RESUMO
The proper establishment of plants is essential for the efficient use of resources such as water and light. Besides, even after seed storage and sowing the uniform establishment of plants is essential for their success. Crotalaria ochroleuca and Crotalaria spectabilis are important medicinal plants with poor seed germination rate, occasionally. The effects of seed priming in both C. ochroleuca and C. spectabilis were evaluated in seed performance even after seeds storage for up 90-days. Experimental assays were performed in a randomized design with gibberellic acid (GA3, 100 ppm), polyethylene glycol (PEG 6000, -0.2 MPa) and PEG (-0.2 MPa) + GA3 (100 ppm) solutions during seed priming in four replicates. Seeds not submitted to priming treatments constituted control. Seeds physiological performance were evaluated immediately and even after 30, 60 and 90-days seed dry-storage. The data obtained in each experiment were submitted to variance analysis (ANOVA) adopting a confidence level of 95%. The effects of seed priming with PEG and GA3 during seed ageing were significant for germination variables of C. ochroleuca and C. spectabilis. During dry storage, seed viability of both species gradually decreased and the first symptoms were delayed seed germination, especially more evident for C. ochroleuca, even in primed or non-primed seeds. Afterwards, C. ochroleuca seeds previously GA3 primed had higher results of root protrusion (86%), hypocotyls elongation (76%) and complete seedlings (75%) than non-primed seeds (control). These findings shown a good potential of hormopriming to attenuate damage during the seed aging of C. ochroleuca.
Assuntos
Crotalaria , Plântula , Germinação/fisiologia , Sementes/fisiologiaRESUMO
The safflower crop is considered a great alternative for crop rotation since drought tolerance and low production cost are attractive for its choice. However, safflower seeds show dormancy soon after dispersal from the mother plant, making it difficult to successfully establish plants using newly harvested seeds. The influence of temperature, gibberellin and light/dark on dormancy break of safflower seeds during storage were investigated. In a completely randomized design, freshly harvested seeds or stored for 100 and 200 days (paper bag, 20 °C/ 60% UR) were treated with GA3 (0 and 100 µM), at 4, 10 and 25 °C, in the presence and absence of light, during the germination test. Seeds were evaluated for germination percentage, germination speed and seedling survival after 21 days. The temperature of 10 °C, in combination with GA3 (0/100 µM), or light/dark, provided the highest seed germination results, for freshly-harvested seeds and stored seeds. Collectively, these observations indicate that dormancy was not affected by gibberellic acid (100 µM GA3) and the germination results at 21 days were significantly higher, in relation to the use of GA3, under light or dark. Recently harvested seeds could efficiently germinate at 10 °C in the dark, while seeds dry-stored at 20 °C had decreased germination percentages.
Assuntos
Carthamus tinctorius , Germinação , Germinação/fisiologia , Temperatura Baixa , Temperatura , Plantas , Sementes/fisiologiaRESUMO
Abstract The safflower crop is considered a great alternative for crop rotation since drought tolerance and low production cost are attractive for its choice. However, safflower seeds show dormancy soon after dispersal from the mother plant, making it difficult to successfully establish plants using newly harvested seeds. The influence of temperature, gibberellin and light/dark on dormancy break of safflower seeds during storage were investigated. In a completely randomized design, freshly harvested seeds or stored for 100 and 200 days (paper bag, 20 °C/ 60% UR) were treated with GA3 (0 and 100 µM), at 4, 10 and 25 °C, in the presence and absence of light, during the germination test. Seeds were evaluated for germination percentage, germination speed and seedling survival after 21 days. The temperature of 10 °C, in combination with GA3 (0/100 µM), or light/dark, provided the highest seed germination results, for freshly-harvested seeds and stored seeds. Collectively, these observations indicate that dormancy was not affected by gibberellic acid (100 µM GA3) and the germination results at 21 days were significantly higher, in relation to the use of GA3, under light or dark. Recently harvested seeds could efficiently germinate at 10 °C in the dark, while seeds dry-stored at 20 °C had decreased germination percentages.
Resumo A cultura do cártamo é considerada uma ótima alternativa para a rotação de culturas na segunda safra, uma vez que a tolerância à seca e o baixo custo de produção são atrativos para sua escolha. Entretanto, as sementes de cártamo apresentam dormência logo após a dispersão da planta-mãe, dificultando o êxito do estabelecimento de plantas com a utilização de sementes recém-colhidas. A influência da temperatura, giberelina e luz/escuro na superação de dormência de sementes de cártamo durante o armazenamento foram investigados. Em um delineamento inteiramente casualizado, as sementes recém-colhidas ou armazenadas durante 100 e 200 dias (em saco de papel, 15 °C/ 60% UR) foram submetidas às doses de GA3 (0 e 100 µM), às temperaturas de 4, 10 e 25 °C, na presença e ausência de luz, durante o teste de germinação. As sementes foram avaliadas quanto à germinação, velocidade de germinação e sobrevivência das plântulas após 21 dias. A temperatura de 10 °C, em combinação com o uso de GA3 (0/100 µM), ou luz/escuro, proporcionou os maiores resultados de germinação de sementes em relação às demais temperaturas, para as sementes recém-colhidas e armazenadas. Coletivamente, essas observações indicam que a dormência não foi afetada pelo ácido giberélico (100 µM GA3) e os resultados de germinação aos 21 dias foram significativamente maiores, em relação ao uso de GA3, no claro ou no escuro. As sementes recém-colhidas germinam eficientemente na temperatura de 10 °C no escuro, enquanto as sementes armazenadas a 20 °C apresentaram redução da germinação.