TAILIEUCHUNG - Rest andactivityinvegetativebuds of treesP.ChampagnatrueLaboratoire de

Rest and activity in vegetative buds of trees P. Champagnat rue Laboratoire de Phytomorphog6n6se, Universite Blaise-Pascal, 4, Ferrand, France Ledru, F-63000, Clermont- Introduction Rest of buds, particularly on trees or shrubs, may have 3 different origins: 1) unfavorable environmental conditions (for instance low temperatures); in this case, the bud is called ’quiescent’; 2) correlative inhibitions exerted by other organs or parts of the plant, more or less distant from the considered bud. Those may be called ’long distance correlative inhibitions (LOis)’; the apical dominance exerted by the terminal bud over axillary buds on growing shoots is the most studied example of LDI; 3) some intrinsic properties of the bud itself, such as. | 9s Ann. Sci. For. 1989 46 suppl. 9s-26s Forest Tree Physiology E. Dreyer et al. eds. Elsevier INRA Rest and activity in vegetative buds of trees p. Champagnat Laboratoire de Phytomorphogénèse Université Blaise-Pascal 4 rue Ledru F-63000 Clermont-Ferrand France Introduction Rest of buds particularly on trees or shrubs may have 3 different origins 1 unfavorable environmental conditions for instance low temperatures in this case the bud is called quiescent 2 correlative inhibitions exerted by other organs or parts of the plant more or less distant from the considered bud. Those may be called long distance correlative inhibitions LDIs the apical dominance exerted by the terminal bud over axillary buds on growing shoots is the most studied example of LDI 3 some intrinsic properties of the bud itself such as when the bud remains at rest even if all usual sources of correlative inhibition have been removed and if environmental conditions are favorable in this case the bud is called dormant Champagnat 1983 . In fact taking into account the structural complexity of most buds and the strong interrelationship they maintain with their shoot axis we will show that the rest of the meristematic region and related tissues depends upon short distance inhibitions SDIs exerted either by the bud s basal tissue or by the adjacent shoot-axis tissues. For over 50 years investigations on bud rest have mainly focused on plant growth regulators and their possible involvement in apical dominance or in dormancy. They did not lead to generally accepted conclusions Samish 1954 Champagnat 1965 Wareing and Saunders 1971 Phillips 1975 Saunders 1978 Hillman 1984 . A few papers Vegis 1964 1965a b Guern and Usciati 1972 1975 Miginiac 1974 McIntyre 1977 and especially recent reviews by Mauget 1987 Tamas 1987 and Powel 1987 have emphasized the necessity of setting the problem on much wider biochemical and physiological bases. That will be the aim of the present paper with emphasis on the following .

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