RISPOSTA MORFOLOGICA E PRODUTTIVA ALLA RIDUZIONE DELLA DENSITÀ DI SEMINA IN COLZA (B. napus L. var. oleifera)

In recent years, due to the increasing diffusion of oilseed rape among oilseeds, this crop has undergone a strong genetic breeding. At European level many seed companies are interested on this oilcrop, selecting genotypes with improved characteristics, such as seed yield, oil content, environmental adaptability, structure and morphology of the plant. Together with open pollinated varieties, characterized by average yields, low price of seeds, and large environmental adaptability; nowadays CHH hybrids (Composite Hydrid Hybrid) are rapidly diffusing in the market. These genotypes, with an elevate price of their seeds, are able to insure increased yields in terms of both seed and oil. It is possible to distinguish between normal size hybrids, characterized by high vegetative growth and consequently outstanding potential yields, and semi-dwarf ones, that, although, they are not able to reach the same productivity potential, they could better adapt to some area in which lodging problems strongly negatively effect final yield.