Seed germination and seedling emergence of the invasive exotic species, Clausena excavata

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

Dimorphic cypsela germination and plant growth in Synedrella nodiflora (L.) Gaertn. (Asteraceae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effect of light and temperature on seed germination in Tibouchina mutabilis (Vell.) Cogn. (Melastomataceae)

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

Germination of Styrax camporum Pohl. seeds in response to substrate types, moisture contents and the seed morphology

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Temporary storage of jussara palm seeds: effects of time, temperature and pulp on germination and vigor

As sementes da palmeira juçara (Euterpe edulis Mart.) são recalcitrantes, apresentando baixa longevidade e sensibilidade à desidratação e ao armazenamento em temperaturas baixas. Neste trabalho foram estudadas condições de temperatura mais adequadas ao armazenamento temporário destas sementes com e sem a polpa. Frutos maduros foram colhidos em 24 plantas provenientes da coleção de palmeiras do Instituto Agronômico (IAC) localizada em Ubatuba, estado de São Paulo, e encaminhadas, em embalagem impermeável, à Faculdade de Ciências Agronômicas da UNESP, Campus de Botucatu (SP). Metade dos frutos foi despolpada e outra metade foi mantida com polpa, sendo ambas armazenadas em sacos fechados de polietileno (20 µm de espessura) mantidos em temperaturas de 5; 10; 15 e 20-30ºC. Amostras para os testes de qualidade foram retiradas aos 0; 3; 6; 9 e 12 dias após a colheita dos frutos. As sementes armazenadas com polpa foram despolpadas imediatamente antes da instalação dos testes. Foram avaliados o grau de umidade das sementes, porcentagem de germinação, comprimento e matéria seca das plântulas. Os resultados mostraram que há efeito positivo de pós-amadurecimento em sementes de Euterpe edulis. Um período de armazenamento de 9 a 12 dias, após a colheita e antes da semeadura, favoreceu a germinação e o vigor das sementes de juçara. Os efeitos foram maiores para sementes armazenadas sem polpa do que com polpa. Temperaturas na faixa de 5 a 20-30ºC são igualmente adequadas para o armazenamento temporário de sementes sem polpa. No entanto, para sementes com polpa, a temperatura de armazenamento não deve exceder a 20ºC, visto que um decréscimo na germinação e no vigor e um acréscimo no número de botões germinativos apodrecidos e sementes mortas foram observados na temperatura de 20-30ºC.

Effects of maturation and scarification on seed germination of Syagrus schizophylla (Mart.) glass. (Arecaceae)

Syagrus schizophylla (Mart.) Glass. belongs to the Arecaccae family. This palm is native of Brazil and presents great potential for use in gardens and cultivation in pot. Palms species, with relatively few exceptions, can only be propagated from seeds; even so, there are no reports in the literature about the germination of this palm seeds. The seed maturity is a factor that interferes in the success of the germination process. For some species, studies showed that palm seeds germinated better when the fruits were completely ripe (showing full color) and for other, when they were with green coloration. Several species of the Arecaccae family presents physical dormancy of seeds in varied degrees, demanding treatments for improve germination. The objective of this work was to study the effects of maturation and of the scarification on seed germination of S. schizophylla. The experimental design used was a factorial 3 x 2 (3 maturation stadiums: green, half-ripe - yellow and completely ripe - red; and mechanical scarification: with and without), entirely casualized, with four replications of 15 seeds per plot. The seeds (with 32,43% of humidity) were placed in plastic boxes with sand (60% of humidity, placing water according to weight in each three days), under controlled conditions of alternated temperature of 25-35 degrees C, photoperiod of 12 hours. The percentage of germination and the speed germination index (SGI) were evaluated until 79 days. It was observed that, so much for germination percentage as for SGI, there was not significant difference for the interaction among the two factors, maturation stadium and scarification, however, there were significant differences among the maturation stadiums and between seeds scarified or not. The seeds from green fruits presented lower germination percentage and slower germination when compared with seeds from yellow or red fruits; the seeds from yellow or red fruits didn't differ statistically to each other. To seeds scarificated, independently of the maturation stadium, presented germination percentage significantly larger and the germination was significantly faster when compared with the seeds without scarification.

Study of seed-germination and etiolation of seedlings in Emilia-sonchifolia (l) dc and Emilia-fosgerbii nicolson (Asteraceae)

The germination of seeds of Emilia sonchifolia (2n) and E. fosgerbii (4n) was analysed and our results indicate that the former present light insensitive seeds and the latter germinated only under continuous white light. The germination of seeds under shade light presented no differences between both species, However under continuous white light, which maintain 70% of Pfr, the velocity of germination was greater in Emilia sonchifolia when compared to Emilia fosbergii, indicating that the threshold of 4n seeds were greater than 2n seeds. The analysis of the fluence response curves for etiolating process indicated that the process presented no differences between both species. The same was observed for the effect of the shade light in the etiolating process.

Effect of fruit maturation stage and light on seed germination of Aiphanes aculeata

Despite their spiny nature, Aiphanes palms are popular as ornamentals. They can be grown in various soil conditions, but achieve fast, luxuriant growth in sheltered positions with plenty of water. Shaded conditions are the best when plants are young. The objective of this study was to evaluate the effect of fruit maturation stage and light on the germination of seeds of A. aculeata. Fruits were collected at three different maturation stages: (1) yellow, (2) red, (3) collected on the ground without the fleshy mesocarp (removed by birds and insects). The fleshy mesocarp was also removed in treatments (1) and (2). All fruits were then treated with thiram and 25 seeds per plot were seeded in trays full of sand. The treatments (2) and (3) were subdivided in two other treatments: (a) 12 h photoperiod, (b) continuous darkness. The temperature was maintained at 30 degrees C. Seed germination began 34 days after sowing. After 160 days, the final germination percentage was (1) 54,67%, (2a) 61,33%, (2b) 65,33%, (3a) 38,00% and (3b) 45,33%. The best treatment was (2) independently of the light conditions.

Effect of pre-imbibition and osmoconditioning on seed-germination in Phaseolus-vulgaris L. under water-stress

The effect of osmoconditioning and controlled water sowing was analysed in seeds of Phaseolus vulgaris L. cv. carioca on germination under water stress conditions. The pre-sowing in water at low temperature to limit germination resulted in the increase in the tolerance to water stress. The osmoconditioning with PEG for 48 hours increased the tolerance of bean seeds to water stress of -0.51MPa. The osmoconditioning or controlled water sowing can be used as a practice to increase the tolerance of bean seeds to water stress before planting in the field.

Seed maturation and effect of temperature regime on Trema micrantha (L.) Blume seed germination

T. micrantha (L.) Blume (Ulmaceae), a common pioneer tree species in Brazil, is used in the restoration of degraded areas. The fruits are fleshy and indehiscent, with only one water impermeable seed. During the fruiting period, fruits of different colours are found at the same time on the same branch. This research aimed to correlate fruit colour with other physical indicators of seed maturity and to Verify the effect of temperature regime on seed germination. Collected fruits were separated in to green, green-red and red colour and for each of these maturation stages, size, moisture content and dry matter of both fruits and seeds were determined. Seeds were scarified with sulphuric acid and submitted to a germination test conducted at constant (20 degreesC, 30 degreesC and 40 degreesC) and alternating (20-30 degreesC, 30-40 degreesC and 20-40 degreesC) temperatures for 15 weeks. Seed germination percentage and speed were analysed after five weeks and the fmal percentage of germinated and Viable seeds after 15 weeks. Seed maturity is attained when the fruits are green-red. At this stage, moisture content was about 64% for fruits and 10% for seeds. Alternating temperature was required for seed germination and 20-30 degreesC was the best option. Most seeds had germinated after five weeks, providing mature seeds, acid scarification and alternating temperature were used.

EFFECT OF DROUGHT AND DEFOLIATION STRESS IN THE FIELD ON SOYBEAN SEED-GERMINATION AND VIGOR

Although drought and defoliation stress have been shown to reduce soybean [Glycine max (L.). Merr.] yield, little information has been published regarding their effects on soybean seed quality. Field experiments were conducted in 1986, 1987, and 1989 to evaluate the effect of drought and defoliation (1989 only) stress during soybean seed development on seed germination and vigor. Essex (MG [maturity group] V) and Union (MG III) were grown in 1986 and 1987, and Harper (MG III) and McCall (MG 00) in 1989. Moisture treatments were either well watered or drought stressed during seed development (R5 to R7). In 1989, a total defoliation treatment was also imposed at R6 as an additional stress factor. There were significant reductions in yield and yield components following drought stress in all 3 yr and following defoliation in 1989. Leaf conductance and transpiration also decreased in the drought stress treatments. There was no effect of drought stress on seed germination or seed vigor as measured by accelerated aging germination and the cold test across the four cultivars (determinate and indeterminate) and 3 yr. In 1989 slight changes in 3-d germination and conductivity occurred for some drought stress treatments. Most of this response, however, was related to increased occurrence of hard seed, which does not represent an indication of a change in vigor. Seed germination and vigor were significantly reduced for small, flat, shriveled, and underdeveloped seeds that only occurred following defoliation. These seeds represented a small portion of the seed lot that would normally be removed during conditioning. The data suggest that drought stress would have no effect on seed germination or vigor, unless the stress was severe enough to produce shriveled, flat, underdeveloped seeds.

On the germination and dormancy of dispersal units of Brachiaria decumbens STAPF

The effect of light and temperature on germination of Brachiaria decumbens as well as the action of some dormancy breaking chemicals were tested. Two seed batches stored different times were used. The results show that seeds failed to respond to alternating temperature regimes and different light qualities. Seeds were indifferent to white light at 25 degrees C. KNO3, ethanol and H2SO4 failed to break seed dormancy, whereas KCN and H2O2 partially reduced dormancy of two month stored seeds. The results suggest a metabolic character of dormancy in ''new'' (freshly collected) seeds and confirm the occurence of two types of dormancy in B. decumbens seeds.