Geraldo Rogério Faustini Cuzzuol

Erythrina speciosa (Leguminosae-Papilionoideae) under soil water saturation: morphophysiological and growth responses.

BACKGROUND AND AIMS Erythrina speciosa is a Neotropical tree that grows mainly in moist habitats. To characterize the physiological, morphological and growth responses to soil water saturation, young plants of E. speciosa were subjected experimentally to soil flooding. METHODS Flooding was imposed from 2 to 4 cm above the soil surface in water-filled tanks for 60 d. Non-flooded (control) plants were well watered, but never flooded. The net CO(2) exchange (A(CO2)), stomatal conductance (g(s)) and intercellular CO(2) concentration (C(i)) were assessed for 60 d. Soluble sugar and free amino acid concentrations and the proportion of free amino acids were determined at 0, 7, 10, 21, 28 and 45 d of treatments. After 28, 45 and 60 d, dry masses of leaves, stems and roots were determined. Stem and root cross-sections were viewed using light microscopy. KEY RESULTS The A(CO2) and g(s) were severely reduced by flooding treatment, but only for the first 10 d. The soluble sugars and free amino acids increased until the tenth day but decreased subsequently. The content of asparagine in the roots showed a drastic decrease while those of alanine and gamma-aminobutyric increased sharply throughout the first 10 d after flooding. From the 20th day on, the flooded plants reached A(CO2) and g(s) values similar to those observed for non-flooded plants. These events were coupled with the development of lenticels, adventitious roots and aerenchyma tissue of honeycomb type. Flooding reduced the growth rate and altered carbon allocation. The biomass allocated to the stem was higher and the root mass ratio was lower for flooded plants when compared with non-flooded plants. CONCLUSIONS Erythrina speciosa showed 100 % survival until the 60th day of flooding and was able to recover its metabolism. The recovery during soil flooding seems to be associated with morphological alterations, such as development of hypertrophic lenticels, adventitious roots and aerenchyma tissue, and with the maintenance of neutral amino acids in roots under long-term exposure to root-zone O(2) deprivation.

Aspectos nutricionais na vegetação de manguezal do estuário do Rio Mucuri, Bahia, Brasil

The existence of monospecific zones is characteristic of mangroves of the river Mucuri, BA, where Laguncularia racemosa L. and Rhizophora mangle L. occupy regions under higher influence of the tide and Avicennia germinans L. is limited to places with lower salinity. The mangrove vegetation can be classified in riverine forests (margin of the river) and basin forests (interior). Physico-chemical parameters of the sediment and their relationship with the concentration of foliar nutrients were related to the distribution of the species. The results showed that A. germinans dominates sites with lower pH, salinity, charge for cationic exchange and silt values and higher clay content than the other two species. The substract of R. mangle was characterised by higher organic matter and fine sandy structure. Regarding the soil, the riverine and the basin forests presented sandy and loamy soils, respectively. Sediments of A. germinans showed the lowest macronutrient contents while R. mangle showed the highest ones, mainly in the cationic exchanges (K, Ca and Mg). Species restricted to the sites with high macronutrient contents showed lower foliar concentration of chemical elements. A. germinans accumulated higher macronutrient content while L. racemosa and specially R. mangle were higher in micronutrient. Despite of growing in richer substract in Mn, L. racemosa accumulated the smallest contents of this element in leaves. The low values of Fe and Zn concentration factor in R. mangle and of Mn in L. racemosa suggest that these species are more adapted to the occupation of sites with larger concentrations of those micronutrients.

Composição química do sedimento e de folhas das espécies do manguezal do estuário do Rio São Mateus, Espírito Santo, Brasil

We analyzed nutrient concentrations in leaves and sediments, and element accumulation capacity in foliar tissues of Avicennia germinans (L.) Stearn., Avicennia schaueriana Staft & Leechm., Laguncularia racemosa (L.) Gaertn. f. and Rhizophora mangle L. in four sites along the Sao Mateus River estuary mangrove, Espirito Santo State, SE-Brazil. In sediment, elements decrease following the sequence: Mg > Ca > Fe > K > Mn > P > Zn > Cu and showed inter and intraespecific variation. Avicennia leaves showed the greatest N, K and Mg concentrations and lowest Ca concentrations. Rhizophora mangle presented the greatest Mn concentration, and Laguncularia racemosa the greatest Fe level. Sediment nutrient concentrations reflected the influence of granulometry in this compartment. Nutrient accumulation in leaves varied according to species and study site but it was not correlated with sediment concentrations. Results confirmed the mangrove role as a biogeochemistry barrier blocking heavy metal up to tropical coastal areas. However, it is necessary periodic sampling so that it can be possible a better understanding of the nutrient dynamic.

Light as an indicator of ecological succession in brazilwood (Caesalpinia echinata Lam.)

The ecophysiological behavior of brazilwood (Caesalpinia echinata Lam.) plants was evaluated as affected by light quantity and quality. Nine-month-old plants were cultivated under 0%, 50%, and 80% artificial shading, and natural shading imposed by a closed canopy for a period of 392 days. At the end of that period growth parameters were measured, including relative growth rate (RGR), net assimilation rate (NAR), leaf area ratio (LAR), specific leaf mass (SLM) and root:shoot ratio (R:S). Higher leaf area, dry mass and RGR were obtained under 50% artificial shade. Under full sunlight (0% shade), growth was satisfactory showing higher R:S and SLM. Growth was inhibited under 80% artificial and natural shading indicating that C. echinata is not pioneer-succession or climax specie. Simulating a gap, plants cultivated under artificial shade (50%) were transferred to full sunlight for an interval of 192 h, during which net photosynthesis (A), transpiration (E), stomatic conductance (gs), deficit of pressure vapor (VPDleaf-to-air) and the efficiency quantum potential of photosystem II (Fv/Fm) were analyzed. Plants transferred to full sunlight presented severe burning and abscission of the leaflets, as well as inhibition of A and of the photochemical efficiency of PSII (Fv/Fm). This observation associated with the reduced growth under full sunlight and better performance under moderate shade suggests characteristics of intermediate species.

Controle da calogênese do pau-brasil in vitro

The present work dealt with the in vitro control of callogenesis of brazilwood. The induction of callogenesis is the first step to obtain embryos and seeds. In order to control the callogenesis of Caesalpinia echinata, leaf discs of brazilwood in different developmental stages were used combined with the growth regulators 2,4-D (0, 5, 10, 20, 50, 100 mg/L) and 6-BAP (2,0 mg/L), cultivated in the Murashige and Skoog (1962) medium supplemented with sucrose (30 g/L), myo-inositol (100 mg/L) and agar (7,5 g/L). The effect of 6-BAP (0, 0,5, 1,0, 2,0, 5,0 and 10 mg/L) on the growth of meristematic shoot apexes was also tested. Juvenile leaves cultured with low concentrations of 2,4-D (5 and 20 mg/L) and young leaves treated with high concentrations of 2,4-D (50 and 100 mg/L) produced callus, without presenting significant differences between light and dark. As for the oxidation control, the best results were provided by activated charcoal, which inhibited callogenesis. The transfer of callus from the MS culture medium with high concentrations of 2,4-D (5,0, 10,0 and 20,0 mg/L) to the medium without growth regulators stimulated the formation of pro-embryonic masses (PEMs). The media without growth regulators, 2,0 mg/L of 2,4-D and 0,5 mg/L of 2,4-D, increased the number of embryogenic calluses and pre-embryonic masses. There were structures similar to global and heart shaped somatic embryos only at 0,5 mg/L 2,4-D .

Soluções nutritivas para cultivo e produção de frutanos em plantas de Vernonia herbacea

The limited growth of rhizophores of Vernonia herbacea in Hoagland solution demanded the definition of a nutrient solution for plants of V. herbacea, aiming at the increase of the rhizophore biomass and fructan production. This solution, named Vernonia, is comprised of Ca(NO 3 ) 2 .4H 2 O 2.5 mmol L -1 , KNO 3 2.3 mmol L -1 , KH 2 PO 4 0.52 mmol L -1 , Mg(NO 3 ) 2 .6H 2 O 1.7 mmol L -1 and Na 2 SO 4 1.3 mmol L -1 . Its effect on plants was compared to that of Hoagland solution, both with different ionic strengths, 50%, 100% and 200%. The effect of the solutions on plant growth and fructan content was evaluated twice in a six-month period. Plants did not survive up to two months, when cultivated in 200% Hoagland solution. The 50% Vernonia solution was the most effective for rhizophore biomass increase and fructan production per plant. Growth of aerial organs was promoted in 100% Hoagland and Vernonia solutions. Compared to Hoagland, Vernonia solution contains less macronutrients, which confirms the hypothesis that plants adapted to the oligotrophic soils of the cerrado, as V. herbacea, demand less mineral nutrients to achieve full growth.

Growth, photosynthate partitioning and fructan accumulation in plants of Vernonia herbacea (Vell.) Rusby under two nitrogen levels

The effect of two nitrogen concentrations on fructan accumulation and plant growth was analysed in plants of Vernonia herbacea during a year period. Plants of this species accumulate inulin-type fructans in the underground reserve organs (rhizophores). The plants were cultivated in glasshouse conditions and received weekly nutrient solutions containing 1.3 mmol.L-1 NO3- (N-limited) or 10.7 mmol.L-1 NO3- (N-sufficient). Plants treated with N-sufficient solution presented an increase in total growth with higher biomass, more but smaller leaves resulting in higher total leaf area, higher net assimilation rate, specific leaf mass and higher biomass allocation to aerial organs. In addition, these plants presented higher contents of reducing sugars and lower fructan contents. In contrast, N-limited plants showed reduced total growth with lower biomass, higher biomass allocation to underground organs and higher fructan contents. Therefore, although N-limited plants presented a higher fructan concentration, the amount of fructan produced per plant was similar in both N treatments.

Spatial and temporal variation of the nutrients in the sediment and leaves of two Brazilian mangrove species and their role in the retention of environmental heavy metals

A variacao espacial e temporal das concentracoes de nutrientes das folhas e do sedimento entre as raizes de Laguncularia racemosa (L.) Gaertn. f. e Rhizophora mangle L. foi analisada no manguezal do estuario do Rio Sao Mateus, Espirito Santo, Brasil. No tecido foliar, os nutrientes seguiram a ordem: N > Ca > K > Mg > S > P > Fe > Mn > Zn > Cu, havendo diferenca significativa entre especies e sitios de estudo. Em geral, os teores de K foram mais elevados no periodo seco em relacao ao periodo chuvoso, para ambas as especies analisadas, enquanto que Ca e Cu exibiram maiores concentracoes no periodo chuvoso, para Laguncularia racemosa. No sedimento, os nutrientes seguiram a ordem: Mg > Ca > Fe > K > Mn > P > Zn > Cu, em geral, com menores concentracoes no sitio onde o sedimento foi mais arenoso. Registrou-se variacao significativa das concentracoes de nutrientes do sedimento entre os periodos analisados, mas o padrao sazonal nao foi claro para todos nutrientes. Concentracoes de nutrientes determinadas nas folhas de ambas as especies nao se correlacionaram com as concentracoes dos respectivos sedimentos. O fator de concentracao foi menor que 1,0 para Fe e entre 1,0 e 3,7 para Mn, Zn e Cu. Estes resultados fornecem evidencias fisiologicas sobre a relevância destas especies arboreas para o papel dos manguezais como barreira biogeoquimica ao trânsito de metais pesados.

Morphological and physiological adjustments of Brazilwood (Caesalpinia echinata Lam.) to direct solar radiation

This study aimed to characterize the alarm and resistance phases of stress of Caesalpinia echinata under intense irradiance in order to better define its position on forest succession. The alarm phase was identified by rapid reduction in the maximum quantum yield of PSII primary photochemical reactions (ΦP0 = FV/FM) and Performance Index (PIABS) followed by total leaf abscission in the first week of exposure to direct sunlight. The new leaves grown showed recovery of chlorophyll a parameters, increase in blade thickness, elongation of the palisade and spongy parenchymas, higher water content, and reduction of specific leaf area. These changes were associated with the osmoprotector of sucrose and antioxidative of raffinose effects, which indicate an efficient adjustment system to intense irradiance in the resistance phase of stress. However, the continuous decrease in photosynthetic pigments in the resistance phase combined with the photodamage in the fluorescence of Chl a and total abscission of leaves in the alarm phase are strong indications that C. echinata is a shade and late or climax species in forest succession.

Germinação de sementes de Matelea maritima (Jack.) Woods (Asclepiadaceae)

Seeds of M. maritima germinate at an optimum temperature of 25°C, with maximum values in light, the process being optimized by alternate temperatures of 25/35°C. Mechanical scarification promotes germination. In uncoated seeds germination is promoted and enhanced both in light and in darkness. Temperature and time of storage affect seed photosensitivity: positive photoblastism is lost in seeds maintained at room temperature for 90 days while being maintained in seeds kept at low temperature (10°C). The tetrazolium test showed that at 180 days of storage, 46% of the seeds remain viable. Topochemical analysis indicates that the main storage of these seeds located in the cotyledons is protein.