Growth and Development of Horticultural Crops (1+1)

Definition-photoperiodic induction

• Plants may require one or more inductive cycles for flowering. An appropriate photoperiod in 24 hours cycle constitutes one inductive cycle. If a plant which has received sufficient inductive cycles is subsequently placed under unfavorable photoperiods, it will still flower. Flowering will also occur if a plant receives inductive cycles after intervals of unfavorable photoperiods (i.e., discontinuous inductive cycles.) This persistence of photoperiodic after effect is called photoperiodic induction.
  
  1. An increase in the number of inductive cycles results in early flowering of the plant. For instance Xanthium (a short day plant) requires only one inductive cycle and normally flowers after about 64-days. It can be made to flower even after 13 days if it has received 4-8 inductive cycles. In such cases the number of flowers is also increased.
  2. Continuous inductive cycles promote early flowering than discontinuous inductive cycles. Some of the examples of plants which require more than one inductive cycle for subsequent flowering are Biloxi soybean (SDP) -2 inductive cycles; Salvia occidentalis (SDP)-17 inductive cycles; Plantago lanceolata (LDP) – 25 inductive cycles.