Duration of cell cycle, onset of S phase and induced mitotic synchronisation in seeds of opium poppy, Papaver somniferum L.

Duration of mitotic cell cycle and its component phases in root-tip meristem of P. somniferum was determined following autoradiographic detection of mitotic rythms during the traverse of cell cycle. The mitotic cycle time thus estimated was found to be 12.6h of which the distribution of component phases was G1 = 1.75 h, S = 6.3 h, G2 = 3.75 h and division phase (M) = 0.8 h. Dry seeds were metabolically activated by soaking in water to show that the first batch amongst the asynchronous population of cells in the seeds enters into S phase after 18 h of such soaking at 16 degrees C. Mitotic synchrony to the tune of 80% could be realised when such presoaked seeds were administered 5 mMole hydroxyurea for 20 h at 16 degrees C.