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lighting Optimum Number of Lighting Hours?

Roguejim

Roguejim

What I would like to know, is if there has ever been a published scientific study, or experiment to determine the optimum number of hours of articial lighting that plants need, in my case, HPS lighting.

I'm not asling how long you leave your lights on, just whether there has been a published scientific study or experiment...
 
I've read all I can find and found nothing that sounded to have found the truth.  While doing so I also experimented in my grow room and have concluded that 24/7 light is just fine if you can also provide nutrients and H2o in the proper amounts per species 24/7 which is really hard to do.  Much easier to just sit them outside and water when dry. :shh:  
 
Oi, I hate when I don't download some pdf files.. might take me a while to find it, but I have read one or two studies.
 
 
Effects of Photoperiod on Vegetative Growth, Flowering and Fruiting of Capsicum frutescens L. and C. annuum L. in Japan
Abstract only - requested full text from author.
 
Growth Analysis of Sweet Pepper (Capsicum annuum L.) Interacting Effects of Irradiance, Temperature and Plant Age in Controlled Conditions*
 
Continuous fluorescent illumination enhances growth and fruiting of pepper [Capsicum annuum]
 
Somewhat conflicting, cultivar appears to play a large role. Still trying to track down another based around hourly growth rate.
 
Google Scholar and Sci-hub are useful for tracking down articles, there is also a wiki page for research/citation search engines.
 
miguelovic said:
Oi, I hate when I don't download some pdf files.. might take me a while to find it, but I have read one or two studies.
 
 
Effects of Photoperiod on Vegetative Growth, Flowering and Fruiting of Capsicum frutescens L. and C. annuum L. in Japan
Abstract only - requested full text from author.
 
Growth Analysis of Sweet Pepper (Capsicum annuum L.) Interacting Effects of Irradiance, Temperature and Plant Age in Controlled Conditions*
 
Continuous fluorescent illumination enhances growth and fruiting of pepper [Capsicum annuum]
 
Somewhat conflicting, cultivar appears to play a large role. Still trying to track down another based around hourly growth rate.
 
Google Scholar and Sci-hub are useful for tracking down articles, there is also a wiki page for research/citation search engines.
Click to expand...
Thankss.  So, what is your opinion of hours under a 400watt HPS?
 
18 if you aren't using the heat from the light. The one article I'm looking for documented hourly growth rates and showed diminishing returns for the final 6 hours under continuous lighting. Can't recall if more than one cultivar was grown. The "common sense" axiom 25% less light, 25% less growth is thrown around a lot, but even if true, I see it as 25% less power used. Also a allows you to avoid a bit of the peak hour rates. My thinking is generally that from equipment to plants to people, a bit of down time every 24 hours is beneficial in most circumstances. The odd time I've left lights on to eke out a bit of extra growth.
 
I had my CFLs on for 24 hrs.I am thinking of starting mine out under the 600 HPS this year so will have them on for 18hrs just to help the powerbill a bit
 
This is my first season with 400 watt HPS. After2 months, several plants need to be repotted into #2 pots. Before, I always got by with #1 pots. So, I'm cutting the light back to 14 hours, from 18 hours.
 
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