Dormancy and like—dormancy in ash—trees deprived of seasonal variations

Summary Ash-seedlings were cultivated for 7 years, in a phytotron room under controlled conditions, with no seasonal variation. In the terminal bud, the sequence of rest and of growth activity was characterized as a function of time. The GO-1 blockage of the nuclei in rest was recognizable by 3 markers, the distribution of nuclear DNA content, the water content and the presence of intravacuolar polyphenolic compounds in the shoot—apex of the ash-bud. The terminal buds deprived of seasonal variations, alternated between rest and active growth. The ability to follow the seasonal cycle was shown during the first years. This was progressively lost and after 5 years after germination, ail the terminal buds were asynchronous. However, the ability to seasonal dormancy was immediately expressed when these young plants were replanted outdoor, just before the summer solstice, and submitted to the natural conditions: the synchronism of bud—opening was restored and the survival rate was 85 % after 3 years. Thus, the ...