Cátia Henriques Callado

Periodicity of growth rings in some flood-prone trees of the Atlantic Rain Forest in Rio de Janeiro, Brazil

Abstract. The periodicity of growth ring formation was studied in Tabebuia cassinoides (Lam.) DC, Tabebuia umbellata (Sond.) Sandwith, Symphonia globulifera L., and Alchornea sidifolia Müll. Arg. in a swamp forest within the Atlantic Rain Forest of the state of Rio de Janeiro, southeastern Brazil. Mechanical wounds of the vascular cambium allowed cyclic growth to be observed, and the position of latewood relative to the wounds was analysed. Radial growth was correlated with phenology, temperature, precipitation, photoperiod, flooding regime, and endogenous rhythms. All species showed annual growth rings; however, there were different patterns of radial growth. Phenology was an important factor influencing the activity of the vascular cambium. The period of leaf abscission was correlated with the formation of latewood in three of the species studied, but it occurred at different times for each species. Flooding was a determinant of periodic growth in T. cassinoides; photoperiod was indirectly responsible for radial growth rhythm in T. umbellata, and endogenous rhythms accounted for the radial growth rhythm of S. globulifera and A. sidifolia.

Annual growth rings in the mangrove Laguncularia racemosa (Combretaceae)

Stem discs from trees of known age were used to determine the periodic nature of the growth rings formed in Laguncularia racemosa and to describe the anatomical features of these rings. The growth rings were scarcely distinct on microscopic examination, but they were well distinguishable macroscopically, with alternating light brown and dark brown layers. Cross-dating analysis revealed the occurrence of annual growth rings in L. racemosa. The existence of annual growth rings in L. racemosa suggests that it may have great potential for dendrochronology and should encourage age-related studies on the dynamics of mangrove forests. These studies can be important for the evaluation of climate change impact on mangrove ecosystems, as well as for the analysis of effects related to climate variability on plant communities.

CAMBIAL GROWTH PERIODICITY STUDIES OF SOUTH AMERICAN WOODY SPECIES – A REVIEW

This paper reviews histological studies of cambium activity in South American woody species and provides future research prospects. The majority of the studies almost exclusively describe radial increment and/or its periodicity. There are 15 papers concerning the cambial activity of 17 woody species from the South American flora and 3 exotic species in 4 countries that were published to date. Despite endogenous factors affecting the radial meristem, the seasonality of rains has been identified as the main factor influencing cambial activity in the tropics and subtropics. There is a lack of standardization and a need for improvement and discussion concerning the methods used. Moreover, radial growth studies conducted by monitoring cambium cell production are still scarce in South America, especially when considering the high diversity of the continent’s flora and ecosystems.

In vitro propagation of Cleome spinosa (Capparaceae) using explants from nursery-grown seedlings and axenic plants

SummaryTwo independent experiments were performed to establish micropropagation of Cleome spinosa from stem segments. In the first experiment, direct shoot organogenesis on hypocotyl explants from 2-mo.-old nursery-grown seedlings was obtained on Murashige and Skoog medium with different combinations of benzyladenine (BA) and 6-furfurylaminopurine, added either individually or in combination. Best proliferation rates occurred in the presence of 2.2 and 4.4 μM BA and the highest mean number of shoots was produced in response to 4.4 μM BA. In the second experiment, regeneration via direct organogenesis was also obtained from nodal and internodal segments of axenic plants cultured in the presence of BA (4.4 and 8.8 μM) in association with indole-3-acetic acid (IAA) (0.57 and 1.14 μM). Internodal explants were the most responsive on all media tested. The best mean number of shoots per explant was achieved on medium with 4.4 μM BA in association with 0.57 μM IAA. Histological studies of the globular structures formed at the apical portion of the explants revealed direct shoot regeneration and adventitious shoot differentiation from meristematic centers around the vascular bundles of the primary regenerants. All shoots elongated and rooted on MS0 medium. The acclimatization rates ranged between 70 and 84%. Plants reached to maturity and flowered 4 mo. after transfer to ex vitro conditions.

ANATOMICAL FEATURES OF GROWTH RINGS IN FLOOD-PRONE TREES OF THE ATLANTIC RAIN FOREST IN RIO DE JANEIRO, BRAZIL

The anatomical features of growth rings of 13 representative species of the swamp forests within the Atlantic rain forest of the State of Rio de Janeiro, southeastern Brazil, were studied. Most species showed distinct rings. The growth ring boundaries were marked by fibrous zones frequently associated with marginal parenchyma bands, and growth ring boundary features were characteristic of the particular families and genera analysed. Leaf fall can be related to the occurrence of growth rings in seven species, whereas in evergreen species growth rings can be related to flooding. In Euphorbiaceae species, flooding regime differences (periodical or permanent) are related to the shape and distribution of new cells produced by the cambium and, thus, growth ring structure.

RADIAL GROWTH DYNAMICS OF TABEBUIA UMBELLATA (BIGNONIACEAE), A FLOOD-TOLERANT TREE FROM THE ATLANTIC FOREST SWAMPS IN BRAZIL

We studied the annual radial growth of Tabebuia umbellata (Sond.) Sandwith (Bignoniaceae) and its relationship to rainfall, temperature, photoperiod, flooding and phenology. This species showed cyclic annual growth. Growth was the greatest during the rainy season and flooding. Growth was associated with the presence of mature leaves on the trees. No increase in girth was observed during the dry season or during defoliation or flowering. The mean rate of radial growth was c. 6 mm/year. This flood-tolerant species maintained and increased radial growth during flooding.

Does growth rhythm of a widespread species change in distinct growth sites

This study is aimed to understand responses in growth rhythm to different climatic conditions of the widespread deciduous species Cedrela odorata. Our own research was conducted in Nova Iguacu. Rio de Janeiro State, Brazil) and compared with literature data from Aripuana. Mato Grosso State, Brazil), Manaus. Amazonas State, Brazil) and Barinas. Barinas State, Venezuela). Growth periodicity was evaluated through leaf phenological behavior and radial growth. In Nova Iguacu, leaf phenology was monitored monthly and radial growth was evaluated by cambial histological analysis of samples collected in wet and dry seasons. In the other sites, the authors evaluated the growth rhythm by dendrometer bands. Growth always occurs in the wet season, even when there is no water deficit during the dry season. Thus, the species is considered conservative concerning the maintenance of growth seasonality. Nevertheless, C. odorata was able to change its growth period, following local seasonality of its different growth sites. Therefore we suggest caution when performing climate analysis from a chronology using trees that grow in different periods of the year.

Studies on cambial activity: advances and challenges in the knowledge of growth dynamics of Brazilian woody species

The lack of specific research on the sequence of events that determine plant growth from meristem until wood formation represents a gap in the knowledge of growth dynamics in woody species. In this work, we surveyed published studies concerning cambial activity of Brazilian native species aiming at allowing the comparison of applied methods and obtained results. The annual cambial seasonality was observed in all the investigated species. Nevertheless, we found high heterogeneity in the used methodologies. As a result from this analysis, our opinion points to the need for standardizing sampling protocols and for discussing the suitability of experimental designs. This will help to define with greater precision the factors that determine the radial growth in the different tropical ecosystems.

Somatic embryogenesis and plant regeneration from callus cultures of Cleome rosea Vahl

This paper describes a protocol for the efficient vegetative propagation of Cleome rosea by somatic embryogenesis. Leaf and stem explants from nursery-grown seedlings of C. rosea were cultivated on Murashige and Skoog (MS) medium supplemented with indole-3-acetic acid (IAA), a -naphthaleneacetic acid (NAA), 4-amino-3,5,6-trichloropicolinic acid (picloram) or 2,4-dichlorophenoxyacetic acid (2,4-D). Nodular calli were produced from both explant types in the presence of 4.5 and 9.0 µM 2,4-D. Embryo development and maturation were achieved when calli from stem explants were transferred to media containing a ten-fold reduction of 2,4-D concentration initially used (0.45 and 0.90 µM). Leaf-derived calli did not form embryos with the same treatments. The highest frequency of embryogenic callus formation (85%) and number of embryo per callus (13.45 ± 2.8) were achieved during the first subculture on medium supplemented with 0.90 µM 2,4-D. Embryo conversion into plantlets was achieved following transfer to growth regulator-free MS medium solidified with 2 g.L-1 phytagel. An acclimatization rate of 53% was found three months after transfer to ex vitro conditions and the recovered plants presented a normal phenotypic aspect.

Wood Anatomy of Some Anaueria and Beilschmiedia Species (Lauraceae)

The wood anatomy of the species Anaueria brasiliensis Kosterm., Beilschmiedia emarginata (Meissn.) Kosterm., B. rigida (Mez) Kosterm. and B. taubertiana (Schw. et Mez) Kosterm. (Lauraceae) is described. The taxonomy and ecology of these species, important components of the Amazonian forest or Atlantic forest of southeastern Brazil, are discussed as related to wood anatomy. The main anatomical differences are: presence, type, arrangement and location of inorganic inclusions and secretory cells, and the arrangement of the axial parenchyma.