Two experiments were conducted in 1994 and 1995 to compare the field performance of photoperiod sensitive (PS) and photoperiod insensitive (PI) oat (Avena sativa L) genotypes. In the first experiment, bulks of PS and PI lines from four covered oat crosses, as well as the cultivars Sylva, Newman, the PI naked oat cultivar AC Lotta and the breeding line NO820-3L were tested at seven locations across Quebec and Ontario. The second experiment was a seeding. date trial performed at Ste-Anne-de-Bellevue in which individual PS and PI lines of three covered oat crosses were utilized. In the multi-location experiment, the PI genotypes generally reached the different growth stages significantly earlier. At Normandin, Quebec the northernmost site, PS genotypes had consistently higher yields than the PI genotypes. At one southern site (Elora, Ontario), PI bulks yielded more than their PS counterparts. The PS genotypes sometimes had higher leaf numbers in most of the seven locations. In the experiment with different seeding dates, the PS lines had significantly higher numbers of leaves, biomass, grain weight per plant, harvest index, and yield compared to the PI lines. The response of the PS and PI lines to delayed sowing was similar. There was a progressive reduction in the number of days to reach Zadoks' 30, heading, and maturity: and a reduction in height, above-ground biomass, and yield with delayed sowing. Number of culms, leaves, and fertile culms, and harvest index were not affected by delayed sowing. Based on the results of these experiments, it seems that the Di1 gene does not confer any consistent yield advantage or disadvantage. Nevertheless, there may be some northern environments for which photoperiod sensitive oat genotypes are better suited.

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Orientador: Lilian Beatriz Penteado Zaidan / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-07T09:17:44Z (GMT). No. of bitstreams: 1 Rondon_JosimaraNolasco_D.pdf: 1536546 bytes, checksum: 297d7328b9b2a132fca75bfad73844c8 (MD5) Previous issue date: 2006 / Resumo: Uma população de Bauhinia holophylla Steud. localizada no cerrado sensu stricto da Reserva Biológica e Estação Experimental de Moji Guaçu (RBEE de Moji Guaçu) foi estudada quanto a sua fenologia reprodutiva, expectativa de vida foliar, predação de sementes, germinação, fotoperíodo e regeneração natural. O padrão de distribuição da população adulta e jovem de B. holophylla, na área estudada é do tipo agregado. A população jovem e adulta de B. holophylla na RBEE de Moji Guaçu pode ser considerada juvenil, concentrando a maioria dos indivíduos nas primeiras classes de crescimento em altura e diâmetro. A expectativa média de vida da folha no primeiro ano de estudo foi de 8,2 meses, enquanto no segundo ano foi de 7,6 meses. A produtividade primária da fração folhas de 21 plantas de B. holophylla amostradas foi mais intensa nos meses de julho a agosto, durante o período de estudo (dois anos), portanto, durante a estação seca. A fração flores e botões esteve associada ao período da estação chuvosa, com produção maior nos meses de novembro a janeiro. A mortalidade foliar coincidiu com o período de menor precipitação na estação seca. A queda total das coortes foliares ocorreu ao mesmo tempo, na estação seca, estando a presença da folha durante a estação chuvosa, relacionada à produção de fotoassimilados para a planta, que serão usados na reprodução e/ou armazenados como amido no xilopódio. Plantas de B. holophylla apresentaram maior altura e diâmetro caulinar, e maior número de folhas nos tratamentos fotoperiódicos de 16 e 20 horas que nos tratamentos de 8 e 12 horas. A predação de sementes é uma das principais causas da inexistência de plântulas no cerrado. Contudo, a regeneração natural não está comprometida devido à presença do xilopódio. As sementes de B. holophylla são neutras à luz para a germinação e germinam em uma faixa ampla de temperatura. A permanência efêmera de sementes de B. holophylla no banco de sementes do solo de cerrado deve-se muito provavelmente à neutralidade à luz e velocidade de germinação alta em temperaturas na faixa de 25ºC a 30ºC. Práticas de manejo na RBEE de Moji Guaçu a partir do controle de larvas e de insetos predadores são fundamentais para aumentar a produção de sementes sadias de B. holophylla. Investigações sobre auto-ecologia, serapilheira, fenologia reprodutiva e dinâmica populacional devem ser propostas para espécies do Cerrado. Essas investigações podem auxiliar nos programas de recuperação de áreas remanescentes de cerrado e constituem modelos para estudos de populações de espécies vegetais do cerrado / Abstract: A population of Bauhinia holophylla located at a cerrado area in the Reserva Biológica e Estação Experimental de Moji Guaçu was studied in relation to reproductive phenology, leaf life span, seed predation, seed germination and aspects of plant regeneration. The distribution pattern of the juvenile and adult population is considered agregated. This population can be considered on the juvenile stage, due to, the greater number of plants concentrate in to the first size classes (height and diameter). The mean leaf life span was 8.2 months in the first year and 7.6 months in the second year. The primary productivity of leaves was more intense, during dry season (July-August). Leaf mortality with the period of the minor precipitation registered (dry season). Flower and bud production was associated to the wet season. Leaf fall ocurred during dry season. The new leaves could garantee the production of photoassimilates that would be utilized by all plant organs in their metabolic activities and as a reserve carbohydrate stored in the xylopodium as starch. Higher stems and stem diameter and leaf number in plants were observed in the photoper iodic treatments of 16h and 20 hours (long days) than in plants maintened in 8h and 12 hours (short days). Seeds predation is the principal cause of inexistence of seedlings in that the cerrado area. However, plant regeneration is provided by xylopodium. The seed is neutral to light for germination at the temperature range of 20ºC to 35ºC. Germination speed germination at 25ºC in the dark was higher than under light. The ephemeral permanence of the seeds of B. holophylla in the cerrado soil seed bank, is probably due to neutrality of light and their fast germination at 25ºC-30ºC. Thus, management polices at the Reserva Biológica e Estação Experimental de Moji Guaçu to decrease larvae and predator insects are fundamental to enlarge the production of healthy seeds of B. holophylla. Investigation on auto-ecology, litter and reproductive phenology, may give important information about of species occurring in the Cerrado. Investigations can support recuperation programmes of remnant cerrado areas and constitute model to study populations of plants species the Cerrado / Doutorado / Biologia Vegetal / Doutor em Biologia Vegetal

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<i>Abutilon</i> x <i>hybridum</i>, flowering maple has the potential to become a profitable floriculture crop. However, growing guidelines need to be developed in order to produce a proportional, well-branched, and uniform-flowering pot plant. The objective of this research project was to form a foundation on which a commercial growing program could be developed. Growing flowering maple under short-day conditions (SD) significantly reduced plant height. Plants grown under SD were nearly half as tall as those plants grown under long-day conditions (LD). Also, plants grown under SD flowered an average of 5 days earlier than those plants grown under LD. Ancymidol at 50 ppm was successful in the reducing the height of nonpinched plants. Chemical pinching agents, including mefluidide and Atrinal, induced more lateral branch development and increased flower production of both seed-grown and cutting-grown plants. As the concentration of mefluidide and Atrinal increased, so did the number of flowers that were produced. Atrinal at 1000 ppm appeared to be the treatment of choice for producing the most aesthetic and marketable flowering maple plant. A foliar application of GA₄₊₇ at 100 ppm was successful in elongating peduncles without producing a disproportional increase in plant height. The peduncles of both seed-grown and cutting-grown plants receiving 100 ppm GA₄₊₇ were nearly twice as long as the controls. Thus, GA could be used to improve the flower display of <i>Abutilon</i>. / M.S.

Thesis (Ph. D.)--University of Oregon, 2002. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 174-182).

Onions are widely produced within the tropics, but little scientific research has been done specifically on the Eritrean cultivars, like Hagaz Red 1 and 2 (HR I, and HR 2). Many onion cultivars are limited in their range of adaptation due to the combined effects of photoperiod and temperature. A priority for research on the crop was to elucidate the local crop's growth response to environmental conditions, particularly temperature and daylength. The Eritrean cultivars HR I and 2 and an American (Louisiana) cultivar Red Creole (RC) grown in South Africa were grown in growth rooms under all combinations of three daylengths (11.5h, 12h, 12.5h) and three day/night temperatures (25/12°C, 30/15°C and 35/18°C). Growth responses were determined at 108 days and by using a growing degree day (GDD) base. A broken-stick regression model was used to determine the points of inflection, indicating the initiation of bulbing. Based on leaf area and plant height data, mathematical differentiation equations and coefficient of determination (R2) were applied to determine the base temperature (6.4°C) for these particular cultivars. All three cultivars needed at least 12 h daylength for bulb initiation when assessed by a bulbing ratio >=2.0. A bulbing ratio >=2.0 characterizes the onset of bulbing. Under a 11.5 h daylength, a temperature higher than 25/12°C decreased vegetative growth. Temperature in this region may be a supra-optimal condition for the growth of these cultivars at this daylength. However, the 25/12°C and 30/15°C temperatures were found to be ideal for onion bulb production under 12 hand 12.5 h daylengths. The three cultivars (HR I, HR 2 and RC) showed very similar growth response to the daylength and temperature interactions. The thermal presentation of plant growth indicated that there were relationships between bulb initiation and rate of leaf area growth under inductive conditions (12 hand 12.5 h). Under the 12 h daylength, cultivars needed 343, 482, and 597 GDD units before bulb initiation and 405, 432, and 431 GDD to increase the rate of leaf area development at 25/12°C, 30/15°C, and 35/18°C, respectively. Under a 12.5 h daylength, these cultivars needed 344, 423, and 432.2 GDDs to initiate bulbing and 140, 411, and 579 GDDs to increase leaf growth rates at 25/12°C, 30/15°C, and 35/18°C, respectively. In the 12 h daylength, bulbing was initiated and followed by an increased rate of growth of leaf area. However, the reverse happened for the 12.5 h daylength. Overall, where plant response to temperature can be expressed as the rate of progress towards a morphogenetic change, GDD values can be used to predict a plant developmental stage at a particular temperature. It must be concluded that temperatures induced significant variations in growth components (leaf number, plant height, leaf area), and affected bulbing response. The findings in this study confirmed that the cultivars require only a certain fixed amount of thermal time for their development at a particular temperature, and that, if anything, the slow growth rate at the higher temperature must be due to supra-optimal temperatures. They also require a minimum 12 h photoperiod for bulb formation. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.