Petterson Baptista da Luz

Germinação de sementes de Dypsis decaryi (Jum.) Beentje & J. Dransf. (Arecaceae)

Dypsis decaryi (Jum.) Beentje & J. Dransf. e uma importante palmeira comercializada para fins ornamentais. Embora seja propagada sexuadamente, nao ha informacoes na literatura sobre os fatores que afetam a germinacao das sementes dessa especie. Objetivou-se, neste trabalho estudar o efeito da temperatura e do substrato na germinacao de sementes de Dypsis decaryi. O delineamento experimental foi o inteiramente casualizado em esquema fatorial 6 x 2 (seis temperaturas: 25oC, 30oC, 35oC, 20-30oC e 25-35oC e ambiente combinadas com dois substratos: vermiculita e areia), com 5 repeticoes de 20 sementes. Anotou-se, diariamente, o numero de sementes germinadas adotando como criterio de germinacao a protrusao do botao germinativo. Apos 35 dias houve estabilizacao dos dados e foi calculado o Indice de Velocidade de Germinacao (IVG) e a porcentagem de germinacao (dados transformados em arc sen √x/100) cujas medias foram comparadas pelo teste de Scott-Knott, a 5% de probabilidade. Observou-se que maiores porcentagens de germinacao de sementes de Dypsis decaryi foram obtidas quando colocadas para germinar em areia nas temperaturas ambiente de laboratorio (93%), 25-35oC (92%) e 25oC (86%), e em vermiculita, nas temperaturas de ambiente (91%), 20-30oC (87%), 30oC (83%), 25-35oC (80%) e 25oC (76%). As sementes germinaram mais rapido em condicoes de ambiente de laboratorio independentemente do substrato. Na temperatura de 35oC a porcentagem de germinacao foi bastante reduzida tanto em areia (21%) como em vermiculita (38%); as sementes germinaram mais lentamente e a germinacao foi desuniforme.

Germinação de sementes de dalbergia nigra (Vell.) Allemao ex Benth. (Fabaceae-Papilionoideae) no armazenamento

Dalbergia nigra (Vell.) Allemao ex Benth. (Brazilian rosewood) is a highly economically valuable species because of its wood quality and ornamental potential, mainly due to its well formed canopy and the delicacy of its foliage. Unfortunately, these features contributed to list it as an endangered Brazilian species (IBAMA Regulation number 06/92). This work had as its objective to study the quality of Dalbergia nigra seeds submitted to increasing storage periods. Fruits from trees located at the Botanical Institute of Sao Paulo were collected in October 2003. After harvested, the fruits were sun dried and the seeds manually separated. The seeds were stored in closed transparent plastic bags under refrigeration (6o C ± 2). Monthly, during 690 days, 200 seeds were removed from the refrigerator. One hundred (100) seeds were used in germination tests, which consisted of four repetitions with 25 seeds each; and the other 100 were used in the determination of water content. The germination tests were conducted in a B.O.D. chamber at 25o C under a 12 hour photoperiod. The analyzed variables were; the germination percentage, germination velocity index, and dry mass of the seedlings. The results indicated that after 360 days of storage, the seeds showed germination percentage close to 50% and reduction of the germination velocity index to half, whereas the dry mass accumulation was the most compromised. The initial and final germination percentages were 87% and 36%, respectively. We concluded that Dalbergia nigra seeds present orthodox behavior and can be stored for a period of approximately two years in plastic bags at low temperature, compromising 50% of their germination capacity.

Efeito da aplicação de ácido giberélico no crescimento da palmeira-ráfia

Lady Palm is of great economic importance due its commercial interest. It is an ornamental plant growing in shadowy places, resistant to sun exposure and very appreciated for its beauty and ornamental value. Its commercial value is associated to plant height and shoot number. The aim of this work was to stimulate lady palm growth by applying the plant growth regulator gibberellic acid. Plantlets of R. excelsa approximately one year old were sprayed every 21 days (4 applications) with gibberellic acid solution at concentrations of 0; 75; 150; 225 and 300 mg L-1. The results showed that gibberellic acid was efficient in promoting the growth of the species and was statistically significant for petioles, leaf length and plant height. Petiole dry and fresh mass did not show any significant difference between treatments for stem diameter, with root dry and fresh mass having a higher value for the control than for the 225 and 300 mg L-1 treatments. Due to the higher height and leaf architecture changes observed, gibberellic acid can be used as a tool to stimulate Lady Palm growth, adding commercial value to the plantlets.

Avaliação da qualidade fisiológica de sementes de feijão-caupi pelo teste de condutividade elétrica

Evaluation of cowpea seed quality by electrical conductivity The electrical conductivity of the seed soaking solution is a procedure recommended for the evaluation of vigor in pea and soybean seeds. However, it was not so well established in other species. The objective of this work was to evaluate their effects on physiological quality of cowpea seeds. Four batches of cowpea seeds were tested for germination, first count of germination, germination percentage, emergence percentage, rate of emergence, radicle and variations in electrical conductivity (temperature 25 °C; volumes of 75 mL and 100 mL of water, 25 and 50 seeds, and 2, 4, 8, 12 and 24 hours periods). The experimental design was a completely randomized with four replicates for each treatment. Based on these results, it was found that the electrical conductivity test was efficient in the separation of seed lots according to their vigor levels.

Efeitos de nitrogênio, fósforo e potássio no crescimento de Rhapis excelsa (Thunberg) Henry ex. Rehder (Palmeira-Ráfia)

Rhapis excelsa e uma das palmeiras ornamentais mais cultivadas no mundo, indicadas principalmente para vasos e areas de sombra. A maioria das palmeiras apresenta crescimento lento. O objetivo deste estudo e acelerar o processo de producao de mudas. Analisaram-se os efeitos da adubacao realizada com nitrogenio, fosforo e potassio, sob o crescimento da especie, ao longo de 8 meses. As mudas com altura de 3,80 cm foram plantadas em substrato constituido de partes iguais de terra e vermiculita. Realizaram-se aplicacoes semanais de NPK, diretamente no solo, na concentracao de 10 mg.L-1 de substrato, utilizando-se como fonte: MAP (P), sulfato de amonio (N) e cloreto de potassio (K). Os tratamentos foram constituidos de todas as combinacoes possiveis destes nutrientes, mais uma testemunha. O experimento foi mantido em casa-de-vegetacao com nebulizacao. Avaliaram-se os resultados com base na producao de materia seca da parte aerea e das raizes, area foliar, diâmetro do caule, numero de folhas e altura do estipe. O nutriente que proporcionou um maior desenvolvimento e crescimento da palmeira Rhapis excelsa foi o nitrogenio, influenciando de forma positiva na maioria dos parâmetros analisados. Verificou-se melhor desenvolvimento das mudas com a aplicacao de N, independente da combinacao com P e ou K.