Especies de lianas da Reserva Municipal de Santa Genebra, Campinas-SP : longevidade das sementes e crescimento inicial

AUTOR(ES)
DATA DE PUBLICAÇÃO

1997

RESUMO

Lianas (climbers) are plants that rely on mechanical support to grow taller. They are copious in natural and man-made clearings. The objectives of this study were: a) to verify the germination and viability of seeds stored in natural conditions, under the forest canopy (RSG). b) to observe the initial growth of seedlings maintained under full sunlight and shaded conditions (under vegetation canopies). The species studied in this work were: Aristolochia galeata, Bidens brasiliensis, Byttneria catalpifolia, Canavalia parviflora, Chamissoa altissima, Cissus sicyoides, Dalechampia pentaphylla, Dicella bracteosa, Dioscorea sp., Gouania virgata, Mascagnia anisopetala, Mutisia coccinea, Oxypetalum molle, Pithecoctenium crucigerum, Rhynchosia phaseoloides, Serjania multiflora, Solanum flaccidum. Ripe fi-uits were collected in the forest and germinated in Petri dishes at of 25°C in continuous light. For seed longevity, the diaspores were placed in aluminium trays with sterilized soil (three replicates for each species). At regular times, the trays were analysed for germinated, lost through predatory action and apparently viable seeds. To study the initial growth of the seedlings, lots of all these species were maintained in two conditions: forest edge and closed forest (shaded conditions). Most of the seeds germinated in adequate conditions of moisture, light and temperature of 25°C, except S. flaccidum which presented low germination. Physical dormancy was observed in B. catalpifolia,C. parviflora, C. sicyoides, D. pentaphylla, G. virgata, M coccinea, O. molle, and R. phaseoloides. Under the canopy, seeds of A. triplinervia and D. bracteosa showed high germination forming a carpet of seedlings. Hard coated seeds presented a high percentage of viability in natural conditions as for example: B. catalpifolia, C.parviflora, C. sicyoides, D. pentaphylla, G. virgata and R. phaseoloides. Althougth the seeds of G. virgata and D. pentaphylla present a hard tegument, they suffered a high rate of predation. Seedlings of the studied lianas showed high rates of growth in full sunlight when compared to those under canopy (low PPFD). It was noted that at the edge of the forest, B. brasiliensis presented a high increment of dry mass, while in Dioscorea sp. this increment was low. Under the forest, C. parviflora and O. molle attained a high accumalation of dry mass, and both produced a volute stem. Most of the species presented higher growth of the shoot than roots, except in D. bracteosa and Dioscorea. But in general no significative differences between root/shoot were found in both treatments. Although the lianas are considered heliophytes, most of the studied species survived under deep shaded forest for approximately 100 days. Nevertheless, B. brasiliensis, C. sicyoides, M. coccinea and P. crucigerum showed a high mortality rate under this condition

ASSUNTO(S)

plantas - crescimento longevidade clorofila sementes

ACESSO AO ARTIGO

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