An insight into seed priming response of Crotalaria ochroleuca and Crotalaria spectabilis during storage.

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.

Regulation of dormancy break and germination of safflower seeds: the role of GA3, light and cold temperatures.

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.