Carlos Vinício Vieira

Aspectos fisioanatômicos de plantas jovens de Cupania vernalis camb. submetidas a diferentes níveis de sombreamento

Cupania vernalis camb. (Sapindaceae) is a species commonly found in almost all forest associations, mainly in savanna-like vegetation (cerrado) and galeria woods, spreading over the states of Minas Gerais, Mato Grosso, Sao Paulo and reaching as far as Rio Grande do Sul. The species stands out mainly by its use in mixed planting to recover degraded areas of permanent preservation, for its fruits being much appreciated and consumed by birds and, still used in folk medicine against asthma and convulsive coughs. Leaf anatomy studies are highly important for the understanding of the adaptive plasticity of a species subjected to different environmental conditions, as it is correlated with processes such as gas exchanges and CO2 assimilation, as well as other processes inherent to plant growth. This work aimed to study the effect of different shading levels (full sunshine, 30%, 50% and 70%) on leaf anatomy and gas exchanges of Cupania vernalis camb plantlets. The results showed greater photosynthetic rate, increase in stomatal conductance, blade thickness, number of stomata per area and thickness of cell wall on leaves of plants grown under full sunshine and 30% shading. Positive correlations were observed between gas exchange traits and leaf anatomy. Based on these results, it is possible to conclude that the species used in this study has a great anatomic plasticity in relation to the tested shading levels, supporting in this way a better development of the seedlings under different environmental conditions.

Crescimento inicial de plantas de Cryptocaria aschersoniana Mez. submetidas a níveis de radiação solar

The cultivation of native essences with economical or conservacionist purpose needs a serie of cares that need some previous knowledgment of the physiological and ecologic characteristics of the diverses phases of the life cycle. The study of the growth and development of a plant under different environmental conditions offers to the researcher a good clue on which the best conditions to grow a particular species. It was aimed at to evaluate the initial growth and the concentration of chlorophylls in young plants of Cryptocaria aschersoniana Mez. (Canela-Batalha) submitted to levels of reduction of solar radiation: 0% (full sunlight), or 30, or 50 or 70%. The results demonstrate that the concentration of total chlorophyll was larger in the plants grown under 70% of shading, the same happened with the ratio of chlorophyll a/b. The greatest plant height was observed in the plants grown in 50% of shading. From the standpoint of total biomass accumulated and root dry matter, the best performance was observed in the plants under 30% of shading and the higher leaves dry matter accumulation was verified in the plants grown under 30 and 50% shading. It is ended that the best ones growing conditions for seedlings of Cryptocaria aschersoniana Mez. (Canela-Batalha) were the levels of 30 and 50% of reduction of the incident solar radiation.

Alterações morfológicas e alocação de biomassa em plantas jovens de espécies florestais sob diferentes condições de sombreamento

The selection of native and/or exotic species for recovery of degraded or perturbed environment can be associated with the acclimatation potential of species in different conditions of shading. In this context, the objective of this research was to evaluate the effect of shading (0%, 30% and 50% of interception of the incident solar radiation) on growth, biomass allocation and chlorophyll levels in young plants of forestry species from different ecological groups: Maclura tinctoria (L.) D. Don ex Steud. (moreira), Senna macranthera (Collad.) Irwin et Barn. (fedegoso), Hymenaea courbaril L. var. stilbocarpa (Hayne) Lee et Lang. (jatoba) e Acacia mangium Willd. (acacia). The results obtained showed that the higher chlorophyll levels were observed in shaded conditions for all species. The climax lighting demanding specie (moreira) showed the highest growth. In sunny conditions, the pioneer species (acacia) produced more leaves while the climax light demanding species (moreira) produced more roots. These observations indicated that these species are capable of acclimation to different conditions of radiation availability, a result that should be considered in regeneration programs of degraded environment and management of natural areas.

Germinação in vitro de murici-pequeno (Byrsonima intermedia A. Juss.)

ABSTRACT The murici-pequeno ( Byrsonima intermedia A. Juss.) is a medicinal plant of cerrado that presents difficulties of sexual propagation due to a low rate of seed germination and plant emergency in the field. The objective of this work was study aspects of the in vitro germination of murici-pequeno evaluating the effects of MS and WPM culture media and different concentrations of BAP. Mature fruits were collected from native plants and their seeds and embryos excised and used as explants. The results indicated that the most effective culture media used for the in vitro seed and embryo germination were MS and WPM 50%, both with no sucrose, presenting 60 and 100% germination, respectively. The use of BAP is not required for in vitro embryo germination. Index terms: Germination in vitro , murici-pequeno, medicinal plant, Byrsonima intermedia . (Recebido para publicacao em 23 de outubro de 2003 e aprovado em 13 de agosto de 2004) INTRODUCAO Sao poucos os estudos sobre a germinacao de especies nativas do Cerrado. Com o crescente interesse por parte dos pesquisadores, aos poucos se revela o po-tencial dessa vegetacao (COELHO, 1999). No caso do murici-pequeno (

Alterações morfofisiológicas em folhas de cafeeiro (Coffea arabica L.) consorciado com seringueira (Hevea brasiliensis Muell. Arg.)

One alternative to reduce the effects of the production instability and of the insecurity of world budget over coffee growers is the cultivation of rubber tree intercropped with coffee. However, the productivity of both cultures is affected strongly by the climatic variations and for the crop system. The objective of this research was to perform evaluations of gas exchanges, chlorophyll fluorescence (Fv/Fm ratio) and leaf anatomy of coffee trees in cropped in different systems with rubber tree and environment. Four intercropping systems were studied as described: full sun coffee (C), three coffee cultivation lines between double strip of rubber tree (SSCCCSS), one coffee cultivation line between rubber tree strips (SCS) and three coffee plants for one rubber tree in the same cultivation line (SCSCS). The coffee plants of the (SSCCCSS), (SCS) and (SCSCS) systems showed smaller values of net photosynthesis rate (A), stomatal conductance (gs) and transpiration (E) and highest values of Fv/Fm ratio than that observed for the (C) system. The coffee plants cropped in the (C) system presented the highest average leaf thickness and also the largest thickness of palisade and lacunar parenchymas and stomatal index. These results indicate that coffee leaves have a great anatomic plasticity when cropped at full sun light or under shaded caused by rubber trees.

Efeito da temperatura e do tegumento na germinação de sementes de Calophyllum brasiliense

A crescente demanda por informacoes de especies com potencial para serem implantadas em ambientes degradados, torna fundamental o conhecimento fisiologico da germinacao de sementes, visando sua exploracao mais racional. Objetivou-se neste trabalho, estudar o comportamento da embebicao das sementes, determinar a temperatura otima da germinacao e o efeito da retirada de tegumento sobre a germinacao de sementes de Calophyllum brasiliense Cambess. O teste de germinacao foi realizado em rolos de papel, com quatro repeticoes de 25 sementes, em delineamento inteiramente casualizado. Os resultados da curva de embebicao demonstraram que o envoltorio (endocarpo + tegumento) dificulta a absorcao de agua pela semente. Quanto a temperatura, observou-se uma maior germinabilidade nos regimes termicos de 30oC (constante) e 30/20oC (alternada), sendo que, o maior indice de velocidade de germinacao (IVG) tambem ocorreu a 30oC. As sementes incubadas a 10oC, 15oC e 40oC nao germinaram. Menores valores de tempo medio de germinacao foram observados nos regimes termicos de 30oC, 30/20oC e 35oC. Nao foram verificadas diferencas significativas quanto a germinabilidade das sementes com e sem tegumento, porem, o tegumento reduziu a velocidade de germinacao.

Germinação e armazenamento de sementes de Camboatã (Cupania vernalis Cambess.) sapindaceae

Sementes de Cupania vernalis Cambess. possuem caracteristicas recalcitrantes quando submetidas a secagem, alem de curta longevidade, necessitando da aplicacao de conhecimentos relacionados a fatores que interferem no armazenamento. Objetivou-se com esta pesquisa avaliar as variacoes fisiologicas de sementes de C. vernalis quando submetidas a diferentes temperaturas e teores de agua, durante o armazenamento. No armazenamento, sementes com graus de umidade de 40%, 35% e 30% foram acondicionadas em sacos plasticos e armazenadas sob temperatura controlada de 10oC e 25oC, com umidade relativa de 60%, avaliadas quanto ao grau de umidade, porcentagem de germinacao e indice de velocidade de emergencia, nos tempos de 0, 120 e 240 dias. O tratamento em que as sementes continham 40% de grau de umidade e armazenadas a temperatura de 10oC favorece a conservacao das sementes de C. vernalis.

Crescimento e anatomia foliar de plantas jovens de Mikania glomerata Sprengel (guaco) submetidas a diferentes fotoperíodos

Mikania glomerata Sprengel e uma importante especie medicinal popularmente conhecida como guaco, coracao-de-jesus, guaco-liso, guaco-cheiroso, cipo-caatinga e erva-de-cobra. Foram estudados os fotoperiodos de 8, 12, 16 e 20 horas. Apos 90 dias de tratamento, determinaram-se o peso de materia seca total, particionada (entre folhas, ramos e raizes), area foliar, razao de area foliar, razao de peso foliar e area foliar especifica. O crescimento das plantas variou em funcao do fotoperiodo, havendo um acrescimo na materia seca total e particionada ate 16 horas de fotoperiodo, seguido de uma queda, quando o fotoperiodo foi aumentado de 16 para 20 horas. A area foliar e o numero de folhas foram crescendo ate o fotoperiodo de 20 horas. Houve reducao da area foliar especifica e na razao de area foliar com o aumento do fotoperiodo. Quanto a razao de peso foliar, houve tambem um decrescimo nesse carater quando o fotoperiodo aumentou de 8 para 16 horas; em contrapartida, quando o fotoperiodo aumentou de 16 para 20 horas, houve uma tendencia de aumento. Foi verificado efeito dos tratamentos no espessamento dos tecidos foliares. O fotoperiodo influenciou positivamente as caracteristicas associadas ao crescimento, anatomia foliar e fotossintetica, como producao de biomassa total, area foliar, numero de folhas, particionamento de biomassa para os diversos orgaos da planta.

Efeito da secagem e de diferentes temperaturas na germinação de sementes de Protium widgrenii Engler

Protium widgrenii Engler (Burseraceae) conhecida como almecega-vermelha, e uma especie nativa, ocorrendo desde Minas Gerais ate o Rio Grande do Sul, em quase todas as formacoes florestais e considerada de grande utilidade para plantios mistos destinados a recomposicao de areas degradadas de preservacao permanente. Objetivou-se com este trabalho estudar o efeito da dessecacao e de diferentes regimes termicos sob a germinacao de suas sementes. Foram utilizadas sementes com umidade inicial de 51% e sementes dessecadas a 13% de umidade, as quais foram submetidas a um pre-tratamento a frio (5oC/24 horas) e, posteriormente distribuidas em tres rolos de papel germtest, em câmaras de germinacao do tipo BOD e em diferentes temperaturas (15; 25; 35oC constantes e escuro e, 30-20oC, D/N.). Sementes com 51% de umidade apresentaram maior germinacao a 25oC e menor a 35oC, com menor IVG a 15oC e o maior a 25oC. Com a dessecacao a 13% de umidade, as sementes a 15oC apresentaram menores IVG e germinacao. A porcentagem final de germinacao a 15oC foi maior em sementes com 51% de umidade e IVG menor a 25oC em sementes dessecadas.