Here is some good info on the different techniques:
Supercropping is a term given to a group of techniques that, when used in conjunction, will produce greatly improved yields over untreated plants. Various methods can be used when supercropping, and they are outlined below.
You can use one or all methods of supercropping, modified to your individual needs. The end result is an increased yield.
Crimping
Crimping is an advanced technique whereby you break the inner herd of the plant without damaging the outer, which is where all the plants strength comes from. Break open the stalk of a cannabis plant and you'll notice immediately the hard, outer herd. This is where textiles come from. The soft inner, lighter colored material is pure cellulose - the phloem and xylem.
In vascular plants, phloem is the living tissue that carries organic nutrients, particularly sucrose, a sugar, to all parts of the plant where needed. In trees, the phloem is the innermost layer of the bark, hence the name, derived from the Greek word φλοιος (phloios) for "bark". The phloem is mainly concerned with the transport of glucose and starch made during photosynthesis.
The plant passes water and nutrients cell to cell through this network of cellulose. Breaking the plant's inner walls will cause it to rebuild. But it rebuilds these networks better than they were before; it rebuilds so fast (under good growth conditions) that 24 hours later the plant is using the new highways and it's increased capacity for moving water and nutrients.
This technique can begin as early as the seedling stage. Twisting the plant gently, using both hands so you don't pull on it's roots. Work each of the plants branches every 2", up to once week. Do this by grasping the spot to be treated with two fingers of each hand. Use one hand to stabilize, while the other gently, slowly twists. Or you can twist with both hands in opposite directions, slowly until you feel a slight snap. When the plant's get heartier you will actually be able to hear it.
On smaller branches, you do not need to twist, as firm finger pressure will rupture the herd.
BENDING
Plants naturally bend towards the light. They do this for their benefit, trying to better get into position to receive more light. Why wait for plants to evolve, use your smarts to bend plants into positions that are beneficial. Bending the tip of a branch over into a position where there's no vegetation will speed growth for 2 reasons:
First the branch tip you moved is now getting more unobstructed light by moving it to an area free of vegetation. Second, the area you moved the branch away from is also receiving more light than before. So those parts of the plant also benefit from the move. Potential for growth is increased.
TYING
Forceful confinement or the use of string, twist-ties or a brace of some kind may be required to keep bent branches from simply growing back to their original position. Massage the bending point of the branch with the fingers of one hand while slowly bending -- only intuition will tell you when you've reached the breaking point. Some branches don't have a breaking point, you can tie them in a knot a they'll still grow. Others will snap as soon as you try to bend them. It will take practice and a few broken branches before you learn how far, if at all, any given branch can be manipulated.
TOPPING
Never top an unhealthy plant. Topping is a simple technique of cutting the tip or top of a branch off using sharp scissors. It doesn't matter if it's the main(stem) top or the tip of a side shoot, the resulting effect will be the same. Instead of one top or tip resulting in a single bud, the treated shoot splits and produces 2 or more tips.
It is debatable whether or not this practice will actually increase or decrease the size of buds or overall yield. A healthy plant generally thrives under careful stressing and physical manipulation. This is not something you want to overdue, start slowly and increase the frequency and intensity of your pruning practices over consecutive crop cycles. Gain some experience so you can recognize when you have overdone it.
Thanks to
Smokin Moose for the info.
Dr.Kran