Osmotic conditioning and shading on the germination and on the initial growth of <italic>Myracrodruon urundeuva</italic> Allem&#227;o seedlings

<p id="para1">The present work aimed to evaluate the osmotic conditioning and shading on the germination and on the initial growth of aroeira seedlings. The seeds were pre-imbibed in solutions with different concentrations of PEG (polyethylene glycol) and KNO₃ and incubated at 10&#176;C and 20&#176;C temperatures, during 0 (control), 12 and 24 hours. After these periods, the seeds were dried until they reached the initial levels of humidity. After that, they were put for germinating in BOD (Biochemical Oxygen Demand) chambers, at alternated 20-30&#176;C. The control treatment and the pre-conditionings that presented the best results in BOD germination were selected, PEG (-1.0 MPa) + KNO₃ (-1.0 MPa) and KNO₃ (-1.0 MPa), with pre-imbibition for 12 h and incubated in BOD at 20&#176;C. The seeds were sowed on trays and then they were transplanted, keeping under a net covered with 50% and 70% of shading and at sunlight. The osmotic conditioning did not change the seeds germination in BOD, but the highest aerial part size was observed in PEG -1.0 MPa + KNO₃-1.0 MPa treatment. The shading levels at 50% and 70% and the osmotic conditioning with PEG -1.0 MPa + KNO₃-1.0 MPa offered a higher emergence in a greenhouse condition; however, at sunlight the seeds presented a better index of quality on the 145^th day.</p><br><p id="para2">O presente trabalho objetivou avaliar o condicionamento osm&#243;tico e o sombreamento na germina&#231;&#227;o e no crescimento inicial de mudas de aroeira. As sementes foram pr&#233;-embebidas em solu&#231;&#245;es de diferentes concentra&#231;&#245;es de PEG (Polietilenoglicol) e KNO₃ e incubadas em temperatura de 10&#176;C e 20&#176;C durante 0 (controle), 12 e 24 horas. Ap&#243;s estes per&#237;odos as sementes foram secas at&#233; atingirem os n&#237;veis iniciais de umidade. Posteriormente elas foram colocadas para germinar em BOD (Demanda Bioqu&#237;mica de Oxig&#234;nio) na temperatura de 20-30&#176;C. O tratamento controle e os pr&#233;-condicionamentos que apresentaram os melhores resultados de germina&#231;&#227;o em BOD foram selecionados, sendo PEG (-1,0 MPa) + KNO₃ (-1,0 MPa) e KNO₃ (-1,0 MPa), com pr&#233;-embebi&#231;&#227;o por 12 horas e incubados em BOD a 20&#176;C. As sementes foram semeadas em bandejas e posteriormente transplantadas, permanecendo sob telado coberto com sombrite de 50% e 70% de sombreamento e a pleno sol. O condicionamento osm&#243;tico n&#227;o alterou a germina&#231;&#227;o das sementes em BOD, por&#233;m o maior tamanho de parte a&#233;rea foi observado no tratamento PEG-1,0 MPa+KNO₃ -1,0 MPa. Os n&#237;veis de sombreamento de 50 e 70% e o condicionamento osm&#243;tico com PEG-1,0 MPa+KNO₃-1,0 MPa proporcionaram maior emerg&#234;ncia em casa de vegeta&#231;&#227;o, entretanto a pleno sol as mudas apresentaram melhor &#237;ndice de qualidade aos 145 dias.</p

Campomanesia adamantium (Cambess.) O. Berg seed desiccation: influence on vigor and nucleic acids

The aim of this study was to evaluate the sensitivity of Campomanesia adamantium seeds to desiccation by drying in activated silica gel (fast) and under laboratory conditions (slow). To assess the sensitivity of the seeds to desiccation, we used drying with silica gel and drying under laboratory conditions (25 °C), in order to obtain seeds with moisture content of 45, 35, 30, 25, 20, 15, 10 and 5%. The physiological potential of the seeds after desiccation was evaluated by measuring primary root protrusion, percentage of normal seedlings, germination seed index, seedling length, total seedling dry mass, electrical conductivity and DNA and RNA integrities. The C. adamantium seeds were sensitive to desiccation and to a reduction in moisture content to 21.1% or less by desiccation using silica gel, and to 17.2% or less by desiccation under laboratory conditions; impairment of the physiological potential of the seeds was observed at these low moisture content levels. The integrity of the seed genomic DNA was not affected after drying seeds in the two methods. However, drying in silica gel to 4.5% moisture content and drying under laboratory conditions to 5.4% moisture content resulted in the loss of seed RNA integrity

Effect of storage in overcoming seed dormancy of Annona coriacea Mart. seeds

The aim of this study was to evaluate the effect of pre-treatments on overcoming dormancy of A. coriacea seeds. Seeds were processed and stored in polyethylene bags at temperatures of at -18°C (42% RH), 5°C (34% RH), 15°C (60% RH) and 25°C (34% RH), during 0, 30, 60, 90, 120 and 150 days. After storage, seeds were immersed in 350 mg.L−1 gibberellic acid for 144 hours. Sowing was carried out in plastic bags containing Red Latosol + Bioplant®. Moisture content, emergence percentage, emergence speed index, length and dry mass of seedlings, were evaluated. The experimental design was completely randomized in a factorial with four replications of 50 seeds each. The seed storage at 5°C and subsequent immersion in gibberellic acid was efficient to reach high percentage, emergence speed and plant growth. A. coriacea seeds showed non-deep simple morphophysiological dormancy wherein the physiological component can be overcome after the seeds are storage at 5°C for a maximum period of 53 days and subsequent immersed in exogenous GA (350 mg.L−1 for 144 hours)

Osmotic conditioning and shading on the germination and on the initial growth of Myracrodruon urundeuva Allem&#227;o seedlings

The present work aimed to evaluate the osmotic conditioning and shading on the germination and on the initial growth of aroeira seedlings. The seeds were pre-imbibed in solutions with different concentrations of PEG (polyethylene glycol) and KNO3 and incubated at 10&#176;C and 20&#176;C temperatures, during 0 (control), 12 and 24 hours. After these periods, the seeds were dried until they reached the initial levels of humidity. After that, they were put for germinating in BOD (Biochemical Oxygen Demand) chambers, at alternated 20-30&#176;C. The control treatment and the pre-conditionings that presented the best results in BOD germination were selected, PEG (-1.0 MPa) + KNO3 (-1.0 MPa) and KNO3 (-1.0 MPa), with pre-imbibition for 12 h and incubated in BOD at 20&#176;C. The seeds were sowed on trays and then they were transplanted, keeping under a net covered with 50% and 70% of shading and at sunlight. The osmotic conditioning did not change the seeds germination in BOD, but the highest aerial part size was observed in PEG -1.0 MPa + KNO3-1.0 MPa treatment. The shading levels at 50% and 70% and the osmotic conditioning with PEG -1.0 MPa + KNO3-1.0 MPa offered a higher emergence in a greenhouse condition; however, at sunlight the seeds presented a better index of quality on the 145th day