Light and Plants : Circadian Clock of Plants – Part 2
Following Light Science Vol. 18 – Light and Plants : Circadian Clock of Plants – Part 1, in this newsletter, I’d like to discuss modification of plant circadian clock possibly for commercial purpose, disturbance of circadian clock of plants by artificial lightings and the effort of mankind to solve the problems of artificial lightings.
British and Australian scientists reported in the prestigious scientific journal, Nature Plant, in January 2018 that modified plant circadian rhythm can lead to groundbreaking increase in plant yield. Lighting for 22 hours a day on some specific wheat variety enabled production of 6 generations per year (Figure 1).

Figure 1. Dr. Brande Wulff at John Innes Institute in the United Kingdom led research of speed-breeding of wheat by modification of circadian rhythm (Photo Credit: Heliospectra).
Continuous lighting for 24 hours a day, however, damages plants causing physiological abnormalities such as chlorosis. Especially, plants under street lights were found to reduce visits of nocturnal insect pollinators by more than 60% (Figure 2; ref. Vol 21 – Effect of Artificial Lighting on Insects), and even worse, Perilla plants may barely produce seeds. Turning off lights is as important as lighting for plants.

Figure 2. In the experiments in the Bernese Prealps with cabbage thistles, continuous artificial lighting at night reduced visit of nocturnal insect pollinators by 60% and seed production by 15% (Knop et al., Nature, 2017; Photo Credit : University of Bern).    
Light Pollution Policy came into effect in France on last January 1st. It aims to attenuate the level of disturbance to humans, flora, fauna and ecosystem and to aid enjoying the night sky. It is the first meaningful movement of mankind to reduce light pollution by and detrimental effects of artificial lighting.
Jinwon Kim, Ph.D. 

* Next week’s topic : Light therapy awarded a nobel prize

You can find "Interesting Story about Light Science” series on the link below.
Seoul Semiconductor /
97-11, Sandan-ro 163beon-gil, Danwon-gu, Ansan-si, Gyeonggi-do, Republic of Korea