Mineral deficiency symptoms were observed in leaves of yellow passionfruit plantlets grown in MS medium (Murashige and Skoog, 1962) with 1.0 mg l 21 (3.0 mM) gibberellic acid. Initially, leaves showed interveinal chlorosis, followed by bleaching of the leaves and retarded growth. Leaf mineral analysis was done and compared to mineral requirements suggested for passionfruit in the literature. Several modifications were made to the inorganic composition of MS medium, according to mineral deficiencies, mainly of Fe and Ca, and possible toxicity of Cl. The concentration of the elements in the new medium (MSM) was based on the mineral composition of leaves of healthy plants. The chemical equilibrium was checked using the software Geochem (Sposito and Mattigod, 1980) and final adjustments were made to ensure good availability of nutrients. To test the efficiency of the modified medium nodal segments were cultured in both MS and MSM supplemented with 3.0 mg l 21 (13.3 mM) 6-benzyladenine. After three subcultures mineral analysis of the leaves was done. Severe mineral deficiency was observed on the leaves of plantlets cultured in MS, while plantlets cultivated in MSM had green leaves. A comparison of the mineral analysis of plantlets in both media showed a fairly large increase in Ca, Cu, Fe, Mg and S and decrease in levels of B and Cl in plantlets cultivated in MSM. A slight increase or decrease in other elements was also observed. Subculture of the chlorotic plantlets into MSM showed that the visual symptoms of mineral deficiency disappeared in 2±4 wk.
Many different species of Bromeliaceae are endangered and their conservation requires specific knowledge of their growth habits and propagation. In vitro culture of bromeliads is an important method for efficient clonal propagation and in vitro seed germination can be used to maintain genetic variability. The present work aims to evaluate the in vitro growth and nutrient concentration in leaves of the epiphyte bromeliads Vriesea friburguensis Mez, Vriesea hieroglyphica (Carrière) E. Morren, and Vriesea unilateralis Mez, which exhibit slow rates of growth in vivo and in vitro. Initially, we compared the endogenous mineral composition of bromeliad plantlets grown in half-strength Murashige and Skoog (MS) medium and the mineral composition considered adequate in the literature. This approach suggested that calcium (Ca) is a critical nutrient and this was considered for new media formulation. Three new culture media were defined in which the main changes to half-strength MS medium were an increase in Ca, magnesium, sulfur, copper, and chloride and a decrease in iron, maintaining the nitrate:ammonium rate at ≈2:1. The main difference among the three new media formulated was Ca concentration, which varied from 1.5 mm in half-strength MS to 3.0, 6.0, and 12 mm in M2, M3, and M4 media, respectively. Consistently, all three species exhibited significantly higher fresh and dry weight on M4, the newly defined medium with the highest level of Ca (12 mm). Leaf nitrogen, potassium, zinc, magnesium, and boron concentrations increased as Ca concentration in the medium increased from 1.5 to 12 mm.
Conduziu-se este trabalho, em condições de viveiro e de campo para avaliar o efeito do boro sobre o crescimento em altura e diâmetro e a sobrevivência de mudas de eucalipto. O delineamento experimental utilizado foi o de blocos casualizados em esquema fatorial 5 x 2: cinco doses de boro (0, 0,325, 1,3, 5,2 e 20,8 mg L-1) na forma de octaborato e duas espécies de eucalipto (Eucalyptus grandis w. Hill ex Maiden e Eucalyptus saligna Sm), com cinco repetições. Pelos resultados, verifica-se que as mudas cultivadas com 5,2 e 20,8 mg L-1 de B apresentam redução significativa no crescimento em altura e no diâmetro do caule. Nas condições de campo, a aplicação de até 20,8 mg L-1 não afeta a sobrevivência das mudas das duas espécies de eucalipto. Observou que, nas condições de viveiro, o E. saligna é mais sensível à fitotoxidez de boro do que o E. grandis.
, pelas sugestões e criticas ao trabalho. Ao Curso de Pós-Graduação em Ciências Florestais da E.S.A. "Luiz de Queiroz", por esta oportunidade de aprimoramento. Ao Conselho Nacional de Desenvolvimento Científico e Tecnológico, pela concessão de bolsa de estudo. À Smithers-Oasis Company do Brasil, pela doação do OASIS Epuma Floral. Ao técnico de laboratório, José Roberto Romanini, por todo auxílio prestado durante o desenvolvimento do trabalho. Ao Paulo Pomperrnayer Neto, pela valiosa ajuda durante o desenvolvimento do trabalho.
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