Mauro Vasconcelos Pacheco

GERMINAÇÃO DE SEMENTES E CRESCIMENTO INICIAL DE PLÂNTULAS DE Tabebuia aurea (Silva Manso) Benth. & Hook f. ex S. Moore

Tabebuia aurea is a native arboreal species that can be used in recomposition programs of degradated areas, as ornamental plant and for production of wood of quality. The objectives of this study were to evaluate the effects of the temperature and substrate on seed germination and initial growth of T. aurea seedlings. The experiment was developed in a completely randomized design in factorial scheme 5 x 5 with temperatures of 25, 30, 35, 20-30 and 20-35oC; and substrates: paper towels, and into sand, vermiculite, coconut fiber and Tropstrato®, with four replications of 25 seeds each. The following parameters were also analyzed: germination, first germination count, germination speed index, average time of germination, length and dry weight matter of the shoot and the root.xa0 The temperatures and substrates influenced the analyzed parameters, except for the final percentage of germination, which varied from 84 to 94%. The optimal temperatures for germination were 30 and 35oC. The substrates paper towels roll and sand can be recommended to evaluate the physiological quality of T.aurea seeds.

FENOLOGIA DE Poincianella pyramidalis (TUL.) L. P. QUEIROZ E SUA RELAÇÃO COM A DISTRIBUIÇÃO TEMPORAL DA PRECIPITAÇÃO PLUVIAL NO SEMIÁRIDO BRASILEIRO

A remarkable feature of the Brazilian semi-arid region is its highly irregular distribution of rainfall in space and time, with two marked periods: the rainy season, with erratic precipitation, of highly variable intensity; and the dry season, the critical period of prolonged drought, when the plant species of the Caatinga (desert vegetation found in northeastern Brazil) express their most remarkable trait, the deciduousness. In such conditions, plant species have their dynamics of growth and development in accordance with rainfall events. Thus, the objective of this study was to characterize the phenophases of Poincianella pyramidalis and their relationship with the temporal distribution of rainfall, which takes place in the form of water pulses. For the phenological study, 32 trees were selected, identified and monitored fortnightly on Acude Farm, located in the municipality of Soledade, PB state, Brazil. To quantify the phenological events, Fourniers percent index and the activity index were adopted, recording the presence and absence of the following phenophases: sprouting, appearance of flower buds, flowering (anthesis), fruiting and senescence, whose data were related to the water pulses and inter-pulses. It was found that the sprouting, flower-bud and flowering phenophases in Poincianella pyramidalis happen synchronously with the temporal distribution of rain pulses in its habitat. The intensity and duration of phenophases in the development of Poincianella pyramidalis depend upon the extent and frequency of the water pulses throughout the rainy season. Total leaf senescence in Poincianella pyramidalis occurs when the inter-pulses of rainfall intensify as the dry season progresses, characterizing deciduousness.

BIOMETRIA DE FRUTOS E SEMENTES DE MATRIZES DE Poincianella pyramidalis (TUL.) L.P. QUEIROZ

Estudos para esclarecer os níveis de variabilidade genética e a distribuição em populações naturais de espécies nativas como a catingueira são essenciais para sustentar diretrizes e estratégias de conservação genética (OTSUBO et al., 2015). Neste sentido, a avaliação biométrica de frutos e sementes tem sido um importante instrumento para identificar a variabilidade genética dentro de populações de uma mesma espécie e as relações entre esta variabilidade (GONÇALVES et al., 2013). Além disto, a massa e o tamanho permitem a diferenciação das sementes na formação de lotes mais homogêneos, possibilitando a uniformidade e o aprimoramento da emergência e vigor das sementes (CARVALHO & NAKAGAWA, 2000).

DORMÊNCIA DE SEMENTES E PRODUÇÃO DE MUDAS DE Dimorphandra mollis Benth.

Dimorphandra mollis Benth. is an important native forest species coming from Cerrado and Caatinga due to its economical and ecological use, what justifies the existence of programs of seedling production. This paper aimed to study the efficient methodology to overcome dormancy in seeds and to evaluate, in natural nursery, the effects of distinct substrates and the fertilization on the initial growth of plants. The following treatments applied: T1 - control (seeds whithout scarification); T2 – manual scarification with sandpaper number 50; T3 - immersion in water at 80 and (T4) at 100oC; T5 - boil in water at 100oC for 10, (T6) 30 and (T7) 60 seconds; T8 - chemical scarification with sulfuric acid for 20, (T9) 30 and (T10) 40 minutes. For the seedling production, the experiment was arranged in 4 x 2 factorial, complete randomized design (4 substrates: Tropstrato® pure, and the others: Tropstrato®, coconut fiber and vermiculite with organic compost; without and with fertilization). The best results for overcoming dormancy are obtained with the manual scarification with sandpaper no50 or boil in water at 100oC for 10 seconds. The coconut fiber and the vermiculite with organic compost are good substrates for the seedling production of Dimorphandra mollis .