Reduction of generative organs and yield by three winter rape varieties (hybrid, line and GM hybrid) and different cultivation levels

brassica napus clima climat climate conduite de la culture crop management cultivation cultivo czech republic deblossoming fertilisation fertilizer application genetic engineering genetically modified organisms graine hybride hybrids manejo del cultivo plant reproductive organs pratique culturale pure lines rendement rendimiento seeds semilla suppression de fleurs variedades varieties yields