Robério Anastácio Ferreira

Vigor e viabilidade de sementes de Senna multijuga (Rich.) Irwin et Barn. e Senna macranthera (Collad.) Irwin et Barn.; num banco de sementes em solo de viveiro

Seed viability of tropical forest species in seed soil banks is not well known. This research aimed to evaluate the seed vigour and potential viability of S. multijuga and S. macranthera in direct sowing under nursery conditions and to test the efficiency of the tetrazolium test to determine quickly the seed viability of these species. The germination test, tetrazolium test and seedling emergence test can be used to evaluate seed viability of two species. The tetrazolium test (concentration 0,075%, and 30oC) was also used to evaluate the potential viability at 6, 12 and 18 months from seeds in a soil bank. S. multijuga seeds presented 93,1%; 65,3%; 52,5% and 17,7% potential viability at sowing and after 6, 12 and 18 months, in the soil bank respectively, and S. macranthera presented 79,3%; 73,9%; 32,5% and 14,7% at sowing and after 6, 12 and 18 months in soil bank, respectively. The species studied had typical behavior of a persistent seed bank.

Morfologia de frutos, sementes, plântulas e plantas jovens de Dimorphandra mollis Benth. - faveira (Leguminosae-Caesalpinioideae)

Foram estudados os aspectos morfologicos externos e internos do fruto e da semente, alem de aspectos externos do processo germinativo e das fases de plântula e planta jovem de Dimorphandra mollis Benth. O trabalho foi realizado em laboratorio e casa de vegetacao, sendo observado que os frutos sao indeiscentes, as sementes sao albuminosas, a germinacao e epigea fanerocotiledonar e, na fase de planta jovem, ocorre um espessamento das raizes primaria e secundarias. Os resultados apresentados podem ser uteis em estudos taxonomicos, em trabalhos de laboratorio e viveiro, bem como para estudos de regeneracao natural.

Aspectos morfológicos de plântulas e mudas de trema

O conhecimento dos caracteres morfologicos de plântulas e mudas e de grande importância em trabalhos de laboratorio, viveiros de producao de mudas e estudos de avaliacao da regeneracao natural, facilitando assim, o reconhecimento e a identificacao das especies. Neste sentido, os objetivos deste trabalho foram descrever e ilustrar os aspectos morfologicos externos do desenvolvimento de plântulas e mudas de trema (Trema micrantha (L.) Blum.) - ULMACEAE, para fins de identificacao taxonomica. O reconhecimento taxonomico da especie e possivel por meio dos caracteres morfologicos externos, seja a partir da plântula ou da muda. Aspectos como a germinacao fanerocotiledonar e a modificacao da filotaxia, passando de protofilos opostos para metafilos alternos sao importantes para a identificacao da especie.

Longevidade de sementes de mutamba (Guazuma ulmifolia Lam. - Sterculiaceae) no solo em condições naturais

The objective of this research was to evaluate the seed viability of mutamba (G. ulmifolia) at different times of burying and depth in the soil in an induced soil seed bank. A randomized block design was used in a 3 x 3 factorial scheme with four plots. The treatments used were three soils depths (0, 2 and 4cm) and three times (3, 4 and 5 months after burying). Each plot had 500 seeds in a bag (10x10cm) buried in nursery soil. The evaluations were seed viability with intact seed, using germination tests, obtaining the number of root emergences, normal seedlings and hard seeds. Further, the number of losses in the soil seed bank were evaluated. The results obtained showed that the mutamba seeds (G. ulmifolia) could stay viable in the soil seed bank after 5 months (25% of total seed buriying showing 72% viability). Seeds on the soil surface and 2cm deep had better average of root emergence and normal seedling percentage than that 4cm deep. The percentage of losses in soil seed bank is 61%, regardless of depth or time.