-(Wood anatomy of Croton urucurana Baill. (Euphorbiaceae) from soils in different moisture levels). Stem wood of Croton urucurana grown in flooded, moist, and dry soil areas, were studied. Twenty-two quantitative wood anatomical features of vessel elements, fibres, axial parenchyma, and rays were analysed. The characteristics average values for each soil type were statistically compared. Soil moisture data were obtained during one year for all the areas fortnightly; water soil retention curve was also obtained for characterisation of moisture levels. Fourteen anatomical features differed statistically at level of 5% of significance, for specimens of two different places, at least regarding soil moisture. Ten features were significantly different for specimens in dry and flooded soil conditions. The frequency and the vessels diameter are larger in flooded specimens, and smaller in specimens from dry areas. The data reflects the well-known condition for specimens from dry soils; however they reveal a new fact: the frequency and vessels diameter increasing in the specimens that live in the stressing condition of flooded soils.Key words -Croton urucurana, flooded soil, stem, wood anatomy RESUMO -(Anatomia do lenho de Croton urucurana Baill. (Euphorbiaceae) de solos com diferentes níveis de umidade). Este estudo analisou a anatomia do lenho de indivíduos de Croton urucurana de áreas com o solo alagado, úmido e seco. A estrutura anatômica foi analisada quantitativamente através de medições de vinte e duas características, envolvendo os elementos de vasos, as fibras, os parênquimas axial e radial; o valor médio das características em cada tipo de solo foi comparado estatisticamente. Foram obtidos dados de umidade de solo, quinzenalmente, no período de um ano, de cada uma das três áreas, juntamente com a curva de retenção de água do solo para a caracterização do nível de umidade. Quatorze características, ao nível de 5% de significância, apresentaram-se diferentes nos espécimes de pelo menos duas localidades diferentes de solo. De tais características, dez apresentaram-se significativamente diferentes entre os espécimes de solo da condição seca e alagada. A freqüência e o diâmetro dos vasos, apresentaram-se com médias maiores nos espécimes do solo alagado, e menores nos de solo seco. Tal dado revela um fato novo: o aumento da freqüência e do diâmetro dos vasos dos espécimes que vivem na condição estressante do solo alagado.Palavras-chave -anatomia do lenho, caule, Croton urucurana, solo alagado

The effects of auxins and cytokinin on callus formation, growth and regeneration of Gracilaria tenuistipitata Chang et Xia and G. perplexa Byrne et Zuccarello (Gracilariales, Rhodophyta) are reported. Plant growth regulators (PGR) in concentrations ranging from 0.1 to 100.0 µ mol of indole-3-acetic acid, 2,4-dichlorophenoxyacetic acid (2,4-D), and kinetin (K) were added to the ASP 12-NTA solid medium (0.7% agar), and apical and intercalary segments (5 mm long) were inoculated as initial explants. K stimulated growth rates of intercalary segments of G. tenuistipitata in a linear relation, and 2,4-D (1.0 µ mol) and K (10.0 µ mol) stimulated growth rates of apical and intercalary segments of G. perplexa , respectively. The simultaneous formation of apical, basal, and intermediate calluses is reported for the first time in axenic tissue cultures of red algae. With intercalary segments of G. tenuistipitata , basal callus induction rates were higher than those of apical and intermediate calluses in the majority of treatments, and auxins had stimulatory effects on the formation of all callus types. In apical segments of G. perplexa , intermediate callus formation was stimulated only by treatment with 1.0 µ mol of K, while apical callus formation was stimulated by indole-3-acetic acid (1.0-10.0 µ mol), 2,4-D (10.0-100.0 µ mol), or K (0.1 µ mol). Intercalary segments of G. perplexa developed only intermediate calluses, and the majority of treatments with PGR stimulated higher rates than those presented by apical segments. Potential for regeneration (development of adventitious plantlets originated from callus cells) was higher in apical calluses than in basal and intermediate calluses developed in intercalary segments of G. tenuistipitata . Moreover, auxins and cytokinin were essential to the induction of regeneration in intermediate calluses, while specific concentrations stimulated regeneration from basal and apical calluses. Plant regeneration in G. perplexa was observed only after transferring calluses from solid to liquid medium, and the majority of treatments with PGR had stimulatory effects. Regenerating plants of G. perplexa developed tetrasporangia, and released tetraspores giving rise to adult gametophytes. Our results indicate that auxins and cytokinin have a regulatory role in the growth and morphogenesis in G. tenuistipitata and G. perplexa , and diversity of responses presented by both species is related to specific developmental systems.

-(Comparative wood anatomy of Xylopia aromatica (Lam.) Mart. in "cerrado" and plantation area of Pinus elliottii Engelm.). The anatomical structure of Xylopia aromatica (Lam.) Mart. wood was analyzed comparing stem and root samples from a caracteristic "cerrado" area, and another area with cultivated monoculture of Pinus elliotti Engelm. Both areas are inside the "Reserva Biológica e Estação Experimental de Moji-Guaçu". The samples were collected by non-destructive method. The quantitative analyzed characteristics data were obtained by counting and measuring in vessel elements, fibers, axial and radial parenchyma, in both histological sections and dissociated tissue. These data were submitted to the no parametric proof of Mann-Whitney that showed significant differences for 12 of the 18 analyzed characteristics. Among these, only intervessel pits diameter, vessel-ray pits diameter, and axial parenchyma percentage, showed larger averages for the plantation area specimens. Soil moisture data were obtained together with water soil retention curve. The structural analysis demonstrated the presence of growth rings delimited by radially flattened walls fibres observed in all studied specimens. This characteristic indicates a physiologic and anatomical adaptation of specimens to the drought period that occurs annually in the region. The low secretory idioblast occurrence in plantation area specimens indicates the possible physiologic alterations induced by the presence of Pinus elliottii plantation in "cerrado" area. Key words-"cerrado", plantation Pinus, wood anatomy, Xylopia aromatica RESUMO-(Anatomia comparada do lenho de Xylopia aromatica (Lam.) Mart. em áreas de cerrado e de plantação de Pinus elliottii Engelm.). A estrutura anatômica do lenho de Xylopia aromatica (Lam.) Mart. foi analisada pela observação do caule e da raiz de espécimes provenientes de duas áreas de cerrado, uma com vegetação característica e outra, em que a vegetação original foi substituída por monocultura de Pinus elliotti Engelm. As duas áreas situam-se na Reserva Biológica e Estação Experimental de Moji-Guaçu. As amostras foram coletadas pelo método não destrutivo. Os dados quantitativos das características analisadas foram obtidos mediante contagens e medições nos elementos de vasos, fibras e parênquima axial e radial, através das secções histológicas e tecido dissociado. Esses dados foram submetidos à prova não paramétrica de Mann-Whitney que mostrou diferenças significativas para 12 das 18 características analisadas. Dentre essas, apenas o diâmetro das pontoações intervasculares e das radiovasculares e a porcentagem de parênquima axial, apresentaram médias maiores para os espécimes da área de plantio. A análise estrutural do lenho demonstrou a presença de anéis de crescimento, delimitados pelo achatamento das paredes radiais das fibras, observada em todos os espécimes, indicando uma adaptação fisiológica e anatômica ao período de seca que ocorre anualmente na região. A baixa ocorrência de idioblastos secretores, nos espécimes da área de pl...

The effects of auxins and cytokinin on callus formation, growth and regeneration of Gracilaria tenuistipitata Chang et Xia and G. perplexa Byrne et Zuccarello (Gracilariales, Rhodophyta) are reported. Plant growth regulators (PGR) in concentrations ranging from 0.1 to 100.0 µ mol of indole-3-acetic acid, 2,4-dichlorophenoxyacetic acid (2,4-D), and kinetin (K) were added to the ASP 12-NTA solid medium (0.7% agar), and apical and intercalary segments (5 mm long) were inoculated as initial explants. K stimulated growth rates of intercalary segments of G. tenuistipitata in a linear relation, and 2,4-D (1.0 µ mol) and K (10.0 µ mol) stimulated growth rates of apical and intercalary segments of G. perplexa , respectively. The simultaneous formation of apical, basal, and intermediate calluses is reported for the first time in axenic tissue cultures of red algae. With intercalary segments of G. tenuistipitata , basal callus induction rates were higher than those of apical and intermediate calluses in the majority of treatments, and auxins had stimulatory effects on the formation of all callus types. In apical segments of G. perplexa , intermediate callus formation was stimulated only by treatment with 1.0 µ mol of K, while apical callus formation was stimulated by indole-3-acetic acid (1.0-10.0 µ mol), 2,4-D (10.0-100.0 µ mol), or K (0.1 µ mol). Intercalary segments of G. perplexa developed only intermediate calluses, and the majority of treatments with PGR stimulated higher rates than those presented by apical segments. Potential for regeneration (development of adventitious plantlets originated from callus cells) was higher in apical calluses than in basal and intermediate calluses developed in intercalary segments of G. tenuistipitata . Moreover, auxins and cytokinin were essential to the induction of regeneration in intermediate calluses, while specific concentrations stimulated regeneration from basal and apical calluses. Plant regeneration in G. perplexa was observed only after transferring calluses from solid to liquid medium, and the majority of treatments with PGR had stimulatory effects. Regenerating plants of G. perplexa developed tetrasporangia, and released tetraspores giving rise to adult gametophytes. Our results indicate that auxins and cytokinin have a regulatory role in the growth and morphogenesis in G. tenuistipitata and G. perplexa , and diversity of responses presented by both species is related to specific developmental systems.