Both the physiological and biochemical control of budburst in the grapevine, Vitis Vinifera L. were investigated. It was found that the accuracy of a predictive model for grapevine budburst based on ambient temperature was limited under the experimental conditions. There was a significant correlation of 4.7 ± 0.3 days between the days of maximal xylem exudation and budburst over the 3 years of investigation. The co-relationships between daily xylem exudate volume and a range of environmental parameters were considered. It was found that soil temperature was highly correlated against daily xylem exudation. Ambient temperature and soil moisture were significantly correlated with xylem exudation, however the coefficients of correlation were much lower than that of soil temperature. Rainfall showed only a very limited correlation with daily xylem exudate flow. Seasonal variations in the pH and the carbohydrate and inorganic nutrient concentrations of xylem exudate were investigated. Exudate carbohydrate concentrations fell from 660 µM before the day of maximal xylem exudation to zero levels within 4 weeks. Xylem exudate pH was found to consistently fall to a minimum at the time of maximal exudate flow. Exudate concentrations of the metallic cofactors Ca, K, Mg, Mn and Zn varied directly with daily exudate flow, suggesting some sort of flow-dependent mobilisation of these nutrients. A growth promontory oligosaccharide fraction was prepared by partial acid hydrolysis of grapevine primary cell wall material. This fraction significantly increased control growth of the Lemna minor L. bioassay over a limited ‘window’ of bioactivity. A growth inhibitory oligosaccharide fraction, similar in activity to abscisic acid was isolated from grapevine xylem exudate prior to budburst. The exudate concentration or efficacy of this substance declined after budburst such that there was no apparent growth inhibition. A model is proposed for grapevine budburst whereby an oligosaccharide growth inhibitor is gradually removed from the xylematic stream under the effects of soil temperature, allowing the surge of metabolic activity and vegetative growth that constitute budburst.

<p>Recent changes in the timing of annual events are a sign that climate change is already impacting ecosystems. Carbon sequestration by forests increases with longer growing seasons. Biodiversity can be affected by mis-timing of events through shading interactions and frost damage. Projecting forests' ability to provide these ecosystem services in the future requires an understanding of trees' phenological responses to a new climate. I begin by proposing a first order definition of an `optimal' phenological response to warming: that the mean temperature following budburst should remain essentially constant. Analogously, the temperature preceding senescence can serve the same role. </p><p>To understand which environmental cues will drive future changes in phenology, I assimilate clues from observational and experimental literature. For budburst in woody plants, spring warmth, over-winter chilling and light drive nearly all behavior, but species' responses vary widely. Species using chilling or light as safety mechanisms against budburst during mid-winter thaws are thought to be less able to phenologically track a warming climate. However, I show that even species cued solely by spring warmth are likely to under-track temperature changes. Fall cues are more idiosyncratic, and a plant's driver of senescence is likely to vary from year to year. </p><p>Models are a tempting method to untangle species budburst cues and forecast phenology under warmer climate scenarios. I tested two models' ability to recover parameters used to simulate budburst data. The simpler model was cued only by spring warmth while the complex one modulated warmth requirements with chilling exposure. For the simple model, parameters could be recovered consistently from some, but not all, regions of parameter space. The complex model's parameters were largely unrecoverable. To understand the consequences of parameter uncertainty, I applied both models to an 18 year phenological record of 13 deciduous tree species. While a few species fell into identifiable regions of the simple model's parameter space, most did not, and projected budburst dates had wide parameter-derived uncertainty intervals. These bands were wider still under a 5°C warming scenario. Even greater uncertainty resulted from the complex model.</p><p>To better understand plants' potential for growing season extension I subjected seedlings to warmer climates in a series of open-topped chambers in sites at each end of the eastern deciduous biome. Soil and air were heated to 3 or 5°C above ambient, or left unheated. For nearly all species, warming hastened budburst and germination and delayed senescence. However, these events failed to track temperature changes, happening at warmer temperatures in hotter chambers. Individual species showed a remarkable variability of all events' dates within treatments, and even within chambers. Because phenological traits are heritable, this offers a potential for evolutionary response to climate change.</p><p>This research has shown that while individual trees extend their growing seasons under warmer temperatures, they typically under-respond to the magnitude of warming, suggesting forests' capacity for increased carbon sequestration may reach a limit. However, within populations, trees vary substantially in their phenological responses, forming a possibility for evolutionarily adaptation to changing cues.</p> / Dissertation

No description available.

Over the last 150 years the natural nighttime environment has been drastically altered by the proliferation of artificial light. The amount of artificial light at night is on the increase, and there is a current trend to replace older lighting with more energy efficient types such as light emitting diodes (LEDs) or ceramic metal halide; in Cornwall, UK, there has been a relatively recent replacement of the street lighting, from low pressure sodium to ceramic metal halide. Alongside the increasing amount of artificial nighttime light, recent research has highlighted declines in macro moth numbers. Given the well-known ‘flight-to-light’ behaviour of moths, and the negative effects this behaviour can have, alongside other known and potential ways in which nighttime light can affect moths, the increasing amount of artificial light in the environment is a suspected contributor to the declines. It is particularly important to understand how modern lighting technologies will impact upon moths, as different spectra of light are known to vary in terms of how attractive they are. As a means to determine the potential impact of different street lighting types on moths, particularly the ceramic metal halide lighting rolled out in Cornwall, UK, we compared the attractiveness to macro moths, of a number of increasingly used, energy efficient, street lighting types. We found that shorter wavelength metal halide lighting attracted significantly more individuals and species of moth than longer wavelength high pressure sodium lighting. In a second experiment, we also found ceramic metal halide lighting to be more attractive to macro moths than LED lighting. Reduced emissions of short wavelength UV light was deemed the likely reason behind the fewer macro moths attracted to the high pressure sodium and LED lighting. Interestingly, we also found striking differences in the relative attractiveness of the different lighting types to different moth groups. The metal halide lighting attracted significantly more Noctuidae than high pressure sodium lighting, whereas both high pressure sodium and metal halide lighting were equally attractive to Geometridae. Understanding accurately the extent to which different groups of moth are attracted to different wavelengths of light could be useful in determining the impact of artificial light on moth populations. In addition to impacting moths through attraction, artificial light has the potential to alter the day length as perceived by organisms, which at mid- to high latitudes is utilised by certain species as an abiotic cue to ensure the coincidence of development with favourable environmental conditions. Due to a paucity of knowledge on how raised ambient nighttime light levels affect moths and the trophic levels with which they interact, we carried out analyses into the impact of nighttime light on the winter moth and its host plant oak; a well-studied model system, where synchrony between moth egg hatch and oak budburst is important for the moth’s survival. Firstly we carried out an analysis looking at the relationship between the amount of nighttime light and the date of oak budburst. Spatially referenced budburst dates were matched with satellite imagery of nighttime lighting and average spring temperature data, and the relationship between the variables was analysed. Model predictions suggested that oak budburst occurs earlier in brighter areas. In addition, the predicted advance of budburst in brighter areas was still apparent when analysing only the data points that fell outside of large urban areas, where the urban heat island effect is likely reduced. The findings suggested that artificial nighttime light may be causing an advance in oak budburst. To follow up the spatial analysis we carried out a field experiment. We used light cages that simulated various nighttime lighting scenarios to test whether oak budburst and winter moth egg hatch were affected by low intensity light at night. In contrast to the spatial analysis, there was no significant relationship found between light treatment and the phenology of either oak budburst or winter moth egg hatch. However, there was a suggestion in the data that the higher buds of the oak saplings emerged earlier in the yellow light treatment, highlighting the need for further research into the potential impact of artificial nighttime light on phenology and species interactions. In conclusion, the findings of this research project provide information useful to those seeking ecologically sensitive lighting solutions, and also highlight a potential tool to assist in determining whether light at night is a causative factor behind apparent moth declines. In addition, they suggest that artificial light at night may be affecting the phenology of an ecological system at a national scale. Finally, this research project has highlighted the complexity of the ecological impacts of artificial light at night, and also a need for further research.

La phénologie du débourrement est un caractère majeur d’adaptation des arbres à leurenvironnement en milieu tempéré. Notre objectif a été de caractériser les contraintes biotiques (oïdium) etabiotiques (températures hivernales et printanières / gels tardifs) s’exerçant sur le débourrement afind’expliquer les patrons de variation phénologique intra et inter populationnelle observés chez le chêne(Quercus petraea) le long d’un gradient altitudinal. Nous avons utilisé une approche combinantobservations in situ, expérimentation, et modélisation. Nous avons mis en évidence que l’évitement desgels tardifs printaniers est un caractère adaptatif majeur le long du gradient altitudinal. La tardiveté dudébourrement pourrait être due à des besoins plus importants en température de forcing. Par ailleurs, lechampignon n’est pas adapté localement à la phénologie de son hôte et les individus et les populationssont alors inégalement exposés à la maladie. En montant en altitude, les chênes sont de plus en plusexposés au champignon, mais les facteurs environnementaux sont défavorables à une plus forte infection.A basse altitude, l’oïdium et les gels tardifs favorisent des phénotypes phénologiques opposés(respectivement précoces vs. tardifs) ; la combinaison des deux contraintes pourrait donc contribuer aumaintien de la forte diversité phénologique observée. D’autre part, nous avons observé que l’infection parl’oïdium engendre une augmentation du polycyclisme chez les semis de chêne au cours de la saison decroissance, ce qui les rend moins résistants aux gels hivernaux. Nous montrons qu’il est important que lesmodèles phénologiques à visée prédictive intègrent la phase de chilling aboutissant à la levée dedormance. Le manque de chilling ne semble pas encore un facteur limitant, mais la tendance actuelle à undébourrement de plus en plus précoce sera probablement freinée voire inversée au milieu du siècle enbasse altitude, dans la marge sud de distribution de Q. petraea. / Budburst phenology is a major adaptive trait of trees to the environment in temperateclimate. Our aim was to characterize the biotic (powdery mildew) and abiotic (winter and springtemperatures / spring frost) constraints acting on budburst in view to explain the patterns of intra and interpopulations’ phenological variation observed in sessile oak (Quercus petraea) along an elevation gradient.We based our approach on in situ monitoring, experimentation and modeling. Our results highlight that theavoidance of late spring frosts is a major adaptive trait along the elevation gradient. The lateness inbudburst might be due to higher requirements in forcing temperatures. Otherwise, the fungus is not locallyadapted to its host phenology so oak individuals and populations are unequally exposed to the disease.With increasing elevation, oaks are more and more exposed to the fungus, but the environmental factorsare unfavorable to higher infection. At low elevation, powdery mildew and late spring frosts favor oppositephonological phenotypes (early-flushing vs. late-flushing trees, respectively); the combination of the twopressures may thus contribute to the maintenance of the observed high phenological diversity. We alsoshowed that powdery mildew infection induced an increased polycyclism during the growing season in oakseedlings, which made them less resistant to winter frosts. Predictive phenological models will have toinclude the chilling phase which conditions dormancy breaking. Although the lack of chilling is not yet alimiting factor, the current trend in increasingly advanced budburst will certainly be slowed or even reversedin the middle of the century at low elevation, in the southern margin of the distribution area of Q. petraea.

This thesis contains information from the study of Norway spruce clones, which possess certain inheritable traits (1) of value for timber used in building constructions (i.e. higher wood basic density, elasticity, and resistance to crashing) and (2) greater wood yield. The following growth and quality traits of 90 clones in Baisogala seed orchard of Radviliškio forest enterprise were assessed: stem height and diameter, crown diameter, branching type and class of budburst. Significance of differences among the clones was estimated for all the these traits. Correlation coefficients among qualitative and quantitative traits were calculated. Owing to relatively lower radial increment and thicker annual ring, clones of brushy and flat branching types produced wood of a higher basic density and, thus, of a greater quality. A more slowly growth of clones with the above mentioned branching types was observed on their progeny as well. Therefore, if there is no need for stems of a relatively larger diameter, it would be more rational to produce Norway spruce stands of flat and brushy branching types.

No description available.

Le pommier (Malus Xdomestica Borkh.) cultivé en climat à hiver doux, avec un manque d'une quantité suffisante d'heures de températures froides, présente des anomalies morphologiques et physiologiques. Sur le plan de la phénologie, il s'agit notamment d'un débourrement printanier tardif et désynchronisé entre les différents bourgeons d'un même arbre. Sur le plan agronomique, la floraison et la nouaison sont irrégulières et étalées dans le temps et conduisent à une faible production de fruits. L'objectif de ce travail de thèse est premièrement de mieux caractériser les effets des températures hivernales sur le débourrement et la croissance des bourgeons axillaires en distinguant les effets respectifs des températures hivernales et du génotype. Il s'agit ensuite de vérifier l'hypothèse que les effets des températures sur le débourrement du bourgeon s'effectue via les effets sur son statut hydrique. Les travaux ont été réalisés en France et au Brésil. En France, les expérimentations ont porté sur quatre cultivars à fort besoin (‘Granny Smith', ‘Royal Gala', ‘Starkrimson') ou faible besoin (‘Condessa') en froid, cultivés en hiver froid (conditions extérieures) et doux (serres climatisées). Nous montrons que le débourrement résulte d'une séquence d'évènements où la température hivernale joue un rôle primordial sur les mécanismes de sortie de dormance et donc sur le débourrement proprement dit, durant la période froide. Les caractéristiques propres du cultivar jouent par contre un rôle dans la croissance ultérieure des bourgeons et donc dans l'architecture finale de la pousse du pommier. Par ailleurs, la chute tardive des feuilles, caractéristique du pommier en hiver doux, a peu d'effets sur le débourrement et la croissance des bourgeons. L'analyse du statut hydrique des bourgeons a été réalisée sur le tiers distal des pousses de pommier caractérisé par une forte fréquence de ramification en climat à hiver froid. Nous montrons que, dans la période allant de l'endordormance à la phase de pré-débourrement, la conductance hydraulique à la jonction entre l'axe porteur et le bourgeon varie peu au cours de l'hiver et entre cultivars. Par ailleurs, durant cette même période le potentiel hydrique intra-bourgeon reste négatif, entre -4.35 and -2.24 MPa. Enfin, quel que soit le cultivar, nous ne montrons pas de relation entre les températures hivernales, le potentiel hydrique ou la teneur relative en eau des bourgeons, et l'aptitude au débourrement ultérieur. Ces résultats suggèrent que le bourgeon est hydrauliquement isolé de son axe porteur pendant toute la période hivernale jusqu'à quelques jours précédant le débourrement. Les expérimentations au Brésil ont porté sur le cultivar ‘Eva ‘ à faible besoin en froid, cultivés en conditions naturelles d'hiver doux. Il s'agissait de vérifier les effets possibles de la position du bourgeon le long de l'axe porteur sur sa taille et sa teneur relative en eau. Nous montrons que, tout au long de l'hiver, les bourgeons distaux sont caractérisés par une plus grande taille et une teneur relative en eau plus élevée que les bourgeons proximaux avec une forte augmentation de la teneur relative en eau une semaine avant le débourrement printanier. Le débourrement acrotone semble donc résulter d'une évolution rapide du statut hydrique du bourgeon en fin d'écodormance. L'ensemble des résultats acquis en France et au Brésil, sur des cultivars caractérisés par des besoins variables en froid hivernal, indique que l'aptitude au débourrement printanier des bourgeons de pommier est davantage lié à un « effet rameau entier » qu'au statut hydrique proprement dit des bourgeons individuels, tout au moins jusqu'à quelques jours avant le débourrement effectif. La pousse annuelle de pommier apparait donc comme une unité morphologique et physiologique intégrée qui, dans un contexte climatique donné, conditionne le statut hydrique de chaque bourgeon et son aptitude au débourrement. / The apple tree (Malus Xdomestica Borkh.) presents morphological and physiological anomalies when grown in mild winter climates with insufficient winter chilling to overcome winter dormancy. Symptoms are typically delayed and erratic budburst, entailing desynchronized flowering and fruit-set and poor agronomic performances. This thesis aimed at gaining more insights on the following issues. Firstly, what are the effects of winter temperatures on axillary burdburst and bud outgrowth, and what are the respective effects of winter temperatures and cultivar?, and secondly, is there a link between the temperature-dependent budburst and bud water status? Works were done in France and Brazil. In France, experiments were carried out in controlled conditions on four apple cultivars characterized by either high chilling (‘Granny Smith', ‘Royal Gala', ‘Starkrimson') or low chilling (‘Condessa') requirements and were submitted to outdoor-cold and greenhouse-mild winter temperatures. We showed that the actual shoot architecture and budburst resulted from an ordered sequence of events with a pivotal role of winter temperatures on the dormancy completion of individual lateral buds. Endogenous factors related to the cultivar branching pattern overtook the temperature effect on the lateral bud outgrowth. Furthermore, the delayed senescence and subsequent leaf persistence during winter, characterizing the apple tree in the mild winter temperature conditions, had only a weak effect on the topological distribution of budburst and lateral outgrowth. The analyses of bud water status were done on distal buds only, characterized by high budburst frequency in cold winter conditions. We showed that, from endodormancy to the pre-budburst stage, xylem conductance at the stem-to-bud junction did not show consistent changes across cultivars and winter temperature treatments. Bud water potential had negative values, between -4.35 and -2.24 MPa, depending on cultivars and winter temperature treatments. Moreover, whatever the cultivar, there were no significant trends across dates for the effects of winter temperatures on bud water potential and relative water content without a consistent relationship with actual spring budburst frequency. These results suggested that lateral buds were hydraulically isolated from the parent stem during winter until a few days before budburst. The other set of experiments was carried out in Brazil, under mild winter conditions, on the low chilling apple cultivar ‘Eva'. The objectives were to gain more insights on the effect of the position of the over-wintering lateral bud along the whole-parent shoot on bud size and water content. Results highlighted that distal buds were larger and had a higher water content than proximal buds with a strong increase of water content a week before spring budburst. It was concluded that the acrotonic pattern of budburst was mainly established during ecodormancy. As a whole, we showed that spring budburst seemed more related to a whole-shoot effect than to the water status of the individual bud during winter dormancy. Our study substantiated the importance of the whole shoot as an integrated morphological and physiological unit in driving budburst and further growth.

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No. of bitstreams: 2 Tese Juliano Dutra Schmitz.pdf: 9582623 bytes, checksum: f579b0458e2ab6f4ae5579715de842ea (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2014-12-03 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / A macieira (Malus X domestica Borkh.) apresenta anomalias fisiológicas quando cultivada em regiões de inverno ameno, onde o frio hibernal é insuficiente para superação da dormência. Assim, na presente tese foram estudados três temas de pesquisa. No tema 1 estudou-se a distribuição e fenologia da brotação e crescimento inicial da ramificação primaveril; No tema 2 estudou-se a brotação primaveril através da determinação do status hídrico de gemas laterais e da condutância hidráulica do xilema. O tema 3 realizou-se a análise do comportamento da brotação primaveril de uma cultivar de baixo exigência em frio cultivada em inverno ameno. Para isso, foram montados dois dispositivos experimentais: Experimento 1: realizado em Montpellier/França, onde foram estudadas quatro cultivares de macieira, com diferentes requerimentos em frio (‘Condessa’, ‘Granny Smith’, ‘Royal Gala’ e ‘Starkrimson’), submetidas a dois regimes térmicos (inverno frio, condições naturais de Montpellier; e inverno ameno, temperatura controlada em casa-de-vegetação). Experimento 2: realizado com a cultivar de baixo requerimento em frio ‘Eva’ sob regime térmico hibernal ameno (condição natural de Capão do leão/Brasil). A partir do experimento 1, dois artigos foram redigidos . Conclui-se a partir dos resultados obtidos (artigos 1 e 2) que as temperaturas hibernais têm o principal efeito na distribuição da ramificação ao longo do eixo principal e no tempo para brotação; a presença de folha das plantas submetidas ao regime térmico de inverno ameno não afeta a distribu ição de ramos prolépticos vegetativos; a cultivar exerce efeito no crescimento da ramificação. Com relação ao status hídrico, conclui-se que durante o inverno (período de dormência) as gemas laterais permanecem hidraulicamente isoladas do eixo principal; assim como o potencial de brotação está relacionado a um efeito ramo inteiro (todo eixo principal) do que ao potencial individual de cada gema lateral. Através do experimento 2, um artigo foi elaborado, tendo por objetivo testar a hipótese que a posição em que a gema lateral está localizada sobre o eixo principal têm efeito na brotação primaveril, no conteúdo de água e tamanho das mesmas. Pode-se concluir deste estudo que uma semana antes a brotação, as gemas localizadas na zona distal possuem maior potencial de crescimento (maior frequência de brotação e menor tempo médio para brotação), além de apresentarem maior umidade ponderal e tamanho. / The apple tree (Malus X domestica Borkh.) presents morphological and physiological anomalies when grown in mild winter climates with insufficient winter chilling to overcome winter dormancy. Symptoms are typically delayed and erratic budburst, entailing desynchronized flowering and fruitset and poor agronomic performances. This thesis aimed at gaining more insights on the following issues. Firstly, what are the effects of winter temperatures on axillary burdburst and bud outgrowth, and what are the respective effects of winter temperatures and cultivar?, and secondly, is there a link between the temperature-dependent budburst and bud water status? Works were done in France and Brazil. In France, experiments were carried out in controlled conditions on four apple cultivars characterized by either high chilling (‘Granny Smith’, ‘Royal Gala’, ‘Starkrimson’) or low chilling (‘Condessa’) requirements and were submitted to outdoor-cold and greenhouse-mild winter temperatures. We showed that the actual shoot architecture and budburst resulted from an ordered sequence of events with a pivotal role of winter temperatures on the dormancy completion of individual lateral buds. Endogenous factors related to the cultivar branching pattern overtook the temperature effect on the lateral bud outgrowth. Furthermore, the delayed senescence and subsequent leaf persistence during winter, characterizing the apple tree in the mild winter temperature conditions, had only a weak effect on the topological distribution of budburst and lateral outgrowth. The analyses of bud water status were done on distal buds only, characterized by high budburst frequency in cold winter conditions. We showed that, from endodormancy to the pre-budburst stage, xylem conductance at the stem-to-bud junction did not show consistent changes across cultivars and winter temperature treatments. Bud water potential had negative values, between -4.35 and -2.24 MPa, depending on cultivars and winter temperature treatments. Moreover, whatever the cultivar, there were no significant trends across dates for the effects of winter temperatures on bud water potential and relative water content without a consistent relationship with actual spring budburst frequency. These results suggested that lateral buds were hydraulically isolated from the parent stem during winter until a few days before budburst. The other set of experiments was carried out in Brazil, under mild winter conditions, on the low chilling apple cultivar ‘Eva’. The objectives were to gain more insights on the effect of the position of the over-wintering lateral bud along the whole-parent shoot on bud size and water content. Results highlighted that distal buds were larger and had a higher water content than proximal buds with a strong increase of water content a week before spring budburst. It was concluded that the acrotonic pattern of budburst was mainly established during ecodormancy. As a whole, we showed that spring budburst seemed more related to a whole-shoot effect than to the water status of the individual bud during winter dormancy. Our study substantiated the importance of the whole shoot as an integrated morphological and physiological unit in driving budburst and further growth.