Abstract
The experiment was carried out to study the effect of vernalization on morphological and histochemical changes of shoot apex in Raphanus.
In this experiment, several varieties with different ecotypes were used as materials. The seeds were sown in greenhouse. The 1st group of the seedlings were grown at 20 to 25°C and the 2nd group were grown at 5 to 10°C during the whole period of growth. The 3rd group of the seedlings were grown at 20 to 25°C until the 4th leaf stage, afterwards, for the rest period of the growth, were grown at low temperature 5 to 10°C for the purpose of vernalization. At each stage, their shoot tips were taken and fixed in carnoy′s solution for morphological and histochemical studies. The preparations were made with paraffin method and stained with PAS and Brachet reaction methods.
The results were as follows:
1. The morphological change of the shoot apex was accelerated by vernalization.
2. The number of apical tunica layer changed from 3 to 2 at the end of vernalization.
3. Both PAS and Brachet reactions became remarkable gradually during the process of vernalization.
4. The changes of the morphological and histochemical reactions resembled the adult stage of the ordinally culture.
5. These results were also obtained in Brassica which has been reported.
