Transfer by grafting of the effect of thermal induction of generative development in winter rape (Brassica napus var. oleifera L.)

The feasibility was studied of transferring the flowering factor in winter rape from vernalized plants to plants in which generative development was not induced by cold treatment. In a series of grafts made under field conditions scions from non vernalized plants were grafted into stems of vernalized ones at the phase of bud and flower formation. Non vernalized scions adopted the ability to generative development from vernalized stock. The transfer of the flowering stimulus was more effective in the case of grafts performed at the top of cut off stems than in the case of scions grafted on the side of a stem. The activity of the flowering factor in vernalized plants was the highest at or just before the bud formation phase. The responsiveness to the flowering factor transferred from vernalized stock was highest in 60- to 80-day-old scions. Analysis of the effect of age of the stock on the duration of the particular generative phases in grafted scions indicates that in vernalized plants of winter rape there may be more than one transferable factor that enables full generative development