Light is one of the environmental signals that regulate axillary shoot development. However, little is known about molecular and physiological mechanisms regulating the development of the axillary shoot in response to light signals. Molecular events associated with the enhanced apical dominance of phytochrome B mutant sorghum (Sorghum bicolor) were analyzed to reveal processes mediating axillary shoot development in response to light. The enhanced apical dominance of phyB-1 mutant sorghum is due to inhibition of bud outgrowth and is accompanied by upregulation of the dormancy-associated gene (SbDRM1) in the buds. Increased expression of the Teosinte Branched1 (SbTB1) gene (encoding a putative transcription factor that represses bud outgrowth) suggests that the inhibition of bud outgrowth in phyB-1 sorghum is due to the absence of active phyB to repress SbTB1. The results were confirmed by growing wild type seedlings at high plant density or with supplemental farred (FR) light that induces enhanced apical dominance. However, the SbTB1 gene is not involved in the inhibition of bud outgrowth induced by defoliation in wild type seedlings. The results indicate variations in molecular mechanisms among different signals inhibiting branching. Increased expression of SbMAX2 (which encodes an F-box protein that represses bud outgrowth) in buds repressed by light and defoliation suggests common mechanisms at the downstream end of pathways inhibiting branching. The expression levels of several cell cycle-related genes including SbPCNA, SbHis4, SbCycD2, SbCycB and SbCDKB were down-regulated in the repressed buds of FRtreated and defoliated seedlings indicating the suspension of cell division in those buds. However, these cell cycle-related genes were continuously expressed in the repressed buds of phyB-1, suggesting that inhibition of bud outgrowth in phyB-1 is not associated with down-regulation of cell cycle-related gene expression. The down-regulation of cell cycle-related genes in the buds of FR-treated wild type seedlings indicates that other sensors, in addition to phyB, regulate bud outgrowth in response to FR enrichment. The approaches used and results achieved will provide direction for future research on this important topic.

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Open Access Article

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Potato tubers are used as food and seed. Post-harvest conditions affect tubers for both usages, since physiological changes occur during tuber storage. The objective of this work was to assess the processing quality and time until tuber sprouting of advanced clones of potato. We evaluate thirteen clones and two check varieties of potato in a storage room at 10ºC in two years. The processing quality was evaluated right before loading and after 30, 60, 90 and 120 days of storage for the fresh and dry weight content, chip color and reduced sugars. The experiment was a factorial of clone and storage time in the complete random design, with four repetitions. The percentage of fresh weight loss increased over time during storage, mainly at 120 days. The assessed clones presented dry weight content between 17.4% to 25.2 % during the cold storage. Chip color showed an intense yellow tone and acceptable color classification for the processing industry, even with the increase of reduced sugars during storage. The storage at 10 ºC extended in a 100 days the sprout process. The refrigerated storage promote physiological changes on the tubers, but this changes don´t compromise the use in the industry processing and also allows to increase the storability period of the tubers for both consumption and seeds. / Os tubérculos de batata são destinados tanto para a alimentação quanto para a propagação. Ambas as finalidades são influenciadas pelas condições de armazenamento, que é capaz de promover mudanças fisiológicas nos tubérculos. O objetivo deste trabalho foi avaliar a qualidade de processamento e o tempo de armazenamento até a brotação dos tubérculos de clones avançados de batata. Foram avaliados 13 clones de batata e duas testemunhas, que foram submetidos ao armazenamento em câmera refrigerada a uma temperatura de 10 ºC em dois anos. A qualidade de processamento foi avaliada no momento do armazenamento, imediatamente após a cura, e aos 30, 60, 90 e 120 dias. Os caracteres avaliados foram massa fresca e seca, coloração de chips e o teor de açúcares redutores. Também foi anotado o número de dias para o rompimento da dormência e da dominância apical, quando respectivamente os tubérculos apresentaram um e dois brotos com pelo menos 2 mm de comprimento. O experimento foi um fatorial de clones e épocas de avaliação segundo o delineamento experimental inteiramente casualizado, com quatro repetições. O percentual de perda de massa fresca foi crescente ao longo do armazenamento refrigerado, sobretudo aos 120 dias. Os clones avaliados apresentaram teor de massa seca entre 17,4 % a 25,2 % ao longo do armazenamento refrigerado. A coloração de chips apresentou uma tonalidade amarela intensa e uma classificação aceitável para a indústria, mesmo com o aumento no teor de açúcares redutores após o armazenamento. O armazenamento a 10 ºC prolongou o processo de brotação em até 100 dias de armazenamento. O armazenamento refrigerado promove mudanças fisiológicas nos tubérculos, mas estas mudanças não comprometem a utilização na indústria de processamento, e também possibilita armazenar os tubérculos por um longo período para o consumo e plantio.

Made available in DSpace on 2014-08-20T13:25:42Z (GMT). No. of bitstreams: 1 Dissertacao_ Fernando_Jose_ Hawerroth.pdf: 3146259 bytes, checksum: 9a1582822ee01601422d0cc7ea2ea69e (MD5) Previous issue date: 2008-03-30 / Temperature is the main climate factor related to induction, maintenance and dormancy release in apple (Malus domestica Borkh.). The inadequate chilling exposure for this species causes the occurrence of budbreak problems, resulting in decrease in yield potential. Thus, the knowledge of physiological principles and environmental factors determining the dormancy phenomenon, especially winter temperature effects, it is necessary for the cultivars efficient selection in a productive region. Similarly cultural practices can be developed and adapted to minimize the problems cause by lack chilling during winter. The budbreak promoters application is one of main management s strategies used to decrease the problems of insufficient winter chilling on temperate fruit trees. Because the influence of budbreak promoters on plant s productive behavior, detecting this effects along of productive season became important. This study aimed to evaluate the budbreak and depth dormancy of apple cultivars exposed to different chilling conditions during the winter, and evaluate the apple productive response by budbreak promoters application. For this, three experiments were carried out in this research. In the first experiment, one-yearold twigs of Castel Gala and Royal Gala cultivars, grafted on M7 rootstock, were submitted to temperatures of 5, 10 and 15 C for different exposure periods (168, 336, 672, 1008 and 1344 hours). After treatments execution, the plants were kept in a greenhouse at 25ºC. Budbreak was quantified when accumulated 3444, 6888, 10332, 13776, 17220 and 20664 GDHºC after temperature treatments. The cultivars responded differently to temperature effect during the winter period. The temperature of 15 °C showed greater effectiveness on Castel Gala budbreak, while temperatures of 5 and 10ºC showed better performance in Royal Gala apple trees. It was not possible to estimate chilling requirement of cultivars studied through autumn grafted twigs, because the low budbreak obtained, derived of high apical dominance expressed by apple tree in this evaluation system. The objective of the second experiment was to evaluate the dormancy progression of apple cultivars with different chilling requirements. One-year-old twigs of Castel Gala , Condessa , Daiane , Fuji , Imperatriz and Royal Gala cultivars were exposed to 0, 336, 672, 1008 and 1344 chilling units at 4.5 ± 0.5 º C. After chilling exposure, the twigs were segmented into four cuttings (terminal, axillary superior, axillary median and axillary basal) and placed in growth chamber at 23±1ºC. The depth dormancy was measured by the mean time of budbreak (MTB). Through the method was not possible to group the cultivars according chilling requirement, indicating that correlation between the depth dormancy and chilling requirement isn t observed for all apple cultivars. In the third experiment were evaluated different hydrogen cyanamide and mineral oil combinations on phenology, budbreak and fruit production of Imperial Gala and Suprema s Fuji apple trees, during 2007/2008 growing season. Five budbreak promoters treatments were tested (1. control; 2. mineral oil 3.2%; 3. mineral oil 3.2% + hydrogen cyanamide 0.20%; 4. mineral oil 3.2% + hydrogen cyanamide 0.39%; 5. mineral oil 3.2% + hydrogen cyanamide 0.59%). The budbreak promoters application anticipated and reduced the blooming period, increasing the blooming overlap between Imperial Gala and Suprema´s Fuji cultivars. The budbreak promoters equalized and increased the budbreak in axillary and terminal buds, with the major budbreak level observed in Imperial Gala cultivar with 0.44% of hydrogen cyanamide and 3.2% of mineral oil treatment. The increase of hydrogen cyanamide concentration showed the tendency to decrease the fruit set. It was observed different treatment responses on production and mean fruit weight, probably to be related to fruit production predominance in different fructification structures. / A temperatura é o principal fator climático relacionado a indução, manutenção e superação da dormência na macieira (Malus domestica Borkh.). O inadequado suprimento em frio para esta espécie determina a ocorrência de problemas relacionados a brotação, repercutindo na diminuição do potencial produtivo. Dessa forma, o conhecimento dos princípios fisiológicos e dos fatores ambientais determinantes no fenômeno da dormência, sobretudo o efeito das temperaturas hibernais, faz-se necessário para a eficiente seleção de cultivares em determinada região produtora, assim como para eficiente elaboração e adequação de práticas culturais para minimização dos problemas oriundos do insuficiente acúmulo de frio hibernal. A aplicação de indutores de brotação é uma das principais estratégias de manejo utilizadas para minimizar os problemas da falta de frio em frutíferas de clima temperado. Em razão da influência dos indutores de brotação sobre a resposta produtiva das plantas, a mensuração de seus efeitos ao longo do ciclo produtivo torna-se importante. Este estudo objetivou avaliar a brotação e profundidade de dormência de cultivares de macieira frente a diferentes condições de exposição ao frio durante o período hibernal, e avaliar a resposta produtiva de macieiras frente à aplicação de indutores de brotação. Para tanto, foram realizados três experimentos. No primeiro experimento, ramos de um ano das cultivares Castel Gala e Royal Gala, enxertadas no porta-enxerto M7, foram submetidos as temperaturas de 5, 10 e 15ºC durante diferentes períodos de exposição (168; 336; 672; 1008 e 1344 horas). Após a efetivação dos tratamentos, as plantas foram mantidas em casa de vegetação a 25ºC. A brotação foi quantificada quando acumulada soma térmica de 3444, 6888, 10332, 13776, 17220 e 20664 GDHºC após tratamentos térmicos. As cultivares estudadas responderam diferentemente as temperaturas durante o período hibernal. A temperatura de 15ºC apresentou maior efetividade na brotação de gemas da cultivar Castel Gala, enquanto as temperaturas de 5 e 10ºC apresentaram melhor desempenho na cultivar Royal Gala. Não foi possível estimar o requerimento em frio das cultivares estudadas através do uso de ramos enxertados no outono, visto os baixos percentuais de brotação obtidos, decorrentes da alta dominância apical apresentada pela macieira neste sistema de avaliação. O objetivo do segundo experimento foi avaliar a dinâmica da dormência em cultivares com diferentes requerimentos em frio. Ramos de um ano das cultivares Castel Gala, Condessa, Daiane, Fuji, Imperatriz e Royal Gala foram expostos a 0, 336, 672, 1008 e 1344 unidades de frio a 4,5±0,5ºC. Após a exposição ao frio, os ramos foram segmentados em quatro estacas (terminal, axilar superior, axilar mediana e axilar inferior) e colocados em câmara de crescimento à 23±1ºC. A profundidade de dormência foi avaliada pelo tempo médio para brotação das gemas (TMB). Através do método utilizado não foi possível agrupar as cultivares segundo o requerimento em frio, indicando que a correlação entre a profundidade de dormência e o requerimento em frio não é valida para todas as cultivares de macieira. No terceiro experimento foram avaliadas diferentes combinações de cianamida hidrogenada e óleo mineral sobre a fenologia, brotação de gemas e produção de frutos em macieiras Imperial Gala e Fuji Suprema , durante o ciclo 2007/2008. Foram testados cinco níveis de indutor de brotação (1. testemunha; 2. óleo mineral 3,2%; 3. óleo mineral 3,2% + cianamida hidrogenada 0,20%; 4. óleo mineral 3,2% + cianamida hidrogenada 0,39%; 5. óleo mineral 3,2% + cianamida hidrogenada 0,59%). A aplicação dos indutores de brotação antecipou e reduziu o período de florescimento, aumentando a coincidência de florescimento das cultivares Imperial Gala e Fuji Suprema. Os indutores de brotação uniformizaram e aumentaram a brotação de gemas axilares e terminais, obtendo-se máxima brotação na cultivar Imperial Gala com 0,44% de cianamida hidrogenada e 3,2% de óleo mineral. O aumento da concentração de cianamida hidrogenada apresentou a tendência de diminuir a frutificação efetiva. Observaram-se respostas diferenciadas entre tratamentos quanto à produção e a massa média dos frutos, podendo ser atribuídas ao predomínio da produção de frutos em distintas estruturas de frutificação.

About 70% of the plant species in the temperate zone are characterised by clonal growth, clonal species are also in majority in the Arctic and Subarctic where they affect the structure and composition of the vegetation. It is therefore of great importance to increase our knowledge about clonal plants and their growth and life histories. I have investigated how ramets of the stoloniferous plant Linnaea borealis are affected by the naturally occurring variation in environmental factors, such as: light, nutrient and water availability. Moreover, I examined the seed set and how supplemental hand pollination affects seed set in L. borealis, and also investigated the significance of the apical meristem for shoot population fitness. All studies were performed under field conditions in northern Sweden in a Subarctic environment and most are experimental. The results show that nutrient resorption from senescing leaves is not significantly affecting the growth and nutrient pools of the ramet. This implies that the growth of L. borealis ramets is not governed by micro-site resource availability. However, removal of light competition resulted in increased branching and number of lateral meristems produced, reduced growth, and decreased root:shoot ratio on a per ramet basis. Thus, ramets of L. borealis can efficiently exploit favourable light patches through plastic growth. Apical dominance exerts a significant effect on shoot population fitness and can be lost through rodent grazing. However, loss of apical dominance is dependent on the timing of grazing, if the apical meristem is removed early in the autumn the ramet can repair the loss until the next summer. If grazing occur during spring the dry weight and leaf area production is affected negatively. Seed production in L. borealis in the Abisko area varies between years and sites, and was unaffected by supplemental hand pollination treatment, implying that there is no lack of pollinator activity.

Ações de restauração ecológica muitas vezes são requeridas como ferramentas para adequação de propriedades rurais às leis vigentes, para a conservação da biodiversidade e manutenção dos serviços ecossistêmicos em áreas públicas e privadas. Deste modo, o desenvolvimento de métodos de baixo custo e que possam ser aplicados em larga escala tem grande relevância ecológica, econômica e social, pois além de aplicados em médias e grandes propriedades, têm especial aptidão para serem usados pelos pequenos proprietários. Neste contexto, o presente estudo tem como objetivo geral: i) avaliar, por meio de dois experimentos, a sobrevivência e o crescimento de indivíduos de espécies arbustivo-arbóreas da Floresta Estacional Semidecidual introduzidas por meio de semeadura direta ou plantio de mudas; e ii) avaliar a possibilidade de se controlar as gramíneas competidoras nas entrelinhas por meio da capina tradicional, da criação de um dossel transitório nas entrelinhas pela semeadura de milho, ou pelo aumento da área das copas via poda da gema apical das espécies de recobrimento. O primeiro experimento constituiu-se da semeadura direta de 36 espécies arbustivo-arbóreas aliada ao plantio de milho na entrelinha como forma de controle de gramíneas invasoras. Resultados mostram que 77,8% das espécies semeadas emergiram, o número de indivíduos encontrado, quando comparado ao número de indivíduos esperados, representou apenas 8% dos mesmos. As espécies com maiores taxas de emergência foram Hymenaea courbaril, Pterogyne nitens, Chrysophyllum gonocarpum, Peltophorum dubium e Mabea fistulifera, representando mais da metade dos indivíduos encontrados. Com relação ao plantio do milho, observou-se que sua presença controlou como desejado as gramíneas invasoras. No segundo experimento, realizou-se o plantio em linhas de mudas de espécies arbóreas aliado a duas estratégias para controle de gramíneas invasoras, criação de um dossel transitório pelo plantio do milho nas entrelinhas, ou a indução do aumento da área das copas de indivíduos das espécies de recobrimento por meio da poda de suas gemas apicais. A sobrevivência dos indivíduos não foi influenciada pela presença do milho e poda das gemas apicais das espécies de recobrimento. O número de bifurcações dos indivíduos podados aumentou. Todavia, a área da copa foi, até os nove meses de observação aqui realizados, menor nos indivíduos podados do que nos não podados. O plantio de milho nas entrelinhas evitou que a área fosse colonizada significativamente por gramíneas invasoras, exercendo um controle sobre essas espécies similar àquele do controle tradicional com capina química. Logo, a utilização do milho para controle de gramíneas é indicada nas ações de restauração, por proporcionar a redução dos custos de restauração, reduz-se os riscos de contaminação química do meio ambiente e do trabalhador rural, e possibilita uma geração de renda proveniente da produção do milho. Além das vantagens ecológicas e econômicas, o milho apresenta uma vantagem social, pois ele torna a prática da restauração mais atrativa para os pequenos produtores, e como consequência há um maior envolvimento dos mesmos nas ações de adequação ambiental de suas propriedades. / Ecological restoration actions are often required as tools for adapting rural properties to existing laws for biodiversity, conservation and maintenance of ecosystem services in public and private areas. Thus, it is necessary to develop techniques that present affordable costs of implantation and maintenance, and that provide a diversification of the income of the owner, through a direct and short term economic return. In this context, the present study aims to evaluate, through two experiments, the survival and growth of individuals of shrub-tree species of the Semideciduous Seasonal Forest introduced through direct sowing or planting of seedlings, and the possibility and differences in controlling invasive grasses between the lines through traditional weed control, the creation of a transitional canopy between the lines by sowing maize, or by increasing the area of the canopies via pruning of the apical bud of some species. The first experiment consisted of the direct seeding of 36 shrub-tree species of the Semidecidual Seasonal Forest allied to the planting of maize in the interline as a form of control of invasive grasses. The results of this experiment show that 77.8% of the seeded species emerged, the number of individuals found when compared to the expected number of individuals, represented only 8% of it. The species that most stood out were Hymenaea courbaril, Pterogyne nitens, Chrysophyllum gonocarpum, Peltophorum dubium and Mabea fistulifera, representing more than half of the individuals that were found. Regarding the planting of maize, it was observed that its presence controlled the invading grasses as desired. In the second experiment, planting was carried out in seedling lines of arboreal species of the Semidecidual Seasonal Forest with two strategies to control invasive grasses: (i) the creation of a transitional canopy by the planting of maize between the lines; (ii) the induction of the individuals crown area increase of the species from the covering group by pruning their apical buds. The survival of all individuals was not influenced by the presence of maize and pruning of the apical buds of the covering group species. There was no difference between the death of pruned and non pruned individuals, and pruning increased the number of bifurcations of individuals. However, the crown area was, up to nine months of observation, smaller in pruned individuals than in non pruned individuals. Maize planting between the lines prevented the area from being colonized significantly by invasive grasses, controlling these species development in a similar way of the traditional control with herbicide application, thus showing an alternative to it. Therefore, its use is indicated in the restoration actions as reductions in restoration costs are possible in controlling the grasses with this method as well as providing a possible generation of income from the maize production. In addition to the ecological and economic advantages, maize has a social advantage, since it makes the restoration practice more attractive for small producers. Consequently there is a greater involvement of the same in the restoration and environmental conservation actions.

<p>About 70% of the plant species in the temperate zone are characterised by clonal growth, clonal species are also in majority in the Arctic and Subarctic where they affect the structure and composition of the vegetation. It is therefore of great importance to increase our knowledge about clonal plants and their growth and life histories. I have investigated how ramets of the stoloniferous plant <i>Linnaea borealis</i> are affected by the naturally occurring variation in environmental factors, such as: light, nutrient and water availability. Moreover, I examined the seed set and how supplemental hand pollination affects seed set in <i>L. borealis</i>, and also investigated the significance of the apical meristem for shoot population fitness. All studies were performed under field conditions in northern Sweden in a Subarctic environment and most are experimental.</p><p>The results show that nutrient resorption from senescing leaves is not significantly affecting the growth and nutrient pools of the ramet. This implies that the growth of<i> L. borealis </i>ramets is not governed by micro-site resource availability. However, removal of light competition resulted in increased branching and number of lateral meristems produced, reduced growth, and decreased root:shoot ratio on a per ramet basis. Thus, ramets of <i>L. borealis </i>can efficiently exploit favourable light patches through plastic growth. Apical dominance exerts a significant effect on shoot population fitness and can be lost through rodent grazing. However, loss of apical dominance is dependent on the timing of grazing, if the apical meristem is removed early in the autumn the ramet can repair the loss until the next summer. If grazing occur during spring the dry weight and leaf area production is affected negatively. Seed production in <i>L. borealis</i> in the Abisko area varies between years and sites, and was unaffected by supplemental hand pollination treatment, implying that there is no lack of pollinator activity.</p>

About 70% of the plant species in the temperate zone are characterised by clonal growth, clonal species are also in majority in the Arctic and Subarctic where they affect the structure and composition of the vegetation. It is therefore of great importance to increase our knowledge about clonal plants and their growth and life histories. I have investigated how ramets of the stoloniferous plant Linnaea borealis are affected by the naturally occurring variation in environmental factors, such as: light, nutrient and water availability. Moreover, I examined the seed set and how supplemental hand pollination affects seed set in L. borealis, and also investigated the significance of the apical meristem for shoot population fitness. All studies were performed under field conditions in northern Sweden in a Subarctic environment and most are experimental. The results show that nutrient resorption from senescing leaves is not significantly affecting the growth and nutrient pools of the ramet. This implies that the growth of L. borealis ramets is not governed by micro-site resource availability. However, removal of light competition resulted in increased branching and number of lateral meristems produced, reduced growth, and decreased root:shoot ratio on a per ramet basis. Thus, ramets of L. borealis can efficiently exploit favourable light patches through plastic growth. Apical dominance exerts a significant effect on shoot population fitness and can be lost through rodent grazing. However, loss of apical dominance is dependent on the timing of grazing, if the apical meristem is removed early in the autumn the ramet can repair the loss until the next summer. If grazing occur during spring the dry weight and leaf area production is affected negatively. Seed production in L. borealis in the Abisko area varies between years and sites, and was unaffected by supplemental hand pollination treatment, implying that there is no lack of pollinator activity.

No description available.