RESUMO O conhecimento sobre o desenvolvimento inicial das mudas é fundamental para o sucesso de atividades de reflorestamento e de plantio em florestas naturais. O objetivo deste trabalho foi avaliar o desenvolvimento inicial e a eficiência de uso de água e nitrogênio por mudas de quatro espécies florestais nativas e exóticas (Calophyllum brasiliense (nativa), Eucalyptus urograndis (exótica), Toona ciliata (exótica) e Tabebuia impetiginosa (nativa)) com idade de aproximadamente 120 dias após a semeadura por 120 dias após o transplante em condições de casa de vegetação. Foram realizadas amostragens destrutivas para avaliar a biomassa seca (folha, caule, raiz e total), área foliar, relação raiz/parte aérea e nitrogênio total nas mudas. Com base nessas variáveis, foram calculados os parâmetros fisiológicos de crescimento e a eficiência de uso de água, que foi obtida pela razão entre o total de biomassa seca acumulada e a evapotranspiração dos vasos no período, determinada através de pesagens diárias em balança de bancada. Ao final de 240 dias após a semeadura, Calophyllum brasiliense e Tabebuia impetiginosa apresentaram maior produção de biomassa seca total e Toona ciliata apresentou maior relação raiz/parte aérea. Não houve diferenças entre a taxa de crescimento relativo das espécies avaliadas. Eucalyptus urograndis, Toona ciliata e Calophyllum brasiliense apresentaram os maiores valores de razão de área foliar, Toona ciliata, Tabebuia impetiginosa e Eucalyptus urograndis apresentaram os maiores valores de área foliar específica, Eucalyptus urograndis e Calophyllum brasiliense apresentam os maiores valores para razão de massa foliar e Tabebuia impetiginosa, Toona ciliata e Eucalyptus urograndis apresentaram os maiores valores de taxa de assimilação líquida. Com base na quantificação do nitrogênio total, Tabebuia impetiginosa e Toona ciliata foram as espécies mais eficientes no uso do nitrogênio. Eucalyptus urograndis apresentou a maior evapotranspiração enquanto Calophyllum brasiliense e Tabebuia impetiginosa foram as espécies mais eficientes no uso de água.

ABSTRACT The knowledge about the early development of seedlings is critical to the success of reforestation and planting in natural forests. The aim of this study was to evaluate the initial development and efficiency of water and nitrogen use by seedlings of four native and exotic species (Calophyllum brasiliense (native), Eucalyptus urograndis (exotic), Toona ciliata (exotic) and Tabebuia impetiginosa (native)) with age of approximately 120 days after sowing for 120 days after transplantation in green-house conditions. Destructive samples were carried out to assess the dry biomass (Leaf, Stem, Root and Total), leaf area, the root shoot ratio and total nitrogen in seedlings. Based on these variables, it was calculated the physiological parameters of growth and efficiency of water use, which was obtained by the ratio between the total dry biomass accumulation and evapotranspiration of vessels in the period, determined by daily weighing in a balance bench. At the end of 240 days after sowing, Calophyllum brasiliense and Tabebuia impetiginosa produced more total biomass and Toona ciliata showed higher root shoot ratio. There were no differences between the relative growth rate of the species evaluated. Eucalyptus urograndis, Toona ciliata and Calophyllum brasiliense showed the highest values of leaf area ratio, Toona ciliata, Tabebuia impetiginosa and Eucalyptus urograndis showed the highest values of specific leaf area, Eucalyptus urograndis and Calophyllum brasiliense show the highest values for leaf mass ratio and Tabebuia impetiginosa, Toona ciliata and Eucalyptus urograndis showed the highest values of net assimilation rate. Based on quantification of total nitrogen, Tabebuia impetiginosa and Toona ciliata were the most efficient species in the use of nitrogen. Eucalyptus urograndis presented the highest evapotranspiration while Calophyllum brasiliense and Tabebuia impetiginosa were the most efficient species in water use.

A emissão de etileno, a respiração e as transformações físicas e químicas em mamões da cv Golden e dos híbridos Tainung 01 e UENF/CALIMAN01 (UC01), colhidos no estádio 0 de maturação (fruto maturo com casca 100% verde) e mantidos a 25ºCº e 80% % UR foram avaliados durante a fase de amadurecimento. Os resultados mostram diferenças significativas entre os genótipos, em todas as características avaliadas. O mamão 'Golden'apresentou taxasrespiratória e de emissão de etileno bastante superiores às registradas para o Tainung 01 e UC01, indicando climatério característico. O mamão UC01 foi o que manteve a coloração verde de casca por mais tempo e apresentou a menor firmeza do fruto no estádio 0. Os resultados também mostram a relação entre os picos respiratório e de etileno, com a perda de firmeza. Houve aumento no teor de sólidos solúveis (SS) no mamão UC01, não observado nos demais. A acidez titulável (AT) e a razão SS/ AT variaram durante o amadurecimento apenas na cv Golden. Os resultados indicam que os três genótipos mais comercializados no Brasil diferem fisiológica e bioquimicamente durante o amadurecimento, com os hibridos Tainung 01 e UC01 mostrando-se mais sensíveis à ação do etileno do que a cv. Golden, o que é importante ao manejo pós-colheita destes frutos.

The emission of ethylene, respiration and physical and chemical changes of papaya Golden cultivar, and of the hybrids Tainung 01 and UENF/CALIMAN01 (UC01), harvested at 0 maturity stage (mature fruit with 100 % green skin) and stored at 25ºC and 80% RH have been evaluated during the ripening. The results show significant differences between genotypes in all evaluated traits. The 'Golden' papaya had shown respiratory rates and ethylene emission higher than those recorded for the Tainung 01 and UC01, indicating characteristic climacteric. The papaya UC01 has been the one which kept the green color of the skin for longer time and has shown lower firmness of fruit in 0 maturity stage. The results also show the relationship between the respiratory and ethylene peaks, with loss of firmness. There was an increase in soluble solids (SS) in papaya UC 01, not observed in the others. The titratable acidity (TA) and the ratio SS/TA did vary during ripening only in papaya 'Golden'. The results indicate that the three genotypes more commercialized in Brazil differ physiologically and biochemically during ripening, with hybrids Tainung 01 and UC01 being more sensitive to the action of ethylene than the Golden cultivar, which is important to the postharvest management of these fruits.

This study describes the influence of edaphic factors on the floristic composition of an area of cerradão (woodland savanna) in the city of Campo Grande, located in the Brazilian central-west. In 10 plots (5 × 20 m each), we evaluated all trees with a diameter at breast height > 4.77 cm. Soil samples were analyzed for each plot in order to determine edaphic variables correlated with species composition. We sampled 1180 individuals of 61 species. The evenness index was 0.74, which indicates uneven distribution of species, which was explained by a high abundance of Qualea parviflora, Curatella americana, Qualea grandiflora, Terminalia argentea and Astronium fraxinifolium. We registered more trees in the smallest diameter class and in the middle layer of the vertical structure. The soil was dystrophic with a clay texture, which explains the higher abundance of species related to dystrophic cerradão. However, we also found some trees typical of mesotrophic cerradão and deciduous forests, which could be attributable to the presence of patches of fertile soil within the dystrophic cerradão or could indicate that those mesotrophic species are tolerant of lower levels of soil nutrients.

The plant hormones brassinosteroids (BR) and ethylene (ET) act together to regulate plant metabolism. We used BR and 1-methylcyclopropene (1-MCP, an ET action inhibitor) to elucidate the interactions between both hormones for the regulation of mitochondrial respiratory pathways in papaya fruit. The exogenous application of the 24-epibrassinolide (epiBR) enhanced the alternative oxidase (AOX) capacity. While treatment with Brz2001 (Brz is a specific inhibitor of the BR synthesis) also enhanced AOX capacity, these effects lacked in fruit treated simultaneously with epiBR and Brz. Changing the BR level had no effect on ET emission rate in the first 24 h, but a reduction in ET emission was observed in Brz-treated fruit on the fifth day. Together with Brz, epiBR increased the ET production on the fifth day, following the day in which the treatment was carried out. When the ET sensitivity of fruit was inhibited by the application of 1-MCP, the effects of epiBR and Brz were opposite to those obtained without 1-MCP. AOX capacity was slightly inhibited by epiBR in fruit pre-treated with 1-MCP. Data suggest that BR and ET act antagonistically, therefore regulating, directly or indirectly, AOX capacity during papaya fruit ripening.