|Authors: ||H. Shimizu, Z. Ma, S. Tazawa, M. Douzono, E.S. Runkle, R.D. Heins|
|Keywords: ||Dendranthema × grandiflorum, growth retardant, internode elongation, image processing, light quality|
Blue light (400 to 500 nm) has been reported to have an inhibitory effect on plant extension growth.
Thus, application of blue light could be used as an alternative to growth retarding chemicals to suppress plant height.
Experiments were performed to determine if blue light could be used to inhibit internode elongation of chrysanthemum (Dendranthema × grandiflorum cv.
Reagan). Experiments were performed in a controlled environment cabinet containing eight controllable fluorescent lamps and blue light-emitting diodes (LEDs). A CCD camera with sensitivity to infra-red light and an infrared illuminator were used to obtain plant images during the day and night.
The plant images were obtained every 10 minutes over a three-week period.
Plants were exposed to light from fluorescent lamps from 0630 to 1830 HR and a 4-h night interruption (NI, from 2230 to 0230 HR) was delivered by fluorescent lamps or blue LEDs.
Internode elongation was relatively slow during the 12-h base photoperiod and increased during darkness.
Compared to the NI delivered by fluorescent lamps, the blue LED NI inhibited internode elongation by approximately 60%. The inhibitory effect of blue light occurred during the night interruption and in the subsequent light period.
These results indicate that blue light could be used to inhibit extension growth and therefore could reduce the application of plant growth retarding chemicals.
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