1. We are currently experiencing issues with viewing and uploading images, our team is working on the issue.
    Dismiss Notice

All COB Users - Lettuce Grow Challenge!!

Discussion in 'LED and other Lighting' started by OneHitDone, Apr 10, 2016.

  1.  
    Diysystem

    Diysystem Member

    OneHitDone

    The discolouration in lettuce from LED is the biggest issue to tackle. We cant sell a product like that. After that is umol/W, to get over 3 umol is what i'm personally aiming for as the biggest cost for growing indoors is electrical bills.

    Got more money for light research, do you have any tips?
     
    OneHitDone likes this.
  2.  
    frica

    frica Well-Known Member

    http://www.cornellcea.com/attachments/Cornell CEA Lettuce Handbook .pdf
    See page 10 and 13.

    Uniform light distribution is required in the Pond Growing Area. A supplemental light intensity within the range of 100-200 µmol/m 2 /s (for a total of 17 mol/m 2 /d 1 of both natural and supplemental lighting) at the plant level is recommended. It should be noted that 17 mol/m 2 /d is the light integral that worked best for the particular cultivar of boston bibb lettuce that we used. For some cultivars, 15 or mol/m 2 /d is the maximum amount of light that can be used before the physiological condition called tipburn occurs.

    Also:
    An overhead fan (paddle fan - Figure 14) is used to blow air vertically down onto the lettuce plants at the rate of 140 cubic feet per minute. The airflow increases plant transpiration. This increase in transpiration increases the transport of nutrients, especially calcium, from the roots to the young, fast-growing lettuce leaves. The greater rate of nutrient transport provides sufficient amounts of calcium to the leaves and, therefore, prevents tipburn. Without this airflow, lettuce must be grown under reduced light levels (for example at 12 mol/m 2 /d instead of 17 mol/m 2 /d but realize that this data is only for cultivar Ostinata which is no longer available), which slows the rate of growth. The actual daily light integral target that can be achieved with and without vertical airflow before tip burn occurs is a function of cultivar selection, spacing and airflow. The numbers given above are examples of what has been successful in our situation and are not the only solution and no attempt was made to establish airflow maxima and minima.

    This is another paper, and uses another light schedule.
    http://www.agriculturejournals.cz/publicFiles/71067.pdf

    The results reveal the following: (1) judged by the dynamics of anti-oxidative enzyme activity, there was no light stress to occurr in the 100, 200 and 400 μmol/m2 s treatments, a mild light stress occurred in the 600 μmol/m2 s treatment, and a serious light stress occurred in the 800 μmol/m2 s treatment; (2) increased light intensity gradually reduced the contents of soluble protein and nitrate in lettuce, whereas the content of soluble sugar remarkably increased. The biomass of a single plant of lettuce in the 600 µmol/m2 streatment was the highest and second highest in the 400 µmol/m2 streatment but was the lowest in the 100 µmol/m2 s treatment. No significant difference in the biomass of single plant was observed between the 400 and 600 µmol/m2 s treatments. Based on these results, the range of 400 µmol/m2 s to 600 µmol/m2 s is a recommendable light intensity for lettuce production.


    So basically if you start going towards 600 PPFD you will start getting light stress on the lettuce.

    So try to stay around 200-600.


    900 PPFD is nice for marijunana because it can take that much light with ease, but for lettuce you need a mild light intensity. Like 200-400 PPFD.

    It's not the colour of the light that's the problem, it's the intensity.

    If you are having problems, lower light intensity.
    Or maybe add a fan for airflow.

    Lettuce is no marijuana, marijunana loves to be in the spot lights.
    Lettuce is like a shy kid.

    Also, I'm not completely sure but I bet hydroponic lettuce is also able to take a higher light intensity without tip burn than soil grown lettuce.
     
    OneHitDone and Diysystem like this.
  3.  
    frica

    frica Well-Known Member

    I wonder how tomatoes would do under my current LED bulb panel. (120w currently)

    My pepper plant's stem is thick as fuck already and it has extremely stocky growth.

    Edit: still have some tomato seeds.
     
    Last edited: Mar 20, 2017
  4.  
    Diysystem

    Diysystem Member

    Frica

    Great to see someone more reading studies about lettuce ^^
     
  5.  
    pinner420

    pinner420 Well-Known Member

    Not sure ive seen 3 days growth like this
     

    Attached Files:

    Dreddd likes this.
  6.  
    Dreddd

    Dreddd Active Member

    Holy hell thats a lot of growth for 3 days.. 9w you said...
     
  7.  
    pinner420

    pinner420 Well-Known Member

    Yep 10 dollar bulb. It appears to be working better than on lettuce.
     
    Dreddd likes this.
  8.  
    muleface

    muleface Well-Known Member

    I found it doesn't matter on lettuce really the light as much as how you use it. a nice even spread, GOOD airflow (very important), not too much intensity. @frica is correct, pot (tomatoes) will take a hell of a lot of abuse from light, but lettuce will get really crappy really fast.

    Here is my new grow area in progress.

    http://www.rollitup.org/t/general-rambling-sponsored-by-muleface.931540/page-5

    i have no idea how to link to the actual post. its the one at the bottom with all the pictures
     
    Last edited: Mar 20, 2017
    pinner420 likes this.
  9.  
    Dreddd

    Dreddd Active Member

    2700k? i'm running 2x14.5w 2700k osrams on my beefstake tomato, i wonder how low wattage we can go to get fruits with LED bulbs..
     
    pinner420 likes this.
  10.  
    VegasWinner

    VegasWinner Well-Known Member

    try adding more red and blue to your spectrum Deep red and royal Blue should help out. You can get a 50w cob of each color and it will put the green back in your lettuce.
     
  11.  
    pinner420

    pinner420 Well-Known Member

    4k 85 cri..
     
  12.  
    OLD MOTHER SATIVA

    OLD MOTHER SATIVA Well-Known Member

    3500k 80cri led here..does salad well..will try 5000 some day

    hps -->not so much
     
  13.  
    OneHitDone

    OneHitDone Well-Known Member

    Come on folks, we need some good quality harvest pics of the lettuce finished under these different said lighting treatments. ;)
     
  14.  
    muleface

    muleface Well-Known Member

    i grew some lettuce under 3k/4k lights. it had really thick leaves, and it grew really fast. I was also growing in coco under the 3k lights, vs 6500k lights using nft .

    again, i don't think it really matters with lettuce. i think getting the right amount of light and the even coverage is key. I'd bet you could grow under incandescent bulbs and get lettuce to grow just fine. heat may be an issue there.

    my existing lettuce crop has gone full seed. they look crazy, like monster plants. they are all dying and turning brown, they have huge stalks coming out the middle of them
     
    OneHitDone likes this.
  15.  
    OneHitDone

    OneHitDone Well-Known Member

    Hold on! This is my best LED Lettuce attempt to date. Chinese 20W Recessed "Cool White" Ceiling Light.
    I am excited to see how this one turns out! :hump:

    IMG_1091.jpeg IMG_1092.jpeg
     
    Evil-Mobo, muleface and pinner420 like this.
  16.  
    muleface

    muleface Well-Known Member

    i think that's going to turn out great! toss 2 more under that light. that 20 watt will easily get you a good 1 sf of growing area, maybe a bit more. keep the pics coming. Be sure to give them a bit of a breeze.

    where did you pick up the light?
     
  17.  
    OneHitDone

    OneHitDone Well-Known Member

    Ebay Specials. I looked high and low for something to replace some T12 Circline Fluorescents in my kitchen fixtures and these worked perfect.
    Bought a 10 pack cause it made them cheap and had one extra so of course I just had to try to grow with it lol
    I really like the "inderect" diode placement in these. It makes the light exiting the diffuser smooth with no individual diode "Hot Spots"


    http://www.ebay.com/itm/37146047714...49&var=640826218574&ssPageName=STRK:MEBIDX:IT
     
    muleface likes this.
  18.  
    muleface

    muleface Well-Known Member

    are they actual 20 watts at the wall? Those are pretty cool. you could get a 1x1 pot and 25w square version and grow all kinds of stuff in there, and it would be completely portable. you might even be able to get a dwarf tomato plant to grow.

    so no heat sink, or driver needed, just plug and go? awesome!
     
  19.  
    OneHitDone

    OneHitDone Well-Known Member

    I'll put the KillAWatt on it after to verify. The driver is included (you can see it sitting on top) and available as "Dimmable" or "Non-Dimmable"
     
  20.  
    PicklesRus

    PicklesRus Well-Known Member

Share This Page