INCIDENCE DU CALIBRE DES SEMENCES DE CAROTTE (DAUCUS CAROTA) SUR LA GERMINATION ET L'EMERGENCE
In a range of temperature of 5 to 30°C, no difference of the final percent of germination has been registered. The thermical optimum is the same in all cases. About the speed of germination, it seems that the smallest seeds germinate slightly faster than the biggest ones. There is an high sensibility to the cold and hot temperatures. With alternate temperature (20°–35° ; 20°–40° ; 20°–45° ; 20°–50°), we have shown that there is some differences between grade, the big seeds seem to be more sensitive with a slower germination, but with no effect on the final percent of germination up 45°C. When alternate temperature reaches 50°C, the final percent of germination is affected.
Concerning seedling emergence, the big seeds have a more important emergency strength than the small seeds. In situation of soil crusting, the emergency of big seed is higher than the smallest. In dry period, small seeds grade have a faster emergence.