Floraison et réversion chez Sinapis alba. III. Effets immédiats et différés de divers régimes d'éclairement appliqués pendant la phase post-inductrice

Abstract

Transferring induced plants to a dysperiod, under different light intensities, brings in apical organs the following disruptions: (i) a general slowing down (braking), all the more since light intensity is lower, of organogenetic activity in the apical meristem of the main inflorescence, and propagation of reproductive functioning to apical meristems of the subjacent lateral buds; (ii) some arrests in floral development, which allow the definition of two critical stages, corresponding respectively with initiation of floral parts and their final growth; (iii) a change in correlations between the apical meristem of the main inflorescence and subjacent lateral formations: flowers and young lateral axes. Apparently, competitive relationships are set up which lead in some cases to the death of young flowers and even of the apical meristem. In more severe conditions, the development of floral buds remains below the first critical stage and the apical meristem becomes dominant. When plants are returned to inductive conditions, these buds which were blocked for a long time develop into leaf–branch couples, making up an inflorescence reversion. The possible links between pollen degeneration and the second critical stage, and between leaf growth and the end of "crisis" during the braking phase, are considered. The use of different parameters for a quantitative evaluation of reversion is discussed.