Photoperiodic Induction and Synchronization of Flowering in Sugarcane Hybrids for Breeding Programs

Profuse and synchronized flowering is a prerequisite for breeding crop plants. Sugarcane, known for its highly variable flowering behavior, requires specific photoperiodic regimes. Repeated experiments in photoperiodic chamber (for 3 years) and field trials (for 2 years) were attempted to standardize the physiological interventions required for induction of flowering as well as its synchronization. Flowering was induced in 36 out of 46 clones treated in the photoperiodic chamber with two sets of treatments, commencing with a photoperiod of either 12 h 45 min or 12 h 55 min, followed by declining day length at the rate of 60 s day −1 for 85 and 75 cycles, respectively. Histological studies indicated conversion of vegetative to reproductive bud due to photoperiodic treatments, while temperature was a determining factor for panicle emergence or reversion to vegetative state. In the field trials, night interruption (with lighting for a period of 30 days) followed by post-inductive constant photoperiod of 12 h 40 min delayed flowering by a minimum of 4 days up to 39 days. These experiments confirmed that sugarcane flowering may be manipulated through photoperiodic treatments for the successful hybridization of desired parental clones in breeding programs.