Navigation Links
How exposure to irregular light affects plant circadian rhythms

AARSLEV, DENMARKScientists know that plants can actually "sense" day length, and "schedule" their growth to coincide with specific environmental conditions. These natural events are based on the circadian clock, a 24-hour system found in most biochemical and physiological processes. Plants grow better in circadian conditions that correspond to natural environments, but until now researchers have not understood how plants' internal circadian clocks respond to irregular lighting environments such as those found in many greenhouses.

Greenhouses in northern latitudes rely heavily on supplemental light sources to extend the number of light hours during the day. To conserve electricity and lower costs, newer low-energy input systems use lights only during less expensive off-peak hours and turn lighting off during peak load periods in the afternoon and in the morning. These systems, though more cost-effective than conventional lighting methods, create irregular lighting patterns of natural sunlight interrupted with artificial lightinga challenge for both growers and plants.

Danish scientists Katrine Heinsvig Kjaer and Carl-Otto Ottosen from the Department of Horticulture at Aarhus University published a study in a recent issue of the Journal of the American Society for Horticultural Science that sheds light on the question of plants' response to interruptions in lighting cycles. "Circadian rhythms are believed to be of great importance to plant growth and performance under fluctuating climate conditions. However, it has not been known how plants with a functioning circadian clock respond to irregular light environments that disturb circadian-regulated parameters related to growth", they explained.

For their experiments, the team used 300 cuttings of chrysanthemum (Chrysanthemum morifolium 'Coral Charm') grown in 19 hours of light for 2 weeks. The plants were then randomly placed in either of two greenhouse compartments with similar temperatures and carbon (CO2) concentration. "The plants were exposed to supplemental light provided as irregular light breaks during the night, which we achieved by controlling the light based on forecasted solar irradiance and electricity prices', explained the authors. "Growth, in terms of carbon gain, was linearly correlated to both day length and daily light integral."

The scientists observed that chrysanthemum plants grown in short days with irregular light breaks during the night showed more rapid leaf development and stem growth than plants grown in a climate with a consecutive long light period, proving that low average light intensity promotes expansion of the photosynthetic area of the plants. Though the experiments showed that irregular light periods disturb circadian rhythm and induce changes in leaf characteristics, the authors noted that the study also proved that plants can naturally adapt to irregular light periods.

Kjaer and Ottosen say their research should help greenhouse operators realize energy savings in the area of supplemental light usage.


Contact: Michael W. Neff
American Society for Horticultural Science

Related biology news :

1. Exposure to chemical BPA before birth linked to behavioral, emotional difficulties in girls
2. Dangers of exposure to white light
3. Mold exposure during infancy increases asthma risk
4. LSUHSC conducts landmark study of mid, long-term health effects of oil exposure
5. Mercury vapor released from broken compact fluorescent light bulbs can exceed safe exposure levels
6. E. coli bacteria more likely to develop resistance after exposure to low levels of antibiotics, reports a study in Microbial Drug Resistance
7. Exposure to BPA has been underestimated, new MU research says
8. New study suggests link between chronic estrogen exposure and high blood pressure
9. CDC assesses potential human exposure to prion diseases
10. Parental exposure to BPA during pregnancy associated with decreased birth weight in offspring
11. Prenatal exposure to certain pesticides may negatively impact cognitive development in children
Post Your Comments:
Related Image:
How exposure to irregular light affects plant circadian rhythms
(Date:11/18/2015)... new scientific discoveries deepen our understanding of how cancer ... challenges in better using that knowledge to guide treatment ... children continue to survive pediatric cancer, that counseling may ... John M. Maris, M.D ., a pediatric oncologist ... --> John M. Maris, M.D ., ...
(Date:11/17/2015)... Paris from 17 th until ... from 17 th until 19 th November ... has invented the first combined scanner in the world which scans ... Until now two different scanners were required: one for passports ... on the same surface. This innovation is an ideal solution ...
(Date:11/17/2015)... Nov. 17, 2015  Vigilant Solutions announces today that ... Board of Directors. --> ... retiring from the partnership at TPG Capital, one of ... over $140 Billion in revenue.  He founded and led ... the TPG companies, from 1997 to 2013.  In his ...
Breaking Biology News(10 mins):
(Date:11/24/2015)... ... 2015 , ... The United States Golf Association (USGA) today announced Dr. Bruce ... Presented annually since 1961, the USGA Green Section Award recognizes an individual’s distinguished service ... , Clarke, of Iselin, N.J., is an extension specialist of turfgrass pathology in the ...
(Date:11/24/2015)... Nov. 24, 2015 /CNW/ - iCo Therapeutics ("iCo" or ... financial results for the quarter ended September 30, ... Canadian dollars and presented under International Financial Reporting ... ," said Andrew Rae , President ... iCo-008 are not only value enriching for this ...
(Date:11/24/2015)... QUEBEC CITY , Nov. 24, 2015 /PRNewswire/ - ... the request of IIROC on behalf of the Toronto ... this news release there are no corporate developments that ... price. --> --> ... --> . --> Aeterna Zentaris ...
(Date:11/24/2015)... ... 2015 , ... This fall, global software solutions leader SAP and AdVenture Capital ... and pitch their BIG ideas to improve health and wellness in their schools. , ... win the title of SAP's Teen Innovator, an all-expenses paid trip to Super Bowl ...
Breaking Biology Technology: