Early Increase in the Mitotic Index in the Shoot Apex ofLolium temulentumcv. Ceres During the Floral Transition

Six-week-old Lolium temulentum cv. Ceres plants were induced to flower by a single long day (Day 1). Cell proliferation was analysed in the apex during the period extending from Day 1 to Day 3. A stimulation of mitotic and DNA synthetic activities was observed in the apical summit at 8 h of the photoextension period of the LD, i.e. before any apparent movement of the floral stimulus out of the leaves and well in advance of apex evocation.