GA4+7+ N-(Fenilmetil)-aminopurina na germinação de sementes e emergência de plântulas de Passiflora cincinnata Mast.

A espécie Passiflora cincinnata Mast. é silvestre, não-comercial, conhecida popularmente como maracujá-do-mato. Pode ser aproveitada como planta ornamental ou medicinal, além de ser comestível e ser considerada potencialmente importante para uso como porta-enxerto. O trabalho foi realizado no Departamento de Botânica, Instituto de Biociências da Unesp, Câmpus de Botucatu-SP, e objetivou avaliar o efeito dos reguladores vegetais GA4+7 + N-(fenilmetil)-aminopurina na germinação de sementes, emergência e desenvolvimento de plântulas de P. cincinnata Mast.. As sementes foram obtidas junto à Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA) Semi-Árido a partir de plantas cultivadas no Campo Experimental da Caatinga, Petrolina-PE. Foram realizados dois experimentos, sendo o primeiro em laboratório, para estudo da germinação, e o segundo em casa de vegetação, para estudo da emergência e desenvolvimento das plântulas. em ambos os experimentos, foi utilizado o delineamento experimental inteiramente casualizado, cada um com 11 tratamentos de diferentes concentrações de GA4+7 + N-(fenilmetil)-aminopurina (zero; 100; 200; 300; 400; 500; 600; 700; 800; 900 e 1.000 mg L-1) e cinco repetições cada. Para análise dos dados, foram utilizadas análise de variância e análise de regressão. Com base nos resultados obtidos, concluiu-se que os reguladores vegetais, G A4+7 + N-(fenilmetil)-aminopurina, incrementaram o processo germinativo, bem como a emergência e o desenvolvimento de plântulas de P. cincinnata Mast..

Fotoperíodo, temperatura e reguladores vegetais na germinação de sementes de Passiflora cincinnata Mast.

A espécie Passiflora cincinnata Mast., pertencente à família Passifloraceae, é silvestre e popularmente conhecida como maracujá-do-mato, sendo considerada importante na produção de porta-enxertos, uma vez que é tolerante à seca, a doenças causadas por bactérias e a nematóides, além de poder ser utilizada em programas de melhoramento genético. O trabalho teve como objetivos estudar o efeito da luz e da temperatura e a interação entre temperatura e reguladores vegetais na germinação de sementes de Passiflora cincinnata Mast. Foi constituído de três experimentos: no primeiro, estudou-se o efeito da luz e da temperatura na germinação de sementes; no segundo, o efeito de diferentes concentrações dos reguladores vegetais GA4+7 + N-(fenilmetil)-aminopurina na germinação das sementes e, no terceiro, a interação entre temperatura e reguladores vegetais na germinação das sementes. O delineamento experimental foi inteiramente casualizado para todos os experimentos e os dados foram submetidos à análise de variância e comparação das médias pelo teste Tukey, a 5% de probabilidade. É possível observar que a luz exerce efeito inibitório sobre a germinação das sementes, e que os reguladores vegetais, GA4+7 + N-(fenilmetil)-aminopurina, são eficientes na superação da dormência, além de ampliarem os limites de temperatura da germinação. A temperatura alternada 20-30ºC mostra-se a mais adequada para a germinação de sementes dessa espécie.

Potencial de inibição da regeneração de raízes e plântulas em sementes germinantes de Eugenia pyriformis

O objetivo deste trabalho foi avaliar o potencial de inibição da formação de raízes e plântulas, em sementes germinantes de uvaieira (Eugenia pyriformis), fragmentadas e fissuradas. As sementes foram separadas por tamanho em dois grupos. Cada grupo foi separado em dois subgrupos, um dos quais foi submetido a teste de germinação. As sementes de cada subgrupo foram submetidas a dois tipos de incisão (total ou parcial) e, em seguida, foram avaliadas quanto à produção de raízes e plântulas. em sementes com incisão parcial, que apresentavam apenas uma plântula desenvolvida, completou-se a incisão até que as metades fossem separadas. A metade com a raiz foi descartada, e sua complementar foi colocada para germinar, para avaliação da produção de raízes e plântulas nessas frações sem raízes. em todos os experimentos, utilizou-se o delineamento inteiramente casualizado, em arranjo fatorial 2x2 (tamanho das sementes x germinação visível) e 2x4 (tamanho das sementes x tipo de incisão). As sementes fracionadas de uvaieira apresentam potencial para regeneração de raízes e plântulas, e podem produzir mais de uma muda por semente. A germinação inicia processos de inibição da regeneração de novas raízes e plântulas na semente, e a incisão dos cotilédones pode bloquear essa inibição.

The development of seedlings from fragments of monoembryonic seeds as an important survival strategy for Eugenia (Myrtaceae) tree species

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

The Antigerminative Activity of Twenty-Seven Monoterpenes

Monoterpenes, the main constituents of essential oils, are known for their many biological activities. The present work studied the potential biological activity of twenty-seven monoterpenes, including monoterpene hydrocarbons and oxygenated ones, against seed germination and subsequent primary radicle growth of Raphanus sativus L. (radish) and Lepidium sativum L. (garden cress), under laboratory conditions. The compounds, belonging to different chemical classes, showed different potency in affecting both parameters evaluated. The assayed compounds demonstrated a good inhibitory activity in a dose-dependent way. In general, radish seed is more sensitive than garden cress and its germination appeares more inhibited by alcohols; at the highest concentration tested, the more active substances were geraniol, borneol, (+/-)-beta-citronellol and alpha-terpineol. Geraniol and carvone inhibited, in a significant way, the germination of garden cress, at the highest concentration tested. Radicle elongation of two test species was inhibited mainly by alcohols and ketones. Carvone inhibited the radicle elongation of both seeds, at almost all concentrations assayed, while 1,8-cineole inhibited their radicle elongation at the lowest concentrations (10(-5) M, 10(-6) M).

Reproductive biology and recruitment of Xiphopenaeus kroyeri in a marine protected area in the Western Atlantic: implications for resource management

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Forest fragment size and microhabitat effects on palm seed predation

The establishment of plant species depends crucially on where the seeds are deposited. However, since most studies have been conducted in continuous forests, not much is known about the effects of forest fragmentation on the maintenance of abiotic and biotic characteristics in microhabitats and their effects on seed survival. in this study, we evaluated the effects of forest fragmentation on the predation upon the seeds of the palm Syagrus romanzoffiana in three microhabitats (interior forest, forest edge and gaps) in eight fragments of semi-deciduous Atlantic forest ranging in size from 9.5 ha to 33,845 ha in southeastern Brazil. Specifically, we examined the influence of the microhabitat structure, fauna and fragment size on the pattern of seed predation. Fragments < 100 ha showed similar abiotic and biotic characteristics to those of the forest edge, with no seed predation in these areas. Forest fragments 230-380 ha in size did not present safe sites for S. romanzoffiana seed survival and showed high seed predation intensity in all microhabitats evaluated. In fragments larger than 1000 ha, the seed predation was lower, with abiotic and biotic differences among gaps, interior forests and forest edges. In these fragments, the survival of S. romanzoffiana seeds was related to squirrel abundance and interior forest maintenance. Based on these results, we concluded that there are no safe sites for S. romanzoffiana seed establishment in medium- and small-sized fragments as result of the biotic and abiotic pressure, respectively We suggest that on these forest fragments, management plans are needed for the establishment of S. romanzoffiana, such as interior forest improvement and development in small-sized sites in order to minimize the edge effects, and on medium-sized fragments, we suggest post-dispersal seed protection in order to avoid seed predation by vertebrates. our findings also stress the importance of assessing the influence of forest fragmentation on angiosperm reproductive biology as part of the effective planning for the management of fragmented areas. (c) 2006 Elsevier Ltd. All rights reserved.

Spatial variation in post-dispersal seed removal in an Atlantic forest: Effects of habitat, location and guilds of seed predators

Studies of post-dispersal seed removal in the Neotropics have rarely examined the magnitude of seed removal by different types of granivores. The relative impact of invertebrates, small rodents, and birds on seed removal was investigated in a 2,178 ha Atlantic forest fragment in southeastern Brazil. We used popcorn kernels (Zea mays-Poaceae) to investigate seed removal in a series of selective exclosure treatments in a replicated, paired design experiment that included forest understory, gaps, and forest edge sites. We recorded the vegetation around the experimental seed stations in detail in order to evaluate the influence of microhabitat traits on seed removal. Vertebrate granivores (rodents and birds) were surveyed to determine whether granivore abundance was correlated with seed removal levels. Seed removal varied spatially and in unpredictable ways at the study site. Seed encounter and seed use varied with treatments, but not with habitat type. However, seed removal by invertebrates was negatively correlated with gap-related traits, which suggested an avoidance of large gaps by granivorous ants. The abundance of small mammals was remarkably low, but granivorous birds (tinamous and doves) were abundant at the study site. Birds were the main seed consumers in open treatments, but there was no correlation between local granivorous bird abundance and seed removal. These results emphasize the stochastic spatial pattern of seed removal, and, contrary to previous studies, highlight the importance of birds as seed predators in forest habitats. (c) 2007 Elsevier Masson SAS. All rights reserved.

Seed deposition patterns and the survival of seeds and seedlings of the palm Euterpe edulis

The seed deposition pattern created by a seed disperser is one of the components of the efficiency of a species as seed disperser, and ultimately may influence the recruitment of a plant species. In this study, we used the seeds of a bird-dispersed forest palm, Euterpe edulis, to investigate the effects of two distinct seed deposition patterns created by birds that defecate (clumped pattern) and regurgitate seeds (loose-clumped pattern) on the survival of seeds experimentally set in an E. edulis-rich site, and of seedlings grown under shade-house conditions. The study was conducted in the lowland forest of Parque Estadual Intervales, SE Brazil. Clumped and loose-clumped seeds were equally preyed upon by rodents and insects. Although clumped and isolated seedlings had the same root weight after 1 year, the isolated seedlings survived better and presented more developed shoots, suggesting intraspecific competition among clumped seedlings. Our results indicate that animals that deposit E. edulis seeds in faecal clumps (e.g. cracids, tapirs) are less efficient seed dispersers than those that regurgitate seeds individually (e.g. trogons, toucans). Intraspecific competition among seedlings growing from faecal clumps is a likely process preventing the occurrence of clumps of adult palms. (C) 2001 Editions scientifiques et medicales Elsevier SAS.

Aspirin increases tolerance to high temperature in seeds of Raphanus sativus L. cvar Early Scarlet Globe

The incubation of seeds of Raphanus sativus L. cvar Early Scarlet Globe with 10 mu M aspirin resulted in increase in the temperature range for germination. The analysis of percentage germination and germination rates indicated the increase in the optimum temperature from 21.4 to 26 degrees C although at 32.6 degrees C 80.8% of seeds germinated with aspirin and no germination in the control. The analysis of the kinetics of seed germination indicated that aspirin treatment resulted in germination by decreasing the enthalpy of activation of the process. The aspirin treatment also resulted in the synchronization of seed germination. on the base of our results we propose aspirin application in practice to increase the tolerance to high temperature and to synchronize seed germination at least in Raphanus sativus L. cvar early scarlet globe.

Germinação de sementes de Drymaria cordata (L.) Willd. ex Roem & Schult.: efeito do potencial hídrico

Modelos matemáticos baseados no conceito de graus dia (thermal-time) e Ψw dia (hydrotime) podem ser usados para a elaboração de modelos mais gerais sobre a germinação e emergência de plântulas no campo, podendo ser uma importante ferramenta para estudos sobre a biologia de plantas daninhas e seu controle. Neste trabalho, avaliou-se a germinação de sementes de D. cordata em resposta ao potencial hídrico (Ψw), usando-se o modelo Ψw dia. Tanto a germinabilidade como a velocidade de germinação decresceram linearmente com a redução do Ψw, atingindo valores próximos a zero em -0.8 MPa. em temperatura ótima, a taxa de queda na germinação foi maior em comparação com as temperaturas sub- e supra-ótima. O Ψw base (Ψwb) mediano foi similar entre as temperaturas sub-ótima (19 ºC) e supra-ótima (32 ºC), mas foi maior (menos negativo) à temperatura ótima (25 ºC), mostrando que sementes de D. cordata são menos sensíveis à redução do potencial hídrico à 19 ºC do que à 25 ºC. O Ψw dia foi maior para sementes germinadas à temperatura sub-ótima do que à temperatura ótima, mostrando que a velocidade de germinação num dado potencial hídrico é maior em temperatura ótima. A quantidade de Ψw dia necessária para a germinação foi maior em temperatura supra-ótima do que em temperatura ótima, e menor em temperatura supra-ótima do que em sub-ótima. em geral, Ψw dia foi relativamente constante entre as diferentes sub-populações. O modelo de Ψw dia pode descrever bem o efeito do potencial hídrico sobre as curvas de germinação (porcentagem acumulada x tempo), especialmente às temperaturas sub-ótima e supra-ótima.

Pollination biology of Syngonanthus elegans (Eriocaulaceae - Poales)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Linking frugivore activity to early recruitment of a bird dispersed tree, Eugenia umbelliflora (Myrtaceae) in the Atlantic rainforest

Seed dispersal by animals is a complex process involving several distinct stages: fruit removal by frugivores, seed delivery in different microhabitats, seed germination, seedling establishment, and adult recruitment. Nevertheless, studies conducted until now have provided scarce information concerning the sequence of stages in a plant's life cycle in its entirety. The main objective of this study was to evaluate the immediate consequences of frugivore activity for Eugenia umbelliflora ( Myrtaceae) early recruitment by measuring the relative importance of each fruit-eating bird species on the establishment of new seedlings in scrub and low restinga vegetation in the Atlantic rainforest, Brazil. We conducted focal tree observations on E. umbelliflora trees recording birds' feeding behaviour and post-feeding movements. We also recorded the fate of dispersed seeds in scrub and low restinga vegetation. We recorded 17 bird species interacting with fruits in 55 h of observation. Only 30% of the handled fruits were successfully removed. From 108 post flight movements of exit from the fruiting trees, 30.6% were to scrub and 69.4% to low restinga forest. Proportion of seed germination was higher in low restinga than in the scrub vegetation. Incorporating the probabilities of seeds' removal, deposition, and germination in both sites, we found that the relative importance of each frugivorous bird as seed dispersers varies largely among species. Turdus amaurochalinus and Turdus rufiventris were the best dispersers, together representing almost 12% probability of seed germination following removal. Our results show the importance of assessing the overall consequence of seed dispersal within the framework of disperser effectiveness, providing a more comprehensive and realistic evaluation of the relative importance of different seed dispersers on plant population dynamics.

Testing the quick meal hypothesis: the effect of pulp on hoarding and seed predation of Hymenaea courbaril by red-rumped agoutis (Dasyprocta leporina)

Red-rumped agoutis (Dasyprocta leporina) are important seed dispersers/predators of Neotropical large-seeded plants. Several species of seeds cached by agoutis have an edible reward, in contrast to temperate rodent-dispersed diaspores. The quick meal hypothesis states that the presence of a reward such as edible pulp will enhance the efficiency of rodents as seed disperses by satiating the animal and, consequently, reducing seed predation and enhancing hoarding. In this study, this hypothesis was tested using as the reference system the pulp and seeds of Hymenaea courbaril. Seeds with and without pulp were offered to agoutis and the behaviour of each individual was recorded. Since the probability of predation and hoarding were complementary, we used the probability of predation. The proportion of agoutis that preyed on at least one seed was similar for seeds with (42.8% of individuals) and without (40.0% of individuals) pulp. In agoutis that preyed upon at least one seed, the probability that they killed a seed did not differ between seeds with (0.17 +/- 0.03) and without (0.20 +/- 0.08) pulp. Hence, these results do not support the 'quick meal hypothesis'.

Frugivoria e dispersão de sementes pelo lagarto teiú Tupinambis merianae (Reptilia: Teiidae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)