INDUCTION OF GENERATIVE DEVELOPMENT OF WINTER RAPE (BRASSICA-NAPUS L VAR OLEIFERA) IN RELATION TO VERNALIZATION CONDITIONS AND AGE OF VERNALIZED PLANTS

Germinating seeds and young winter rape plants were vernalized 56-63 d ays at 5 or 2-degrees-C under nine-hour days or in darkness. The highe st percentage of generative plants and the most rapid flowering were o btained following the vernalization of young seedlings and germinating seed under conditions of nine-hour day, at 5-degrees-C. The least eff ective induction of generative development followed the vernalization at 2-degrees-C in continuous darkness. The vegetation period from the end of vernalization till the beginning of flowering was the shortest when four-week-old plants were vernalized under conditions of nine-hou r day, yet the vegetation period from the beginning of germination to flowering was the shortest when seed germinating under conditions of n ine-hour day were vernalized. The period was ''tending as older plants were being vernalized. Data indicating that the optimal temperature f or vernalization of older plants is higher than for germinating seed a nd young seedlings were obtained.