Not too sure that sort of stress precipitates more resin production. The most effective method to increase thc percentage in your grow, is to start with high thc genetics, not trying to be a dick either.
On the subject of stressing a plant to produce more resin activity:
I think UV stress, and temperature stress in certain genetics, may promote higher levels of trichomes to be thrown out. It is my understanding plants produce trichomes in part, to refract UVA and UVB rays accross the plant for a few reasons. Depending upon the gentics and growing conditions, a plant can utilize every bit of radiation or be damaged by too much.
Think Hindu Kush area of the world; short growing season, high altitude, very windy, 36* N the equator.
-Short, dark, resin covered plants able finish life quickly fair better than plants lacking those traits.
That is why gentics play the biggest role. Considering a big portion of modern strains are hybrids with afgan/hindu region genetics, playing to natural triggers can be beneficial to resin production.
What is interesting is if you look at from-the-equator-sativas, they can produce extreme amounts of thc for different conditions and reasons than an indica up in some afgan mountain range. The Sativa needs tons of clear crystals to act as a sort of sunblock, for the plants flowers, and potentially developing seeds. Heavy UV rays are thrown out by that equatorial sun. While the indica in Afgan may produce an extreme amount of resin to collect as much UV as possible, and be dark purple to collect as much light as it can on some cliff or in some valley. It only has a few months to finish life and beat the weather. Pretty cool stuff once you start exploring"I Need Tech Help"