Regulation of flower production in chrysanthemum (Chrysanthemum morifoliumRamat.) through photoperiodic treatments

Studies were conducted on the effect of photoperiodic treatments on regulation of flower production in two standard varieties of chrysanthemum viz. Thai Ching queen and Purnima. The plants raised through rooting of terminal cuttings were maintained under long day (LD) condition from 15 August to 15 February by interrupting the night period daily for two hours from 10 pm to 12 am by placing the pots under CFL lamps (23 Watt). These plants were periodically shifted to natural day length (ND) condition from September to February. Time of flower production in both the varieties was significantly affected by photoperiod treatments. Transferring plants from ND to natural short day length (SD) condition in September and October decreased number of days to produce flowers as compared to those maintained continuously under ND condition w.e.f. August. The plants transferred from LD to ND condition in the month of November and December took longer to reach commercial flower harvesting stage where as those transferred to ND condition in the months of January and February produced flowers in minimum number of days, respectively. Flower production in two varieties under study could be extended to end of April but the post harvest quality of flowers produced decreased due to rise in temperature in March and April.