It comprises a first chassis (2) provided with a first plurality of sowing elements (3), said first chassis (2) including at least one portion (2a, 2b, 2c, 2d) horizontally extensible from a transporting position to a working position, said frame (1) comprising at least a second chassis (4) provided with a second plurality of sowing elements (5) and means (6) for vertically moving said sowing elements from an upper transporting position to a lower working position in which the sowing elements (5) of said second chassis (4) are placed aligned with respect to the sowing elements (3) of the first chassis (2), and it is characterized in that said second chassis (4) is attached to the extensible portion (2a, 2b, 2c, 2d) of said first chassis (2), so that said second chassis (4) can be horizontally moved with said extensible portion (2a, 2b, 2c, 2d) to adapt the position of its elements to the kind of sowing.
