Seed morphoanatomy of the genus Passiflora L. (Passifloraceae) by scanning electron microscopy and light microscopy.

Morphoanatomical analysis of seeds contributes to knowledge of the development of seedlings and identification of species, as well as supporting conservation studies. The conservation of the species belonging to the Passiflora genus is crucial due to of the threats to the genetic resources of these species. Thus, the objective of this study was to morphoanatomically characterize Passiflora seeds, verify possible injuries to the tissues after cryopreservation and thus contribute to the conservation strategies of the species of this genus. Initially, seeds of Passiflora coccinea, P. edulis, P. gibertii, P. maliformis, P. morifolia, P. setacea, P. suberosa, and P. tenuifila collected from the Passion Fruit Active Germplasm Bank of the Embrapa Cassava and Fruits research unit (Embrapa Mandioca e Fruticultura) were analyzed. Then, their length, width and thickness, shape of the base and tip, and ornamentations present on the body and edge of the seeds were evaluated. The seeds of the species were placed in cryotubes and immersed in liquid nitrogen to assess possible cryoinjuries. The tegument and tissues of the seeds were examined by scanning electron microscopy. The seeds had varied biometric data, with average values of 4.63 mm for length, 3.28 mm for width, and 1.51 mm for thickness. Six ornamentation types were observed: reticulate for the species P. coccinea; finely reticulate for P. edulis; foveolate reticulate for P. gibertii and P. setacea; alveolate reticulate for P. maliformis and P. tenuifila; coarsely reticulate for P. morifolia; and falsifoveolate reticulate for P. suberosa. Some seeds suffered tegument cracks due to the freezing in liquid nitrogen, but without physiological damages to the embryo and endosperm. The cryopreservation of the seeds in the presence of the tegument significantly reduced the cryoinjuries caused to the embryo. Cryopreservation can be promising for long-term conservation of passion fruit seeds.

Cryopreservation and germinative behavior of Passiflora spp. seeds.

Cryopreservation is an interesting strategy for the long-term conservation of the seeds of the majority of cultivated plants as well as many of the corresponding wild parents. The objective of this study was to evaluate the response of the seeds of different passion fruit species to cryopreservation, as well as to apply multivariate tools to better understand the germinative behavior after thawing, to support the application and repeatability of these methods with other Passiflora species. Seeds of P. coccinea, P. edulis, P. gibertii, P. maliformis, P. morifolia, P. setacea, P. suberosa and P. tenuifila were submitted to cryopreservation, and after thawing the following variables were analyzed: emergence percentage (%); mean emergence time (days); mean emergence speed (plantlets.day-1); uncertainty (bit); and synchrony (bit). We applied multivariate analysis of variance (MANOVA) and canonical discriminant analysis (CDA) to the data. The seeds of all the species withstood the freezing well, indicating that cryopreservation is a viable alternative for long-term conservation of Passiflora genetic material. The emergence percentage, average emergence speed and average emergence time were the variables that contributed the most to separation of the species in the first canonical discriminant function (Can1). The seeds of the species studied were found to be tolerant to desiccation because they remained viable even with low water content. The results showed that seeds could be cryopreserved successfully both with and without prior desiccation.

Overcoming dormancy in stored and recently harvested Passiflora cincinnata Mast. seeds / Superação de dormência em sementes de Passiflora cincinnata Mast. armazenadas e recém-colhidas

The treatment of seeds using growth regulators can overcome seed dormancy and increase the emergence and development of seedlings. The objective of this research was to evaluate the effect of different concentrations of GA4+7 + N-(phenyl methyl)-aminopurine on the dormancy breaking of Passiflora cincinnata Mast. seeds recently harvested and stored for six years. The study was conducted in a greenhouse at Embrapa Cassava and Tropical Fruits, in completely randomized design, in a 2 x 4 factorial scheme, with the following factors: year of seed harvest (2010 and 2016) and the emergence promoter GA4+7 + N-(phenyl methyl)-aminopurine at four concentrations (0%; 0.03%; 0.45% and 0.90%), with 4 replicates of 25 seeds. Emergence percentage, first count, emergence speed index, number of leaves, root length, stem diameter, dry matter of shoots, roots and total, and root/shoot ratio were evaluated. The results showed that GA4+7 + N-(phenyl methyl)-aminopurine is recommended to overcome dormancy of Passiflora cincinnata in recently harvested seeds (2016) and increase the emergence of seedlings from seeds stored for six years in cold chamber (2010). The emergence promoter concentration of 0.03% can be used to overcome dormancy in recently harvested seeds and maintains the vigor of seeds stored for six years. Passiflora cincinnata seeds remain physiologically viable for six years and their emergence is potentiated by the use of GA4+7 + N-(phenyl methyl)-aminopurine.

O tratamento de sementes com reguladores de crescimento pode superar a dormência das sementes, aumentar o vigor e o desenvolvimento das mudas. O objetivo desta pesquisa foi avaliar o efeito de diferentes concentrações de GA4 + 7 + N- (fenilmetil) -aminopurina na quebra de dormência de sementes de Passiflora cincinnata recentemente colhidas e armazenadas por seis anos. O estudo foi conduzido em uma estufa na Embrapa Mandioca e Fruticultura, em delineamento inteiramente casualizado, em esquema fatorial 2 x 4, com os seguintes fatores: ano de colheita de sementes (2010 e 2016) e promotor de emergência GA4 + 7 + N - (fenilmetil) - aminopurina em quatro concentrações (0%; 0,03%; 0,45% e 0,90%), com 4 repetições de 25 sementes. Foram avaliados a porcentagem de emergência, a primeira contagem, o índice de velocidade de emergência, o número de folhas, o comprimento da raiz, o diâmetro do caule, a matéria seca da parte aérea, das raízes, total e a relação raiz/parte aérea. O GA4 + 7 + N - (fenilmetil) - aminopurina é recomendado para superar a dormência de Passiflora cincinnata em sementes recentemente colhidas (2016) e aumenta a emergência de sementes armazenadas por seis anos em câmara fria. A concentração do promotor de emergência de 0,03% pode ser usada para superar a dormência em sementes recentemente colhidas e potencializa o vigor das sementes armazenadas durante seis anos. As sementes de Passiflora cincinnata permanecem fisiologicamente viáveis por seis anos e seu vigor é potencializado pelo uso de GA4 + 7 + N - (fenilmetil) - aminopurina.