Induction of Generative Development of Winter Rape (Brassica napus L. var. oleifera) in Relation to Vernalization Conditions and Age of Vernalized Plants

Abstract

Germinating seeds and young winter rape plants were vernalized 56–63 days at 5 or 2°C under nine‐hour days or in darkness. The highest percentage of generative plants and the most rapid flowering were obtained following the vernalization of young seedlings and germinating seed under conditions of nine‐hour day, at 5°C. The least effective induction of generative development followed the vernalization at 2°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‐hour day, yet the vegetation period from the beginning of germination to flowering was the shortest when seed germinating under conditions of nine‐hour day were vernalized. The period was extending as older plants were being vernalized. Data indicating that the optimal temperature for vernalization of older plants is higher than for germinating seed and young seedlings were obtained.

Effect of Completion of Vernalization on Generative Development of Winter Rape (Brassica napus L. var. oleifera) Plants

“…Comple-36 and DUBERT tion of vernalization constitutes thus only an additional factor modifying the vernalization proper. On the other hand the differentiated effect of vernalization completion on the formation of flower buds and their development into flowers can be interpreted as confirming the opinion that the generative development of winter rape is controlled by at least two different factors appearing as a result of vernalization (DUBERT et al 1984).…”