Objetivou-se com este trabalho avaliar a sensibilidade à dessecação e a longevidade durante o armazenamento de sementes de Eugenia pyriformis Cambess. (uvaia). Os frutos utilizados foram coletados em matrizes localizadas na cidade de Amambai-MS. Para o estudo da sensibilidade à dessecação, foi utilizado o protocolo baseado na redução do nível de hidratação das sementes a cada cinco pontos percentuais, obtendo-se sementes com teores de água de 45; 40; 30; 25; 20; 15; 10 e 5%. Para estudar a longevidade das sementes durante o armazenamento, foram testadas as condições de câmara fria e seca (16±1Cº/40% UR), geladeira (5±1Cº) e freezer (-18±1ºC) durante 30 dias, e as sementes que não foram submetidas ao armazenamento constituíram o tratamento-controle. A semeadura foi realizada entre areia a 20/30ºC com 10h de luz/14h de escuro em B.O.D. As sementes de uvaia são sensíveis à dessecação e não toleraram a secagem a 5% de teor de água. As sementes recém-beneficiadas apresentaram germinação de aproximadamente 77% e com a secagem até 5% houve a redução para 15% de germinação. A diminuição do teor de água provocou a redução da massa fresca, comprimento de raiz primária, hipocótilo e total de plântulas e tempo médio de germinação. As condições de armazenamento sob temperaturas baixas e a secagem reduziram a germinação das sementes, indicando assim o comportamento recalcitrante das sementes de uvaia.

This study aimed to evaluate the tolerance of Psidium guineense Swartz seeds to air-dry storage and priming. Desiccation tolerance was analyzed for seed moisture content of 15%, 10% and 5%. The longevity of seeds during storage was analyzed in seeds with 5% and 10% moisture content maintained in cold and dry chamber (16˚C ± 1˚C/40% RH), laboratory environment (25˚C ± 2˚C/60% RH), refrigerator (5˚C ± 1˚C) and freezer (−18˚C ± 1˚C) during 90 days, and the priming effect in seeds that were imbibed for 5 or 10 days in polyethylene glycol 6000 at osmotic potentials of −0.3 MPa, −0.5 MPa, −0.7 MPa and −1.3 MPa. The quality of seeds was evaluated after desiccation, storage, and priming by the seeds germination, fresh weight of seedlings, seedlings growth, and germination medium time. The experimental design was completely randomized, with four replications of 25 seeds each one. Although a reduction in seed germination and seedling growth was observed in seeds with 10% and 5% moisture content, drying did not cause complete loss of seed germination and seedling development. Sour guava seeds exhibited an orthodox response to desiccation tolerance and storage. Seed germination and seedling growth were reduced with increased osmotic potential of osmoconditioning. However, conditioning of 10 days increased the seeds germination and optimized the average germination time to 20 days. The seeds of Psidium guineense are able to tolerate desiccation and storage for up to 90 days at a temperature of 5˚C ± 1˚C and priming for 10 days is a promising technique for propagation of P. guineense.

This work aimed to evaluate the effect of pre-treatments with gibberellin, the initial substrate humidity, and incubation temperature on the germination of Psidium guineense Swartz seeds. The seeds were submitted to four pre-treatments with gibberellin (GA3 ) (50 and 100 mg L-1)and distilled water during 24 hours, and control. Sowing was carried out on Germitest® paper that was moistened with distilled water at humidity levels corresponding to 1.5 and 2.5 times the weight of dry paper. The seeds were then incubated at a constant temperature (25 or 30 °C) and alternate temperatures (20-30 °C). Experiments were randomized, with a factorial scheme 4 × 2 × 3 (pre-treatment × initial substrate humidity × temperature) with four replicates of 25 seeds each. Germination rate and seedling growth of P. guineense were not affected by pre-germination treatments. For an optimum germination rate and seedling growth, seeds of P. guineense should be sown at alternate temperatures of 20-30 °C or 25 °C and in substrate moisture of 1.5 or 2.5 times the dry paper mass.

Physiological conditioning of seeds has been shown to increase the uniformity of seedlings; thus, it has been useful for propagating native tree species from the Brazilian Cerrado which, otherwise, are difficult to propagate successfully. The objective of this work was to evaluate the effect of physiological conditioning of Alibertia edulis seeds by soaking for 5 or 10 days in solutions of varying osmotic potential. After conditioning, seeds were dried down to original water content, sown on sheets of germitest paper inside gerbox plastic boxes, and incubated at 25˚C. We evaluated the effect of conditioning by studying seed germination and vigor. Seed conditioning by osmotic pretreatment showed positive effects; however, germination and growth of seedlings from seeds conditioned at osmotic potentials of −0.3 to −0.7 MPa were reduced. Osmoconditioning for 10 days at −0.7 MPa resulted in increased percent germination, indicating that the longest imbibition period in the osmotic solution of the lowest osmotic potential (−1.3 MPa) favored the seed germination process.A. edulis seeds did not require conditioning to attain high germination rates; nonetheless, osmotic conditioning reduced average seed-germination time.