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.

Produçäo de milho em cultivo exclusivo ou consorciado com soja e qualidade de suas silagens / Forage production and silage quality of corn plant consortiated or not with soybean

Com o objetivo de produzir silagens mais protéicas, foram testados quatro cultivares de soja consorciados com milho em dois arranjos culturais: linhas alternadas de milho e soja ou linha alternada com duas linhas de soja, em delineamento de blocos ao acaso. Mediram-se as produçöes de MS e de PB e determinou-se a qualidade das silagens. A produçäo de MS e de PB näo foi aumentada no arranjo com maior concentraçäo de soja. As silagens apresentaram reduzido teor de MS, pH normal e elevada porcentagem de PB. Foi recomendado para a regiäo o arranjo alternado de linhas de milho e soja, utilizando os cultivares Dourados e Ocepar-9 e também que o corte das forrageiras para ensilagem fosse mais tardio, quando o milho estivesse no estádio fisiológico de farináceo para semiduro