of ENSO and their influence on weather conditions, crop seasons years was apart in Neutral, La Niña and El Niño. The data generated from the analysis of variance and the means of Scott- Knott test at 5% probability of error was taken. In addition, the VSCA were subjected to analysis of probability distribution, verifying that the Weibull, lognormal and normal distributions has the best represent the distribution of values of severity of leaf spots on sunflower, both for the entire cycle and for the subperiods emergency-end of anthesis and early reproductive-final stage of anthesis sunflower. It was also found that the period between early February and late April is more favorable to leaf spots, while sowing dates from August 1 to October 16, resulting in lower severity values, differing significantly from later sowings. In El Niño years suffer the greatest severities of disease, followed by La Niña years, and finally with the lowest values of VSCA for Neutrals years. / O girassol é uma espécie alternativa para o sistema de plantio direto e rotação de culturas. Sua inserção neste sistema proporciona melhorias edáficas e interrupção do ciclo de pragas e doenças causadoras de perdas de produtividade nas culturas agrícolas mais semeadas. Além destes benefícios, esta espécie possui características de maior tolerância ao déficit hídrico do que culturas tradicionais como a soja e o milho, mantendo produtividades satisfatórias mesmo em anos considerados secos. Para a sua inclusão no sistema de rotação e manutenção de produtividades satisfatórias é necessário o conhecimento das melhores datas semeadura. Como as condições meteorológicas tem variabilidade interanual, é necessária a análise de risco para uma mesma data de semeadura, através de um estudo de probabilidade com uma série longa de dados meteorológicos para sua melhor definição. Este trabalho objetiva determinar a data de semeadura do girassol na qual ocorre menor severidade das manchas foliares de alternária e septória, na Região Central do RS. Para isso adaptou-se e calibrou-se um algoritmo provendo um sistema de previsão de doenças, baseado em dados de duração do molhamento foliar, temperatura do ar durante o período de molhamento foliar, e chuva, obtendo-se os valores de severidade calculada acumulados (VSCA) durante todo o ciclo. Nesta adaptação e calibração utilizaram-se dados de seis experimentos realizados no Departamento de Fitotecnia desde o ano de 2007. Os dados meteorológicos estimados para valores horários de 1968 até 2011, a partir das leituras padrão, e a utilização deste algoritmo, foram simuladas para 14 diferentes datas de semeadura espaçadas em 15 dias, iniciando em 01 de agosto e finalizando em 16 de fevereiro de cada ano. Devido à variabilidade interanual do fenômeno ENOS e sua influência sobre as condições meteorológicas, os anos separados em Neutros, La Niña e El Niño. A partir dos dados gerados foi feita a análise de variância e o teste de médias de Scott-Knott a 5% de probabilidade de erro. Além disso, os VSCA obtidos foram submetidos a análise de distribuição de probabilidade, verificando-se que as distribuições Weibull, lognormal e normal representam melhor a distribuição dos valores de severidade máxima das manchas foliares no girassol, tanto para o ciclo completo quanto para os subperíodos emergência-final da antese e início da fase reprodutiva-final da antese do girassol. Verificou-se ainda que o período entre o início de fevereiro e o final de abril é mais favorável às manchas foliares, enquanto que as datas de semeadura de 01 de agosto a 16 de outubro resultam nos menores valores de severidade, diferindo significativamente das semeaduras posteriores. Em anos El Niño ocorrem as maiores severidades das doenças, seguido pelos anos de La Niña, e finalmente com os menores valores de VSCA para os anos Neutros.

No description available.

Africa's miombo woodlands constitute one of the most important dry tropical forests on earth, yet the hydraulic function of these woodlands remains poorly researched. Given the current predictions of increased aridity by the end of this century in the miombo ecoregion, understanding the likely response of miombo woodlands tree species to water stress is crucial in planning adaptation strategies. Predicting the response of miombo woodlands to future climate trends is hampered by a lack of knowledge on the physiology of the common miombo woodlands tree species. In particular, plant-water relations for this woodlands type are not well understood. An understanding of plant-water relations for this woodlands type will provide insights into how water limits tree species distribution in this ecosystem. This will also improve our prediction model on the likely response of this ecosystem to predicted climate change. For this reason, the overall objective of this research was to evaluate the hydraulic architecture and xylem vulnerability to cavitation for nine principal miombo woodlands tree species differing in drought tolerance ability and habitat preference. This was achieved by; examining the hydraulic properties and evaluating the extent to which each hydraulic design was vulnerable to water stress-induced xylem cavitation; investigating how seasonal changes in plant-water relations influences seasonal patterns of leaf display and; analyzing the relationship between stem hydraulic supply and leaf functional traits related to drought tolerance ability. This research has found that drought-intolerant tree species with mesic specialization have more efficient stem hydraulic systems than co-occurring habitat broad ranging species. Broad ranging tree species attain wider habitat distribution by adjusting their hydraulic supply in response to changing ecosystem water availability. The finding that hydraulic properties differ significantly between tree species with contrasting habitat preference suggests that tree hydraulic design may have some adaptive ecological role in influencing species habitat preferences in miombo woodlands. The evaluation of xylem vulnerability to cavitation revealed that mesic specialized tree species were more vulnerable to water stress-induced cavitation than habitat broad ranging tree species. Vulnerability to cavitation in individuals from the same broad-ranging species growing in contrasting habitats showed only marginal and statistically insignificant (P > 0.05) differences between wet and dry sites. In the investigation of the influence of seasonal changes in stem water relations on seasonal leaf display, seasonal rhythms in stem water status were found to exert significant controls on leaf phenology. Mesic specialists had strong stem water controls throughout the year in comparison to broad ranging tree species. An analysis of the relationship between stem hydraulic supply and leaf functional traits suggests that stem hydraulic supply constrains leaf biomass allocation patterns among miombo tree species. Mesic specialists tend to invest more in leaf longevity than broad ranging tree species. This thesis has uncovered some interesting relationships between plant-water-relations and the distribution of miombo woodlands tree species. These results lead to the conclusion that in an event of increased ecosystem drying under future climate trends, tree species with mesic specialisation are at a greater risk of experiencing cavitation related species mortality than broad ranging ones.

La zone sahélienne a connu une baisse des précipitations et d’importants changements d'utilisation des terres ces dernières décennies qui ont conduit à une forte régression du couvert ligneux. Pourtant, Guiera senegalesis J.F. Gmel est une Combretaceae semi-sempervirente, dont la dominance s'est accrue avec la pression agricole dans la bande soudano-sahélienne où elle joue un rôle socio-économique et agroforestier important. Elle constitue donc un bon modèle pour étudier les réponses hydriques du couvert ligneux actuel à la sécheresse et les modifications de ces réponses sous l'effet de la coupe.Les objectifs de ce travail de thèse étaient : 1) de caractériser et quantifier les processus de régulation hydrique chez G. senegalensis et de déterminer ses limites fonctionnelles, afin d’estimer sa marge de sécurité dans ses conditions actuelles de croissance, 2) d’estimer l’effet de la coupe annuelle sur ses processus de régulation et 3) d’analyser les variations de ses traits foliaires en fonction de la saison et des conditions de croissance.Les mesures et les observations ont été réalisées d’avril 2009 à février 2011 sur une jachère âgée, sur une jeune jachère et sur deux champs de mil adjacents aux deux jachères respectivement. A l'échelle de l'arbuste, le potentiel hydrique foliaire et la conductance stomatique ont été mesurés au cours de ces deux saisons de croissance sur un échantillon d'arbustes dans les trois types de couvert. Le taux de transpiration foliaire et la conductance hydraulique sol-feuille en ont été déduits. A l’échelle du rameau, ont été suivi la dynamique du nombre de feuilles, de la surface moyenne des feuilles, du diamètre moyen des tiges qui les portent. La durée de vie moyenne des feuilles et leur masse surfacique ont été mesurées. La courbe de vulnérabilité à la cavitation de l'espèce, qui est la perte de la conductivité hydraulique en fonction du potentiel hydrique, a été réalisée à partir de plusieurs segments de branches passés au CAVITRON en laboratoire.Les principaux résultats obtenus sont que la fermeture des stomates qui permet à l’espèce de réguler ses pertes en eau a lieu à un niveau faible de cavitation du xylème (30%). Ainsi, l’espèce peut survivre dans les conditions sahéliennes grâce à une « marge de sécurité » positive de +0,6 MPa. La régulation stomatique couplée à un ajustement foliaire permet à l’espèce de maintenir son équilibre hydrique au cours de la saison sèche chez les arbustes matures non perturbés. La baisse des potentiels hydriques foliaires de base et minimum en réponse à la sécheresse saisonnière est isohydrodynamique et est plus élevé chez les arbustes matures, suggérant que les repousses de l'année sont moins stressées. De plus, la coupe a pour effet de découpler l’ajustement foliaire de la régulation stomatique et entraîne une production de feuilles et une croissance des jeunes rameaux continues tout au long de l'année chez les repousses, grâce à une conductance hydraulique sol-feuille deux fois plus élevée que chez les arbustes matures. Enfin, la durée de vie des feuilles s’allonge avec l’âge des rameaux d'une année comme avec l'âge du peuplement, tandis que la masse surfacique foliaire augmente progressivement de la même façon quand on passe de la saison des pluies à la saison sèche, quel que soit l'âge du peuplement.Ces traits fonctionnels contribuent à ce que l’espèce puisse à la fois résister aux conditions de sécheresse dans lesquelles elle croît et ré-allouer de façon intense des ressources, stockées probablement dans les racines, à la reconstruction rapide de sa partie aérienne à la suite d'une coupe. Les limites d'une telle stratégie restent cependant à identifier, en particulier le seuil d'épuisement des ressources sous l'effet de la répétition annuelle des coupes. / Sahel suffered from severe rainfall decreases combined to great changes in land use during the last decades that led to strong decrease in the woody cover. However, Guiera senegalesis J.F. Gmel is a semi-evergreen Combretaceae whose dominance rose with crop pressure in the Sudano-Sahelian band where it plays an important socio-economic role through agroforestry. Consequently, this is a good model to study hydric responses of the present woody cover to drought and the effect of cutting on these responses.The aims of this work were: 1) to characterize and quantify hydric regulation processes in G. senegalesis and to determine its specific functional limits, in order to estimate its safety margin in its current growth conditions, 2) to estimate cut effect on these processes and 3) to analyze variations of its leaf traits according to the season and its specific growth conditions.Measurements and observations were conducted from April 2009 to February 2011 on an old fallow, on a young fallow, and on the two crop fields adjacent to the two fallows respectively. At the shrub scale, leaf water potential and stomatal conductance were measured during the two growing seasons on shrub samples in the three cover type. The leaf transpiration rate and the soil-to-leaf conductivity were deduced. At the stem scale, the dynamics of the number of leaves, the mean leaf area (LMA), the mean diameter of the stems that carry them, the mean leaf life span, and the leaf mass per area were monitored. The species vulnerability curve to cavitation, which is the loss of conductivity as a function of the water potential, was obtained from several peaces of branches treated in a CAVITRON at the laboratory.The main results obtained were that the stomatal closure that allows species to regulate its water loss occurs at a low rate of xylem cavitation (30%). Thus, the species can survive in its Sahelian conditions thanks to a positive “safety margin” of +0.6 MPa. Stomatal regulation coupled with leaf adjustment allows the species to maintain its water balance during the dry season in mature and undisturbed shrubs. The decrease in predawn and midday leaf water potentials in response to seasonal drought was isohydrodynamic, and it was greater in mature shrubs, suggesting that current year resprouts are under less stress. In addition, cutting decouple leaf adjustment from stomatal regulation, leading to continuous leaf production and young stem growth all over the year, thanks to a soil-to-leaf conductivity seven times higher in the current year's resprouts than in the mature shrubs. Finally, leaf life span increases with the current year's stem age as well as with the stand age, while the LMA progressively increases from the rainy season to the dry season, similarly whatever the stand age.These functional traits contribute to the species resistance to the drought conditions under which it grows, but also, following the cutting, to intensively re-allocate resources, probably from the root reserve, to the fast re-building of the aerial part. However, the limits of such a strategy remain to be identified, especially the resource exhaustion threshold under repetitive yearly cutting.

O tempo de vida e o desenvolvimento foliar sempre foram questões que intrigaram a humanidade, para além da questão científica, há um interesse até mesmo estético, uma vez que as folhas senescentes do hemisfério Norte e algumas do hemisfério Sul mudam sua coloração de verde para vermelho ou para um amarelo vistoso. Do ponto de vista científico o tempo de vida foliar está associado à produtividade das plantas, bem como às características estruturais das folhas. No entanto, a maioria dos trabalhos enfoca apenas a folha individualmente e não aborda o ponto que o tempo de vida foliar é, na verdade, um produto das taxas de nascimento e de mortalidade que ocorrem no nível da copa. Este é provavelmente o fator que faz com que haja um grande contraste na literatura sobre o tempo de vida foliar. Do ponto de vista ecológico analisam-se apenas as consequências do tempo de vida foliar, sem levar em consideração os mecanismos fisiológicos responsáveis pela mortalidade. Os trabalhos fisiológicos, por outro lado, enfocam em causas da mortalidade - o aumento na quantidade de hexoses e/ou mudanças nos reguladores de crescimento - sem levar em consideração as conseqüências do tempo de vida foliar. Este trabalho visa integrar estas duas visões. Como o nitrogênio é um dos minerais que possuem um efeito profundo no tempo de vida foliar, este foi usado como ferramenta para modificar o tempo de vida foliar de plantas de Senna alata, uma planta pioneira da família Leguminosae, que apresenta crescimento rápido. Foram realizados dois experimentos. No primeiro foi definida a melhor fonte de nitrogênio para o desenvolvimento da planta usando concentrações iguais de NO3, NH4 e NH4NO3. E no segundo experimento foi estudado o efeito de diferentes concentrações da melhor fonte. Em ambos os casos, a expansão, a biomassa, a fotossíntese (somente no segundo experimento) e teores e composição de carboidratos não estruturais, foram acompanhados para cada folha da planta. No primeiro experimento observou-se que ocorreu um aumento na taxa de mortalidade sem efeito na taxa de iniciação foliar, este fato levou a uma diminuição na longevidade das folhas, o que diminuiu o número de folhas na copa, mas não alterou a estrutura vertical da copa. A quantidade de hexoses na fase de senescência parece estar envolvida com o aumento na taxa de mortalidade através do mecanismo sensor de açúcares e como atuou diminuindo o tempo de senescência das folhas, levou a uma mudança no desenvolvimento foliar. No segundo experimento não houve diferença na mortalidade, mas um aumento na iniciação foliar, assim, conforme a concentração de nitrogênio aumentou, a longevidade das folhas tendeu a aumentar e o número de folhas na copa aumentou, mudando a estrutura vertical desta. Como obervado no primeiro experimento, a baixa concentração de hexoses durante a fase de maturidade pareceu ser o mecanismo que impediu a senescência foliar e que, portanto, modificou o desenvolvimento foliar por aumentar a sua fase de maturidade / Leaf life and development have always been intriguing aspects of nature. Even beyond the scientific scope, the aesthetics of such natural processes, illustrated in many different cases, such as when senescent northern hemisphere leaves (as well as some leaves found in the southern hemisphere) change colors from Green to re dor bright yellow. From a scientific standpoint, leaf life span is related to the plants&prime; productivity, as well as the structural characteristics of the leave themselves. Unfortunately, most current academic studies focus specifically on leaves, neglecting the fact that leaf life span is intimately related to birth and mortality rates at the canopy. This is possibly the greatest issue surrounding academic controversies and discussions regarding leaf life span. From na ecologic perspective, only the consequences deriving from leaf life are analyzed, while all mortality-related physiological mechanisms are not considered. Physiological studies, on the other hand, focus on causes of mortality - increased amount of hexoses and/or changes in growth regulators - but fail to consider the consequences of leaf life span. This article attempts to integrate both standpoints. As one of the minerals with greatest effect on leaf life span, nitrogen Will be used as a way to alter leaf life span during the experiments. In the first experiment we Will establish the most adequate nitrogen source, using the same NO3, NH4 and NH4NO3 concentrations. In the second experiment, we Will assess the effect of different concentrations in such nitrogen source. The first experiment indicated na increase in the mortality rate with no impact over the leaf initiation process, which decreased leaf life span and the amount of leaves in the canopy, but did not change the canopy vertical structure. The amount of hexoses in the senescence phase is responsible for the mortality rate increase and, by shortening the leaves&prime; senescence process, ultimately changed the leaves&prime; development. The second experiment did not indicate changes in the mortality rate, but prompted the leaf initiation process. Therefore, as the nitrogen concentratio increased, so did the leaves&prime; life span and the amount of leaves in the canopy, altering its vertical structure. During the maturity phase, the low hexose concentration seemed to be the mecanism responsible for hidering the leaf senescence process and, therefore, modified the leaves&prime; development by the increasing the maturity phase.

Red alder (Alnus rubra) is a tree species with high economic and ecological importance. It is subject to defoliation during unpredictable, episodic outbreaks of tent caterpillars (Malacosoma spp.) that result in reduced growth, decreased wood production, unsightly appearance and mortality in severe cases. Alder trees are weakened by severe and repeated tent caterpillar defoliation, and this can increase the susceptibility of the trees to other pests, diseases and drought. Repeated attack by tent caterpillars can cause decline in red alder populations, which can have potential negative impacts on the ecological and economic benefits of the species. Evidence from other species has shown that plants produce phytochemicals for defense against herbivores at a cost to growth and reproduction, but the relative magnitude of the cost of allocating available resources to defense depends on the level of the resources, and the plant genotype. The quality of a plant as food for herbivores is influenced by leaf physical and biochemical traits, and these traits change during a growing season or upon attack by herbivores. My research aimed to explore the defense mechanisms of red alder against western tent caterpillars (Malacosoma californicum) and determine the resistance variation among and within red alder populations, and to evaluate red alder available resource (nitrogen) allocation to defense and growth. Bioassay feeding trials were conducted in 2014 and 2015 with western tent caterpillars (WTC) (M. californicum) on twenty red alder clones from ten provenances. Phenology and quality of red alder leaves as food for the defoliators were analyzed to determine if budburst, leaf chemical content, water content or physical traits are major determinants of western tent caterpillars preference for red alder leaves. In another experiment, one-year-old seedlings from 100 half-sib red alder families were treated with two levels of ammonium nitrate (NH4NO3) in two growing seasons in a common garden. Growth, herbivore defense-related traits and root nodulation were measured and ranked among the plant genotypes and between the two nitrogen (N) treatments. Leaves from the two N treatments and different alder families were also used for bioassay feeding trials with WTC larvae to determine effects of N and genotype on red alder herbivory resistance. In my final experiments, I harvested and analyzed leaves from three-year-old red alder trees from five different families on eight dates from early April to mid-October 2016 to quantify oregonin and total phenolics concentrations, and wound induction experiments were conducted to determine if the concentrations of the chemicals vary during a growing season and upon attack by insects. Alder clones and families differed in percentage leaf area eaten by caterpillars and in leaf defense traits. The concentrations of foliar phenolic compounds negatively correlated with the percentage leaf area eaten by the caterpillars, but the results suggest a threshold, above which the concentration of each of the chemicals appeared to reduce WTC feeding, individually. Particularly, foliar oregonin concentration above 20 % leaf dry weight consistently appeared to reduce feeding by caterpillars. N availability had significant effects on red alder seedling total dry biomass and leaf N concentration. There was a clear trade-off between red alder seedling growth, and content of the phenolic compounds and leaf thickness, which supports the growth-differentiation balanced hypothesis in relation to resource availability. The concentration of oregonin varied during the growing season and there were no significant responses of any of the measured compounds to wounding. The results suggest that red alder foliar oregonin, condensed tannin and total phenolics are constitutive defenses and are not wound-induced. The effects of leaf total phenolic and condensed tannin concentrations on insect herbivory have been documented by past studies but the effects of oregonin concentration in red alder leaves on tent caterpillar feeding is a novel finding. / Graduate / 2020-04-18

Made available in DSpace on 2017-07-10T19:24:35Z (GMT). No. of bitstreams: 1 Samara Rodrigues[1].pdf: 1486003 bytes, checksum: 31d0e0cb1c9c341ca0e307d3684010b1 (MD5) Previous issue date: 2009-07-08 / Weeds can negatively affect the quantity and quality on orchards fruit yield. They usually occur in clusters in a given area, not evenly distributed throughout the entire field. Thus, the site-specific application of herbicides makes possible the use of control methods, decreasing the entire cost. In this work, both spatial and temporal variability of broad-leafed and narrow-leafed weeds were evaluated in an orchard of pear trees, using tools of precision agriculture. The experimental area has 1.24 ha, cultivated with 146 pear trees (variety &#8213;Pêra D água&#8214;), located in Nova Laranjeiras, Paraná State, Brazil. The orchard s productivity was through two distinct harvests, given the different reaping point of its fruits. Eighteen pear trees were selected as reference for the four samplings of broad-leafed and narrow-leafed weeds populations, performed per tree, using a 0.5 m x 0.5 m (0.25 m2) wooden frame. Data collected were then used to elaborate maps of mean incidence from both types of weeds. The methodology used was efficient to quantify both types of weeds, since it allows to build maps of the spatial and temporal incidence of both types of plants (broad and narrow). Pear yield showed little correlation with weed incidence. The weeds showed spatial and temporal dependence and such dependence was different due to the leaf type (broad or narrow) and of the position (under the tree canopy or between lines). The western region showed the highest incidence of weeds in the experimental area. / As plantas daninhas podem afetar negativamente a quantidade e a qualidade da produção de frutíferas. Normalmente ocorrem em agrupamentos em uma determinada área, não se distribuindo regularmente. Assim, a definição de unidades de manejo para controle de plantas daninhas viabiliza a aplicação de métodos de controle, diminuindo os custos. O objetivo deste trabalho foi avaliar a variabilidade espacial e temporal das plantas daninhas de folhas largas e estreitas, em um pomar de pereiras, visando definir unidades de manejo. A área experimental tem 1,24 ha, cultivada com 146 pereiras da variedade &#8213;Pêra D'água&#8214;, fica no município de Nova Laranjeiras, Paraná, Brasil. A produtividade do pomar foi obtida em duas colheitas distintas em função da maturação diferenciada dos frutos. Foram selecionadas dezoito árvores de pêra como referência para os quatro períodos de amostragens da população de plantas daninhas de folhas largas e estreitas, utilizando-se um quadro de madeira de 0,5 m x 0,5 m (0,25 m2). Os dados levantados foram usados então para elaborar mapas de incidência de ambos os tipos de plantas daninhas. A metodologia adotada para quantificação das plantas daninhas foi considerada eficiente, pois permitiu que se construísse mapas da incidência espacial e temporal de ambos os tipos de plantas (largas e estreitas). A produtividade de pêra apresentou fraca correlação linear com a incidência de plantas daninhas. As plantas daninhas apresentaram dependência espacial e temporal e esta dependência foi diferente em função do tipo de folha (larga ou estreita) e da posição (copa - linha de plantio ou nas entre-linhas). A região oeste apresentou a maior incidência de plantas daninhas na área experimental.

Made available in DSpace on 2017-05-12T14:47:58Z (GMT). No. of bitstreams: 1 Samara Rodrigues[1].pdf: 1486003 bytes, checksum: 31d0e0cb1c9c341ca0e307d3684010b1 (MD5) Previous issue date: 2009-07-08 / Weeds can negatively affect the quantity and quality on orchards fruit yield. They usually occur in clusters in a given area, not evenly distributed throughout the entire field. Thus, the site-specific application of herbicides makes possible the use of control methods, decreasing the entire cost. In this work, both spatial and temporal variability of broad-leafed and narrow-leafed weeds were evaluated in an orchard of pear trees, using tools of precision agriculture. The experimental area has 1.24 ha, cultivated with 146 pear trees (variety &#8213;Pêra D água&#8214;), located in Nova Laranjeiras, Paraná State, Brazil. The orchard s productivity was through two distinct harvests, given the different reaping point of its fruits. Eighteen pear trees were selected as reference for the four samplings of broad-leafed and narrow-leafed weeds populations, performed per tree, using a 0.5 m x 0.5 m (0.25 m2) wooden frame. Data collected were then used to elaborate maps of mean incidence from both types of weeds. The methodology used was efficient to quantify both types of weeds, since it allows to build maps of the spatial and temporal incidence of both types of plants (broad and narrow). Pear yield showed little correlation with weed incidence. The weeds showed spatial and temporal dependence and such dependence was different due to the leaf type (broad or narrow) and of the position (under the tree canopy or between lines). The western region showed the highest incidence of weeds in the experimental area. / As plantas daninhas podem afetar negativamente a quantidade e a qualidade da produção de frutíferas. Normalmente ocorrem em agrupamentos em uma determinada área, não se distribuindo regularmente. Assim, a definição de unidades de manejo para controle de plantas daninhas viabiliza a aplicação de métodos de controle, diminuindo os custos. O objetivo deste trabalho foi avaliar a variabilidade espacial e temporal das plantas daninhas de folhas largas e estreitas, em um pomar de pereiras, visando definir unidades de manejo. A área experimental tem 1,24 ha, cultivada com 146 pereiras da variedade &#8213;Pêra D'água&#8214;, fica no município de Nova Laranjeiras, Paraná, Brasil. A produtividade do pomar foi obtida em duas colheitas distintas em função da maturação diferenciada dos frutos. Foram selecionadas dezoito árvores de pêra como referência para os quatro períodos de amostragens da população de plantas daninhas de folhas largas e estreitas, utilizando-se um quadro de madeira de 0,5 m x 0,5 m (0,25 m2). Os dados levantados foram usados então para elaborar mapas de incidência de ambos os tipos de plantas daninhas. A metodologia adotada para quantificação das plantas daninhas foi considerada eficiente, pois permitiu que se construísse mapas da incidência espacial e temporal de ambos os tipos de plantas (largas e estreitas). A produtividade de pêra apresentou fraca correlação linear com a incidência de plantas daninhas. As plantas daninhas apresentaram dependência espacial e temporal e esta dependência foi diferente em função do tipo de folha (larga ou estreita) e da posição (copa - linha de plantio ou nas entre-linhas). A região oeste apresentou a maior incidência de plantas daninhas na área experimental.