Effect of photoperiod on growth characteristics in Chrysanthemum morifolium Ramat. cv. Zembla using high pressure sodium light

This experiment was conducted to study the effect of photoperiod on growth characteristics in chrysanthemum cv. Zembla during 1st October 2014 to 20th December 2014 in naturally ventilated greenhouse at Centre for Protected Cultivation Technology (CPCT), IARI, New Delhi. Chrysanthemum cv. Zembla was exposed under different photoperiodic treatments of day length extension illuminating from high pressure sodium (HPS) for 6, 9, 12, 15 days @ 15 h/day in growth chamber. All the growth parameters (plant height, number of leaves, internode length and leaf area)varied significantly during different stages of growth and found that the increase in photoperiod by 15 days using high pressure sodium (HPS) lighting resulted in a significant increase in stem elongation and leaf number. Increased plant height (46.25 and 42.70 cm), internodal length (2.70 and 2.63 cm) and leaf number (32.75 and 29.75) were observed in cv. Zembla due to long day extension treatments as compared to the control. Flower bud appeared at the earliest (57 days) in the plants without any exposure to the photoperiod. However, flower opening delayed with increase in day length exposure from 6 days (66 days) to 15 days (68 days) treatments. The results also revealed that supplemental high pressure sodium lighting significantly increased in plant height, internodal length as well as leaves number with increase in day length (photoperiod).