Light Intensity vs. Internote Density Question....

[Tarbosh]

I've heard from fellow growers that it is optimal to raise your lights overtime slowly with plant growth as to get optimal light as to keep internodes as tight as possible.... now here is where my conflict in question arises.... in reading "MJ Flower Forcing" by Tom Flowers, he says that if you are setting up a room, it is only necessarry to have 400s dispursed amongst the room and it will be more than adequate to light a commercial room..... where as the average closet grower must raise and lower his lights to get optimal product and tightest internode length...... can some one please explain this relation and the ratio that relates to such situations? Also can someone please also explain the ratio of how many plants you need to flower immediately vs. one or two plants vegging forever.... to effectively get the same yield and results.... say 1g/per watt......Any and all insights are appreciated!


Peace Love Positivity,

-=T

 

[ogrefugee]

internode spacing... if you genetics are proned to stretch (and the only way to find out is to grow it out) then the more light the plants get, the closer the nodes are. I personally like as little of stretch as possible to give me nice tight nugget. But genetics and light are pretty much key in this one.

Next Question:

Genetics, environment, the grower, and luck all have to do with yield, taste, and potency. There is no one right answer to your question

You can yeild 400g's from a 400w'er using tons of different methods... most are time consuming and tedious. You could LST and scrog one plant in hydro for 2 months and get it, or do a 20 plant sog...

you wanna get to 1g/w? practice.

 

[Guest]

I get more than 1g/w, have been for years. And thats in soil. 3 gallon containers.

 

[Jnugg]

Hmmmm.Definately the more intense the light the shorter the internodal length will be but also try fooling with your day and nite temps,something called Diff.I really don't want to take the time to write this but you never know who it may help so here we go.

Taken from High Times' 2006 Seed Guide.


What's The Dif?
Manipulating Plant Performance with Professional Temperature Control.
By Proffessor Potter.


Growers know that ambient temperatures play an important role in plant development.You don't have to have a Ph.D. in plant physiology to understand that temperature determines the rate of bio-chemical reactions,the relative amount of products created by enzymes within plant cells,and those products' transport and allocation in plant tissues.Temperature also influences the production,interaction and activity of plant hormones.Mayb a Ph.D. would help,but even a novice grower can use advanced temperature control to help grow a better crop.Here is the gist of it.

Plants are generally and obviously seen to be best adapted to temperature regimes in which daytime growing temperatures are,on average,higher than nightime growing temperatures.However,for reasons not fully understood-or at least not fully explained here-the difference in day/night temperature influences stem and internodal elongation.Higher relative night temperatures result in plants with shorter internodes (the distance between branches or nodes).By creating night temperature equal to or higher than day temperatures in the growing area,we can grow shorter,more compact plants without sacrificing flower number or size.This method of temperature control is called DIF.

DIF is not an acronym;it's simply short for "difference."DIF is the difference in average day temperature (ADT);in practice,the "average" is usually dropped and the equation is given as DT/NT.If your growing area's temperature is 76F during the day and 70F at night,then the DIF is +6.The term DIF was originally coined to refer to conditions in which the average day temperature is lower than the average night temperature,producing a negative DIF.For example,if DT= 76F and NT= 85F then the DIF= -9F.


Dr. Royal Heins,a distinguished proffessor of horticulture at Michigan State University,coined teh term DIF.He recognized the phenomenon of plant response to higher night than day temperatures;it was an accidental discovery that arose from and experiment being conducted by one of his students.DIF is not a natural phenomenon-in nature,night temperature seldom exceeds day temperature-and was unknown to horticulture until the 1980's.By manipulating it,we can confuse the natural hormone balance in the plant to influence it's growth.

A partial explanation for the DIF phenomenon is that the syntesis or action of a gibberelic acid,which contributes to cell-wall elongation,is inhibited.Similarly,auxin,another plant hormone that influences cell elongation,may also be inhibited.Given that plant hormones seldom work alone,it may be a combination of these or other factors.No one really knows for sure,but we are working on it.Whatever the reason,the effect of the DIF means that the plant will grow more compactly with warmer night temperatures than with cooler-than-day night temperatures.


DIF is useful in negating the effect of plant crowding,which,due to the plants response to the far-red light (heat) emitted by it's neighbors,stimulates stem elongation.The influence of radiant far-red light from non-biological sources also cuase stem elongation and "stretching" under lower light conditions.Under high light and otherwise optimal conditions,DIF is used for reducing plant height and promoting denser flower formations.


Some of the first research with the DIF was done with Easter lillies and poinsettias,bot important horticulture crops.In commercial horticulture,it is important to track height and time blooms in order to meet specific target dates for marketing.
The DIF,and variations of it,are now used by professional plant growers around the globe for crops as diverse as corn,sage,tomatoes,impatients and,occasionally,cannabis.


How much should the DIF be?It depends on the crop.Ester lillies show the greatest effect at a DIF of -15 degrees celsius,poinsettias at -12 degrees celsius,and fuchsia at -20 degrees celcius.For some crops,there are tadeoffs;the greatest effect isn't necessarily the most economic or physiologically desirable.Additonally,the DIF change from positive to zero has a more marked effect than from zero to negative.Commercially,the typical maximum DIF is usually no more than -6 degrees celsius and is typically -2 or-3 degrees celsius,since night heating and cooling raises costs.Further,there is a tradeoff between hight control and flowering time,leaf area and fruit development.Reducing the day temperature to accomadate DIF reduces the growth rate in heat-loving plants,and a high negative DIF has been demonstrated to reduce relative flower number and size in several species.


For cannabis,the best DIF for day/night temperatures is probably zero if you grow in a medium-light garden and maintain day temperatures of 80F - that is,day and night time temperatures should be the same.In a low-light garden,a negative DIF may actually have a detrimental effect,as seen in chrysanthemums.A possitive DIF has traditionally been recommended for indoor cannabis horticulture,and it may be desirable for a low-light garden.But if you have free reign to control temperature and you grow in a medium- or high - light garden,you might try a DIF of -2 degrees celsius or -3 degrees celsius.But given the cost and difficulty of heating and cooling,a high-light growing area-especially one pushing the plants with supplementary Co2 and higher day temperatures-might require and alternative.


There is an alternative to using the DIF as a function of DT and NT.This technique doesn't have an official acronym,but in commercial growing it's referred to as "cold-air dump" *CAD).This is when the temperature in the growroom is lowered after sunrise (lights on) to below the NT for one or two hours.The CAD relies on the plant's response to the change between night and day.Stem elongation has been found to be at it's highest rate at the end of the dark period and the beginning of the light period.Cooling during only the first two hours of the day dramatically stem elongation in poinsettias.This technique is usually the most economocal and is used more frequently in commercial flower production.


In a cannabis growing operation that I am familiar with,a more refined version of CAD is being used with excellent results.This "invisible greenhouse" hydroponics operation uses 85 percent of available sunlight,with a supplemental 400-watt high-pressure sodium light and Co2 fetilization up to 1200 ppm.With the high-light and Co2 fertilization,dat temperatures are run at 85F-90F and the growth rate is outstanding.Because of the high DT,raising the NT to create a negative DIF would be uneconomical and would probably stress the plants.In this operation,the day temperature is extended for several hours after dusk,then gradually diminished to a night temperature of 27 degrees celsius.One hour befor "dawn" (lights on),it is raised to 30 degrees celsius and then lowered to 25 degrees celsius to stimulate a CAD,before returning to the day temperature of 30 degrees celsius.The effect is most notable with sativa cultivars,but indica cultivars also do exceptionally well in this system.Internode length is shortened,and the flowering tops are dense and compact but very large.This is only one of the horticultural techniques used in the operation;however,the effect is noticeable and seperable from other influences in this high-yeild system.


Manipulating the day and night temperatures is a proven method in the world of horticulture,has helped reduce the use of chemical growth regulators,and is used to increase productivity and assist with timing crops to the day and hour.The cold-air dump similarly is coming into it's own as a cropping method.So DT/NT or CAD,what's the DIF?For cannabis,either can be used to improve plant performance,depending on what growing parameters are used.It's just a matter of how you do that funky stuff you do.

 

[Tarbosh]

someone said.... MH in veg results in tight internodes, while under HPS, they are prone to stretch.......

 

[Jnugg]

This is true but I wouldn't worry much about it.

 

[ft100]

you dont think you will worry, but wait. i have a c13 cab kinda like yours jnugg and i flowered at 10 inches and they were lsted. now i have 28 inch lsted monsters and i am running out of vertical space. how close can a 400 watter get to the tops in a cab like this and still give a good distribution to all plants? i have glass in a daystar ac just so you all know. i am 12 days into stretch and if they grow more then 2 inches i am overgrown.

 

[Guest]

FT100 no prob man just squeeze stem gently about 1/2 half up bend side ways and stake,all done, yes it is safe and there is no choice if you are that close already!! Tarbosh, I have MH,HPS & flouros I now use 190 watts of flouros about 2" over seedlings,The MH worked good to but the flouros keep the plants very short(cause lights are soooo close) the neg is under branches stay short and a little under developped but once in flower they grow quick and the internodes are I feel very short, well until the HPS 2week stretch

 

[Tarbosh]

so .... flouros....mh....hps...... hell yea!


thanks much! any additions are always welcome!


Peace Love Positivity


-=T

 

[vhGhost]

Great read nnug !!! bringing night temps up a bit wouldn't be so hard!!!

 

[CB420]

the answer youve all been waiting for (drum roll)

tie those babies down
if you got stretch, sativa, tie em down and youll be fine.

bending stems doesnt do any good for the plant, slows down growth for the whole thing, not just the part you bend, and what you end up is making your plant more vunerable to diseases, i agree its easy to bend em down, and i used to do it, but its so much easier to LST these days, and you yeild 10 times more.