Department of Biology, Gum Nanak Dev University, Amritsar
*Present address: Fruit Research Station, Punjab Agriculture University, Bhatinda-151001
All the three plant types of Amaranthus, viz., A. caudatus f. albiflorus, A. caudatus f. caudatus and A. tricolor var. tristis are qualitative short day plants with 16.00, 15.50 and 15.00 hr critical photoperiods and 6, 3 and 5 minimum number of inductive 8-hr photoperiodic cycles requirement for the macroscopic appearance of inflorescence primordial respectively. Whereas, decreasing photoperiod did not affect floral induction in case of A. tricolor var. tristis, it hastened flowering in the two forms of A. caudatur. However, increasing number of inductive cycles hastened floral induction in all the three plant types. Photoperiod does not appear to affect vegetative growth.
