Tomato plants (Lycopersicon esculentum Mill.) were grown in the greenhouse and in the field during 1979 and 1980. The inflorescences were treated with gibberellin (GA4/7) and/or benzyladenine (BA). Root exudate was collected at various stages of growth and development for the estimation of the levels of cytokinins in the plant. Soluble sugars and starch were determined in inflorescences at different stages of development. Partitioning of dry matter between the different plant portions was studied to evaluate growth of tomato plants in two different conditions. The application of GA4/7 and BA to tomato inflorescences promoted the development and increased the number of flowers. These growth regulators substantially increased fruit set and yield of tomatoes in both greehouse and field experiments. Determinations of carbohydrates in inflorescences treated with growth regulators showed higher amounts of soluble sugars and starch over a considerable period of development. The level of cytokinins in root exudate was higher during early phase of vegetative growth. At the time of bud formation and anthesis, the level of cytokinins declined. The quantity of translocated cytokinins in the greenhouse was 4 to 5 times higher than under high temperatures in the field. The low levels of cytokinins were associated with poor flower development. Field grown tomato plants produced more vegetative growth and fewer inflorescences than plants in the greenhouse. Allocation of assimilates to newly developed leaves and low level of growth regulators in buds and inflorescences might contribute towards more vegetative growth but poor flowering under high temperatures.

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FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgico / Empresa Brasileira de Pesquisa AgropecuÃria / As orquÃdeas sÃo plantas ornamentais que se destacam principalmente na floricultura devido à beleza, ao exotismo, à diversidade de cores, aos tamanhos e aos formatos de suas flores. A espÃcie Cattleya labiata e as do gÃnero Phalaenopsis apresentam uma grande oferta de opÃÃes de cores que tornam suas flores muito valorizadas e demandadas para comercializaÃÃo. Cattleya labiata à nativa do Nordeste brasileiro e suas floress sÃo levemente arroxeadas e perfumadas; enquanto que Phalaenopsis sp. produz flores brancas de longa durabilidade. A cultura de tecidos tem sido largamente empregada na multiplicaÃÃo massiva desses dois gÃneros. O estiolamento in vitro permite produzir grande nÃmero de plantas, reduzindo os riscos da ocorrÃncia de variaÃÃo somaclonal. Em razÃo disso, este trabalho teve como objetivo avaliar a influÃncia de diferentes ambientes de cultivo e de concentraÃÃes de BAP (6-benzilaminopurina) e ANA (Ãcido naftaleno acÃtico) no estiolamento in vitro das orquÃdeas Cattleya labiata e Phalaenopsis sp. PlÃntulas oriundas de sementes germinadas in vitro com aproximadamente + 1,0 cm de comprimento foram inoculadas em tubos de ensaio contendo 15,0 mL de meio de cultura MS, acrescido de diferentes concentraÃÃes de BAP (0,0; 2,0 e 4,0 mg L-1), ANA (0,0; 1,0 e 2,0 mg L-1) e ambientes de cultivo (sala de crescimento no escuro e com 16 horas de luz artificial), em esquema fatorial 2 x 3 x 3 (2 ambientes x 3 doses de BAP x 3 doses de ANA). Ao final de 150 dias, foram realizadas as seguintes avaliaÃÃes: a) nÃmero de brotos estiolados; b) nÃmero de nÃs por broto estiolado; c) comprimento da brotaÃÃo principal (cm); d) nÃmero de raÃzes e, e) massa seca total (g). O nÃmero de brotos estiolados e de nÃs (por broto estiolado) em plÃntulas de C. labiata e de nÃs por broto estiolado em Phalaenopsis sp. foram superiores no ambiente em ausÃncia de luz independente do fitorregulador utilizado, entretanto para o nÃmero de brotaÃÃes de Phalaenopsis sp. o ambiente luminoso foi o mais favorÃvel. A espÃcie C. labiata apresentou maior nÃmero de nÃs com a utilizaÃÃo de 2,0 mg L-1 de ANA na ausÃncia de BAP, e a orquÃdea Phalaenopsis sp. proporcionou maior nÃmero de nÃs com o emprego de 2,0 mg L-1 de ANA. Em plÃntulas de C. labiata e Phalaenopsis sp. a altura da brotaÃÃo principal foi superior em ambiente na ausÃncia de luz e, em contraste, o nÃmero de raÃzes e a massa seca total das plÃntulas foram superiores em ambiente na presenÃa de luz, sendo que para C. labiata esses resultados foram independentes do regulador de crescimento utilizado. / Orchids are ornamental plants that stand out mainly in floriculture due to the beauty, the exoticism, the diversity of colors, the sizes and shapes of their flowers. Cattleya labiata and species of the genus Phalaenopsis feature a wide range of color choices that make their flowers much valued and demanded for marketing. Cattleya labiata is native of the Brazilian Northeast and produces purplish and slightly fragrant flowers; and Phalaenopsis sp. produces white flowers for long lasting durability. Tissue culture is widely used in massive multiplication of genres. The in vitro etiolation allows to produce large numbers of plants, reducing the risk of somaclonal variation. For this reason, this study aimed to evaluate the influence of different cultivation environments and concentrations of BAP (6-benzylaminopurine) and NAA (naphthalene acetic acid) in vitro etiolation of the orchids Cattleya labiata and Phalaenopsis sp. Seedlings grown from seeds germinated in vitro with approximately + 1.0 cm in length were inoculated into test tubes containing 15.0 mL of MS medium supplemented with different concentrations of BAP (0.0, 2.0 and 4,0 mg L-1), NAA (0.0, 1.0 and 2.0 mg L-1) and culture environments (dark growth and room with artificial light) in a factorial 2 x 3 x 3 (2 environments x 3 doses of BAP x 3 doses of NAA). At the end of 150 days, the following evaluations were performed: a) number of etiolated shoots; b) number of nodes per etiolated shoot; c) length of the main sprout (cm); d) number of roots, and e) total dry mass (g). The number of etiolated shoots and nodes (per etiolated shoot) on seedlings of C. labiata and nodes per etiolated shoot in Phalaenopsis sp. were higher in the environment in the absence of light independent of the phytoregulator used, however the number of shoots of Phalaenopsis sp. the luminous environment was the most favorable. The species C. labiata showed a higher number of nodes with the use of 2.0 mg L-1 of NAA, in the absence of BAP, and Phalaenopsis sp. provided the highest number of nodes with the use of 2.0 mg L-1 of NAA. In seedlings of C. labiata and Phalaenopsis sp. the height of the main budding was higher in the environment in the absence of light, in contrast, the number of roots and total dry weight of seedlings were higher in luminous environment, and for C. labiata these results were independent regulator growth used.

Somatic embryogenesis (SE) represents potentially very suitable way of plant production - micropropagation - of plants in vitro. The process had been studied for more than thirty years and a lot of knowledge has been gained in the field though new ways based on new knowledge leading to improvement and increase of the effectiveness of cultivation protocols are still under focus in the field. Relatively recent discovery of aromatic cytokinins lead to new knowledge on very positive effects on different morphogenetic and physiological processes during both cultivation in vitro or in vivo treatments. This gave origin to the topic of the present thesis, which focused on study of the effect of meta-topolin (mT), aromatic cytokinin, on proliferation phase of SE on structural level of embryogenic lines of Norway spruce Picea abies (L.) Karst. The aim of the thesis is analysis of structural development of embryogenic lines with the use of anatomical preparations and quantitative stereological methods. The material represented three embryogenic lines: 107 and 34C were obtained from the Forestry and Game Management Research Institute from the lab of Dr. Jana Malá and the line AFO 541, which was used as a standard line. To compare the effect of mT with benzylaminopurine (BAP) on proportion of different...