Studies on Photoperiodic Response in Chrysanthemum (Chrysanthemum morifolium Ramat.) cv. Zembla
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Date
2015
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DIVISION OF FLORICULTURE AND LANDSCAPING INDIAN AGRICULTURAL RESEARCH INSTITUTE NEW DELHI
Abstract
In an experiment conducted on chrysanthemum cv. Zembla in two parts under
different photoperiodic treatments of day length extension illuminating from high pressure
sodium (HPS) and photosynthetically active radiation from LEDs for 6, 9, 12, 15 days @
15h/day under growth chamber. In first experiment high pressure sodium bulbs were used
whereas in the second experiment, light intensity was fixed by making two different LEDs
panels, one composed of 780 white LEDs and in another a mixture of red (624) and blue (156)
LEDs made into a strip backed with power @14.4 W/M, voltage input DC 12V and rating
IP22 controlled with an adaptor AC 110~220V, 12V 5Amp, glued together in an area of 1.0 m
x 1.0 m panel to achieve an interception of light @ 110-120 µmol m-2
sec-1
from 80% red 20%
blue PAR distributed over the plants in uniformity inside the growth chamber. LEDs light
exposure was given for 15 hours as log day (LD) treatment except for control. Every batch
after exposure @ 6, 9, 12, 15 days under was transferred to the chamber with white LEDs.
Among different growth parameters (plant height, number of leaves, internode length,
leaf chlorophyll, leaf area, fresh and dry weight of leaf, net photosynthetic rate, stomatal
conductance varied significantly during different stages of growth and found that the increase
in photoperiod by 15 days using high pressure sodium (HPS) lamp resulted in a significant
increase in stem elongation, 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. Total fresh and dry
weights of the plants were maximum for plants under 15 day length extension treatment.
Total chlorophyll (3.65 and 3.45 mg g -1 FW), net assimilation rate, RGR, CGR and LAI
values were recorded higher in treated plants compared to control. In another experiments
with Long days from LEDs there was an increase in plant height (26.30, 34.30 cm), inter
nodal length (2.60, 2.38 cm), number of leaves (24.50, 23.50) and leaf area (197.35, 188.90
cm
2
) cv. Zembla maximum (15 days) exposure to LEDs. Early flower response was noticed
which was advanced by 6 days as compared with control. Bud and flower diameter (5.78 mm
and 4.71 mm) were maximum. Fresh and dry weight in stems and flower were significant
which might have contributed with increased total chlorophyll (4.33 mg g-1 fw) content as
application of light emitting diodes (LEDs) might resulted in long day effect without
disturbing the required minimum dark period for flower induction.
Description
t-9286
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