Croissance rythmique de quelques végétaux ligneux de régions tempérées cultivés en chambres climatisées à température élevée et constante et sous diverses photopériodes

Abstract

Under continuous light and at a high and constant temperature (25°C) all species observed at least during a year and belonging to genus Betuta, Carpinus, Castanea, Fagus, Quercus, Rhamnus, Salix et Sambucus revealed themselves able to rest and to take up spontaneously their growth. The intervention of a photoperiod or thermoperiod can deeply modify the rhythm but does not cancel it entirely. All transitions exist between a transitory decrease of growth (which can be due to a diminution of the internodes elongation, to a slower rhythm of the plastochrons or to the simultaneous intervention of those two factors), short arrests (about a week) of that growth (which can or cannot correspond to an arrest of the organogenesis at the apex level), resting times of long duration (several weeks or several months). We can express the hypothesis that determinism is, at least partially, the same in all cases. On the bushy species (Sambucus, Rhamnus, Carpinus, even Castanea>) same basilar branchings, with their own rhythmic growth, modify by a correlative inhibition the mode of evolution of the main stem and influence themselses mutually. The periods of rest does not exist or is of very short duration. Comparisons are carried out with the rhythmic growth of woody plants in temperate and equatorial climate as well as with dormancies induced or lifted by some miliey factors, dormaneics the nature of wich could be different. © 1971 Taylor & Francis Group, LLC.