Edmilson Bianchini

Anatomia ecológica de Sebastiania commersoniana (Baillon) Smith & Downs (Euphorbiaceae) submetida ao alagamento

In the woods along the Tibagi River hydrographical basin, in areas subject to periodical flooding, the incidence of S. commersoniana is usual, it often becoming the prevailing species. Plants of this species were kept in well drained and flooded soils for two months, in order to explain some aspects of tolerance to waterlogging. After this period, some plants were returned to the well drained soil in order to check the species behaviour in the re-aeration period. In the roots, flooding induced, an increase of intercellular spaces as well as a thickening of the cortex, and a reduction in the thickeness of the central cylinder. Flooded plants grew less than the control ones, and developed hypertrophic lenticels and some adventitious roots. The re-aired plants recovered in growth. It can be suggested that the morphoanatomical modifications observed are important to explain the tolerance of this species to flooding, if we take into consideration the obtained results, together with those obtained in the literature about floristic and phytosociology, as well as in that dealing with biochemistry.

Photosynthesis, growth and development of Tabebuia avellanedae Lor. ex Griseb. (Bignoniaceae) in flooded soil

Foram estudadas as modificacoes morfo-anatomicas e ecofisiologicas que o alagamento provoca em Tabebuia avellanedae Lor. ex Griseb. (Bignoniaceae), correlacionando-as com sua capacidade de tolerar o excesso de agua no solo. Plantas com tres meses de idade, crescendo em casa de vegetacao, foram submetidas a 56 dias de alagamento e a um periodo de pos-alagamento. A taxa fotossintetica e o crescimento de T. avellanedae decresceram conforme aumentou o tempo de alagamento, mas mesmo nao sendo altamente tolerante, a especie foi capaz de se adaptar a curtos periodos de alagamento. Esta relativa tolerância provavelmente se deve a capacidade apresentada por T. avellanedae de desenvolver estruturas que amenizam os efeitos do alagamento, promovendo a difusao interna de oxigenio da parte aerea para as raizes, tais como rachaduras caulinares, raizes superficiais e lenticelas hipertrofiadas nas raizes. Como nao houve acentuada variacao na anatomia interna de folhas e raizes de T. avellanedae, alteracoes metabolicas provavelmente auxiliaram na sobrevivencia da especie durante o alagamento.

Tolerância à inundação de Cecropia pachystachya Trec. (Cecropiaceae): aspectos ecofisiológicos e morfoanatômicos

To elucidate certain aspects of hypoxia tolerance in Cecropia pachystachya, plants were submitted to 30 days of flooding. Growth and development, stomatal conductance, photosynthetic rates and morpho-anatomy were studied. Root and stem relative growth rates (RGR) were lower in flooded plants. There was no difference in leaf RGR and whole plant RGR. The maintenance of leaf RGR is possibly related to greater sclerophylly in flooded plants. Stomatal conductance and photosynthetic rate decreased due to flooding. Stems and roots, especially the latter, showed morpho-anatomical alterations in flooded plants. The results so far suggest that flood tolerance in C. pachystachya is related to the capacity to maintain satisfactory energy production. The maintenance of a positive energy balance allows this species to maintain a substantial RGR, even under stress with a lower photosynthetic rate. Therefore C. pachystachya may be a strong competitor in flooded areas.

ADAPTATIONS TO FLOODING BY TROPICAL TREES: MORPHOLOGICAL AND ANATOMICAL MODIFICATIONS

Many plant communities subjected to flooding are found in tropical regions and are rich in tree species. Little is known about the flood-tolerance mechanisms these species have developed. However, studies have shown that metabolic, morphological and anatomical adaptations are all important for the survival of these plants in oxygen-deficient conditions. Lenticels hypertrophy, aerenchyma formation, stem hypertrophy and the formation of adventitious roots are among the morphological and anatomical adaptations caused by flooding. These modifications enhance the oxygenization of submerged roots, permitting sufficient energy production for survival. Ethylene, which increases markedly in flooded plants, seems to be the main hormone involved in bringing about these morphological modifications. In the case of the initiation and development of adventitious roots there is a synergism between ethylene and auxin. Broader studies are now necessary to improve the understanding of these questions because of the complexity of the responses of tropical tree species to flooding.

Antimicrobial activity of essential oils from Pimenta pseudocaryophyllus and Tynanthus micranthus

The present study describes the chemical composition and antimicrobial activity of essential oils obtained by hydrodistillation from the leaves of Pimenta pseudocaryophyllus (1.0% w/w) and Tynanthus micranthus (1.1% w/w). GC and GC/MS analysis demonstrated that eugenol was the only component in the T. micranthus essential oil (99.9%) and the major component in the P. pseudocaryophyllus essential oil (92.59%), which also presented methyleugenol, terpinen-4-ol, o-cymene and (E)-caryophyllene, among others. Both the oils presented antimicrobial activity against bacteria, yeast and filamentous fungi tested.The Bioautography test revealed that eugenol was the bioactive component in both the oils against Cladosporium herbarum. This is the first report about the T. micranthus essential oil, and the antifungal activity of P. pseudocaryophyllus. The results confirmed the potential of eugenol-rich essential oils not only as a source of flavor compounds, but also of use as antimicrobial agent in agriculture and in pharmaceutical and food products.

Aspectos morfo-anatômicos e fisiológicos de Peltophorum dubium (Spr.) Taub. submetida ao alagamento e à aplicação de etrel

The effects of flooding and ethrel application on P. dubium for a 70-day period were studied in order to elucidate the aspects of plants tolerance to hypoxia. During the experiment the thickness of the stem base, and the allocation of dry matter for the roots, stems and leaves were evaluated. Flooding increased both the thickness of the stem base as well as a great hypertrophy of the lenticels. The ethrel application did not induce the formation of adventitious roots, but it stimulated the hypertrophy of lenticels. The flooding and/or ethrel application significantly affected the growth and development of the plants. This effect was greater in the flooded plants which had their lenticels sealed. The results show that P. dubium can tolerate periods of flooding, possibly because of the morpho-anatomic modifications induced by variations in the hormone levels, led by ethylene.

Metabolismo respiratório de raízes de espécies arbóreas tropicais submetidas à inundação

Aiming at elucidating certain aspects of the respiratory metabolism of roots of flood-tolerant tropical tree species (Lonchocarpus muehlbergianus, Sebastiania commersoniana and Sesbania virgata) as well as flood-intolerant species (Peltophorum dubium and Schinus terebinthifolius), plants were submitted to 2, 10 and 60 days of flooding. After these periods, the absorption of O2 and liberation of CO2 by the roots were determined. The respiratory metabolism of the roots of tolerant species presented a drop due to flooding. Only S. commersoniana presented a recovery in respiration after 60 days of flooding. The intolerant species S. terebinthifolius did not present alterations caused by flooding in its aerobic metabolism, whereas P. dubium, also intolerant, presented a drop in the absortion of O2 with two days of hypoxia, and recovery after 60 days. The liberation of CO2 in the tolerant species followed the same pattern of O2 absorption, with the exception of S. commersoniana, which presented a reduction in the liberation of CO2 after 60 days of flooding similar to what happened to P. dubium. In S. terebinthifolius there was no significant reduction with flooding. The difficulty in establishing a difference pattern in the respiratory metabolism of the species studied, concerning tolerance to flooding, emphasizes the complexity of tropical plant responses.

Produção de serapilheira e ciclagem de nutrientes de um reflorestamento e de uma floresta estacional semidecidual no sul do Brasil

A producao, o conteudo de N, P, K, Ca e Mg, a transferencia de nutrientes e a taxa de decomposicao da serapilheira foram estudados em uma Floresta Estacional Semidecidual e em um reflorestamento situado adjacente a esta no Parque Estadual Mata dos Godoy, Estado do Parana, Brasil. A deposicao anual de serapilheira foi estimada em 8.212 kg.ha-1.ano-1 na floresta e 5.341 kg.ha-1.ano-1 no reflorestamento. A floresta apresentou nos dois meses apos a seca (setembro e outubro) maior deposicao. Nas duas areas a media anual da concentracao de macronutrientes em g.kg-1, obedeceu a mesma ordem na floresta Ca(31,85) > N(19,94) > K(7,14) > Mg(2,28) > P(0,217) e no reflorestamento Ca(23,02) > N(19,62) > K(7,67) > Mg(1,74) > P(0,302). No reflorestamento a transferencia de nutrientes variou mais durante o ano e a taxa de decomposicao foi menor.

Tolerância à inundação: aspectos da anatomia ecológica e do desenvolvimento de Sesbania virgata (Cav.) Pers. (Fabaceae)

Twenty days seedlings of Sesbania virgata (Cav.) Pers. (Fabaceae) cultivated in green house were flooded by forty days. Flooded plants presented increasing of dry weight and lenght, evident cortical fissures and spongy cortical swelling on the stem basis and root, superficial roots on the soil and adventitious roots. It is possible that the morpho-anatomic plasticity presented by this specie is contribuiting for its hipoxic soils stablishment.

Morphoanatomy and ecophysiology of tree seedlings in semideciduous forest during high-light acclimation in nursery

The recomposition of deforested environments demands the acclimation of seedlings in nurseries. This process induces changes in physiological, anatomical, and morphological traits of plants, favouring their establishment after transplantation to the field. The present study aimed to verify the influence of full-sun acclimation on seedling hardiness. For the purpose, leaf gas-exchange, plant anatomical and morphological parameters of three tree species [Ceiba speciosa (A. St.-Hil.) Ravenna (Malvaceae), Croton floribundus Spreng. (Euphorbiaceae), and Cecropia pachystachya Trecul (Urticaceae)], which are used for reforestation in the Brazilian Atlantic biome, were evaluated. Seedlings were grown under 40% of total PPFD (shaded control) and under full sun (acclimated) for 168 days. The acclimation process induced a higher leaf production rate in C. speciosa and C. floribundus, whereas C. pachystachya seedlings replaced their leaves quickly, irrespective of the light conditions. The newly developed leaves of all three species presented a lower area and thicker palisade parenchyma, resulting in a reduced specific leaf area. The seedlings of C. speciosa and C. pachystachya showed increases in light-saturated net photosynthesis and transpiration rates, whereas water-use efficiency generally remained unchanged in all three species. The full-sun acclimated seedlings of C. pachystachya showed a reduced relative growth rate, lower height/stem diameter (H/D) and shoot to root dry mass ratios, characteristics that may result in greater physical resistance and ability for water and nutrient uptake to support the higher transpiratory demand under full sun. The reduction of the H/D ratio also occurred in the acclimated seedlings of C. speciosa. The seedlings of C. floribundus showed few changes during acclimation, but they did not seem to be affected by excessive light. In spite of the observed differences among the three species, all of them developed hardiness characteristics, mainly related to leaf anatomy, which should favour their establishment after transplantation to the field.