Astragalus lentiginosus, which consists of 36 varieties, is one of the principal locoweeds of western North America. The objectives of this study included identification of some of the major factors affecting germination of the seed and survival of the newly established seedlings for several of these varieties. The seeds of the varieties studied exhibited two mechanisms for dormancy. One is a seed coat that is impermeable to water, and the other is a water-leachable inhibitor. The presence or absence of low-intensity incandescent light (in 14-hour day lengths) had no effect on germination. Of three temperature regimes studied, the regime 7/13 C proved optimal for both total and rapid rate of germination. However, though germinating at lower rates, weeds at -1/4 C and 21/27 C both ultimately reached high percentages of germination. Germination decreased linearly with increasing salinity to almost zero in NaCl solutions of -8.52 bars water potential. Variety araenosus, collected in a salt desert shrub vegetation type showed the highest germination at low temperatures and the greatest salinity tolerance. Seedling survival work was done with both pre-established and established seedlings at the cotyledon to five leaflet stages of development. Seedlings were considered pre-established from the time of germination until the cotyledons were completely unfolded. Afterwards, the seedlings were considered established. Germination and survival of pre-established seedlings were inhibited by day temperatures of 21 C under laboratory conditions. Maximum emergence and survival occurred at the low temperature regime of 4/13 C. However, seedlings of the three to five leaflet stages grew best at day temperatures of 30 C; growth was substantially lower at lower temperatures. Seedlings of var. araenosus displayed the most rapid rate of root growth at 7/12 C while roots of var. vitreus grew at a rate nearly 50 percent lower.

Submitted by (ana.araujo@ufrpe.br) on 2016-06-28T12:47:57Z No. of bitstreams: 1 Cristiane Rocha Albuquerque Lima.pdf: 1669674 bytes, checksum: 8c470f7b42a668a3ae34976123b15507 (MD5) / Made available in DSpace on 2016-06-28T12:47:57Z (GMT). No. of bitstreams: 1 Cristiane Rocha Albuquerque Lima.pdf: 1669674 bytes, checksum: 8c470f7b42a668a3ae34976123b15507 (MD5) Previous issue date: 2007-02-28 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / The guitarfish Rhinobatos cf percelens is a marine ray inhabiting shallow coastal waters in southern hemisphere. The analyzed sample was collected at Caiçara do Norte, off Rio Grande do Norte state (Brazil). Traditional techniques and geometric morphometry were used aiming at identifying the specific status of the exploited species along the Brazilian Northeast coast. For that, comparisons between R. percellens and R. lentiginosus were carried out by means of data obtained from the literature and data from paratypes of both species provided by the Museu Oceanográfico da Universidade do Vale do Itajaí - MOVI. The knowledge of the specific status of fishes composing commercial catches is essential for allocating them in their proper stock units, so that stock assessments can be conducted as well as management measures undertaken. Thus, were used as approach the analysis morphometric, through techniques of image processing, analysis multivariate and geometric morphometric, using for comparison the described pattern widely accepted for each species. Individual images were digitalized through a camera and stored in files of image jpeg. The coordinates of landmarks and pseudo-landmarks definedover the dorsal part of the animal were obtained and matrix of data was submitted to the mentioned techniques allowing comparisons of the form variations among specimens. Results obtained pointed out two groups, consisting the first at dark coloration specimens with numerous white spots, while the second was made up of individuals brown coloration with or without spots. / Rhinobatos cf percellens é uma espécie de raia marinha de águas costeiras. A amostra analisada foi coletada em Caiçara do Norte, no estado do Rio Grande do Norte (Brasil). Técnicas tradicionais e de morfometria geométrica foram usadas com o objetivo de identificar o status específico da espécie explorada na costa Nordeste do Brasil. Para isso, comparações entre R. percellens e R. lentiginosus foram feitas através de dados obtidos na literatura e dados de parátipos de ambas espécies provenientes do Museu Oceanográfico da Universidade do Vale do Itajaí - MOVI. O conhecimento do status específico das espécies exploradas é essencial para alocação em suas próprias unidades de estoque, de forma que estas avaliações possam ser administradas bem como estabelecer medidas de administração. Assim, foram utilizadas como abordagem a análise morfométrica, através de técnicas de processamento de imagem, análise multivariada e morfometria geométrica, utilizando para comparação o padrão amplamente aceito para cada uma das espécies. Imagens individuais foram digitalizadas através de uma câmara e armazenadas em arquivos de imagem jpeg. As coordenadas de marcos anatômicos e pseudosmarcos anatômicos, definidos sobre a região dorsal do animal, foram obtidas e a matriz de dados submetida às técnicas mencionadas permitindo uma comparação das variações da forma entre os espécimes. Resultados obtidos apontaram dois grupos, consistindo o primeiro por espécimes de coloração escura com numerosos pontos brancos, o segundo foi formado por indivíduos de coloração marrom com presença ou não de manchas.